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Space charge measurements for multilayer heterogeneous composite films by thermal pulse method

MEASUREMENT 2024年 235卷

作者： Fang, Jingying Zheng, Feihu Chen, Shijie Tongji Univ Coll Elect & Informat Engn Shanghai 201804 Peoples R China

Multilayer composite films are suitable for high -temperature and high -electric -field insulation, but the accumulation of space charge may lead to the degradation of their insulating properties. However, few studies have been reported on space charge distribution in multilayer composite thin films due to the limitations of space charge measurement techniques. In this study, using Al 2 O 3 /PI and BOPP/PI composite structural samples as numerical examples, we proposed a method for calibrating electric fields in multilayer heterogeneous structures and combined it with the tikhonov regularization algorithm, and successfully reconstructed the electric field distribution inside the samples. Based on this, the experimental results show that the reconstruction of the overall electric field in the BOPP/PI composite samples is consistent with the combined electric field reconstructed after the individual measurements of each layer, which further confirms the feasibility and validity of the use of thermal pulse to measure the charge distribution in multilayer heterogeneous composite films.

关键词： Space charge tikhonov regularization algorithm Thermal pulse method Calibration Multilayer heterogeneous composite films

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An improved model for BDS satellite ultra-rapid clock offset prediction based on BDS-2 and BDS-3 combined estimation

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ACTA GEODAETICA ET GEOPHYSICA 2019年第4期54卷 513-543页

作者： Hu, Chao Wang, Qianxin Min, Yanghai Mao, Ya Gong, Youxing China Univ Min & Technol MNR Key Lab Land Environm & Disaster Monitoring Xuzhou 221116 Jiangsu Peoples R China China Univ Min & Technol Sch Environm Sci & Spatial Informat Xuzhou 221116 Jiangsu Peoples R China Natl Univ Def Technol Undergrad Sch Changsha 410073 Peoples R China

Ultra-rapid clock products provide the main parameters for real-time or near real-time precise point positioning services. However, it has been found that BeiDou ultra-rapid clock offsets do not meet the requirements for high-accuracy applications because of their low accuracy, especially regarding the prediction parts. This study proposes an improved model for BDS satellite ultra-rapid clock offset prediction based on BDS-2 and BDS-3 combined estimation. First, the preprocessing of the clock offset based on frequency data and a denoising method that employed a tikhonov regularization algorithm was introduced to refine the observed series for predictive modeling. Second, given the coexistence of BDS-2 and BDS-3 satellites and the advantages of the BDS-3 onboard atomic clock, inter-satellite correlations between different satellites were used to adjust the stochastic function in estimating the coefficients for the prediction model. Third, to further improve the accuracy of the prediction model, the residuals of the clock offsets were analyzed by partial least squares regression, in which the main components related to the clock offsets were modeled by a back-propagation neural network. Six experimental schemes were introduced to verify the improved model. Experiments were divided into two groups to compare the preprocessing strategy and prediction model. The experimental results indicated: (1) both the BDS-2 and BDS-3 predicted clock offsets were mutually beneficial in the improved model;(2) because of the lower quality of the observed clock offset from BDS-3, preprocessing was used to improve the prediction accuracy by 1.0-15.2% for BDS-2, and reaching 23.2-31.9% for BDS-3;(3) the accuracy of the clock offsets were improved by 30.7-47.3% for BDS-2, and by 49.9-59.3% for BDS-3 within an 18-h period. The proposed improved model was found to have a significant effect on optimizing the ultra-rapid clock products of the International GNSS Monitoring and Assessment Servic

关键词： BeiDou clock offset BDS-2/BDS-3 combined estimation Ultra-rapid prediction clock tikhonov regularization algorithm Inter-satellite correlation Partial least squares regression

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Study on a Novel Localization Approach of Breast Tumor based on Electrical Impedance Tomography 3

Study on a Novel Localization Approach of Breast Tumor based...

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IEEE 3rd Information Technology, Networking, Electronic and Automation Control Conference (ITNEC)

作者： Chen, Xiaoyan Han, Fengze Ji, Zhenyu Li, Shudong Du, Meng Tianjin Univ Sci & Technol Sch Elect Informat & Automat Tianjin Peoples R China Fourth Mil Med Univ Fac Biomed Engn Xian Shaanxi Peoples R China

ISBN: (纸本)9781538662434

A novel approach of breast tumor localization based on electrical impedance tomography (EIT) is proposed. Under the Comsol+Matlab simulation platform, a circular truncated cone model with two layers of electrode array is constructed, the top layer is configured with 8 electrodes and the bottom layer with 12. The neighboring boundary voltages are measured when a pair of neighboring exciting electrodes inject a low-amplitude alternative current signal. An improved tikhonov regularization algorithm is adopted to reconstruct the image. According to the imaging results of each layer, the height of the tumor can be estimated, and K-means clustering algorithm is utilized to achieve the central position of the tumor, thus the location of the tumor can be acquired. The simulation study indicates that the tumor can be identified with errors of height under 5mm and center between 0.5mm to 2mm.

