ORCID Profile
0000-0002-3105-7259
Current Organisation
University of New South Wales Canberra
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Publisher: Elsevier BV
Date: 2023
Publisher: American Physical Society (APS)
Date: 13-10-2021
Publisher: Elsevier BV
Date: 12-2020
Publisher: SPIE
Date: 06-05-2020
DOI: 10.1117/12.2561178
Publisher: Elsevier BV
Date: 02-2020
DOI: 10.1016/J.ULTRAS.2019.106004
Abstract: In this paper, an ultrasonic tomography method based on acoustic multi-parameter full waveform inversion (FWI) is developed for high-resolution reconstructions of velocity and density in metal components. The challenging issue in multi-parameter FWI is to deal with the trade-off effects between different parameters of different natures. Moreover, different parameters have different orders of litudes in the wave-field which make the inversion ill-conditioned. The inverse Hessian has been shown to mitigate the coupling effects and rescale the litudes of different parameters, and then the reliable updates of different parameters are available. The simultaneous reconstructions of velocity and density by using the truncated Gauss-Newton method, in which the inverse Hessian can be considered through a matrix-free conjugate gradient solution of the Gauss-Newton normal equation, are investigated by simulation as well as experiment on the centred inclusions. The results show that this method can effectively alleviate the trade-off effects between velocity and density, and thus the velocity of the inclusion is accurately reconstructed and the reconstruction of the density is well achieved.
Publisher: Elsevier BV
Date: 04-2023
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 2022
Publisher: AIP Publishing
Date: 11-03-2019
DOI: 10.1063/1.5090956
Abstract: Focusing of ultrasonic waves in water plays an important role in various scenarios ranging from biomedical imaging to nondestructive testing. Acoustic metasurfaces have been largely explored for acoustic focusing, but they are generally narrowband and mainly implemented for airborne sound because of their structural complexity. Nevertheless, our previous development of metasurfaces provides a great opportunity to solve the challenges. Here, we present numerically and experimentally the broadband focusing of ultrasonic waves in water with a metasurface lens consisting of an array of deep-subwavelength sized and spaced slots. The slot widths of the metasurface are optimized based on microscopic coupled-wave theory. Due to the non-resonant arrangement, the focusing effect is demonstrated over a broad band of frequencies. The metasurface lens with simplicity and an ultra-compact size provides a feasible means for the design of thin and lightweight ultrasonic devices and is suitable for practical applications in biomedical and industrial fields.
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 03-2022
Publisher: SAGE Publications
Date: 27-02-2023
DOI: 10.1177/14759217231156364
Abstract: In ultrasonic structural health monitoring (SHM) and nondestructive evaluation (NDE), the scattered waves caused by damage sites and defects are the key to damage diagnosis. However, structural components and boundaries also interact with traveling waves, creating events that can bury damage scattered waves. The baseline subtraction method, which directly subtracts the waveform of a damage signal from that of a pristine baseline signal, is a common processing technique to separate these damage scattered waves. However, baseline subtraction is less effective when a component is measured in different environmental/loading conditions from when its baseline was recorded. For instance, baseline subtraction can be ineffective in aerospace structural parts because such parts expect significant and routine changes in ambient temperature, pressure, and humidity. To overcome the limitations of baseline subtraction, this paper proposes to develop an spex-shifted Radon transform (ASRT)-based damage scattered event extraction technique without baseline subtraction. Our proposed ASRT method converts the original time-space [Formula: see text] domain signals to a time delay–curvature–apex offset [Formula: see text] domain, which targets specific geometries of scattered/reflected waves in the [Formula: see text] domain and compresses them into a single point-like region in the new domain. In this domain, identifying and isolating targeted events becomes significantly easier. To benchmark the performance of this baseline-subtraction-free (BSF) method, ASRT is applied for signals acquired from (1) spectral finite element-based simulations to scan a water-immersed steel specimen (2) 3-D wave simulations in a bent aluminum plate, and (3) a full matrix capture for experimentally scanning a high-density polyethylene (HDPE) with multiple holes. The goal in each case is to target and separate events of interest from the original signals using the proposed algorithm. The results suggest the ASRT method is effective as a damage scattered wave extraction tool for ultrasonic SHM and NDE.
