Topological Shadow Of Higher-Order Topological Phases And Non-Hermitian Phases Protected By Generalized Rotational Symmetry,
2022
CUNY Graduate Center
Topological Shadow Of Higher-Order Topological Phases And Non-Hermitian Phases Protected By Generalized Rotational Symmetry, Kai Chen
Dissertations, Theses, and Capstone Projects
Topological phenomena in condensed matter physics have been investigated intensively in the past decades since the discovery of the integer quantum Hall effect (IQHE). For the IQHE, the energy band can be characterized by its topological invariants (Chern number or TKNN invariant), which relates to the quantized Hall conductance directly. Later, this expression was recognized as the first Chern class of a U(1) principal fiber bundle on a torus, where the fibers and torus correspond respectively to the magnetic Bloch waves and the magnetic Brillouin zone. And then, the discoveries of time-reversal symmetric topological insulators in two and three dimensions …
Falcon Neuro: An Event-Based Sensor On The International Space Station,
2022
United States Air Force Academy
Falcon Neuro: An Event-Based Sensor On The International Space Station, Matthew G. Mcharg, Richard L. Balthazor, Matthew P. Borg, Brian J. Mcreynolds, David H. Howe, Colin J. Maloney, Daniel O'Keefe, Rayomand Bam, Gabriel Wilson, Paras Karki, Alexandre Marcireau, Gregory Cohen
Student Publications
We report on the Falcon neuro event-based sensor (EBS) instrument that is designed to acquire data from lightning and sprite phenomena and is currently operating on the International Space Station. The instrument consists of two independent, identical EBS cameras pointing in two fixed directions, toward the nominal forward direction of flight and toward the nominal Nadir direction. The payload employs stock DAVIS 240C focal plane arrays along with custom-built control and readout electronics to remotely interface with the cameras. To predict the sensor’s ability to effectively record sprites and lightning, we explore temporal response characteristics of the DAVIS 240C and …
System Design For The Quantification Of Microbial Motility In Extreme Environments,
2022
Portland State University
System Design For The Quantification Of Microbial Motility In Extreme Environments, Megan Marie Dubay
Dissertations and Theses
Motility of microorganisms is understudied but provides useful insights into their behavior. Organisms' ability to move autonomously changes how they interact with their environment--finding nutrients, interacting with other organisms, and avoiding unfavorable conditions. Understanding motility features can also be used to identify specific species, such as the identification of Vibrio cholerae in human samples. Motility might also be used as evidence of life existing in even the most extreme environments on Earth, and possibly beyond. Specialized microscopy systems can be required to examine the motility of microorganisms due to the nature of the environments to which the instruments are exposed. …
Development Of Intravital Microscopy For Brain Imaging With Improved Spatiotemporal Coverage And Contrast,
2022
Washington University in St. Louis
Development Of Intravital Microscopy For Brain Imaging With Improved Spatiotemporal Coverage And Contrast, Yifeng Zhou
McKelvey School of Engineering Graduate Student Theses & Dissertations
Capitalizing on the Brownian motion of red blood cells, the distinct optical absorption spectra of oxy-hemoglobin and deoxy-hemoglobin, and the blood flow-induced signal decorrelation, multi-parametric photoacoustic microscopy (PAM) is capable of quantifying concentration of hemoglobin (CHb), blood oxygen saturation (sO2), and hemodynamics at the microscopic level via statistical, spectroscopic, and correlation analyses. Multi-parametric PAM has found broad biomedical applications. In fact, there are still much room to further improve the performance and imaging capability of multi-parametric PAM to meet the ever-increasing demanding requirements of biomedical research. To date, there are two main obstacles that prevent multi-parametric PAM from being more …
Advancing The Portability, Field Of View, And Spatiotemporal Resolution Of Multi-Parametric Photoacoustic Microscopy,
2022
Washington University in St. Louis
Advancing The Portability, Field Of View, And Spatiotemporal Resolution Of Multi-Parametric Photoacoustic Microscopy, Fenghe Zhong
McKelvey School of Engineering Graduate Student Theses & Dissertations
Capable of structural, functional, molecular, and metabolic imaging with high spatial resolution in vivo, photoacoustic microscopy (PAM) is an emerging tool in biomedical research. Further, recent advances in multi-parametric acquisition and analysis make PAM uniquely capable of simultaneously mapping the total concentration of hemoglobin (CHb), oxygen saturation of hemoglobin (sO2), and blood flow speed. However, there are multiple major limitations, including, the large footprint, low imaging speed, limited imaging contrast, and insufficient axial resolution, which impedance its applications in basic and translational research. In this dissertation, I presented potential solutions to overcome the limitations above.In the first part of this …
