China
Africa
Explore chapters and articles related to this topic
Synthetic Aperture Radar Techniques for Through-the-Wall Imaging
Published in Moeness G. Amin, Through-the-Wall Radar Imaging, 2017
Three-dimensional (3D) radar images of a scene can be obtained by employing a 2D imaging aperture (the down-range resolution being created through the signal bandwidth). The aperture can be physical or synthetic in one or both dimensions, with monostatic or multistatic configurations. 3D SAR images of a wall based on simulations were reported in [43].
Deep learning-based underground object detection for urban road pavement
Published in International Journal of Pavement Engineering, 2020
Namgyu Kim, Kideok Kim, Yun-Kyu An, Hyun-Jong Lee, Jong-Jae Lee
In this study, a systematic approach to determine a threshold amplitude is proposed based on the statistical distribution of GPR data. A large amount of GPR data collected from urban roads are statistically analysed to determine a proper threshold amplitude to enhance the major features in urban road GPR data. Gurbuz (2012) has reported that the energy of GPR data follows mainly Gamma distribution, and it can be used to determine background statistical distribution and to select appropriate threshold amplitude. His research was based on only 6370 A-scan waveforms collected from 1.8 m × 1.8 m inspection area. In contrast, in this research, totally 13 km-long GPR data were collected using a vehicle-mounted GPR with a scanning width of 1.5 m from urban roads in Seoul, South Korea. All 4,668,720 A-scan signals are statistically analysed to determine the statistical distribution of the GPR data and a proper threshold amplitude accordingly. Here, to collect the A-scan signals, DXG-1820, multichannel antenna manufactured by 3d-Radar (http://3d-radar.com), is used in this study. The device contains 20 pairs of transmitters and receivers, so it can scan 1.5-m-wide traffic lane at once. The 3D GPR system operates at frequency range from 500 to 1800 MHz generated by GeoScopeTM Mk IV, a step-frequency ground penetrating radar system manufactured by 3d-Radar.
A topological framework for real-time 3D weather radar data processing
Published in International Journal of Digital Earth, 2022
Mingyue Lu, Zhangjian Chen, Jin Wang, Qian Zhang, Zaiyang Ma, Min Chen, Yongning Wen
Products based on the current topological framework possess all the detailed information, but the amount of data is also enhanced, which places a great burden on data transportation and visualization, especially in real-time applications. In the meteorological field, detailed information is not always necessary, and sparse information can also meet the requirements well in most scenarios. Therefore, this article employs the LOD (layer of detail) strategy to represent data with different levels of detail. Based on the topological framework, the TPoints are chosen every two (three, four or more) bins in each line (as shown in Figure 6). Then, a new topological framework can be generated with these chosen TPoints, in which the TPoint amounts are much less than those in the original framework. Accordingly, other topological objects together with the connections among them can also be constructed in the same way, as well as the quadtree structure in the new topological framework. Thus, new topological frameworks with fewer data can be constructed for less detailed products. In this way, a hierarchy of various topological frameworks with different levels of data amounts are generated to meet different application scenarios: in subtle scenarios, operations can be conducted in the original topological framework to obtain detailed products, and in general scenarios, operations can be rapidly conducted in shrunken frameworks to obtain less detailed products with less data and better efficiency of data transmission and visualization. In applications, topological frameworks at different detailed levels can be prebuilt in advance to support 3D radar data operations.
Use of NDT systems to investigate pavement reconstruction needs and improve maintenance treatment decision-making
Published in International Journal of Pavement Engineering, 2023
Chunlong Xiong, Jiangmiao Yu, Xiaoning Zhang
This project uses 3D GPR to detect the inner damage of the pavement structure. The 3D GPR is produced by 3D Radar company. The radar host is GEOSCOPE MK IV and the ground-coupled antennas are DXG1820 with a frequency bandwidth of 200–3000 MHz. The utilised 3D GPR can provide 20 emitting and receiving channels of electromagnetic wave signal through a linear combination of 20 pairs of antennas. The separation between antennas is 7.5 cm and the single sampling width of GPR is 1.5 m. The change of GPR's detection parameters will cause the variation of the vehicle speed during data collection and the general vehicle speed ranges from 5 to 60 km/h (Figure 3).