Monitoring Dynamic Properties of Railway Tracks Using Train-borne Vibrometer Measurement

Characterization and Mitigation of Speckle Noise in Laser Doppler Vibrometer on Moving Platforms (LDVom)

Laser Doppler vibrometer (LDV) is a vibration-detecting instrument for noncontact and non-destructive measurement. It is superior to classic contact transducers in terms of the wide frequency range and high measurement resolution. LDV on moving platforms (LDVom) is one of the LDV measurement technology to one-way scan the vibrating surface, so...

Removing speckle noise from the signals of a laser Doppler vibrometer on moving platforms (LDVom) by ensemble empirical mode decomposition

With increasing requirements for structural stability and durability, effective monitoring strategies for existing and potential damage are necessary. A laser Doppler vibrometer on moving platforms (LDVom) can remotely capture large-scale structural vibrations, but speckle noise, a significant signal issue mainly when one-way continuously...

Speckle noise reduction for structural vibration measurement with laser Doppler vibrometer on moving platform

Speckle noise is a major problem for structural vibration measurements with Laser Doppler vibrometer on moving platform (LDVom) due to its highly random, frequent, and broadband nature, especially at high speeds. This paper develops a new post-processing framework to reduce speckle noise based on a case study of LDVom measurements on railway...

Numerical simulation and characterization of speckle noise for laser Doppler vibrometer on moving platforms (LDVom)

Laser Doppler Vibrometer (LDV) is extensively applied in remote and precise vibration measurements for structural monitoring. Speckle noise is a severe signal issue restricting LDV applications, mainly when an LDV scans from moving platforms. Realistic simulations and thorough characterizations of speckle noise can support the despeckle...

Eliminating Speckle Noises for Laser Doppler Vibrometer Based on Empirical Wavelet Transform

This paper presents a novel approach for eliminating speckle noises in Laser Doppler Vibrometer signals based on empirical wavelet transform (EWT). The moving root-mean-square thresholds are utilized to cut off signal drop-outs and produce noise discontinuity that EWT can identify. The extremum ratio behaves as the criterion to reject or accept...

Image processing of optical coherence tomography for image guided dental drilling

In the past two decades, dental implants have been an essential component of the public health. However, lack of a reliable and safe dental surgery imaging modality remains a major problem. Optical coherence tomography (OCT) is an interferometic optical imaging modality that is somewhat similar to B-mode ultrasound but utilizes infrared light...