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作者： Kořínková, Ksenia Brno University of Technology

Disertační práce, jež má teoretický charakter, je zaměřena na vylepšení a výzkum algoritmů pro zobrazování vnitřní struktury vodivých objektů, hlavně biologický... 详细信息

Disertační práce, jež má teoretický charakter, je zaměřena na vylepšení a výzkum algoritmů pro zobrazování vnitřní struktury vodivých objektů, hlavně biologických tkání a orgánů pomocí elektrické impedanční tomografie (EIT). V práci je formulován teoretický rámec EIT. Dále jsou prezentovány a porovnány algoritmy pro řešení inverzní úlohy, které zajišťují efektivní rekonstrukci prostorového rozložení elektrických vlastností ve zkoumaném objektu a jejích zobrazení. Hlavní myšlenka vylepšeného algoritmu, který je založen na deterministickém přístupu, spočívá v zavedení dodatečných technik: level set a nebo fuzzy filtru. Kromě toho, je ukázána metoda 2-D rekonstrukce rozložení konduktivity z jediného komponentu magnetického pole a to konkrétně z-tové složky magnetického toku. Byly vytvořeny numerické modely biologické tkáně s určitým rozložení admitivity (nebo konduktivity) pro otestování těchto algoritmů. Výsledky získané z rekonstrukcí pomocí vylepšených algoritmů jsou ukázány a porovnány.

关键词： Elektrická impedanční tomografie inverzní problém algoritmus pro rekonstrukci obrazu Tikhonovova regularizační metoda level set metoda fuzzy filtr Electrical impedance tomography inverse problem image reconstruction algorithm Tikhonov regularizat

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Imaging irregular structures using electrical capacitance tomography

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MEASUREMENT SCIENCE AND TECHNOLOGY 2021年第7期32卷

作者： Chen, Zhao Chen, Meng Wang, Jiangjiang Liu, Rongzheng Shao, Youlin Liu, Bing Tang, Yaping Liu, Malin Yang, Wuqiang Tsinghua Univ Inst Nucl & New Energy Technol Beijing 100084 Peoples R China Univ Manchester Dept Elect & Elect Engn Manchester M13 9PL Lancs England

Electrical capacitance tomography (ECT) is widely used in research for different applications, e.g. in the petroleum, pharmaceutical and power industries, due to its nonintrusive and noninvasive features and low cost. So far, ECT has been successfully used with regular structures, such as circular and square shapes. However, in some cases, the measurement electrodes cannot be mounted directly on an irregular structure, high temperature objects or corrosive objects. In this work, a method is proposed for ECT to be used with an irregular structure, by filling the gap between the irregular structure and a regular ECT sensor wall. Accordingly, a split matrix method is proposed for image reconstruction. The characteristics of sensitivity maps with the filling method and different structures are investigated. To calculate sensitivity maps, two methods are used: the perturbation method and the potential method, and their effects on image quality are compared. The results show that there is no obvious difference between these two methods for imaging construction, but the potential method is more efficient than the perturbation method. Among different shapes, an image of a triangular object has a large deformation due to its sharp angle and hence the filling method is not suitable for imaging a triangular object. The split matrix method modified by relaxation factors is suitable for irregular structures in general and can generate satisfactory images. A hardware system based on an impedance analyser and a software package have been developed and used to validate the proposed methods. The experimental results show that the proposed method is promising for imaging two-phase flows in irregular structures.

