Analysis of synthetic aperture radar image characteristics for seismic disasters in the Wenchuan earthquake

Li, Zhen; Chen, Quan; Zhou, Jianmin; Tian, Bangsen

doi:10.1117/1.3153906

Cited by 10 publications

(8 citation statements)

References 5 publications

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“…A detailed, comprehensive, and accurate earthquake-triggered landslide inventory is an essential part of improving the understanding of seismic landslide hazard analysis (e.g., Keefer 2002;Harp et al 2011a;Guzzetti et al 2012). After the 2008 Wenchuan earthquake, some landslide inventories were compiled (e.g., Dai et al 2011;Xu et al 2009a;Gorum et al 2011;Huang and Li 2009;Parker et al 2011;Chigira et al 2010;Yin et al 2010a;Qi et al 2010;Li et al 2009;Han et al 2009;Di et al 2010;Chen et al 2009;Ren and Lin 2010;Zhang et al 2010), and correlations of landslide occurrence with geologic and geomorphologic conditions as well as seismic parameters were constructed. However, almost all of the inventories are either incomplete or only record landslide locations; no landslide inventories are comprehensive considering the following seismic landslide mapping criteria: (1) coverage of the entire area affected by landslides, (2) inclusion of all landslides down to a small enough scale, and (3) depiction of landslides as polygons rather than points (Harp et al 2011a).…”

Section: Introductionmentioning

confidence: 99%

Three (nearly) complete inventories of landslides triggered by the May 12, 2008 Wenchuan Mw 7.9 earthquake of China and their spatial distribution statistical analysis

et al. 2013

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Section: Introductionmentioning

confidence: 99%

Three (nearly) complete inventories of landslides triggered by the May 12, 2008 Wenchuan Mw 7.9 earthquake of China and their spatial distribution statistical analysis

et al. 2013

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“…In the 2D matrix array, the combination scheme can be applied to both the azimuthal and elevational direction. For example, if there are L elements combined along both the azimuthal and elevational directions in transmit, the transmit aperture can be divided into blocks of size L×L elements, resulting in the number of transmission events reduced from N 2 to (N/L) 2 . Similarly, the number of receiving channels can be reduced to (N/K) 2 if there are K elements combined along both the azimuthal and elevational directions in receive.…”

Section: E Potential Extension To Three-dimensional(3d) Ultrasound Im...mentioning

confidence: 99%

“…Synthetic transmit aperture imaging (STA) is a technique used in many different fields [1]. It has been widely applied in radar, sonar systems, seismic monitoring [2], and also been explored for nondestructive testing (NDT) [3]. In the standard STA method, one single transmitter is active for each transmission to send out a semi-spherical wave to propagate onto the imaging area, and then all the receivers are used to receive the radiofrequency backscattered echoes.…”

Section: Introductionmentioning

confidence: 99%

Large-Pitch Synthetic Transmit Aperture Imaging: A Feasibility Study

Liu

Kolios

2020

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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We propose to combine synthetic transmit aperture imaging with the micro-beamforming technique (MB-STA) to improve the image quality of the large-pitch synthetic transmit aperture imaging (LPSTA). In LPSTA, nearby array elements are combined as sub-aperture (SAP) without pre-steering delays in both transmit and receive to reduce hardware complexity. In MB-STA , pre-steering delays or microbeamforming within the transmit and receive sub-aperture is introduced to steer the transmission and receiving beams to a focal point. Focusing for the points away from the focal point is then achieved through the image reconstruction using the micro-beamformed RF data in synthetic transmit aperture imaging. Spatial response functions (SRF) are applied in the image reconstruction to compensate for the contrast loss, especially when the targets are located outside the focal region. The simulation results demonstrated that MB-STA can attain an image quality comparable to the standard STA of a fullyindexed array, but with a 66-fold reduction in the number of measurement channels, at the cost of a smaller field of view. Moreover, our experimental results demonstrated that for targets located outside of the focal region, the proposed MB-STA method has better image quality than that of the conventional B-mode imaging with a similar microbeamforming configuration. The proposed method can be extended to 3D ultrasound imaging to reduce its excessive hardware complexity and cost.

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“…Synthetic transmit aperture (STA) imaging is a novel imaging technique which has been widely used in different fields such as radar and sonar systems [1], non-destructive testing (NDT) [2,3], seismic monitoring [4], and medical ultrasound imaging [5,6]. It offers dynamic focusing in both transmit and receive, leading to high resolution and detectability over the entire imaging area [7][8][9][10][11].…”

Section: Introductionmentioning

confidence: 99%

Pseudoinverse Decoding Process in Delay-Encoded Synthetic Transmit Aperture Imaging

Gong

Kolios

2016

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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Recently, we proposed a new method to improve the signal-to-noise ratio of the prebeamformed radio-frequency data in synthetic transmit aperture (STA) imaging: the delay-encoded STA (DE-STA) imaging. In the decoding process of DE-STA, the equivalent STA data were obtained by directly inverting the coding matrix. This is usually regarded as an ill-posed problem, especially under high noise levels. Pseudoinverse (PI) is usually used instead for seeking a more stable inversion process. In this paper, we apply singular value decomposition to the coding matrix to conduct the PI. Our numerical studies demonstrate that the singular values of the coding matrix have a special distribution, i.e., all the values are the same except for the first and last ones. We compare the PI in two cases: complete PI (CPI), where all the singular values are kept, and truncated PI (TPI), where the last and smallest singular value is ignored. The PI (both CPI and TPI) DE-STA processes are tested against noise with both numerical simulations and experiments. The CPI and TPI can restore the signals stably, and the noise mainly affects the prebeamformed signals corresponding to the first transmit channel. The difference in the overall enveloped beamformed image qualities between the CPI and TPI is negligible. Thus, it demonstrates that DE-STA is a relatively stable encoding and decoding technique. Also, according to the special distribution of the singular values of the coding matrix, we propose a new efficient decoding formula that is based on the conjugate transpose of the coding matrix. We also compare the computational complexity of the direct inverse and the new formula.

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Analysis of synthetic aperture radar image characteristics for seismic disasters in the Wenchuan earthquake

Cited by 10 publications

References 5 publications

Three (nearly) complete inventories of landslides triggered by the May 12, 2008 Wenchuan Mw 7.9 earthquake of China and their spatial distribution statistical analysis

Three (nearly) complete inventories of landslides triggered by the May 12, 2008 Wenchuan Mw 7.9 earthquake of China and their spatial distribution statistical analysis

Large-Pitch Synthetic Transmit Aperture Imaging: A Feasibility Study

Pseudoinverse Decoding Process in Delay-Encoded Synthetic Transmit Aperture Imaging

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