Impacts of Infauna and Organic Matter on Seabed Acoustics 

Friday, February 21, 2025, 4:00 p.m. Central Time

Dr. Kevin Lee
Applied Research Laboratories
The University of Texas at Austin
https://www.arlut.utexas.edu/

The seabed, although it composes nearly seventy percent of Earth’s geological surface, remains a frontier. Thus, better understanding of the benthic environment will be required for developing critical seabed infrastructure in support of national defense, the blue economy, and climate applications.   Because acoustic remote sensing is one of the most widely used methods for interrogating wide swaths of the seabed, better fundamental understanding of how benthic processes couple to seabed acoustic properties is also needed. In particular, the impacts of benthic biological processes and biogeochemical properties on surficial sediment acoustic properties and their variability are poorly understood. Nearly all ocean-bottom muddy sediments are consumed through the digestive processes of polychaete worms and other deposit-feeding invertebrates. These diverse infauna communities modify near-surface seabed structure through burrowing, tube-building, and bio-irrigation, contributing to spatiotemporal variability in sediment sound speed, attenuation, and other geoacoustic properties. Furthermore, the presence of microscopic intergranular organic matter impacts sediment cohesion and hence seabed stability, but we are only beginning to understand how this affects sediment acoustic properties or how those relationships can be exploited. This seminar will describe some recent and current basic research efforts in the ARL:UT Environmental Sciences Laboratory related to the intersection of seabed acoustics, biology, and biogeochemistry. 

Advancing Ultrasound Research: Innovations and Applications from an Industry Perspective 

Friday, February 14, 2025, 4:00 p.m. Central Time

Dr. Miguel Bernal
Verasonics Inc.
Kirkland, WA
https://verasonics.com

This talk explores the evolution of ultrasound technology from the origins of conventional line-scan imaging to the modern approaches of ultrafast ultrasound and pixel-based beamforming—the foundational innovation of Verasonics. Starting by outlining the key differences between traditional ultrasound and ultrafast imaging, it will become clear that having a platform that can acquire thousands of frames per second unlocks current and untapped potential in characterization and diagnosis within medical ultrasound imaging. Then, several advanced techniques that leverage ultrafast ultrasound are introduced. These include ultrasensitive Doppler, which enables the visualization of microvascular flow with unprecedented detail; functional ultrasound imaging, a powerful method for mapping brain activity; and ultrasound localization microscopy, which surpasses the diffraction limit to achieve super-resolution imaging of the microvascular. Working with our academic partners, the advancement of these techniques is being actively explored in addition to comparing Verasonics’ previous and next-generation platforms to assess performance improvements as well as previously unrealized capabilities. As these ultrafast techniques continue to advance, there is a growing need to extend them from 2D to 3D imaging, which presents challenges in maintaining high frame rates. To address this, Verasonics developed Sparse Random Aperture Compounding, a novel volume imaging technique designed to enhance frame rates for high-element-count transducer arrays while optimizing data acquisition efficiency. Through collaboration as well as internal research and development, Verasonics continues to push the boundaries of ultrasound, providing flexible and powerful tools to drive innovation across clinical and scientific domains.

Condition Monitoring of Dry Storage Canisters Using Helical Guided Ultrasonic Waves 

Friday, February 7, 2025, 4:00 p.m. Central Time

Guan-Wei Lee
Maseeh Department of Civil, Architectural and Environmental Engineering
The University of Texas at Austin
https://www.caee.utexas.edu

Dry Storage Canisters (DSCs) play a critical role in the safe storage of spent nuclear fuel rods. These canisters, constructed from welded stainless-steel plates, are susceptible to degradation mechanisms such as stress corrosion cracking, which could compromise their structural integrity over time. With the first DSCs in the United States deployed in 1986, there is a growing need to assess and monitor their condition to ensure long-term safety and reliability. However, these canisters are housed within concrete overpacks, significantly limiting access to their surfaces for inspection. Moreover, it is crucial to limit human exposure to radioactive environments during these inspections. To address these challenges, monitoring techniques compatible with robotic systems are essential, which require minimizing the number of sensing points for efficient robot operation. This work focuses on developing an efficient and reliable methodology for both active and passive monitoring of DSCs using helical guided ultrasonic waves (HGUW). This approach aims to overcome the constraints of limited accessibility while enabling accurate assessment of structural integrity.

Modeling Very Low Frequency Wind-Generated Ocean Noise

Friday, January 24, 2025, 4:00 p.m. Central Time

Dr. Christopher A. Stockinger
Applied Research Laboratories
The University of Texas at Austin
https://www.arlut.utexas.edu/

Historically, shipping is assumed to dominate ambient underwater acoustic Noise Levels (NL) from 10 to 100 Hz, however, the data acquired from the north hydrophone triplet of the Comprehensive Nuclear-Test-Ban Treaty (CTBT) station at Crozet Island provides unique wind noise observations with minimal shipping interference. First, NL was correlated to local wind speed through a frequency dependent power relation, and second, the distant wind contributions were modeled through a source density and propagation model. For the source density model, wind-related noise was modeled as a layer of monopole sources located at a quarter-wavelength below the surface to replicate a dipole radiation pattern. The total acoustic intensity received by the array and the modeled wind-related source intensity were both related to wind speed through a power relationship where the two share the same frequency dependent exponent, n. The model parameters were computed empirically from the acoustic and wind speed data. The source layer model accurately predicts the NL within a standard deviation of 3 dB. An important observation is that the exponent n increases as frequency decreases and reaches a value around 7 at 10 Hz, which is much larger than often measured at higher frequencies.