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Application of Array imaging algorithm in Horizontal Well OilWater Two-Phase Water Holdup Measurement

IEEE SENSORS JOURNAL 2023年第3期23卷 2900-2913页

作者： Wu, Yuyan Guo, Haimin Deng, Rui Song, Hongwei Yangtze Univ Coll Geophys & Petr Resources Wuhan 430100 Peoples R China

Due to the effect of gravity differentiation in nonvertical wells and the asymmetry of the space around the wellbore, the fluid flow pattern in the wellborn will change greatly. The water holdup reflects the distribution of water, which lays a foundation for understanding the proportion of oil and gas. Water holdup imaging can intuitively reflect the distribution of each phase and the overall water holdup. In this article, with No. 10 industrial white oil and tap water as the working medium, the local water holdup value was measured in the oil-2013;water two-phase by the capacitance array tool (CAT), and then, the response characteristics of the instrument were analyzed. MATLAB software is used to interpolate the local water holdup data of the array in the oil-2013;water two-phase of the horizontal well. The interpolation algorithms used include bilinear interpolation, cubic spline interpolation, simple inverse distance weighted interpolation, and Gaussian radial basis function (GRBF) interpolation. The results show that the water holdup measured by the CAT shows a good measurement effect at low and medium flow rates. Linear and cubic splines are selected in the case of low flow rate and low water cut in the oil-2013;water two-phase flow with stratified flow pattern. The GRBF is selected under the condition of low flow rate and high water cut. The GRBF was selected under different water cut conditions of middle and high flow rates with dispersed flow pattern.

关键词： Horizontal well imaging algorithm oil-water two-phase stratified flow water holdup.

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An Improved imaging algorithm for HRWS Space-Borne SAR Data Processing Based on CVPRI

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IEEE JOURNAL OF SELECTED TOPICS IN APPLIED EARTH OBSERVATIONS AND REMOTE SENSING 2023年 16卷 126-140页

作者： Guo, Yanan Wang, Pengbo Zhou, Xinkai He, Tao Chen, Jie Beihang Univ Sch Elect & Informat Engn Beijing Peoples R China

In space-borne synthetic aperture radar (SAR), the sliding spotlight mode can acquire images with both high-resolution and wide-swath in azimuth direction. Due to the significant two-dimensional spatial variance of Doppler parameters, the traditional imaging algorithms based on the conventional range models is not available. In this article, the strategy of continuously varying pulse repetition interval (CVPRI) is likely to lead to a novel approach to dealing with the azimuth variance problem to realize high-resolution wide-swath (HRWS) imaging in azimuth direction for sliding spotlight SAR. First, the eighth-order Taylor expansion of the modified equivalent squint range model (MESRM-TE8) is adopted, and the accuracy of MESRM-TE8 is accordingly explained. Then, the properties of the spatial variance for the MESRM-TE8 are analyzed in detail, based on which the strategy of CVPRI is given theoretically to eliminate the azimuth variance. An improved imaging algorithm based on CVPRI is subsequently proposed to address the azimuthal-variant Doppler parameters and realize a batch data processing of a large scene in azimuth frequency domain. The extended scaling method is integrated in this algorithm to uniformly compensate cubic phase modulation introduced by CVPRI and circumvent azimuth time folding caused by subaperture processing in the focused image. Finally, the effectiveness of the CVPRI strategy and the proposed algorithm is demonstrated by the simulation results.

关键词： Continuously varying pulse repetition interval (CVPRI) high-resolution wide-swath (HRWS) imaging algorithm sliding spotlight SAR spatial variance synthetic aperture radar (SAR)

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A Proposal for a Standardized imaging algorithm to Improve the Accuracy and Reliability for the Diagnosis of Thoracolumbar Posterior Ligamentous Complex Injury in Computed Tomography and Magnetic Resonance imaging

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GLOBAL SPINE JOURNAL 2023年第3期13卷 873-896页

作者： Aly, Mohamed M. Al-Shoaibi, Abdulbaset M. Aljuzair, Ali H. Issa, Tariq Ziad Vaccaro, Alexander R. Prince Mohammed Bin Abdulaziz Hosp Dept Neurosurg Riyadh 11514 Saudi Arabia Mansoura Univ Dept Neurosurg Mansoura Egypt Prince Mohammed Bin Abdulaziz Hosp Dept Diagnost Radiol Riyadh Saudi Arabia Rothman Orthoped Inst Orthopaed Surg Philadelphia PA USA

