Dr. Stefano Mariani Profile

Dr. Stefano Mariani

at Imperial College London

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Publications (7)

Proceedings Article | 27 March 2018 Presentation + Paper

High-speed non-contact ultrasound system for rail track integrity evaluation

Francesco Lanza di Scalea, Xuan Zhu, Margherita Capriotti, Albert Liang, Stefano Mariani, Simone Sternini, Robert Wilson

Proceedings Volume 10600, 106000J (2018) https://doi.org/10.1117/12.2295634

KEYWORDS: Inspection, Defect detection, Prototyping, Structural health monitoring, Ultrasonics, Receivers, Sensors, Acoustics, Deconvolution, Ultrasonography

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Ultrasonic rail inspection is the most commonly implemented method for detecting internal rail defects. While the conventional ultrasound wheel probe has gained its popularity within rail maintenance community, it suffers from the limited test speeds (25 mph at most). This paper presents the state-of-the-art developments in ultrasonic rail inspection technique that utilizes non-contact receivers and no active transmitters. The transfer function between two points of the rail is reconstructed by deconvolutions of multiple pairs of receivers that sense the acoustics naturally excited in the rail by the running wheels. The deconvolution process eliminates the random effect of the excitation to reconstruct a stable acoustic transfer function of the rail. A fixed bulk delay and frequency selection technique are introduced to facilitate the power spectral density estimation for robust transfer function reconstruction. A multivariate analysis based on selected features extracted from various frequency bands is conducted on the signals recorded by multiple sensor pairs respectively. Furthermore, damage index traces based on data from different sensor pairs provide system redundancy for improved reliability with the voting logic for damage detection. The proposed approach lends itself to extremely high testing speeds (as fast as the service train speed, e.g. 60 mph and above), that would enable the real-time evaluation of rail track integrity at train operational speeds. A prototype based on this passive-only inspection idea has been constructed and tested with the DOTX216 testing vehicle of the Federal Railroad Administration at the Transportation Technology Center (TTC) in Pueblo, CO in September 2016. Test runs were made at various speeds from 25 mph to 80 mph (the maximum speed allowed on the test track). The results show the feasibility of stable reconstruction of the transfer function from the random wheel excitation, as well as the detection of joints and welds present in the track. Some tests were also conducted on TTC Defect Farm showing the potential for defect defection.

Proceedings Article | 20 April 2016 Presentation + Paper

Extraction of thermal Green's function using diffuse fields: a passive approach applied to thermography

Margherita Capriotti, Simone Sternini, Francesco Lanza di Scalea, Stefano Mariani

Proceedings Volume 9803, 98030U (2016) https://doi.org/10.1117/12.2218998

KEYWORDS: Thermography, Nondestructive evaluation, Defect detection, Signal processing, Structural health monitoring, Acoustics, Image resolution, Interference (communication), Diffusion, Temperature metrology, Infrared cameras

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Proceedings Article | 8 April 2016 Paper

Defect detection performance of the UCSD non-contact air-coupled ultrasonic guided wave inspection of rails prototype

Stefano Mariani, Thompson Nguyen, Simone Sternini, Francesco Lanza di Scalea, Mahmood Fateh, Robert Wilson

Proceedings Volume 9804, 98040N (2016) https://doi.org/10.1117/12.2218989

KEYWORDS: Signal to noise ratio, Ultrasonics, Defect detection, Waveguides, Inspection, Prototyping, Signal detection, Statistical analysis, Wave sensors, Sensors, Head, Receivers, Transducers

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Proceedings Article | 3 April 2015 Paper

Non-contact ultrasonic guided wave inspection of rails: field test results and updates

Stefano Mariani, Thompson Nguyen, Xuan Zhu, Francesco Lanza di Scalea, Mahmood Fateh

Proceedings Volume 9435, 94351O (2015) https://doi.org/10.1117/12.2083774

KEYWORDS: Head, Prototyping, Ultrasonics, Waveguides, Inspection, Defect detection, Receivers, Transducers, Lithium, Sensors

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Proceedings Article | 9 March 2014 Paper

Non-contact ultrasonic guided wave inspections of rails

Thompson Nguyen, Stefano Mariani, Francesco Lanza di Scalea

Proceedings Volume 9064, 90640V (2014) https://doi.org/10.1117/12.2044105

KEYWORDS: Prototyping, Transducers, Sensors, Waveguides, Defect detection, Receivers, Computer simulations, Ultrasonics, Inspection, Signal generators

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Proceedings Article | 19 April 2013 Paper

Non-contact ultrasonic guided wave inspection of rails

Stefano Mariani, Thompson Nguyen, Robert Ronald Phillips, Piotr Kijanka, Francesco Lanza di Scalea, Wieslaw Jerzy Staszewski

Proceedings Volume 8692, 86921L (2013) https://doi.org/10.1117/12.2009179

KEYWORDS: Ultrasonics, Waveguides, Prototyping, Defect detection, Inspection, Statistical analysis, Transducers, Head, Electronic filtering, Signal to noise ratio

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Proceedings Article | 17 April 2013 Paper

Nonlinear guided waves for neutral temperature measurement in continuous welded rails: results from laboratory and field tests

Claudio Nucera, Robert Phillips, Peter Zhu, Stefano Mariani, Francesco Lanza di Scalea, Mahmood Fateh, Gary Carr

Proceedings Volume 8695, 869528 (2013) https://doi.org/10.1117/12.2009763

KEYWORDS: Waveguides, Prototyping, Temperature metrology, Ultrasonics, Wave propagation, Thermal modeling, Dispersion, Liquid phase epitaxy, Structural health monitoring, Head

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Showing 5 of 7 publications

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