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An Indirect Range-Doppler algorithm for Multireceiver Synthetic Aperture Sonar Based on Lagrange Inversion Theorem

IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING 2017年第6期55卷 3572-3587页

作者： Zhang, Xuebo Huang, Haining Ying, Wenwei Wang, Huakui Xiao, Jun Sci & Technol Underwater Acoust Antagonizing Lab Zhanjiang 524022 Peoples R China Chinese Acad Sci Inst Acoust Beijing 100190 Peoples R China Inst Commun Beijing 102249 Peoples R China

This paper presents a novel imaging algorithm which has the capacity of processing multireceiver synthetic aperture sonar (SAS) data based on Vu's spectrum. There are two important issues when developing the fast Fourier-based imaging algorithms. One is the point target reference spectrum (PTRS) with analytical expression in the 2-D frequency domain;the other is the space variance of the PTRS. Vu has solved the first issue based on the Lagrange inversion theorem. However, the second issue has not been solved yet. Our approach in this paper is to apply Vu's spectral result in an indirect range-Doppler (R-D) imaging algorithm. For each transmitter/receiver pair, the close-form azimuth modulation is derived first, and then, range/azimuth coupling can be obtained via the difference between the PTRS and the azimuth modulation. Unlike traditional R-D algorithm, which utilizes the interpolation operation to eliminate the range cell migration (RCM), the RCM correction (RCMC) in this paper is carried out through two steps, i.e., bulk RCMC and differential RCMC. Bulk RCMC accounts for the RCMC in one reference range. Differential RCMC accomplished with a range-dependent subblock post-processing method is used to compensate for the space variant deviation phase error. Via the proposed method, the echoed signal corresponding to each transmitter/receiver pair is processed first. Following which, a high-resolution SAS complex image is obtained by coherent superposition of all the coarse subimages. Numerical simulations and real data processing results show that the proposed method has the similar focusing capabilities with the accurate back projection algorithm across the whole swath. Although the presented method has the disadvantage of latency, it is very easy to make a complete phase center approximation correction, allowing for the tandem nature of the collected data. Besides, the proposed algorithm can handle general case with explicit point of stationary phase (PSP) no matt

关键词： imaging algorithm Lagrange inversion theorem multireceiver phase error subblock synthetic aperture sonar (SAS) transfer function

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Community-acquired pneumonia

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RADIOLOGE 2017年第1期57卷 6-12页

作者： Poetter-Lang, S. Herold, C. J. Med Univ Wien Allgemeines Krankenhaus Dept Biomed Imaging & Image Guided Therapy Wahringer Guertel 18-20 A-1090 Vienna Austria

The diagnosis of community-acquired pneumonia (CAP) is often not possible based only on the clinical symptoms and biochemical parameters. For every patient with the suspicion of CAP, a chest radiograph in two planes should be carried out. Additionally, a risk stratification for the decision between outpatient therapy or hospitalization is recommended. Based on the evaluation of the different radiological patterns as well as their extent and distribution, a rough allocation to so-called pathogen groups as well as a differentiation between viral and bacterial infections are possible;however, because different pathogens cause different patterns an accurate correlation is not feasible by relying purely on imaging. The radiological findings serve as proof or exclusion of pneumonia and can also be used to evaluate the extent of the disease (e.g. monolobular, multilobular, unilateral or bilateral). In cases of prolonged disease, suspicion of complications (e.g. pleural effusion or empyema, necrotizing pneumonia or abscess) or comorbid conditions (e.g. underlying pulmonary or mediastinal diseases) computed tomography is an important diagnostic tool in addition to chest radiography. Ultrasound is often used to diagnose pleural processes (e.g. parapneumonic effusion or pleural empyema).

