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The singularity expansion method (SEM) assumes that the electromagnetic scattering wave of an object has a fixed poles distribution, i.e. the resonant frequency is fixed. So the object can be identified by extracting poles from radar data. While studying ground penetrating radar (GPR) echo signal features of nonmetallic pipelines, the paper finds that the GPR signal's frequency center downshifts when...
We present a one-dimensional scheme to compute an image of a dissipative medium from two single-sided reflection responses without using any model information. One reflection response is measured at or above the top reflector of a dissipative medium and the other is computed as if measured at or above a medium with negative dissipation. The reflection response of a medium with negative dissipation...
Airborne ground penetrating radar (GPR) can be used for detecting underground targets in dangerous area or area covered by heavy vegetation. Since the back projection (BP) imaging method can easily compensate for the electromagnetic wave's refraction effect, it can be a practical imaging method for airborne GPR system. Nevertheless, the conventional BP imaging method usually suffers from high computational...
Ultrawideband radar has been applied in the through-wall life detection since it has high spatial resolution and better wall-penetration capability. In this paper, we perform a through-wall detection of human's motions using UWB radar. We use local mean decomposition (LMD) method to process radar signals reflected from a moving person. LMD is a new iterative approach that decomposes modulated signals...
A novel sensor was previously developed for detecting rock boundaries behind uncut coal for controlling the horizon of the cutting head in long-wall mining environments. This boundary detection method is based on extracting the thickness of the uncut layer from the complex reflection coefficient of a narrowband antenna that is mounted directly on the rotating cutting drum. The main practical challenges...
GPR has been used routinely in Saskatchewan, Canada, potash mines for nearly forty years. In general, the purpose of GPR surveys in potash mines is to map the salt-bed stratigraphy above and below the mined-out rooms. The stratigraphy in the Saskatoon, Saskatchewan area mines consists of a series of salt and potash beds separated by well-known and regionally distributed planar clay seams. The salt-beds...
Vehicle-mounted ground penetrating radar (GPR) is an effective and rapid tool to detect railway subgrade defects. However, the signal to noise ratio (SNR) of the raw GPR data on railway subgrade is much lower than that of other detection sites. The primary noises are caused by radar wave reflections from the rails and steel-concrete sleepers. However, the rail noise is always invariant since the rails...
In cold regions, heaving of the railway subgrade is an important security risk to high-speed railways. It is necessary to monitor the moisture content of the subgrade in order to ensure normal railway operation. Common midpoint (CMP) measurement using ground penetrating radar (GPR) was carried out to estimate the moisture content of railway subgrade. As the subgrade is typically a layered medium,...
Recently, waveform inversion is one of the most popular methods because it can provide sub-wavelength images. In the inversion of field data, the source wavelet must be estimated. Traditionally, the source wavelet is added in the inversion as a new unknown parameter and updated with iterations. When the results of the inversion are the same as the true models, the estimated source wavelet is same...
We have developed 8Ch array GPR system “Yakumo” and have demonstrated the performance of the multistatic radar. At first, the effect of the antenna polarization and the antenna spacing to GPR signal in the multistatic GPR system was evaluated by a laboratory experiment. Using this multistatic GPR system, we can estimate the vertical profile of the electromagnetic wave velocity by CMP method at every...
GPR is a nondestructive detection method which has been widely applied to detect defects in concrete structures. In field geotechnical engineering cases, it is very hard to observe anomalies caused by longitudinal defects using ground-based GPR detection, which produces great difficulties in data processing and interpretation. Compared with the traditional ground-based GPR, the cross-hole GPR can...
Improving understanding of Arctic ecosystem functioning and parameterization of models that simulate freeze-thaw dynamics require advances in quantifying soil and snow properties. Due to the significant spatiotemporal variability of soil properties and the limited information provided by point-scale measurements (e.g., cores), geophysical methods hold potential for improving soil and permafrost characterization...
This paper describes experimental results carried out in skarn deposits with a polarization-sensitive directional borehole radar. This radar employs a dipole array and loop antenna in a borehole (DALAB), which was proposed in a previous study. This radar system was applied to polarimetric radar measurement of a fault and sphalerite veins in skarn. The fault may be regarded as a plane-type reflector...
Holographic radar is a promising method of detecting landmines. Taking advantage of high plan-view resolution, holographic radar is able to discriminate targets from clutter objects. However, as high-frequency electromagnetic waves attenuate fast in soil, the performance of holographic radar in field experiments needs to be validated. Hence, we conduct experiments in different environments with the...
Previous studies have demonstrated that the radar technique is one of the most effective ways to detect human vital signs in certain circumstances. However, the problem of the complex electromagnetic environment at an earthquake disaster site has not been fully explored in the literature to date. To characterize and comprehend the electromagnetic environment in radio frequencies in a typical field...
This paper presents the development of a new pluggable combined low-frequency antenna, involving three frequencies of 12.5MHz, 25 MHz, and 50MHz, aiming to solve the current problems of the small detection range and low precision in mine disaster sources detection in China. Compared with many existing antennas, the novel designed plate-type structure antenna can enhance the directivity and reduce...
Subsurface utility engineering (SUE) concerns are risk mitigation problems requiring confirmation, denial, and new evidence concerning long thin cylindrical conducting utilities illustrated on old, oftentimes unreliable, and out dated utility maps. This case study first presents a scientific, technology, engineering, and mathematical (STEM) description of a revolutionary class of radio detection technology...
The Philippine archipelago lies in the path of seasonal tropical cyclones, and much of the coast is prone to periodic inundation due to storm surges. One example is typhoon Durian, a category 3 storm that made landfall on the 30th November 2006, in Bicol province, on the east central Philippine coast. Satellite imagery from May 2007 reveal that Durian caused significant erosion and breached a sandy...
In this paper, we present a method using singular value decomposition (SVD) which aims at eliminating the random noise and direct wave from ground penetrating radar (GPR) signal. To demonstrate the validity and high efficiency of the eliminating random noise method using SVD, we first tested our proposed method with noisy synthetic data and field data. Then we carried out de-noising process using...
The boundary between the unsaturated and saturated zones is commonly not characterized by a sharp interface, but rather by a gradual increase of water content. The shape of this capillary transition zone (CTZ) depends on the pore-size distribution of the soil and has a strong influence on the signature of GPR reflections. This can be observed when mapping groundwater tables with GPR: high frequencies...
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