Search Results - "Lai, Wallace W. L."

Intensity Normalisation of GPR C-Scans by Luo, Tess X. H., Lai, Wallace W. L., Lei, Zhanzhan

“…The three-dimensional (3D) ground-penetrating radar (GPR) has been widely applied in subsurface surveys and imaging, and the quality of the resulting C-scan…”
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Unfolding WWII Heritages with Airborne and Ground-Based Laser Scanning by Sit, Kathleen Fei-Ching, Pun, Chun-Ho, Lai, Wallace W. L., Chung, Dexter Kin-Wang, Kwong, Chi-Man

“…Considering how difficult it is for a pin in the ocean to be found, painstaking searches among historical documents and eyewitness accounts often end up with…”
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GPR Virtual Guidance System for Subsurface 3D Imaging by Ching, Gabbo P. H., Chang, Ray K. W., Luo, Tess X. H., Lai, Wallace W. L.

“…Three-dimensional GPR imaging requires evenly and densely distributed measurements, ideally collected without the need for ground surface markings, which is…”
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GPR pattern recognition of shallow subsurface air voids by Luo, Tess X.H., Lai, Wallace W.L.

“…•Develop an automatic GPR workflow for subsurface void detection.•The workflow imitates human decision-making process.•The workflow makes interpretation a lot…”
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Forward modelling on GPR responses of subsurface air voids by Luo, Tess X.H., Lai, Wallace W.L., Giannopoulos, Antonios

“…•Compare the performance of FDTD simulation and real data.•The void geometries determine the GPR reflection patterns.•The road structure affects the GPR…”
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Building simplified uncertainty models of object depth measurement by ground penetrating radar by Xie, Fei, Lai, Wallace W.L., Dérobert, Xavier

“…•Uncertainty of depth surveyed by ground penetrating radar is modelled and evaluated.•Evaluated uncertainty is not strongly dependent to the burial depth of…”
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GPR uncertainty modelling and analysis of object depth based on constrained least squares by Xie, Fei, Lai, Wallace W.L., Dérobert, Xavier

“…•Uncertainty of estimated depth by GPR is modelled and analyzed.•Evaluated uncertainty can achieve the order of several centimetres.•Errors of time-zero…”
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GPR-based depth measurement of buried objects based on constrained least-square (CLS) fitting method of reflections by Xie, Fei, Lai, Wallace W.L., Dérobert, Xavier

“…•The model considers the transmitter-receiver separation and the target radius.•The constrained least-square algorithm is iteration free and computation-cost…”
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Perturbation mapping of water leak in buried water pipes via laboratory validation experiments with high-frequency ground penetrating radar (GPR) by Lai, Wallace W.L., Chang, Ray K.W., Sham, Janet F.C., Pang, K.

“…[Display omitted] •We map GPR perturbation patterns of leak point and wetting front.•We analyzed four stages of wetting patterns explained by GPR…”
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Development of a new algorithm for accurate estimation of GPR's wave propagation velocity by common-offset survey method by Sham, Janet F.C., Lai, Wallace W.L.

“…The development of a new algorithm to estimate electromagnetic (EM) wave propagation velocity (v) with shielded ground penetrating radar (GPR) antenna with…”
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Foreword to the special issue on advances in ground-penetrating radar research and applications by Lai, Wallace W. L., Lambot, Sebastien, van der Kruk, Jan

“…THIS Special Issue in IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing (IEEE JSTARS) on ground-penetrating radar research and…”
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Exploring utility system SDI – Managerial and technical perspectives by Pun-Cheng, Lilian S.C., Lai, Wallace W.L., Chang, Ray K.W.

“…•Setting a utility data infrastructure is challenging in view of variable definitions and formats of diverse data sources.•Availability and accuracy of…”
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Characterization of leakage signatures in buried water pipes by ground penetrating radar(GPR) and instantaneous frequency analysis by Zhou, Yimin, Lai, Wallace W.L.

“…The aging and complexity of underground water pipes pose significant challenges to modern society, necessitating long-term monitoring and maintenance to…”
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Superpixel-based change detection for GPR time-lapse slices using fuzzy c-means and the Markov random field method by Zhou, Yimin, Lai, Wallace W.L., Zhu, Xiaolin

“…•Proposes an unsupervised change-detection for GPR C-scans.•Combines FCM and MRF models to integrate adjacent information.•Preserves details, resists noise,…”
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Standardizing nondestructive underground utility survey methods by Lai, Wallace W.L., Sham, Janet F.C.

“…•Standardizing utility survey workflow.•Accreditation based on standardization.•Accuracy and tolerances. Are underground utility (UU) surveys specialist work?…”
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GPR imaging criteria by Luo, Tess X.H., Lai, Wallace W.L., Chang, Ray K.W., Goodman, Dean

“…GPR has been widely acknowledged as an effective and efficient technique for imaging the subsurface. But the process of constructing 3D GPR images (C-scans) is…”
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A blind test of nondestructive underground void detection by ground penetrating radar (GPR) by Lai, Wallace W.L., Chang, Ray K.W., Sham, Janet F.C.

“…Blind test/experiment is widely adopted in various scientific disciplines like medicine drug testing/clinical trials/psychology, but not popular in…”
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Hybrid non-destructive evaluation methods for characterizing chloride-induced corrosion in concrete by Wong, Phoebe T.W., Lai, Wallace W.L., Sham, Janet F.C., Poon, Chi-sun

“…This paper aims to describe a GPR-based phase characterization model for characterizing various phases of invisible chloride contamination, active corrosion…”
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A lab study of coupling effects of electromagnetic induction on underground utilities by Siu, K.L., Lai, Wallace W.L.

“…Electromagnetic induction is the most common technique used for geophysical survey of underground utilities, in planning stage, prior to…”
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GPR wave dispersion for material characterization by Lai, Wallace W.L., Chang, Ray K.W., Völker, Christoph, Cheung, Bella W.Y.

“…•Use of two high-frequency GPR antennas in wide angle reflection and refraction (WARR) mode.•GPR wave dispersion method validated by GPR-WARR setting.•Distance…”
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