检索结果-内蒙古大学图书馆

IEEE International Radar Conference (RadarCon)

作者： Pritsker, Dan Altera Corp San Diego CA USA

ISBN: (纸本)9781479982325

The Global back-projection (GBP) algorithm has been known for use in Synthetic Aperture Radar (SAR) image formation for many years. But, despite many advantages compared to other algorithms, GBP usage is limited. It requires significant computational complexity and consumes more power. This paper presents a high-performance architecture which allows efficient and scalable implementation of the GBP algorithm on a Field Programmable Gate Array (FPGA). Such an architecture is based on a systolic array that performs back-projection in a pipelined way, using parallelism over image pixels and radar pulses. A GBP systolic array is built using specially designed back-projection streaming cores. The cores utilize a floating-point calculation on the FPGA to achieve accurate and high-dynamic range in GBP integration. Results presented herein, show the achieved performance of GBP-based image formation using an FPGA and details the power consumption of the described implementation. Comparison is made to other computational platforms in order to determine advantage for real-time and power constrained SAR applications and platforms.

关键词： Synthetic Aperture Radar SAR back-projection algorithm Image Formation FPGA GPU Floating-Point

来源：评论

学校读者我要写书评

暂无评论

Comparison of SIMO-Based Wavenumber Domain and back-projection Imaging algorithms

Comparison of SIMO-Based Wavenumber Domain and Back-Projecti...

引用

Asia-Pacific Microwave Conference (APMC)

作者： Liu, Shuang Li, Shiyong Zhao, Guoqiang Sun, Houjun Beijing Inst Technol Beijing Key Lab Millimeter Wave & Terahertz Techn Beijing 100081 Peoples R China

ISBN: (纸本)9781479987672

The single-input multiple-output (SIMO) array based imaging system has been applied for remote sensing and concealed weapon detection. In this paper, comparisons of the back-projection (BP) algorithm and wavenumber domain (omega k) algorithm applied to SIMO imaging are provided both in the near-field case and far-field case. Simulations demonstrate that the BP algorithm performs better in the near-field case. For the wk algorithm, there would appear deviation and slight defocusing of the target due to the Taylor approximation in the near-field case. In the far-field case, the imaging result of BP algorithm is almost identical with that of omega k algorithm but the former would need more operation time.

关键词： single input multiple output (SIMO) wavenumber domain algorithm back-projection algorithm two dimensional imaging

来源：评论

学校读者我要写书评

暂无评论

Aperture weighted cardiac reconstruction for cone-beam CT

引用

PHYSICS IN MEDICINE AND BIOLOGY 2006年第14期51卷 3433-3448页

作者： Koken, P. Grass, M. Philips Res Labs Sector Tech Syst D-22335 Hamburg Germany

Multi-row detectors together with fast rotating gantries made cardiac imaging possible for CT. Due to the cardiac motion, ECG gating has to be integrated into the reconstruction of the data measured on a low pitch helical trajectory. Since the first multi-row scanners were introduced, it has been shown that approximative true cone-beam reconstruction methods are most suitable for the task of retrospectively gated cardiac volume CT. In this paper, we present the aperture weighted cardiac reconstruction (AWCR), which is a three-dimensional reconstruction algorithm of the filtered back-projection type. It is capable of handling all illumination intervals of an object point, which occur as a consequence of a low pitch helical cone-beam acquisition. Therefore, this method is able to use as much redundant data as possible, resulting in an improvement of the image homogeneity, the signal to noise ratio and the temporal resolution. Different optimization techniques like the heart rate adaptive cardiac weighting or the automatic phase determination can be adopted to AWCR. The excellent image quality achieved by AWCR is presented for medical datasets acquired with both a 40-slice and a 64-slice cone-beam CT scanner.

关键词： back-projection algorithm COMPUTED-TOMOGRAPHY IMAGE-RECONSTRUCTION SPIRALCT PERFORMANCE EVALUATION TEMPORAL RESOLUTION ARBITRARY PITCH DOSE USAGE backprojection ACQUISITION

来源：评论

学校读者我要写书评

暂无评论

Statistical Approach for Optoacoustic Image Reconstruction in the Presence of Strong Acoustic Heterogeneities

引用

IEEE TRANSACTIONS ON MEDICAL IMAGING 2011年第2期30卷 401-408页

作者： Dean-Ben, X. Luis Ma, Rui Razansky, Daniel Ntziachristos, Vasilis Tech Univ Munich Inst Biol & Med Imaging D-85764 Neuherberg Germany Helmholtz Ctr Munich D-85764 Neuherberg Germany

A method is presented to reduce artefacts produced in optoacoustic tomography images due to internal reflection or scattering of the acoustic waves. It is based on weighting the tomographic contribution of each detector with the probability that a signal affected by acoustic mismatches is measured at that position. The correction method does not require a priori knowledge of the acoustic or optical properties of the imaged sample. Performance tests were made with agar phantoms that included air gaps for mimicking strong acoustic reflections as well as with an acoustically heterogeneous adult Zebrafish. The results obtained with the method proposed show a clear reduction of the artefacts with respect to the original images reconstructed with filtered back-projection algorithm. This performance is directly related to in vivo small animal imaging applications involving imaging in the presence of bones, lungs, and other highly mismatched organs.

