scholarly journals Improved FBAM and GO/PO Method for EM Scattering Analyses of Ship Targets in a Marine Environment

Sensors ◽  
2020 ◽  
Vol 20 (17) ◽  
pp. 4735
Author(s):  
Jinxing Li ◽  
Min Zhang ◽  
Wangqiang Jiang ◽  
Pengbo Wei
Keyword(s):  
Multiple Scattering ◽  
Marine Environment ◽  
Good Accuracy ◽  
Physical Mechanism ◽  
Original Method ◽  
Sar Images ◽  
Em Scattering ◽  
Scattering Field ◽  
Composite Ship ◽  
Scattering Characteristic

The combination of the fact-based asymptotic method (FBAM) and the geometrical optics and physical optics (GO/PO) hybrid method is an effective way to analyze the electromagnetic (EM) scattering from electrically large ship targets in a marine environment because it takes the multiple scattering of the ship targets into consideration as well as the coupling scattering field between the targets and the sea surface. However, regarding an electrically large marine scene that contains a large target, the occlusion judgement process for calculating the multiple scattering field and the coupling field makes it inefficient. To solve this problem, this paper proposes a physical mechanism-based improved method to reduce the invalid occlusion judgment between different patches on the composite ship–ocean scene, and this operation enhances the computational efficiency significantly. With the proposed method, radar cross section (RCS) results of different targets and composite ship–ocean scenes were calculated and compared with the original FBAM and GO/PO method. Numerical results showed that the proposed method had higher efficiency compared with the original method with the same good accuracy. In addition, synthetic aperture radar (SAR) images of a composite ship–ocean scene with different radar parameters and sea conditions were simulated with the proposed method for detection purpose. Finally, the proposed method was used to analyze the EM scattering characteristic of a marine environment with multiple ships.

scholarly journals Simulation of a Wideband Radar Echo of a Target on a Dynamic Sea Surface

2021 ◽  
Vol 13 (16) ◽  
pp. 3186
Author(s):  
Wang-Qiang Jiang ◽  
Liu-Ying Wang ◽  
Xin-Zhuo Li ◽  
Gu Liu ◽  
Min Zhang
Keyword(s):  
Multiple Scattering ◽  
Simulation Method ◽  
Sea Surface ◽  
Synthetic Aperture ◽  
Sar Image ◽  
Sar Images ◽  
Em Scattering ◽  
Scattering Effects ◽  
The Impact ◽  
Multiple Scattering Effects

Unlike a generally rough ground surface, the sea surface varies over time. To analyze the impact of the motion of sea waves on the synthetic aperture radar (SAR) image of a target, the wideband echo simulation method based on a frequency domain is used. For the wideband echo, the electromagnetic (EM) scattering properties of the main frequency components are analyzed by the simulation method. Based on the EM scattering properties, the echo can be accurately simulated by using the inverse fast Fourier transformation (IFFT). Combined with the flight path of the radar, the echo of each pulse can be simulated to obtain the SAR image. The correct evaluation of the EM scattering properties is indispensable to the acquisition of an accurate SAR image. For complex targets, such as ships, the multiple scattering effects have a significant influence on the EM scattering properties. Thus, a rectangular wave beam-based geometrical optics and physical optics (GO/PO) method is introduced to calculate the EM scattering properties, which is more efficient than the traditional GO/PO. The GO/PO method is suitable to simulate SAR images in which the EM scattering properties of each pulse need to be calculated. With these methods, the SAR images of the target on the sea surface are simulated. Based on the comparison of the SAR images between a static and dynamic sea surface, it is found that the region corresponding to the target is blurred and the texture of the dynamic sea is blurrier. The impact of multiple scattering and sea wave motion on target recognition are also analyzed with the SAR images that were generated under different conditions. Some strong scattering points appear when multiple scattering effects are considered. It is also found that the texture of the SAR images, corresponding to the sea surface, changes with the synthetic aperture time.

scholarly journals Coupling Scattering Characteristic Analysis of Dihedral Corner Reflectors in SAR Images

IEEE Access ◽  
2018 ◽  
Vol 6 ◽  
pp. 78918-78930 ◽  
Author(s):  
Zhiming Xu ◽  
Xiaofeng Ai ◽  
Qihua Wu ◽  
Feng Zhao ◽  
Shunping Xiao
Keyword(s):  
Characteristic Analysis ◽  
Sar Images ◽  
Scattering Characteristic

scholarly journals On the Origin of Atmospheric Frontal Lines off the East Coast of Taiwan Observed on Spaceborne Synthetic Aperture Radar Images

2010 ◽  
Vol 138 (2) ◽  
pp. 475-496 ◽  
Author(s):  
Werner Alpers ◽  
Jen-Ping Chen ◽  
Chia-Jung Pi ◽  
I-I. Lin
Keyword(s):  
Synthetic Aperture Radar ◽  
East Coast ◽  
Physical Mechanism ◽  
Mesoscale Model ◽  
Synthetic Aperture ◽  
Katabatic Wind ◽  
Mountain Range ◽  
Sar Images ◽  
Radar Images ◽  
Aperture Radar