关键词： electrical capacitance tomography irregular structure split matrix method image reconstruction algorithm fluidised bed measurement

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Phase Shift Migration With SIMO Superposition for MIMO-Sidelooking Imaging at Terahertz Band

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IEEE ACCESS 2020年 8卷 208418-208426页

作者： Yang, Guan Li, Chao Gao, Hang 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 100039 Peoples R China

In this paper, the enhanced phase shift migration (PSM) algorithm for multi-input-multi-output (MIMO) side-looking (SL) scheme was proposed for the 2-dimension (2D) fast image reconstruction in the terahertz (THz) band. By decomposing the MIMO imaging problem into a superposition of several single-input-multiple-output (SIMO) sub-arrays, the proposed algorithm can be applied to systems with randomly distributed transmitting array. By deriving and applying the modified phase shift factor and necessary phase compensation, zero-padding in the transmitting array and data reorganization in the spatial-frequency domain of the conventional wavenumber domain MIMO algorithm can be totally avoided, which will hopefully further reduce the amount of calculation. A comprehensive MIMO-SL-EPSM algorithm was established in the wavenumber domain. Proof-of-principle experiments in the 0.1-THz band were performed based on a MIMO-SL prototype system. The reconstructed images for different targets with high efficiency and quality demonstrate the theoretical results and the effectiveness of the proposed algorithm.

关键词： Interpolation Imaging Prototypes Explosions Arrays MIMO communication image reconstruction Multiple-input-multiple-output (MIMO) phase shift migration (PSM) terahertz (THz) image reconstruction algorithm

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An imaging algorithm of planar array capacitance sensor for defect detection

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MEASUREMENT 2021年 168卷 108466-108466页

作者： Zhang, Yuyan Sun, Yurong Wen, Yintang Yanshan Univ Key Lab Measurement Technol & Instrumentat Hebei Qinhuangdao 066004 Hebei Peoples R China

Planar array capacitance imaging is a feasible solution for detecting defects in composite components. However, the coplanar arrangement of electrodes in the imaging system renders a soft field effect, which results in unstable or susceptible imaging. The inverse problem of a planar array capacitance sensor system is ill-posed. Hence, a wavelet fusion combined multi-objective threshold programming imaging algorithm is proposed for a planar array capacitive imaging system. Furthermore, initial values of conjugate gradient (CG) and Newton-Raphson (NR) algorithms are optimized using the Tikhonov regularization algorithm. Subsequently, wavelet fusion is introduced to fuse images obtained using the CG and NR algorithms to acquire more detailed information. To further improve the reconstructed quality, a multi-objective threshold programming strategy is proposed. The final reconstruction image is obtained using the optimal threshold. Experimental results show a significantly improved quality of the reconstructed image, thereby verifying the effectiveness of the presented algorithm.

关键词： Planar array capacitance sensor image reconstruction algorithm Wavelet fusion Multi-objective threshold programming

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Implementation method for magneto-acoustic concentration tomography with magnetic induction (MACT-MI) based on the method of moments

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COMPUTERS IN BIOLOGY AND MEDICINE 2021年 128卷 104105-104105页

作者： Yan, Xiaoheng Xu, Zhengyang Chen, Weihua Pan, Ye Liaoning Tech Univ Fac Elect & Control Engn Huludao 125105 Liaoning Peoples R China

Magneto-acoustic concentration tomography of magnetic nanoparticles with magnetic induction (MACT-MI) is a new imaging technology that combines the advantages of the high sensitivity of magnetic particle imaging and the high resolution of ultrasonic imaging. This technique has broad application prospects in the biomedical and molecular imaging fields. In this study, a reconstruction algorithm based on the method of moments (MoM) is proposed for the MACT-MI inverse problem. image reconstructions of the acoustic source and superparamagnetic nanoparticle (SPN) concentration were performed using different shape models, and the reconstructed images were analyzed. In addition, the effect of the radius of the tissue region loaded with SPNs on the quality of the reconstructed images was evaluated. The results demonstrated that the new method could reconstruct the SPN concentration distribution well, and a negative correlation existed between the radius of the imaging model and reconstructed image quality. The finding of this research can potentially contribute to the development of MACT-MI in medicine.