关键词： electrical impedance imaging circular truncated cone model tumor location tikhonov regularization algorithm

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regularization parameter optimization based on the constraint of Landweber algorithm for electrical capacitance tomography

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FLOW MEASUREMENT AND INSTRUMENTATION 2019年 69卷

作者： Xie, Mengtao Yang, Haima Zhao, Kai Yuan, Baolong Li, Jun Liu, Jin Ying, Jie Huang, Yuanshen Ou, Ji Univ Shanghai Sci & Technol Sch Opt Elect & Comp Engn Shanghai 200093 Peoples R China Shanghai Aerosp Equipments Manufacturer Co Ltd Shanghai 200245 Peoples R China Shanghai Huaike Intelligent Technol Co Ltd Shanghai 201999 Peoples R China

Image reconstruction algorithms play an important role in practical applications of electrical capacitance tomography. In the present paper, a combined image reconstruction method is proposed, which takes the results of Landweber algorithm as the constraint condition of tikhonov algorithm's regularization parameter, calculates the regular parameter, inverts the inverse matrix of sensitivity matrix, and finally obtains the dielectric constant distribution;thus, reconstructed images with improved clarity were obtained. Simulation test are carried out to evaluate and analyze the proposed method from image error, correlation coefficient, image reconstruction time, and anti-noise ability. The results revealed that the tikhonov regularization algorithm had excellent anti-noise ability;thus, it significantly improved the clarity of reconstructed images and clearly distinguished the multi-phase flow pattern and distribution.

关键词： Electrical capacitance tomography Image reconstruction tikhonov regularization algorithm regularization parameters

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Improving the spatial resolution of the SR micro-XRF installation by variational tikhonov regularization algorithms

Improving the spatial resolution of the SR micro-XRF install...

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International Conference on Synchrotron and Free Electron Laser Radiation - Generation and Application (SFR)

作者： Sorokoletov, D. S. Rakshun, Ya. V. Voytovich, E. P. Darin, F. A. Budker Inst Nucl Phys Ave Lavrentyeva 11 Novosibirsk Russia Novosibirsk State Univ Str Pirogova 2 Novosibirsk Russia

SR micro-XRF is an x-ray spectral technique for elemental analysis of samples of various natures with a high spatial resolution (0.01 - 50 mkm). The deconvolution problem is needed to solve in order to improve the spatial resolution. In this work the potential to increase this resolution 1.5 time by simplest variational tikhonov regularization algorithms is showed experimentally. The work was performed for the Elemental Analysis Station at the VEPP-3 storage ring. (C) 2016 The Authors. Published by Elsevier B.V.

关键词： micro-XRF synchrotron radiation deconvolution regularization tikhonov regularization algorithm variational regularization

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Improving the Spatial Resolution of the SR Micro-XRF Installation by Variational tikhonov regularization algorithms

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Physics Procedia 2016年 84卷 295-301页

作者： D.S. Sorokoletov Ya. V. Rakshun E.P. Voytovich F.A. Darin Budker Institute of Nuclear Physics av. Lavrentyeva 11 Novosibirsk Russia Novosibirsk State University str. Pirogova 2 Novosibirsk Russia

SR micro-XRF is an x-ray spectral technique for elemental analysis of samples of various natures with a high spatial resolution (0.01 – 50 mkm). The deconvolution problem is needed to solve in order to improve the spatial resolution. In this work the potential to increase this resolution 1.5 time by simplest variational tikhonov regularization algorithms is showed experimentally. The work was performed for the Elemental Analysis Station at the VEPP-3 storage ring.

关键词： micro-XRF synchrotron radiation deconvolution regularization tikhonov regularization algorithm variational regularization

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Total variation optimization for imaging through turbid media with transmission matrix

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OPTICAL ENGINEERING 2016年第12期55卷

作者： Gong, Changmei Shao, Xiaopeng Wu, Tengfei Liu, Jietao Zhang, Jianqi Xidian Univ Sch Phys & Optoelect Engn 2 South Taibai Rd Xian 710071 Shaanxi Peoples R China

With the transmission matrix (TM) of the whole optical system measured, the image of the object behind a turbid medium can be recovered from its speckle field by means of an image reconstruction algorithm. Instead of tikhonov regularization algorithm (TRA), the total variation minimization by augmented Lagrangian and alternating direction algorithms (TVAL3) is introduced to recover object images. As a total variation (TV)based approach, TVAL3 allows to effectively damp more noise and preserve more edges compared with TRA, thus providing more outstanding image quality. Different levels of detector noise and TM-measurement noise are successively added to analyze the antinoise performance of these two algorithms. Simulation results show that TVAL3 is able to recover more details and suppress more noise than TRA under different noise levels, thus providing much more excellent image quality. Furthermore, whether it be detector noise or TM-measurement noise, the reconstruction images obtained by TVAL3 at SNR = 15 dB are far superior to those by TRA at SNR = 50 dB. (C) 2016 Society of Photo-Optical Instrumentation Engineers (SPIE)

关键词： turbid media image reconstruction total variation minimization by augmented Lagrangian and alternating direction algorithms total variation tikhonov regularization algorithm transmission matrix.