Study Design: Systematic Literature Review. Objective: To propose a systematic imaging algorithm for diagnosing posterior ligamentous complex (PLC) injury in computed tomography (CT) and magnetic resonance imaging (MRI) to improve the reliability of PLC assessment. Methods: A systematic review was conducted following PRISMA guidelines. The Scopus database was searched from its inception until July 21, 2022, for studies evaluating CT or MRI assessment of the PLC injury following thoracolumbar trauma. The studies extracted key findings, objectives, injury definitions, and radiographic modalities. Results: Twenty-three studies were included in this systematic review, encompassing 2021 patients. Five studies evaluated the accuracy of MRI in detecting thoracolumbar PLC injury using intraoperative findings as a reference. These studies indicate that black stripe discontinuity due to supraspinous or ligamentum flavum rupture is a more specific criterion of PLC injury than high-signal intensity. Thirteen papers evaluated the accuracy or reliability of CT in detecting thoracolumbar PLC injury using MRI or intraoperative findings as a reference. The overall accuracy rate of CT in detecting PLC injury was 68-90%. Two studies evaluate the accuracy of combined CT findings, showing that >= 2 CT findings are associated with a positive predictive value of 88-91 %. Vertebral translation, facet joint malalignment, spinous process fracture, horizontal laminar fracture, and interspinous widening were independent predictors of PLC injury. Conclusion: We provided a comprehensive imaging algorithm for diagnosing PLC in CT and MRI based on available literature and our experience. The algorithm will potentially improve the accuracy and reliability of PLC assessment, however it needs multicentre prospective validation.

关键词： posterior ligamentous complex thoracolumbar fractures imaging algorithm computed tomography magnetic resonance imaging

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Bistatic ground-based SAR fast imaging algorithm based on subblock division 5

Bistatic ground-based SAR fast imaging algorithm based on su...

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5th International Conference on Geology, Mapping and Remote Sensing (ICGMRS)

作者： He, Junsheng Lai, Tao Huang, Haifeng Wang, Qingsong Wang, Xiaoqing Sun Yat Sen Univ Sch Elect & Commun Engn Shenzhen 518000 Peoples R China

ISBN: (纸本)9798350365719;9798350365726

Bistatic ground-based synthetic aperture radar (GBSAR) can acquire images of targets from different directions, which exhibits distinct imaging characteristics compared to monostatic system and has potentially important applications in multidimensional mountain deformation measurement. However, bistatic GBSAR imaging algorithm still faces problems including complicated bistatic Doppler history, high computational cost and unsuitability for near scenes. In this paper, a novel imaging algorithm for processing bistatic GBSAR data is proposed. After the range cell migration correction based on Keystone transform, the focusing is realized by subblock focusing in range-Doppler domain. The algorithm can adapt to complicated Doppler history of bistatic GBSAR and focus targets in near scenes with relatively high computing efficiency, which is suitable for mountain deformation monitoring. Finally, the validity and reliability of the algorithm are verified by simulated data and measured data.

关键词： synthetic aperture radar ( SAR) ground-based SAR imaging algorithm short aperture imaging

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Baseline-Free Damage imaging algorithm Using Spatial Frequency Domain Virtual Time Reversal

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IEEE TRANSACTIONS ON INDUSTRIAL INFORMATICS 2022年第8期18卷 5043-5054页

作者： de Castro, Bruno Albuquerque Baptista, Fabricio Guimaraes Ardila-Rey, Jorge Alfredo Ciampa, Francesco Sao Paulo State Univ Sch Engn UNESP BR-01049010 Sao Paulo Brazil Dept Elect Engn Lab Transducers & Data Acquisit BR-17033360 Bauru SP Brazil Univ Tecn Federico Santa Maria Dept Elect Engn Santiago 8940000 Chile Univ Surrey Dept Mech Engn Sci Aerosp Div Guildford GU2 7XH Surrey England

Structural health monitoring (SHM) techniques are widely used in industry applications to guarantee the integrity of several types of components. Ultrasonic guided wave (GW) methods for damage imaging typically use baseline signals from the undamaged component, which are often affected by real operational conditions and may not always be available. This article proposes a baseline-free damage imaging algorithm based on spatial frequency domain virtual time reversal (SFD-VTR). Virtual time reversal (VTR) is an alternative to traditional time reversal as it reduces the burden of physically back-propagating re-emitted signals by applying signal operations between the transmitted and received waveforms. However, VTR relies on the reconstruction of the emitted signal in the time domain, which involves significant data manipulation causing sampling errors of reconstructed signals. These errors are largely manifested in nonstationary transient phenomena, such as GW propagation and may lead to poor damage detection. Novel SFD-VTR damage indices were here proposed to enhance defect detection as they do not require the time domain reconstruction of re-emitted signals. Therefore, this work develops a new baseline-free algorithm for damage detection based on a mathematical model of acoustic emission wave propagation for a network of emitter-receivers. The algorithm was validated in aluminum and composite specimens, and it was able to localize material flaws with a maximum localization error of similar to 6 mm and similar to 2 mm for the aluminum and composite samples, respectively, proving to be a promising alternative to SHM systems. Besides, this new mathematical model optimized the traditional methodologies by excluding signal emissions from the setup, and digital signal processing steps.