关键词： Computed tomography Chest radiograph Radiological patterns Pulmonary consolidation imaging algorithm

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algorithm Analysis of Bistatic ISAR 7

Algorithm Analysis of Bistatic ISAR

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7th IEEE International Conference on Electronics Information and Emergency Communication (ICEIEC)

作者： Guo, Baofeng Li, Zhaorui Sun, Huixian Yin, Wenlong Ordnance Engn Coll Dept Informat Engn Shijiazhuang Hebei Peoples R China

ISBN: (纸本)9781509030255

Bistatic ISAR (Inverse Synthetic Aperture Radar) is an ISAR system whose transmitter and receiver are placed in different places. The configuration mode makes it have some differences with monostatic ISAR. Combined with the reality of bistatic ISAR, the paper analyzed four imaging algorithms of bistatic ISAR, and the simulation is carried out. The strengths, weaknesses and applicability of each algorithm are given. The research in this study provides significant evidence for the algorithm application in measured data.

关键词： Bistatic radar ISAR imaging algorithm

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Automatic Location of Blood Vessel Bifurcations in Digital Eye Fundus Images 6th

Automatic Location of Blood Vessel Bifurcations in Digital E...

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6th International Conference on Soft Computing for Problem Solving (SocProS)

作者： Chaichana, Thanapong Sun, Zhonghua Barrett-Baxendale, Mark Nagar, Atulya Liverpool Hope Univ Dept Math & Comp Sci Biomech Elect Res Grp Hope Pk Liverpool Merseyside England Curtin Univ Sch Sci Dept Med Radiat Sci Perth WA Australia

ISBN: (纸本)9789811033254;9789811033247

Retinal blood vessels are linked with hypertension and cardiovascular disease. It is generally known that vascular bifurcation is mainly involved in varying blood flow velocity as well as its pressure. This paper presents an efficient method for automatic location of blood vessel bifurcations in digital eye fundus images. The proposed algorithm comprised of three main steps: image enhancement, fuzzy clustering, and searching vascular bifurcation. The purposed algorithm revealed successful detection of bifurcations upon test images. Results showed improved diagnostic accuracy in identifying bifurcations with use of the proposed algorithm and encourage its use for further applications such as image registration, personal identification and pre-clinical scanning of retina diagnosis.

关键词： Bifurcation Retinal image Fuzzy clustering imaging algorithm Automatic location Fundus image

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The Research of SAR imaging Based on Co-Prime Arrays Sampling

The Research of SAR Imaging Based on Co-Prime Arrays Samplin...

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2017 International Conference on Advances in Materials,Machinery,Electrical Engineering(AMMEE 2017)

作者： Bing Han Pengbo Wang Yue Fang Jincheng Li Zhirong Men School of Electronic and Information Engineering Beihang University Collaborative Innovation Center of Geospatial Technology

ISBN: (纸本)9781510842915

High resolution wide Swath(HRWS) is one of the major development directions of synthetic aperture radar(SAR). However, the high resolution in azimuth direction and the wide range swath impose contradicting requirements on system design, and the conventional SAR systems cannot meet these rising demands. The compressive sensing(CS) theory put forward in recent years provides a way to resolve the contradiction. In the CS framework, the signal can be reconstructed with a sampling rate below the Nyquist frequency, which means that signal can be acquired and processed at a lower rate. This paper provides a sparse sampling method based on the co-prime arrays. The sparse co-prime array is utilized to reduce the echo signal sampling requirement, which can provide more signal sampling space. As a result, high resolution and wide swath can be realized simultaneously. Simulations are performed to validate the presented algorithm.

