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X-WR-CALDESC:Events for Northeastern University College of Engineering
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DTSTART;TZID=America/New_York:20220707T130000
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DTSTAMP:20260514T114454
CREATED:20221103T143228Z
LAST-MODIFIED:20221103T143228Z
UID:34094-1657198800-1657202400@coe.northeastern.edu
SUMMARY:Sara Garcia Sanchez's PhD Dissertation Defense
DESCRIPTION:“Learning and Shaping the Wireless Environment: An Integrated View of Sensing\, Computing and Communication” \nAbstract: \nThe explosive growth in Internet of Things (IoT) deployments and anticipated data volumes that will be generated within future autonomous devices require collecting and processing large amounts of data\, generally transmitted over the wireless channel. Rigid infrastructure deployment that does not adapt to the changing wireless environment is not well suited to handle these new demands. To address this limitation\, this dissertation takes a hands-on approach to equip communication systems with technology to learn from\, interact with and actuate within the environment. Specifically\, we build (i) accurate physics-based predictive models and multimodal sensing techniques to gain awareness of the existing channel\, as well as (ii) novel multidisciplinary approaches to intelligently shape the wireless channel towards enhancing the communication link. \nWe first prove that combining wireless channel modeling\, multimodal sensing and robotics provides significant link performance gains. To this extent\, we adopt a systems approach to study how millimeter wave (mmWave) radio transmitters on Unmanned Aerial Vehicles (UAVs) provide high throughput links under typical hovering conditions. Based on sensing and modeling efforts\, we propose techniques to exploit the information contained in the spatial and angular domains of empirically collected data from GPS\, cameras and RF signals. We demonstrate how to mitigate the impact of hovering by (i) selecting near-to-optimum transmission parameters as compared to the mmWave standard IEEE 802.11ad\, and (ii) proposing corrective coordinated actions at the UAVs from the robotic controls. These methods achieve mmWave beam-tracking and robust link deployment under event(s) impacting link performance\, such as hovering or blockage in the light of sight between transmitter and receiver.\nFinally\, we experimentally demonstrate how the wireless environment can be interactively shaped through the use of Reconfigurable Intelligent Surfaces (RIS). First\, we propose AirNN\, a system capable of partially offloading computation into the wireless domain by realizing analog convolutions with over-the-air computation. We demonstrate that such computation is accurate enough to substitute its digital equivalent in a Convolutional Neural Network (CNN). Second\, we propose a RIS-based spatio-temporal signal modification approach for channel hardening (i.e.\, ensure low power fluctuations in the received signal) in a Single-Input Single-Output link and under rich multipath\, which is common for IoT 5G+ deployments. We prove that our approach achieves channel hardening similar to a classical Single-Input Multiple-Output (SIMO) system while only using a single antenna element at the receiver end. \nAll the above theoretical advances are validated with rigorous analysis and experimentation. \nCommittee: \nProf. Kaushik Chowdhury (Advisor) \nProf. Stefano Basagni \nProf. Josep Jornet
URL:https://coe.northeastern.edu/event/sara-garcia-sanchezs-phd-dissertation-defense/
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DTSTART;TZID=America/New_York:20220707T130000
DTEND;TZID=America/New_York:20220707T140000
DTSTAMP:20260514T114454
CREATED:20221103T143515Z
LAST-MODIFIED:20221103T143515Z
UID:34089-1657198800-1657202400@coe.northeastern.edu
SUMMARY:Alexandria Will-Cole's PhD Proposal Review