关键词： Image reconstruction Video recording Time-domain analysis imaging Informatics Aluminum Mathematical models Baseline-free damage imaging guided waves (GWs) imaging algorithm signal processing ultrasound virtual time reversal (VTR)

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Adaptive Subaperture imaging algorithm for Multiaspect Synthetic Aperture Radar

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IEEE GEOSCIENCE AND REMOTE SENSING LETTERS 2024年 21卷 1页

作者： Yan, Chaobao Huang, Lijia Wang, Xiaochen Teng, Fei Liu, Zhiqu Xiao, Xiulai Chinese Acad Sci Aerosp Informat Res Inst Beijing 100094 Peoples R China Chinese Acad Sci Key Lab Technol Geospatial Informat Proc & Applica Beijing 100190 Peoples R China Chinese Acad Sci Key Lab Target Cognit & Applicat Technol Beijing 100190 Peoples R China Univ Chinese Acad Sci Sch Elect Elect & Commun Engn Beijing 101408 Peoples R China Deqing Acad Satellite Applicat Lab Target Microwave Properties Hangzhou 313200 Zhejiang Peoples R China

A multiaspect synthetic aperture radar (SAR) is a novel imaging mode, which supports high spatial resolution, 3-D imaging, and automatic target recognition. However, traditional SAR imaging algorithms will not only degrade SAR images, but also lose significant angular information. Adaptive subaperture imaging algorithms can solve these problems. Distinguishing between anisotropic targets and isotropic targets and extracting the persistence angle are two main steps in these algorithms, both of which will be improved in this letter. First, a better characteristic coefficient, namely, amplitude statistical coefficient (ASC), is proposed to accurately distinguish between anisotropic targets and isotropic targets. Also, change-point detection is introduced to exactly extract the persistence angle. Besides, this letter attempts for the first time to quantitatively assess the characteristic coefficient indicating the anisotropy. For this purpose, two indicators are proposed: anisotropy discrimination index (ADI) and noise resistance range (NRR). The validity of this letter has been verified through the point target simulation data, the microwave anechoic chamber data, and the Gotcha public release data.

关键词： Anisotropic Apertures Noise Indexes Microwave theory and techniques Microwave imaging Anisotropic magnetoresistance Change-point detection characteristic coefficient imaging algorithm multiaspect synthetic aperture radar (SAR) persistence angle

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A MODIFIED imaging algorithm FOR SPACE-BORNE SLIDING SPOTLIGHT SAR BASED ON AZIMUTH NON-UNIFORM SAMPLING

A MODIFIED IMAGING ALGORITHM FOR SPACE-BORNE SLIDING SPOTLIG...

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IEEE International Geoscience and Remote Sensing Symposium (IGARSS)

作者： Guo, YaNan Cui, Lei Wang, PengBo Chen, Jie Beihang Univ Sch Elect & Informat Engn Beijing Peoples R China Shanghai Inst Satellite Engn Shanghai Peoples R China

ISBN: (数字)9781665427920

ISBN: (纸本)9781665427920

The Continuously Varying Pulse Repetition Interval (CVPRI) technique is an effective method to acquire Synthetic Aperture Radar (SAR) echo data with significant Range Cell Migration (RCM). The non-uniformity of echo data along the azimuth direction is the primary problem faced in the imaging processing caused by the CVPRI. This paper is focused on the reconstruction of Non-Uniformly Sampled (NUS) signal based on the CVPRI. Then, a modified imaging algorithm combined with the azimuth Non-Uniform Sinc Interpolation (NSI) method is proposed to achieve the NUS echo data focusing. Simulations are conducted to validate the effectiveness of the novel reconstruction method as well as the modified imaging algorithm.

关键词： SAR CVPRI NUS signal imaging algorithm NSI reconstruction

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A Novel imaging algorithm for Wide-Beam Multiple-Receiver Synthetic Aperture Sonar Systems

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REMOTE SENSING 2023年第15期15卷 3745-3745页

作者： Zhang, Jiafeng Cheng, Guangli Tang, Jinsong Xie, Zhimin Wu, Haoran Naval Univ Engn Inst Elect Engn Wuhan 430000 Peoples R China Mil Marine Environm Construct Off Beijing 100161 Peoples R China

