PhD Thesis Proposal: Michele Maxson

For info on how to attend via videoconference, email michele.l.maxson@dartmouth.edu.

"A novel lightweight drone based electromagnetic induction sensing for mapping"

Abstract

Permafrost is perennially frozen soil that covers approximately 25% of the Northern Hemisphere including approximately 85% of the land area of Alaska. One impact of climate change is the accelerated thawing of the permafrost, with the region north of the Arctic Circle warming twice as fast as the rest of the globe. As permafrost melts, the soils become unstable and subside causing damage to horizontal and vertical infrastructure. Rapid and accurate mapping of permafrost at scales relevant to the design and maintenance of horizontal and vertical infrastructure has been a long-standing challenge.

Several subsurface sensing techniques have been developed to meet this challenge. Most existing technologies, which provide bulk soil conductivity profiles, provide limited and/or coarse lateral resolutions and do not provide high fidelity data at the depth's permafrost is found. Additionally, most if not all the existing technologies are designed to be deployed either on the ground in cart or sled-based vehicles or on large airborne platforms. These modalities are relatively expensive making repeat data collects over an area of statistically meaningful size impractical.

This thesis introduces:

1. UAS mounted, novel, lightweight, broadband EMI sensor with an FPGA controlled active bucking hardware for collecting high fidelity data quickly and at relatively low cost,
2. enhanced signal processing algorithms, using an orthogonal source method, for mapping soil properties in 3D with unprecedented resolution.

To obtain the high-fidelity data required an EMI system will be built. Preliminary modeling results have shown that varying the sensor height will provide higher resolution in the subsurface, therefore the system will also be mounted on a UAS. A novel FPGA controlled; active bucking system will be designed that can automatically cancel the primary field. To resolve lateral discontinuities in the subsurface, an algorithm employing discrete orthogonal sources will be adopted to supplement current layering models.

The system will be tested in Fairbanks, Alaska at or near CRREL's permafrost tunnel which will provide ground truthing for the system and the models.

Thesis Committee

• Fridon Shubitidze (chair)
• Benjamin Barrowes
• Donald Perovich
• Ryan Halter

Contact

For more information, contact Theresa Fuller at theresa.d.fuller@dartmouth.edu.