关键词： synthetic aperture radar(SAR) imaging algorithm co-prime arrays sparse sampling compressive sensing(CS)

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The diagnostic efficiency of ultrasound guided imaging algorithm in evaluation of patients with hematuria

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EUROPEAN JOURNAL OF RADIOLOGY 2011年第1期79卷 7-11页

作者： Unsal, Alparslan Caliskan, Eda Kazak Erol, Haluk Karaman, Can Zafer Adnan Menderes Univ Fac Med Dept Radiol TR-09100 Aydin Turkey Adnan Menderes Univ Fac Med Dept Urol TR-09100 Aydin Turkey

Purpose: To assess the efficiency of the following imaging algorithm, including intravenous urography (IVU) or computed tomography urography (CTU) based on ultrasonographic (US) selection, in the radiological management of hematuria. Materials and methods: Onehundred and forty-one patients with hematuria were prospectively evaluated. Group 1 included 106 cases with normal or nearly normal US result and then they were examined with IVU. Group 2 was composed of the remaining 35 cases which had any urinary tract abnormality, and they were directed to CTU. Radiological results were compared with clinical diagnosis. Results: Ultrasonography and IVU results of 97 cases were congruent in group 1. Eight simple cysts were detected with US and 1 non-obstructing ureter stone was detected with IVU in remaining 9 patients. The only discordant case in clinical comparison was found to have urinary bladder cancer on conventional cystoscopy. Ultrasonography and CTU results were congruent in 30 cases. Additional lesions were detected with CTU (3 ureter stones, 1 ureter TCC, 1 advanced RCC) in remaining 5 patients. Ultrasonography + CTU combination results were all concordant with clinical diagnosis. Except 1 case, radio-clinical agreement was achieved. Conclusion: Cross-sectional imaging modalities are preferred in evaluation of hematuria. CTU is the method of choice;however the limitations preclude using CTU as first line or screening test. Ultrasonography is now being accepted as a first line imaging modality with the increased sensitivity in mass detection compared to IVU. The US guided imaging algorithm can be used effectively in radiological approach to hematuria. (C) 2009 Elsevier Ireland Ltd. All rights reserved.

关键词： Hematuria Ultrasonography imaging algorithm

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Circular Synthetic Aperture Sonar imaging Using Isometric Angle Characteristic 5th

Circular Synthetic Aperture Sonar Imaging Using Isometric An...

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5th International Conference on Electrical Engineering and Automatic Control (ICEEAC)

作者： Di, Guo-hui Wang, Jun Su, Fu-lin Harbin Inst Technol 92 West Dazhi St Harbin Peoples R China Heilongjiang Bayi Agr Univ Daqing Peoples R China Harbin Inst Technol Weihai Peoples R China

ISBN: (纸本)9783662487686;9783662487662

Circular synthetic aperture sonar (CSAS) can provide fine image of interest region in three dimensions through the sonar movement along a circle at a fixed height. The severe computation complexity of the state-of-the-art imaging algorithms is of great trouble during the usage process of CSAS. According to the relationship between the azimuth and the peak-valued curve of the returns of CSAS, the isometric angle characteristic is revealed in the paper. A fast inverse algorithm of CSAS imaging employing the isometric angle characteristic is proposed combined with CLEAN algorithm. The numerical experiments show the effectiveness and the low computational complexity of the proposed algorithm.

关键词： Circular synthetic aperture sonar (CSAS) Isometric angle Inverse approach imaging algorithm

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Perfect orthogonal waveform scheme used for high-resolution multiple-input multiple-output synthetic aperture radar system

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JOURNAL OF APPLIED REMOTE SENSING 2016年第3期10卷

作者： Li, Shufeng Jin, Libiao Commun Univ China Sch Informat & Engn Dingfuzhuang East St 1 Beijing 100024 Peoples R China

We investigate multiple-input multiple-output (MIMO) synthetic aperture radar (SAR) scheme with an ultra-low side-lobe ratio performance for using complete complementary sequences (CCS) waveform. It is shown that the CCS can be applied in a MIMO SAR system to obtain high resolution in range direction. In addition, the azimuth channel scheme with the multiple subsequences of CCS is also considered. First, we introduce the concept of CCS and establish the transmitter model based on CCS in MIMO SAR system. Then, we propose the corresponding imaging algorithm for employing the CCS to accurately focus the raw data of the MIMO SAR system and derive the range cell migration correction. Considering the signal complexity, we make use of the CCS pairs to analyze the MIMO SAR imaging algorithm. Finally, simulation results demonstrate the validity and feasibility of the proposed MIMO SAR scheme and the potential advantage of CCS. (C) 2016 Society of Photo-Optical Instrumentation Engineers (SPIE)