Publisher: IOP Publishing
Date: 29-01-2020
Abstract: Ultrasonic techniques are able to accurately detect and characterize flaws in homogeneous structures. Elastic reverse time migration (ERTM) is a powerful tool to reconstruct high-resolution images of flaws. To achieve images with better quality, the solution can be obtained by iteratively finding an image generating the modeled data which can best match the measured data in a least-squares sense, i.e. least-squares migration (LSM). Combing ERTM and LSM, conventional elastic least-squares reverse time migration (ELSRTM) methods are based on the assumption of a constant density, which can lead to inaccurate litudes and parameter crosstalk artifacts in the reconstructed images. In this paper, an ultrasonic imaging technique based on the ELSRTM which considers density as well as longitudinal-(L-) and shear-wave (S-wave) velocity variations is explored for imaging flaws in heterogeneous structures. The ELSRTM with density variations can simultaneously reconstruct density and L- and S-wave velocity images, which can provide litude-preserving images and mitigate crosstalk artifacts. This method is applied to numerical as well as physical laboratory experiments and the results appear promising for flaw identification in heterogeneous structures.
Publisher: DEStech Publications, Inc.
Date: 28-09-2017
Publisher: Elsevier BV
Date: 08-2022
DOI: 10.1016/J.ULTRAS.2022.106764
Abstract: With the increasing use of high density polyethylene (HDPE) pipes in nuclear industry which puts safety at the forefront, ultrasonic array imaging methods play a vital role in the structural integrity of HDPE pipe materials. However, the viscoelastic attenuation of HDPE pipe materials significantly decreases the level of signals, leading to a low signal-to-noise ratio caused by electronic noise. In this work, a domain-adapted spatio-temporal singular value decomposition (STSVD) processing algorithm combined with the total focusing method is proposed to improve the ultrasonic array image quality. First, the real-valued radio frequency (RF) data or A-scan signals are demodulated into the complex analytic signals containing in-phase and quadrature (I/Q) components. Then, the STSVD processing algorithm is used to filter the I/Q data, and the filtered I/Q data is converted into RF signals. Finally, the total focusing method is applied to the processed RF signals to produce the image of the region under detection as a stage of post-processing. Experiments are carried out with an ultrasonic linear phased array in contact with the HDPE pipe materials containing multiple side-drilled holes and through-wall notches. Results show that the proposed method can produce images with high quality to provide good inspection and characterization of defects in highly attenuative materials, especially the deeper defects.
Publisher: Informa UK Limited
Date: 13-06-2022
Publisher: ASMEDC
Date: 2011
Abstract: A steel reinforced plastic pipe (PSP), which is composed of two layers of high density polyethylene (HDPE) matrix and a high strength steel wire mesh skeleton, has wide applications in many industrial areas, such as gas and petroleum transportation, etc. In order to achieve higher efficency and lower costs, a large diameter PSP has been developed. However, requirements of the large diameter PSP in safety and economy are much higher, compared with those small diameter PSPs, and some potential problems should be taken into account. In this paper, relevant structural parameters of the large diameter PSP are determined, based on a previously proposed model, and a short-term burst test is carried out. The experiment results agree with the theoretical results quite well. Subsequently, the resistance of vertical pressure and uniform external pressure are evaluated by using experiment investigation and finite element method, respectively. And corresponding results indicate the large diameter PSP with determined structural parameters is qualified to use.
Publisher: Elsevier BV
Date: 10-2019
Publisher: Elsevier BV
Date: 09-2023
Publisher: Elsevier BV
Date: 2022
Publisher: Elsevier BV
Date: 2024
Publisher: AIP Publishing
Date: 15-11-2016
DOI: 10.1063/1.4967790
Abstract: Ultrasonic guided waves are useful to assess the integrity of a structure from a remote location. Recently, tomography techniques have been developed to quantitatively estimate the thickness map of plate-like structures based on the dispersion characteristics of guided waves. In many applications only limited locations are available to place transducers. The missing viewing angles lead to artifacts which can degrade the image quality. To address this problem, this paper applies the regularization method to synthesize the missing components. The regularization technique is performed by an adaptive threshold approach to the limited view reconstruction. The effectiveness of this method combined with the full waveform inversion method is demonstrated by using numerical simulations as well as experiments on an irregularly shaped defect and two flat-bottom defects. The results indicate that the additional components obtained from the regularization method can significantly reduce the artifacts, leading to better reconstruction accuracy.
Location: China
No related grants have been discovered for Jing Rao.