关键词： Acoustic mismatch back-projection algorithm optoacoustic tomography statistical correction

来源：评论

学校读者我要写书评

暂无评论

Characterization of changes in therapeutic ultrasound transducer performance over time using the angular spectrum method

引用

IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL 2007年第5期54卷 1028-1035页

作者： Wu, Xia Worthington, Arthur E. Gertner, Mark R. Hunt, John W. Sherar, Michael D. Princess Margaret Hosp Dept Radiat Phys Toronto ON M4X 1K9 Canada Ryerson Univ Dept Phys Toronto ON Canada Princess Margaret Hosp Div Biophys & Bioimaging Toronto ON M4X 1K9 Canada Univ Toronto Dept Med Biophys Toronto ON Canada Princess Margaret Hosp Dept Med Phys Ontario Canc Inst Univ Hlth Network Toronto ON M4X 1K9 Canada Canc Care Ontario Toronto ON Canada

Strongly focused large aperture transducers used in high-intensity focused ultrasound treatments are prone to manufacturing defects and degradation. Current methods for evaluating transducer quality measure only bulk physical changes of transducers. We have determined the pressure distribution at the transducer surface, using the angular spectrum method, to detect defects of the transducer. Three therapeutic transducers were investigated. The pressure distribution at the focal plane of each transducer was measured and input into a back-projection algorithm to calculate the pressure distribution at the transducer surface. A number of scan window sizes were used for the pressure distribution measurement at the focal plane to determine the effect on the resolution of the calculated pressure distribution at the transducer surface. Results showed that one transducer might have suffered manufacturing defects. The second transducer degraded over 1 year of use with one half of the transducer suffering a partial loss of efficiency. The third transducer remained unchanged over 1 year. The scan window of 40 mm x 40 mm at the focal plane was required to identify defects 6 mm in diameter on the transducer surface. The results demonstrate that the angular spectrum method could be a useful tool for evaluating transducer quality.

关键词： biomedical transducers biomedical ultrasonics patient treatment ultrasonic transducers angular spectrum back-projection algorithm large aperture transducers pressure distribution therapeutic ultrasound transducer Transducers ultrasonic transducers biomedical transducers patient treatment Pressure Distribution biomedical ultrasonics response spectrum method

来源：评论

学校读者我要写书评

暂无评论

WIDE-FIELD CIRCULAR SAR IMAGING: AN EMPIRICAL ASSESSMENT OF LAYOVER EFFECTS

引用

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS 2015年第2期57卷 489-497页

作者： Demirci, Sevket Yigit, Enes Ozdemir, Caner Mersin Univ Dept Elect Elect Engn TR-33343 Ciftlikkoy Mersin Turkey Mersin Univ Vocat Sch Tech Sci TR-33343 Ciftlikkoy Mersin Turkey

In circular synthetic aperture radar (CSAR), targets are usually scanned over the complete azimuthal aperture of 360 degrees. A major challenge inhibiting successful CSAR image production is encountered in two-dimensional imaging of relatively large scenes (i.e. wide-field scenarios). For such cases, the spatially variant radar signature gives rises to image degradations known as layover effects. In this paper, the imaging results for hypothetical and real complex targets using their CSAR data at C band are demonstrated to characterize these effects. In real experiments, a ground-based, outdoor CSAR system is exploited thanks to the circular balcony of a building that provides 270 degrees view of targets. A spherical back-projection algorithm is used to focus near-field data and the reconstructed images are also cleaned out from clutter to more easily visualize the layover artifacts. (c) 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:489-497, 2015

关键词： circular synthetic aperture radar layover back-projection algorithm clutter reduction automatic target detection

来源：评论

学校读者我要写书评

暂无评论

Topography-Dependent Eikonal Traveltime Tomography for Upper Crustal Structure Beneath an Irregular Surface

引用

PURE AND APPLIED GEOPHYSICS 2015年第6期172卷 1511-1529页

作者： Ma, Ting Zhang, Zhongjie Chinese Acad Sci Inst Geol & Geophys State Key Lab Lithospher Evolut Beijing 100029 Peoples R China Univ Chinese Acad Sci Beijing 100049 Peoples R China

Seismic modeling of the crust with nonflat topography can be made by first-arrival traveltime tomography, which faces the challenge of an irregular free surface. A feasible way to deal with this problem consists of expanding the physical space by overlapping a low velocity layer above the irregular surface in order to have a flat topography, besides using the classical eikonal equation solver for traveltime computation. However, the undesirable consequences of this method include seismic ray deviations due to the transition from an irregular surface that is the free boundary to an inner discontinuity lying in the expanded computational space. An alternative solution, called irregular surface flattening, which involves the transformation between curvilinear and Cartesian coordinate systems, has been recently proposed through the formulation of the topography-dependent eikonal equation (TDEE) and a new solver for forward modeling of traveltimes. Based on the solution of this equation, we present topography-dependent eikonal traveltime tomography (hereafter TDETT) for seismic modeling of the upper crust. First-arrival traveltimes are calculated using the TDEE solver and the raypaths with the minimum traveltime that can be found by following the steepest traveltime gradient from the receiver to the source. By solving an algebraic equation system that connects the slowness perturbations with the already determined traveltimes, these variables can be obtained making use of the back-projection algorithm. This working scheme is evaluated through three numerical examples with different topographic complexities that are conducted from synthetic data and a fourth example with somewhat more complicated topography and real data acquired in northeastern Tibet. The comparison of the results obtained by both methods, i.e., physical space expansion above the irregular surface and irregular surface flattening, fully validates the tomography scheme that is proposed to construct seismi

