A New Design to Rayleigh Wave EMAT Based on Spatial Pulse Compression

Jiang, Chuan-Liu; Li, Zhichao; Zhang, Zeyang; Wang, Shujuan

doi:10.3390/s23083943

Cited by 13 publications

(4 citation statements)

References 39 publications

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“…When the receiver is a spatial matched filter, spatial pulse compression (SPC) can be realized, as shown in figure 2(b). Another approach to achiever SPC is to drive an impulse signal to a wavelength modulated meander-line coil and using another identical meander-line coil as the receiver, as shown in figure 2(c) [12]. When a frequency modulated signal is used to drive the wavelength modulated meander-line coil, the generated Rayleigh waves is compressed by the combination of temporal and spatial pulse compression (TSPC), as shown in figure 2(d).…”

Section: Theory Of Temporal and Spatial Pulse Compressionmentioning

confidence: 99%

“…The phase-coded coil spatial pulse compression technique was used to improve the spatial resolution and SNR of Rayleigh waves [11]. An alternative approach is to use impulse signals passing through a pair of linear or nonlinear wavelength modulated meander-line coils [12]. The final signals of Rayleigh waves can be compressed to narrow spikes by either temporal or spatial pulse compression after the processing of the received signals.…”

Section: Introductionmentioning

confidence: 99%

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Generation of ultrashort Rayleigh wave pulses using the combination of temporal and spatial pulse compression technique

Jiang,

Li,

Wang

2023

Phys. Scr.

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Rayleigh waves generated by electromagnetic acoustic transducers (EMATs) have been widely used in nondestructive testing and evaluations. To improve the signal to noise ratio (SNR) and spatial resolution of Rayleigh waves simultaneously, the combination of temporal and spatial pulse compression (TSPC) technique is proposed. By analyzing the topology diagram of the typical pulse compression technique, a frequency modulated signal acts as the stretcher and a wavelength modulated meander line coil acts as the compressor. Experimental results indicate that the ultrasound fields of Rayleigh waves using the proposed TSPC technique show a spike shape in the spatial domain. Compared with the typical meander-line coil EMATs, the TSPC technique shows significant improvement of the generated Rayleigh waves. The SNR has increased by 12 dB while the main lobe width has decreased by about 98%.

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Section: Theory Of Temporal and Spatial Pulse Compressionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Generation of ultrashort Rayleigh wave pulses using the combination of temporal and spatial pulse compression technique

Jiang,

Li,

Wang

2023

Phys. Scr.

Self Cite

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“…Jiang et al proposed a new non-uniform coil structure for a Raleigh wave EMAT (RW-EMAT), which enables signal compression in the spatial domain. The experimental results showed an increase in received signal amplitude by 2.3–2.6 times [ 25 ]. Wang et al found that the position of the backplate affects the pulse width and amplitude of the thickness measurement signal.…”

Section: Introductionmentioning

confidence: 99%

Development of DMPS-EMAT for Long-Distance Monitoring of Broken Rail

Guo

Chui

et al. 2023

Sensors

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The safety of railway transportation is crucial to social and economic development. Therefore, real-time monitoring of the rail is particularly necessary. The current track circuit structure is complex and costly, posing challenges to monitoring broken tracks using alternative methods. As a non-contact detection technology with a lower environmental impact, electromagnetic ultrasonic transducers (EMATs) have become a concern. However, traditional EMATs have problems such as low conversion efficiency and complex modes, which can limit their effectiveness for long-distance monitoring. Therefore, this study introduces a novel dual-magnet phase-stacked EMAT (DMPS-EMAT) design comprising two magnets and a dual-layer winding coil arrangement. The magnets are positioned at a distance equal to the wavelength of the A0 wave from each other, while the center distance between the two sets of coils beneath the transducer is also equal to the wavelength. After analyzing the dispersion curves of the rail waist, it was determined that the optimal frequency for long-distance rail monitoring is 35 kHz. At this frequency, adjusting the relative positions of the two magnets and the coil directly underneath to be one A0 wavelength can effectively excite a constructive interference A0 wave in the rail waist. The simulation and experimental results show that DMPS-EMAT excited a single-mode A0 wave, resulting in a 1.35-times increase in amplitude.

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“…Currently, research on ϕ-OTDR is mainly focused on four aspects: extending sensing distance, improving spatial resolution, expanding frequency response range, and accurately identifying disturbances [9][10][11][12]. Among these, research on improving spatial resolution mainly centers on the use of pulse compression techniques [13][14][15][16]. Research on expanding the frequency response range primarily concentrates on Frequency Division Multiplexing (FDM) [17,18], fused interferometry [19,20], and periodic non-uniform sampling [21,22].…”

Section: Introductionmentioning

confidence: 99%

A Phase-Sensitive Optical Time Domain Reflectometry with Non-Uniform Frequency Multiplexed NLFM Pulse

Li,

Zhang,

Yuan

et al. 2023

Sensors

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In the domain of optical fiber distributed acoustic sensing, the persistent challenge of extending sensing distances while concurrently improving spatial resolution and frequency response range has been a complex endeavor. The amalgamation of pulse compression and frequency division multiplexing methodologies has provided certain advantages. Nevertheless, this approach is accompanied by the drawback of significant bandwidth utilization and amplified hardware investments. This study introduces an innovative distributed optical fiber acoustic sensing system aimed at optimizing the efficient utilization of spectral resources by combining compressed pulses and frequency division multiplexing. The system continuously injects non-linear frequency modulation detection pulses spanning various frequency ranges. The incorporation of non-uniform frequency division multiplexing augments the vibration frequency response spectrum. Additionally, nonlinear frequency modulation adeptly reduces crosstalk and enhances sidelobe suppression, all while maintaining a favorable signal-to-noise ratio. Consequently, this methodology substantially advances the spatial resolution of the sensing system. Experimental validation encompassed the multiplexing of eight frequencies within a 120 MHz bandwidth. The results illustrate a spatial resolution of approximately 5 m and an expanded frequency response range extending from 1 to 20 kHz across a 16.3 km optical fiber. This achievement not only enhances spectral resource utilization but also reduces hardware costs, making the system even more suitable for practical engineering applications.

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A New Design to Rayleigh Wave EMAT Based on Spatial Pulse Compression

Cited by 13 publications

References 39 publications

Generation of ultrashort Rayleigh wave pulses using the combination of temporal and spatial pulse compression technique

Generation of ultrashort Rayleigh wave pulses using the combination of temporal and spatial pulse compression technique

Development of DMPS-EMAT for Long-Distance Monitoring of Broken Rail

A Phase-Sensitive Optical Time Domain Reflectometry with Non-Uniform Frequency Multiplexed NLFM Pulse

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