关键词： multiple-input multiple-output imaging algorithm complete complementary sequence

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Accelerating Spaceborne SAR imaging Using Multiple CPU/GPU Deep Collaborative Computing

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SENSORS 2016年第4期16卷 494-494页

作者： Zhang, Fan Li, Guojun Li, Wei Hu, Wei Hu, Yuxin Beijing Univ Chem Technol Coll Informat Sci & Technol Beijing 100029 Peoples R China Chinese Acad Sci Inst Elect Beijing 100190 Peoples R China

With the development of synthetic aperture radar (SAR) technologies in recent years, the huge amount of remote sensing data brings challenges for real-time imaging processing. Therefore, high performance computing (HPC) methods have been presented to accelerate SAR imaging, especially the GPU based methods. In the classical GPU based imaging algorithm, GPU is employed to accelerate image processing by massive parallel computing, and CPU is only used to perform the auxiliary work such as data input/output (IO). However, the computing capability of CPU is ignored and underestimated. In this work, a new deep collaborative SAR imaging method based on multiple CPU/GPU is proposed to achieve real-time SAR imaging. Through the proposed tasks partitioning and scheduling strategy, the whole image can be generated with deep collaborative multiple CPU/GPU computing. In the part of CPU parallel imaging, the advanced vector extension (AVX) method is firstly introduced into the multi-core CPU parallel method for higher efficiency. As for the GPU parallel imaging, not only the bottlenecks of memory limitation and frequent data transferring are broken, but also kinds of optimized strategies are applied, such as streaming, parallel pipeline and so on. Experimental results demonstrate that the deep CPU/GPU collaborative imaging method enhances the efficiency of SAR imaging on single-core CPU by 270 times and realizes the real-time imaging in that the imaging rate outperforms the raw data generation rate.

关键词： synthetic aperture radar (SAR) advanced vector extensions (AVX) graphics processing unit (GPU) imaging algorithm collaborative computing

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Efficient imaging approach for spaceborne sliding spotlight synthetic aperture radar with a small squint angle

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JOURNAL OF APPLIED REMOTE SENSING 2015年第1期9卷 095039-1-095039-13页

作者： Zhou, Peng Chen, Yanmei Sun, Weifeng Wan, Yong Dai, Yongshou China Univ Petr Coll Informat & Control Engn 66 Changjiang West Rd Qingdao 266580 Peoples R China

Several existing algorithms for squinted sliding spotlight synthetic aperture radar (SAR) suffer from low efficiency, despite their good focusing abilities. Their low speeds are primarily due to the use of wave-number domain (Omega-K) processing after spectrum unfolding in the azimuth frequency domain. Omega-K processing is chosen in these algorithms due to its focusing ability at large squint angles. However, in most scenarios, spaceborne SARs operate with small squint angles that are generally not greater than 5 deg. In these scenarios, Omega-K processing is not necessary and is not preferred due to its computational burden. Thus, in this study, we extend a classic, two-step algorithm based on the chirp z-transformation for the efficient processing of SAR data acquired in spaceborne sliding spotlight mode at a small squint angle. The modified azimuth-filtering and focusing processing is used to compensate for the additional Doppler bandwidth caused by the antenna squinting and is described in detail. The simulation results show the good focusing ability of the proposed algorithm and validate the improvement in computational efficiency. (C) 2015 Society of Photo-Optical Instrumentation Engineers (SPIE)

关键词： spaceborne synthetic aperture radar squinted sliding spotlight synthetic aperture radar small squint angle imaging algorithm

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