关键词： Upper crust first-arrival traveltime tomography velocity structure topography-dependent Eikonal equation solver back-projection algorithm

来源：评论

学校读者我要写书评

暂无评论

Synthetic Aperture Radar Imaging Using a Low-Cost Radar Mounted on a Mini Drone 31

Synthetic Aperture Radar Imaging Using a Low-Cost Radar Moun...

引用

31st IEEE Conference on Signal Processing and Communications Applications (SIU)

作者： Tunc, Orhan Baykut, Suleyman Erer, Isin Istanbul Tek Univ Elekt & Haberlesme Muhendisligi Bolumu Istanbul Turkiye Tubitak Bilgem Bte Radar Teknol Bolumu Gebze Turkiye

ISBN: (纸本)9798350343557

In this study, a low-cost, light-weight side-looking radar system mounted on a mini drone was used to obtain range profiles of ground-based targets using the Synthetic Aperture Radar Strip-map mode configuration. Simulated and real data SAR images are obtained using Range Migration and back-projection algorithms, and the performances of the algorithms in SAR imaging with drone-borne radar system are discussed.

关键词： Synthetic Aperture Radar Drone-borne Radar Lowcost Radar Range Migration algorithm back-projection algorithm

来源：评论

学校读者我要写书评

暂无评论

NON-LINE-OF-SIGHT IMAGING BY MILLIMETER WAVE RADAR

NON-LINE-OF-SIGHT IMAGING BY MILLIMETER WAVE RADAR

引用

IEEE International Geoscience and Remote Sensing Symposium (IGARSS)

作者： Wei, Jinshan Wei, Shunjun Liu, Xinyuan Wang, Mou Shi, Jun Zhang, Xiaoling Univ Elect Sci & Technol China Sch Informat & Commun Engn Chengdu 611731 Peoples R China

ISBN: (纸本)9781665403696

Non-line-of-sight (NLOS) radar imaging technique aims to reconstruct hidden targets that illuminated wave cannot reach directly, which can greatly expand the range of radar detection. In this paper, inspired by synthetic aperture radar (SAR), an effective two-dimensional (2-D) NLOS imaging technique via multiple input multiple output (MIMO) millimeter-wave (MMW) radar is proposed. In the scheme, a 2-D virtual antenna array is synthesized by MIMO antenna scanning, and the multi-bounces echoes is used to obtain 2D NLOS imaging. Then an algorithm via mirror symmetry back-projection (MSBP) is presented for 2-D high-precision focusing of these NLOS echoes. Moreover, a cost-effective 79GHz MMW NLOS experiment system is developed for technical validation. The effectiveness of MMW NLOS radar imaging is verified by near-field multi-targets experiment, and high-precision 2-D imaging results of hidden knives are obtained by MSBP method.

关键词： Non-Line-of-Sight imaging SAR millimeter wave radar back-projection algorithm

来源：评论

学校读者我要写书评

暂无评论

A planar MIMO UWB array design for high-resolution microwave imaging 56

A planar MIMO UWB array design for high-resolution microwave...

引用

56th International Scientific Conference on Information, Communication and Energy Systems and Technologies (ICEST)

作者： Ziani, Djamila Meriah, Sidi Mohammed Derraz, Foued Merad, Lotfi Univ Tlemcen Fac Technol Lab Telecommun Tlemcen LTT Tilimsen Algeria Grad Sch Appl Sci Tilimsen Algeria

ISBN: (纸本)9781665428873

In this paper, a planar multiple input multiple output MIMO UWB array is proposed for 3D microwave imaging applications. According to the virtual array concept, the advantage of the MIMO array lies on improving the angular resolution with a reduced number of antennas, and achieve the same resolution as a fully populated conventional arrays. In addition, the UWB systems provide a better range resolution thanks to their large bandwidth. The frequency diversity and its influence on the system's resolution is also studied. For the MIMO array, an optimal UWB antenna element is designed with more than 128% of fractional bandwidth with no considerable distortion of the transmitted impulse. For the imaging algorithm, the back-projection algorithm is implemented and used for the reconstruction of the images. In order to study the performance of the designed system, the full-wave electromagnetic simulator CST MWS is used which allow the modelling in three-dimensions (3D). The resulting images of a different target materials and dielectric properties confirm the reliability of the proposed system and the impact of the spatial and frequency diversity in the resolution improvement while considerably reducing the cost of the MIMO UWB array.

关键词： UWB antenna MIMO arrays Microwave imaging system back-projection algorithm Object detection

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：