Abstract Frontal lines having offshore distances typically between 40 and 80 km are often visible on synthetic aperture radar (SAR) images acquired over the east coast of Taiwan by the European Remote Sensing Satellites 1 and 2 (ERS-1 and ERS-2) and Envisat. In a previous paper the authors showed that they are of atmospheric and not of oceanic origin; however, in that paper they did not give a definite answer to the question of which physical mechanism causes them. In this paper the authors present simulations carried out with the fifth-generation Pennsylvania State University–National Center for Atmospheric Research Mesoscale Model, which shows that the frontal lines are associated with a quasi-stationary low-level convergence zone generated by the dynamic interaction of onshore airflow of the synoptic-scale wind with the coastal mountain range of the island of Taiwan. Reversed airflow collides with the onshore-flowing air leading to an uplift of air, which is often accompanied by the formation of bands of increased cloud density and of rainbands. The physical mechanism causing the generation of the frontal lines is similar to the one responsible for the formation of cloud bands off the Island of Hawaii as described by Smolarkiewicz et al. Four SAR images are shown, one acquired by ERS-2 and three by Envisat, showing frontal lines at the east coast of Taiwan caused by this generation mechanism. For these events the recirculation pattern, as well as the frontal (or convective) lines observed, were reproduced quite well with the meteorological model. So, it is argued that the observed frontal lines are not seaward boundaries of (classical) barrier jets or of katabatic wind fields, which have characteristics that are quite different from the flow patterns around the east coast of Taiwan as indicated by the SAR images.

An Efficient Way for Studying the EM Scattering From a Marine Environment With Multiple Ships

2020 ◽  
Vol 19 (9) ◽  
pp. 1526-1530
Author(s):  
Jinxing Li ◽  
Min Zhang ◽  
Liuying Wang ◽  
Yongchang Jiao
Keyword(s):  
Marine Environment ◽  
Em Scattering

The Research Development of the Mechanism of Fatigue Crack Initiation Based on Microstructure for Offshore Platform

2014 ◽  
Vol 1004-1005 ◽  
pp. 1325-1330
Author(s):  
Gui Jie Liu ◽  
Yu Qian Wang ◽  
Meng Meng Li
Keyword(s):  
Fatigue Crack ◽  
Marine Environment ◽  
Structural Damage ◽  
Physical Mechanism ◽  
Fatigue Crack Initiation ◽  
Fatigue Loading ◽  
Multiaxial Fatigue ◽  
Offshore Platform ◽  
Development Direction ◽  
Offshore Platform Structure

In the capricious marine environment, the offshore platform structure is exposed to the multiaxial fatigue loading in which damage would be formed in different directions and planes. Evolution of the structural damage physical mechanism caused by marine environment load is more complicated. Based on the analysis of a large number of literatures, this paper reviews the research status of the fatigue crack mechanism in China and abroad, and predicts the development direction in the future.

scholarly journals MONITORING GROUND SUBSIDENCE IN AREAS COVERED BY DENSE VEGETATION USING TERRASAR-X IMAGES: A CASE STUDY OF HANGZHOU

2016 ◽  
Vol XLI-B7 ◽  
pp. 55-59
Author(s):  
H. A. Wu ◽  
Y. H. Zhang ◽  
G. F. Luo ◽  
Y. K. Kang ◽  
Y. M. Zhu
Keyword(s):  
High Resolution ◽  
Good Accuracy ◽  
Ground Subsidence ◽  
Sar Images ◽  
Dense Vegetation ◽  
The Past ◽  
Rms Error ◽  
Subsidence Monitoring

Hangzhou, the capital of Zhejiang province has suffered serious ground subsidence during the past several decades, due to long term over-exploration of groundwater. In this paper, the time series InSAR technique using high resolution SAR images is investigated for the generation of subsidence maps over Hangzhou region. 29 TerraSAR-X images acquired from May 2012 to Sep 2015 are used. The results show that serious subsidence has mainly taken place in suburban area, including Yuhang district, Xiaoshan district and Binjiang district. 4 subsidence centers are discovered, namely Tangqi town in Yuhang with an average subsiding velocity of -29.6 mm/year, Xintang (-30.7 mm/year) in Xiaoshan, Zhujiaqiao town (-25.6mm/year) in Xiaoshan, and Miaohouwang town (-30.1mm/year) in Binjiang. The urban area is stable and ground rebound even take place in some places. The results are compared with 19 levelling measurements. The RMS error between them is 2.9 mm/year, which demonstrates that the high resolution TerraSAR-X images has good accuracy for subsidence monitoring in the southeast of China, covered by dense vegetation.

scholarly journals MONITORING GROUND SUBSIDENCE IN AREAS COVERED BY DENSE VEGETATION USING TERRASAR-X IMAGES: A CASE STUDY OF HANGZHOU

2016 ◽  
Vol XLI-B7 ◽  
pp. 55-59
Author(s):  
H. A. Wu ◽  
Y. H. Zhang ◽  
G. F. Luo ◽  
Y. K. Kang ◽  
Y. M. Zhu
Keyword(s):  
High Resolution ◽  
Good Accuracy ◽  
Ground Subsidence ◽  
Sar Images ◽  
Dense Vegetation ◽  
The Past ◽  
Rms Error ◽  
Subsidence Monitoring

Hangzhou, the capital of Zhejiang province has suffered serious ground subsidence during the past several decades, due to long term over-exploration of groundwater. In this paper, the time series InSAR technique using high resolution SAR images is investigated for the generation of subsidence maps over Hangzhou region. 29 TerraSAR-X images acquired from May 2012 to Sep 2015 are used. The results show that serious subsidence has mainly taken place in suburban area, including Yuhang district, Xiaoshan district and Binjiang district. 4 subsidence centers are discovered, namely Tangqi town in Yuhang with an average subsiding velocity of -29.6 mm/year, Xintang (-30.7 mm/year) in Xiaoshan, Zhujiaqiao town (-25.6mm/year) in Xiaoshan, and Miaohouwang town (-30.1mm/year) in Binjiang. The urban area is stable and ground rebound even take place in some places. The results are compared with 19 levelling measurements. The RMS error between them is 2.9 mm/year, which demonstrates that the high resolution TerraSAR-X images has good accuracy for subsidence monitoring in the southeast of China, covered by dense vegetation.

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