September 2015
Name: Gabriel Bousquet
Department: Mechanical and Ocean Engineering
School: Massachusetts Institute of Technology
Project: Amphibious Dynamic Soaring
Research Advisor: Dr. Michael Triantafyllou and Dr. Jean-Jacques Slotine
Gabriel is a PhD student in the department of Mechanical and Ocean Engineering at MIT. He aims to create bio-inspired monitoring robots able to extract their own propulsive energy from winds and ocean currents. A native of the Southern Alps in France, he received his Bachelor and Masters in condensed matter physics and energy engineering at École Normale Supérieure in Paris. With a long-standing interest in renewable energies and climate sciences, he studied nano-platelets, a material with very promising optical properties applicable to solar energy at ESPCI ParisTech in Paris, and the modeling of Equable Climate (100 to 43 million years ago) at Harvard University. Upon graduation he went to Makani Power --now part of Google[x]--, a company that develops airborne wind turbines, also known as kite power. There, he designed an airfoil specifically optimized for airborne wind power generation. This is when he became passionate about wind energy and how robots and animals can interact with complex flows, both in the air and underwater, in order to extract energy for power generation or propulsion.
Gabriel came to MIT on a Fulbright Science and Technology fellowship and is now working under the joint supervision of Professor Michael Triantafyllou and Professor Jean-Jacques Slotine. He focuses on the interface between applied robotics, nonlinear control and fluid mechanics. He studies the flight strategy of the albatross, called Dynamic Soaring: albatrosses harvest wind energy in order to travel impressive distances, flying up to 3,000 miles per week effortlessly. To accomplish this feat, albatrosses extract wind energy by following a characteristic zig zag pattern that transfers momentum between the windy layer in altitude (~10m) and the boundary layer close to the ocean surface (~1m), in an overall mechanism reminiscent to that of a sailboat. Gabriel’s goal is to design a biomimetically inspired flying robot capable of gliding over the oceans at no energetic cost, constituting a platform able to perform large scale, flexible and scalable monitoring and communication tasks. Specifically, the Link Foundation fellowship will support him in the critical task of experimentally proving the feasibility of the low height flight phase of dynamic soaring and validating its energetic efficiency.
Name: Weiyi Tang
Department: Earth and Ocean Sciences
School: Duke University
Project: A shipboard instrument for underway estimates of marine N2 fixation
Research Advisor: Dr. Nicolas Cassar
Weiyi Tang is a PhD student at Duke University working with Dr. Nicolas Cassar on the development of new methods for the study of the biogeochemical cycling of nitrogen and carbon in the world’s oceans. Before joining Duke in 2014, Weiyi received a Bachelor of Science in Oceanography from Xiamen University in China. After his junior year, he was supported by the Marine Training Project funded by the National Natural Science Foundation of China to study various facets of the marine nitrogen cycle. Under the supervision of Dr. Shuh-Ji Kao at Xiamen University, Weiyi applied 15N and 13C isotope addition and dilution methods to estimate rates of nitrification, N2 fixation and primary production in the South China Sea and Western North Pacific. As part of this project, he had the opportunity to familiarize himself with Isotope Ratio Mass Spectrometry (IRMS) for trace gas analysis of nitrous oxide (N2O) in the oceans. During his undergraduate studies, Weiyi became interested in ocean engineering and the development of instruments and technologies for the study of marine biogeochemical processes.
Marine N2 fixation is a biological process conducted by diazotrophs who reduce nitrogen gas (N2) into bioavailable ammonium (NH4+). Phytoplankton utilize nutrients like ammonium, nitrate and phosphate to support their growth. However, large areas of the world’s oceans are oligotrophic, i.e., depleted in macronutrients such as nitrogen. Under such circumstances, diazotrophs have a competitive advantage. N2 fixers also have a large impact on carbon cycling by increasing the availability of nitrogen in marine ecosystems.
Current approaches to measure N2 fixation typically rely on discrete sampling, resulting in poor spatial and temporal coverage of N2 fixation. With the support of the Link Foundation, Weiyi is designing a new gas extraction system and modifying a Cavity Ring-Down Spectrometer (CRDS) in order to conduct shipboard high-resolution underway measurement of N2 fixation. The diazotrophic activity will be monitored continuously by determining the concentration of ethylene produced from acetylene reduction in a flow-through incubation chamber. Acetylene reduction is a common surrogate reaction for N2 fixation. The underway measurements will broaden our ability to study N2 fixation in the marine environment and its effects on the global carbon cycle.
Name: Yuxi Zhang
Department: Naval Architecture & Marine Engineering
School: University of Michigan
Project: A Measuring System for Simultaneous Current, Wave and Ice Action on Offshore Structures
Research Advisor: Dr. Dale Karr
Yuxi received BS from Tianjin University in 2012 and her MSE from the University of Michigan in 2013 in Naval Architecture and Marine Engineering. As a graduate student, Yuxi developed an interest in ice-structure interaction by studying the dynamic response of a dashed-spring-spot ice structure model using Fourier Series under the instruction of Prof. Dale G. Karr. An improved set of basins of attraction are obtained and results are compared to previous experimental analyses.
Yuxi continued her study as a PhD student with Prof. Karr by joining a Department of Energy (DoE) sponsored Project entitled, “Measurement and Analysis of Extreme Wave and Ice Actions in the Great Lakes for Offshore Wind Platform Design,” in Sept 2013. The project objective is to measure forces exerted on an offshore structure and to develop theoretical modeling of ice impact loads. She worked through the design, fabrication, installation, and operation of the Ice Force Measuring System (IFMS) and assisted in the deployment of the instrumentation in Lake Superior on a Keweenaw Peninsula lighthouse in November 2013. The facilities were in land-fast ice most of the season and substantial quasi-static response was measured. A data acquisition system (DAQ) including transmission of data from strain gages was encased in the IFMS. The strain measurements have added to our knowledge of structural response driven primarily by wind and current forcing. The converted pressures were estimated to vary from 0 psi to 200 psi based on preliminary assessments.
The Link Foundation will support Yuxi’s proposed effort to expand and validate analytical modeling of coupled ice forces on marine structures. A key aspect of such modeling is specific measurement of impact forces in the field. She will be using existing hardware from the current DoE project and extend its usage in the Lake St. Clair, Detroit River system. A core aspect of Yuxi’s dissertation is mechanical modeling of the ice/structure interaction. While the standard structural analysis is to determine structural response given applied loading, Yuxi is faced with the inverse problem. The challenge is to predict the coupled ice forcing from measured structural response. Yuxi plans to use elaborate models (orthotropic plate theory and finite element models) to determine the approximate pressure field from the strain measurements by retaining a limited number of Fourier coefficients in both the prediction of the loading and plate deformations. The calculation of the pressure field from the gauges has already yielded results consistent with expected values from more sophisticated FEA. This approach allows calculating spatially and time variable pressure fields, in an effort to predict extreme ice loading for key design load cases on offshore structures. The project will have assistance for deployment from the Coast Guard Sector Detroit of the Ninth Coast Guard District. Sector Detroit has responsibility for the operational and administrative oversight of operations including aids to navigation, ice breaking, and ice rescue.