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Item Capsule robot pose and mechanism state detection in ultrasound using attention-based hierarchical deep learning(Scientific Reports, 2022-12-07) Liu, Xiaoyun; Esser, Daniel; Wagstaff, Brandon; Zavodni, Anna; Matsuura, Naomi; Kelly, Jonathan; Diller, EricIngestible robotic capsules with locomotion capabilities and on-board sampling mechanism have great potential for non-invasive diagnostic and interventional use in the gastrointestinal tract. Real-time tracking of capsule location and operational state is necessary for clinical application, yet remains a significant challenge. To this end, we propose an approach that can simultaneously determine the mechanism state and in-plane 2D pose of millimeter capsule robots in an anatomically representative environment using ultrasound imaging. Our work proposes an attention-based hierarchical deep learning approach and adapts the success of transfer learning towards solving the multi-task tracking problem with limited dataset. To train the neural networks, we generate a representative dataset of a robotic capsule within ex-vivo porcine stomachs. Experimental results show that the accuracy of capsule state classification is 97%, and the mean estimation errors for orientation and centroid position are 2.0 degrees and 0.24 mm (1.7% of the capsule's body length) on the hold-out test set. Accurate detection of the capsule while manipulated by an external magnet in a porcine stomach and colon is also demonstrated. The results suggest our proposed method has the potential for advancing the wireless capsule-based technologies by providing accurate detection of capsule robots in clinical scenarios.Item Quantitative oxygen atom measurements in lean, premixed, H2 tubular flames(Elsevier, 2021) Marshall, Garrett J; Walsh, Patrick S; Pitz, Robert WQuantitative O-atom profiles are measured for the first time in tubular flames and used to assess the performance of chemical kinetic mechanisms in tubular flame simulations. Atomic oxygen is measured via femtosecond, Two-Photon Laser Induced Fluorescence (fs-TPLIF) to avoid photolytic interference. The fs- TPLIF signal is corrected for collisional quenching from major species concentrations measured by Raman scattering. Temperature-dependent quenching rate in the form of T ^−0.5 for H2O is applied to better represent the actual physics, and all simulations are found to agree with this method. Atomic oxygen is reported in H2/O2 flames diluted with N2 or CO2 at 200 and 400 s ^−1 stretch rates. The oxygen radical data is compared to predictions using three different, detailed chemical kinetic mechanisms. Predictions of profile shape vary slightly, but the peak O-atom number density is calculated within experimental uncertainty by each mechanism.Item Electrically defined topological interface states of graphene surface plasmons based on a gate-tunable quantum Bragg grating(Nanophotonics, 2019-08) Fan, Zhiyuan; Dutta-Gupta, Shourya; Gladstone, Ran; Trendafilov, Simeon; Bosch, Melissa; Jung, Minwoo; Iyer, Ganjigunte R. Swathi; Giles, Alexander J.; Shcherbakov, Maxim; Feigelson, Boris; Caldwell, Joshua D.; Allen, Monica; Allen, Jeffery; Shvets, GennadyA periodic metagate is designed on top of a boron nitride-graphene heterostructure to modulate the local carrier density distribution on the monolayer graphene. This causes the bandgaps of graphene surface plasmon polaritons to emerge because of either the interaction between the plasmon modes, which are mediated by the varying local carrier densities, or their interaction with the metal gates. Using the example of a double-gate graphene device, we discuss the tunable band properties of graphene plasmons due to the competition between these two mechanisms. Because of this, a bandgap inversion, which results in a Zak phase switching, can be realized through electrostatic gating. Here we also show that an anisotropic plasmonic topological edge state exists at the interface between two graphene gratings of different Zak phases. While the orientation of the dipole moments can differentiate the band topologies of each graphene grating, the angle of radiation remains a tunable property. This may serve as a stepping stone toward active control of the band structures of surface plasmons for potential applications in optical communication, wave steering, or sensing.