DESCRIPTION:“Morphology\, Magnetism\, and Transport in Nanomaterials and Nanocomposites” \nAbstract: \nMagnetic thin film materials and bilayer composites enable unprecedented new applications\, ranging from magnetic-based microelectromechanical systems (magnetoelectric sensors\, ultracompact magnetoelectric antennas\, etc.)\, terahertz emitters\, to spin-orbit-torque driven magnetic memories. Here we focus on two subdisciplines within magnetics – magnetoelectrics and spintronics heterostructures. \nThe first aspect of the talk is focused on magnetoelectrics. Strain-mediated magnetoelectric coupling (i.e.\, voltage/electric field control of magnetism\, or magnetic field control of electrical polarization) in bilayer composites has received heightened attention in the research community for applications in memory\, motors\, sensors\, communication etc. The composite ME effect is dependent on the magnetostrictive effect (magnetic-mechanical coupling) and the piezoelectric effect (electrical-mechanical coupling)\, and therefore to improve the composites each constituent phase needs to be optimal. Here we demonstrate the feasibility of machine learning\, specifically Bayesian Optimization methods\, to optimize ferromagnetic materials\, specifically (Fe100−y Gay)1−xBx (x=0–21 & y=9–17) and (Fe100−y Gay)1−xCx (x=1–26 and y=2–18) to demonstrate optimization of structure-property relationships\, specifically the compositional effect on magnetostriction and ferromagnetic resonance linewidth. Following the materials optimization study\, we present voltage control of ultrafast demagnetization in ME heterostructure of (Fe81Ga19)88B12/ Pb(Mg1/3Nb2/3)O3–PbTiO3. Previous studies implement multiple strategies to tune ultrafast demagnetization namely via the laser pump wavelength\, fluence\, polarization\, and pulse duration as these control the total absorbed energy into the film. Here we present an alternate strategy to tune ultrafast demagnetization with application of an electric field in the ME heterostructure to induce magnetic axis rotation. Additionally\, we studied magnetic anisotropy changes and E-field tuning behavior following ultrafast demagnetization. \nThe second aspect of this talk is focused on spintronics heterostructures\, namely ferromagnetic (FM)/topological insulator (TI) or ferrimagnetic insulator (FI)/topological insulator (TI) bilayer composites\, and TI sputter growth and characterization. Bilayer FM/TI and FI/TI heterostructures are promising for spintronic memory applications due to their low switching energy and therefore power efficiency. TIs have been grown with molecular beam epitaxy (oriented\, epitaxial films) and RF magnetron sputtering (amorphous to crystalline oriented films) and have demonstrated large spin-to-charge conversion efficiencies. However\, the reactivity of TIs with FM films is often overlooked in the spin-orbit-torque literature\, even though there are reports that it is energetically favorable for topological insulators to react with metals and form interfacial layers. Here we present the interfacial reaction and antiferromagnetic phase formation between MBE-grown Sb2Te3 and sputtered Ni80Fe20 films. Since FM/TI interfaces are highly reactive and form novel interfacial phases\, which can encourage spin memory loss\, it is critical to explore heterostructures with cleaner interfaces. Recently\, we synthesized chemically stable Y3Fe5O12/Bi2Te3 films\, which should have a chemically sharp interface. We present preliminary structural and magnetic characterization\, followed by proposed experiments to study proximity induced magnetization in these bilayer composites. Concurrent to our investigation spintronic heterostructures\, we seek to optimize sputter deposition of TIs. However\, sputtering TIs requires enhanced control over defects/stoichiometry as these influence bulk transport. We present preliminary results and propose experiments to elucidate structure-transport relationships\, such that we can provide strategies to controllably suppress bulk conduction to access topologically protected surface states. \nCommittee:\nProf. Nian X. Sun (advisor)\nProf. Don Heiman (co-advisor)\nProf. Yongmin Liu\nDr. A. Gilad Kusne\nDr. Todd Monson
URL:https://coe.northeastern.edu/event/alexandria-will-coles-phd-proposal-review/
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BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220707T170000
DTEND;TZID=America/New_York:20220707T180000
DTSTAMP:20260514T114454
CREATED:20220705T135324Z
LAST-MODIFIED:20220705T135324Z
UID:31760-1657213200-1657216800@coe.northeastern.edu
SUMMARY:CommLab: Discussing Your Poster
DESCRIPTION:Join the CommLab for a virtual interactive workshop\, where we will be discussing best practices for presenting your posters.   Bring your poster-even if it is just a draft- and we can help you ensure your story will reach every audience member.  We will also provide tips on how to reduce information overload for your audience\, helping you more effectively convey your research.  Register here by Zoom.
URL:https://coe.northeastern.edu/event/commlab-discussing-your-poster/
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