In existing imaging algorithms for wide-beam multiple-receiver synthetic aperture sonar (SAS) systems, the double-square-root (DSR) range history of each receiver is generally converted into the sum of a single-square-root (SSR) range history and an error term using displaced phase center aperture (DPCA) approximation. Therefore, before imaging, each receiver's error term needs to be individually compensated in the azimuth frequency domain, which is computationally expensive. As a result, a novel wide-beam multiple-receiver SAS system algorithm with low complexity and high precision is suggested. First, the translation relationship between the range histories of the reference receiver and other receivers is used to derive an SSR approximation range history that takes into account the azimuth variance of the non-stop-hop-stop time while ignoring differential range curvature (DRC) between the range histories from different receivers. Then, using the principle of stationary phase (POSP), the two-dimensional (2-D) spectrum of the point target is obtained. Finally, the multiple-receiver data are transformed into monostatic SAS-equivalent data for imaging after phase correction, time delay correction, and azimuth reconstruction. The range-Doppler (RD) algorithm is used as an example to explain the specific steps of the proposed approach. Simulation data and ChinSAS data experiments verify that the proposed algorithm achieves an imaging performance that is comparable to that of the existing wide-beam algorithm, but with much higher computational efficiency, making it suitable for real-time imaging.

关键词： synthetic aperture sonar (SAS) imaging algorithm wide beam relative range shift azimuth variance

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An Improved UAV Bi-SAR imaging algorithm with Two-Dimensional Spatial Variant Range Cell Migration Correction and Azimuth Non-Linear Phase Equalization

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REMOTE SENSING 2023年第15期15卷 3734页

作者： Yan, Junjie Li, Linghao Li, Han Ke, Meng Ma, Xinnong Sun, Xinshuai Beijing Inst Technol Sch Informat & Elect Beijing 100081 Peoples R China

The transmitter and receiver of unmanned aerial vehicle (UAV) bistatic synthetic aperture radar (Bi-SAR) are respectively carried on different UAV platforms, which has the advantages of flexible movement and strong concealment, and has broad application prospects in remote sensing fields. However, the range cell migration (RCM) and azimuth non-linear phase (ANP) of UAV Bi-SAR are seriously spatially variant along the range and azimuth directions, while the UAV Bi-SAR has a short operating range, complex trajectory and wide azimuth beam. Aiming at the problem that the RCM and ANP of UAV Bi-SAR in spotlight mode are difficult to correct and equalize due to the severe two-dimensional (2D) spatial variation, an RCM correction (RCMC) and ANP equalization (ANPE) method based on Doppler domain blocking is proposed. First, the azimuth spatial variance of RCM is eliminated by Doppler blocking, and the range spatial variant RCMC is realized by RNCS. Second, by combining Doppler blocking with azimuth nonlinear chirp scaling (ANCS), this method can adapt to ANPE with larger width and more severe spatial variation. At last, the criteria of Doppler blocking are given in detail, and the effectiveness of the proposed method is verified by UAV Bi-SAR real data and computer simulation.

关键词： UAV Bi-SAR 2D spatial variance Doppler blocking non-linear chirp scaling imaging algorithm

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A 2-D Frequency-Domain imaging algorithm for Ground-Based SFCW-ArcSAR

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IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING 2022年 60卷

作者： Gao, Zhuoyan Jia, Yan Liu, Shuyi Zhang, Xiangkun Chinese Acad Sci Natl Space Sci Ctr NSSC Key Lab Microwave Remote Sensing Beijing 100190 Peoples R China Univ Chinese Acad Sci Sch Elect Elect & Commun Engn Beijing 100049 Peoples R China

Arc-synthetic aperture radar (ArcSAR) can observe the surrounding ground objects at 360 degrees, with the advantages of a wide imaging range and constant azimuth angular resolution. In this article, based on the stepped frequency continuous wave (SFCW), fourth-order Taylor expansion, and the series-inversion method, the accurate phase expression of the 2-D spectrum is derived, and then, the 2-D frequency-domain imaging algorithm (2-D-FDA) for ArcSAR is realized. In the simulation part, the imaging results of 2-D-FDA are compared with the backprojection algorithm (BPA) and Liao's method, which is the reference for 2-D-FDA. The simulation results show that the 2-D-FDA is more applicable to process the data obtained from the antenna with the beamwidth larger than 70 degrees. The SFCW-ArcSAR system consists of a vector network analyzer (VNA), a rotating platform, two antennas, and a control computer. Then, the system is used for the outdoor experiment. The experimental results of the corner reflector show that the point target analysis of 2-D-FDA is consistent with those of the BPA and theory. Under the system parameters in this article, the measured azimuth angular resolution is 0.0177 radian, the peak sidelobe ratio (PSLR) in the range direction is -12.46 dB, and the range resolution is 0.48 m on the ground-range plane. The imaging results of the real scenario processed by BPA and 2-D-FDA are consistent, and the ArcSAR image agrees with the optical image of the experimental scene. The effectiveness and correctness of the 2-D-FDA are verified by simulation and experiment.

关键词： Arc-synthetic aperture radar (ArcSAR) experimental verification ground-based synthetic aperture radar (GBSAR) imaging algorithm stepped frequency continuous wave (SFCW)

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