关键词： Magneto-acoustic concentration tomography with magnetic induction (MACT-MI) Method of moments Inverse problem image reconstruction algorithm

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A learnable end-edge-cloud cooperative network for driving emotion sensing

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COMPUTERS & ELECTRICAL ENGINEERING 2022年 103卷

作者： Ding, Cheng Ding, Fei Gorbachev, Sergey Yue, Dong Zhang, Dengyin Nanjing Univ Posts & Telecommun Sch Int Things Nanjing 210003 Peoples R China Nanjing Univ Posts & Telecommun Jiangsu Key Lab Broadband Wireless Commun & Int Nanjing 210003 Peoples R China Chongqing Univ Educ Sch Artificial Intelligence Chongqing 400065 Peoples R China Russian Acad Engn Moscow Russia Nanjing Univ Posts & Telecommun Coll Automat & Coll Artificial Intelligence Nanjing 210003 Peoples R China

The driver's emotional state directly affects safe driving. Under the "vehicle-human-road-cloud" integrated control framework, we propose an end-edge-cloud collaborative emotion perception network model (EEC-Net). The end side extracts the key frames of the driver's face video stream and performs batch compression;the edge side extracts the region of interest (ROI) of the reconstructed images as the input of the emotion recognition model (tiny_Xception) for classification;the cloud control terminal receives abnormal ROI image data and performs online training to dynamically adjust the operating parameters of the edge model. Finally, we test on open and self-built datasets, and the results show tiny_Xception has a significant improvement in accuracy of 2.45% compared to mini_Xception;the EEC-Net model can reliably perceive the negative emotion period, and the overall system memory consumption is reduced by about 5%, and the network transmission data volume and the computation time of emotion recognition are reduced by 95%, 60% respectively.

关键词： End -edge -cloud human -machine collaboration Video stream key frames extraction image reconstruction algorithm Region of interest Driver emotion recognition

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Using passive and active acoustic methods for impact damage assessment of composite structures

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COMPOSITE STRUCTURES 2019年 226卷 111252-000页

作者： Saeedifar, Milad Mansvelder, Jasmijn Mohammadi, Reza Zarouchas, Dimitrios Delft Univ Technol Struct Integr & Composites Grp Fac Aerosp Engn Delft Netherlands Amirkabir Univ Technol Nondestruct Testing Lab Dept Mech Engn Tehran Iran

This study aims to use the passive and active acoustic-based health monitoring methods for impact damage assessment of composite structures. To this aim, a Carbon Fiber Reinforced Polymer (CFRP) composite plate was fabricated and subjected to a simulated low-velocity impact by performing repeated quasi-static indentation tests where a loading-unloading-reloading test profile with 5 repetitions was adopted. Two Acoustic Emission (AE) broadband sensors and a network of eight piezoelectric (PZT) sensors were attached on the composite plate surface. AE (passive method) was employed during the loading and reloading phases of the indentation tests to online monitor the critical damage occurrence and also specify the damage type while scanning of the plate with Lamb waves (active method) was done to localize the damage when the structure was unloaded. Felicity Ratio (FR) index which was calculated based on the AE data could accurately detect that critical damage occurred during the 5th loading-unloading-reloading stage when the structural integrity dropped to 60% of its initial stage. Furthermore, Lamb wave signals of central frequency 150 kHz localized the impact damage with error of 0.89 cm (3.6% error respect to the shortest dimension of the scanned area).

关键词： Structural Health Monitoring Impact damage diagnostics Acoustic Emission Lamb waves image reconstruction algorithm

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A novel time-difference electrical impedance tomography algorithm using multi-frequency information

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BIOMEDICAL ENGINEERING ONLINE 2019年第1期18卷 84-84页

作者： Cao, Lu Li, Haoting Xu, Canhua Dai, Meng Ji, Zhenyu Shi, Xuetao Dong, Xiuzhen Fu, Feng Yang, Bin Fourth Mil Med Univ Air Force Med Univ Dept Biomed Engn Xian 710032 Shaanxi Peoples R China