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Effect Analysis and Design on Array Geometry for Coincidence Imaging Radar Based on Effective Rank Theory 2

Effect Analysis and Design on Array Geometry for Coincidence...

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2nd ISPRS International Conference on Computer Vision in Remote Sensing (CVRS)

作者： Zha, Guofeng Wang, Hongqiang Yang, Zhaocheng Cheng, Yongqiang Qin, Yuliang Natl Univ Def Technol Sch Elect Sci & Engn Changsha 410073 Hunan Peoples R China

ISBN: (纸本)9781510601543

As a complementary imaging technology, coincidence imaging radar (CIR) achieves super-resolution in real aperture staring radar imagery via employing the temporal-spatial independent array detecting (TSIAD) signals. The characters of TSIAD signals are impacted by the array geometry and the imaging performance are influenced by the relative imaging position with respect to antennas array. In this paper, the effect of array geometry on CIR system is investigated in detail based on the judgment criteria of the effective rank theory. In course of analyzing of these influences, useful system design guidance about the array geometry is remarked for the CIR system. With the design guidance, the target images are reconstructed based on the tikhonov regularization algorithm. Simulation results are presented to validate the whole analysis and the efficiency of the design guidance.

关键词： Coincidence Imaging Radar Array Geometry Design Effective Rank Theory tikhonov regularization algorithm

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The research on tikhonov regularization algorithm in Airborne Gravity Data Downward Continuation

The research on Tikhonov regularization algorithm in Airborn...

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International Conference on Advanced Measurement and Test (AMT 2010)

作者： Cheng, Yi Luo, Jin Xiu, Chunbo Tianjin Polytech Univ Sch Elect Engn & Automat Tianjin Peoples R China

ISBN: (纸本)0878492712

Based on the remove-restore technique, the application of the tikhonov regularization algorithm to reduce the effect of measurement error in the airborne gravity dada in researched. By the experiments of two kinds airborne gravity data, which having constant system error and casual system error, the compare of different downward continuation algorithm is performed. According to the results of simulations, the tikhonov regularization algorithm can effectively reduce the effect of height and the measurement error in the airborne gravity data downward continuation compared to other algorithm.

关键词： Airborne gravity measurement downward continuation tikhonov regularization algorithm error analysis

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Four-Terminal Imaging Using a Two-Terminal Electrical Impedance Tomography System

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IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT 2014年第2期63卷 432-440页

作者： Chen, Jianjun Xu, Lijun Cao, Zhang Zhou, Haili Beihang Univ Sch Instrument Sci & Optoelect Engn Key Lab Precis Optomech Technol Minist Educ Beijing 100191 Peoples R China

Electrical impedance tomography (EIT) is a promising visualization measurement technique to reconstruct media distribution in a region of interest (ROI) through impedance measurements on its boundary. In this paper, a two-to-four-terminal mode is proposed for a two-terminal EIT system to take advantage of the four-terminal imaging mechanism. Using the two-to-four-terminal mode, data are acquired using the two-terminal EIT system, whereas the imaging mechanism is based on the four-terminal mode. To realize four-terminal imaging using a two-terminal EIT system, the mapping formulas of data from the two-to four-terminal mode and vice versa are derived. A novel imaging method based on two-to-four-terminal mode is proposed to decrease the ill conditionedness of the relevant inverse problem and implemented with the conjugate gradient iteration algorithm and the tikhonov regularization algorithm, respectively. Simulation and experimental results validate the feasibility and effectiveness of the proposed method in reconstructing inclusions within the ROI clearly and exactly in both shape and location. Compared with the method based on two-terminal mode, the quality of the images reconstructed using the proposed method can be improved in terms of contrast, resolution, and antiartifact, i.e., reducing the artifacts in the reconstructed images, especially when distinguishing complicated distributions. Meanwhile, the imaging speed is also increased. Moreover, the availability of four-terminal imaging mechanism in a two-terminal EIT system makes it more flexible to choose an appropriate mode according to the application requirements and available instruments.

关键词： Conjugate gradient iteration algorithm electrical impedance tomography (EIT) image reconstruction impedance measurement inverse problem sensitivity tikhonov regularization algorithm two-to-four-terminal mode

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