BackgroundElectrical impedance tomography (EIT) is a noninvasive, radiation-free, and low-cost imaging modality for monitoring the conductivity distribution inside a patient. Nowadays, time-difference EIT (tdEIT) is used extensively as it has fast imaging speed and can reflect the dynamic changes of diseases, which make it attractive for a number of medical applications. Moreover, modeling errors are compensated to some extent by subtraction of voltage measurements collected before and after the change. However, tissue conductivity varies with frequency and tdEIT does not efficiently exploit multi-frequency information as it only uses measurements associated with a single *** paper proposes a tdEIT algorithm that imposes spectral constraints on the framework of the linear least squares problem. Simulation and phantom experiments are conducted to compare the proposed spectral constraints algorithm (SC) with the damped least squares algorithm (DLS), which is a stable tdEIT algorithm used in clinical practice. The condition number and rank of the matrices needing inverses are analyzed, and image quality is evaluated using four indexes. The possibility of multi-tissue imaging and the influence of spectral errors are also *** performance improvement is achieved by combining multi-frequency and time-difference information. The simulation results show that, in one-step iteration, both algorithms have the same condition number and rank, but SC effectively reduces image noise by 20.25% compared to DLS. In addition, deformation error and position error are reduced by 8.37% and 7.86%, respectively. In two-step iteration, the rank of SC is greatly increased, which suggests that more information is employed in image reconstruction. image noise is further reduced by an average of 32.58%, and deformation error and position error are also reduced by 20.20% and 31.36%, respectively. The phantom results also indicate that SC has stronger nois

关键词： Electrical impedance tomography (EIT) Fraction model image reconstruction algorithm Inverse problem

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Novel muon imaging techniques

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PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES 2019年第2137期377卷 1-10页

作者： Yang, Guangliang Clarkson, Tony Gardner, Simon Ireland, David Kaiser, Ralf Mahon, David Al Jebali, Ramsey Shearer, Craig Ryan, Matthew Univ Glasgow Sch Phys & Astron Glasgow G12 8QQ Lanark Scotland Univ Glasgow Lynkeos Technol Ltd Glasgow G12 8QQ Lanark Scotland Natl Nucl Lab Cent Lab Seascale CA20 1PG Cumbria England

Owing to the high penetrating power of high-energy cosmic ray muons, muon imaging techniques can be used to image large bulky objects, especially objects with heavy shielding. Muon imaging systems work just like CT scanners in the medical imaging field-that is, they can reveal information inside of a target. There are two forms of muon imaging techniques: muon absorption imaging and muon multiple scattering imaging. The former is based on the flux attenuation of muons, and the latter is based on the multiple scattering of muons in matter. The muon absorption imaging technique is capable of imaging very large objects such as volcanoes and large buildings, and also smaller objects like spent fuel casks;the muon multiple scattering imaging technique is best suited to inspect smaller objects such as nuclear waste containers. Muon imaging techniques can be applied in a broad variety of fields, i.e. from measuring the magma thickness of volcanoes to searching for secret cavities in pyramids, and from monitoring the borders of countries checking for special nuclear materials to monitoring the spent fuel casks for nuclear safeguards applications. In this paper, the principles of muon imaging are reviewed. image reconstruction algorithms such as Filtered Back Projection and Maximum Likelihood Expectation Maximization are discussed. The capability of muon imaging techniques is demonstrated through a Geant4 simulation study for imaging a nuclear spent fuel cask. This article is part of the Theo Murphy meeting issue 'Cosmic-ray muography'.

关键词： muon imaging inverse problem image reconstruction algorithm

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High-resolution three-dimensional ANGIE T1 mapping of the whole heart

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Journal of Cardiovascular Magnetic Resonance 2015年第SUPPL 1期17卷 W4-W4页

作者： Bhairav B Mehta Michael Salerno Frederick H Epstein Department of Biomedical Engineering University of Virginia Charlottesville VA USA Medicine (Cardiology) University of Virginia Charlottesville VA USA Department of Radiology and Medical Imaging University of Virginia Charlottesville VA USA

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