Perovskite Solar Cells,
2022
Albany State University
Perovskite Solar Cells, Liqiu Zheng Dr., Tyler Hurst, Zhongrui Li
Georgia Journal of Science
The semiconductor perovskite CsPbBr2I was doped with Mn2+ to modulate its optical and photovoltaic performance. The Mn2+-doped CsPb0.9Mn0.1Br2I exhibited improved crystalline quality. Ultraviolet and visible spectroscopy of Mn2+-doped CsPb0.9Mn0.1Br2I revealed enhanced absorption capacity. Although the efficiency was not as good as desired, the enhanced light absorption of CsPb0.9Mn0.1Br2I still boosted the photovoltaic performance when it was utilized as a light absorber in perovskite solar cells, along with a low-cost carbon electrode. Compared with its counterpart …
Towards A Low-Cost Solution For Gait Analysis Using Millimeter Wave Sensor And Machine Learning,
2022
University of Dayton
Towards A Low-Cost Solution For Gait Analysis Using Millimeter Wave Sensor And Machine Learning, Mubarak A. Alanazi, Abdullah K. Alhazmi, Osama Alsattam, Kara Gnau, Meghan Brown, Shannon Thiel, Kurt Jackson, Vamsy P. Chodavarapu
Electrical and Computer Engineering Faculty Publications
Human Activity Recognition (HAR) that includes gait analysis may be useful for various rehabilitation and telemonitoring applications. Current gait analysis methods, such as wearables or cameras, have privacy and operational constraints, especially when used with older adults. Millimeter-Wave (MMW) radar is a promising solution for gait applications because of its low-cost, better privacy, and resilience to ambient light and climate conditions. This paper presents a novel human gait analysis method that combines the micro-Doppler spectrogram and skeletal pose estimation using MMW radar for HAR. In our approach, we used the Texas Instruments IWR6843ISK-ODS MMW radar to obtain the micro-Doppler spectrogram …
Glaciernet2: A Hybrid Multi-Model Learning Architecture For Alpine Glacier Mapping,
2022
University of Dayton
Glaciernet2: A Hybrid Multi-Model Learning Architecture For Alpine Glacier Mapping, Zhiyuan Xie, Umesh K. Haritashya, Vijayan K. Asari, Michael P. Bishop, Jeffrey S. Kargel, Theus Aspiras
Electrical and Computer Engineering Faculty Publications
In recent decades, climate change has significantly affected glacier dynamics, resulting in mass loss and an increased risk of glacier-related hazards including supraglacial and proglacial lake development, as well as catastrophic outburst flooding. Rapidly changing conditions dictate the need for continuous and detailed ob-servations and analysis of climate-glacier dynamics. Thematic and quantitative information regarding glacier geometry is fundamental for understanding climate forcing and the sensitivity of glaciers to climate change, however, accurately mapping debris-cover glaciers (DCGs) is notoriously difficult based upon the use of spectral information and conventional machine-learning techniques. The objective of this research is to improve upon an …
Computational Methods For Propagation Of Optical Fields With The Angle-Impact Wigner Function,
2022
University at Albany, State University of New York
Computational Methods For Propagation Of Optical Fields With The Angle-Impact Wigner Function, Jeremy Wittkopp
Legacy Theses & Dissertations (2009 - 2024)
In designing an optical setup for an experiment, one usually turns to simulations first in order to model the propagation of light through the proposed system. This way, the experimenter can determine if the system is operating as intended. In order for these simulations to be useful, they need to properly describe the propagation of light. In order to simplify calculations, most contemporary software makes assumptions on the nature of the light being propagated. Specifically, simulations typically consider optical fields that are beam-like (i.e., most of the rays comprising the field deviate only slightly in angle from the beam's primary …
Arrayed Waveguide Lens For Beam Steering,
2022
CUNY Queens College
Arrayed Waveguide Lens For Beam Steering, Mostafa Honari-Latifpour, Ali Binaie, Mohammad Amin Eftekhar, Nicholas Madamopoulos, Mohammad-Ali Miri
Publications and Research
Integrated planar lenses are critical components for analog optical information processing that enable a wide range of applications including beam steering. Conventional planar lenses require gradient index control which makes their on-chip realization challenging. Here, we introduce a new approach for beam steering by designing an array of coupled waveguides with segmented tails that allow for simultaneously achieving planar lensing and off-chip radiation. The proposed arrayed waveguide lens is built on engineering the evanescent coupling between adjacent channels to realize a photonic lattice with an equi-distant ladder of propagation constants that emulates the continuous parabolic index profile. Through coupled-mode analysis …
Ultrashort Pulse Laser Filamentation Electrical And Optical Diagnostic Comparison,
2022
University of New Mexico - Main Campus
Ultrashort Pulse Laser Filamentation Electrical And Optical Diagnostic Comparison, James E. Wymer
Optical Science and Engineering ETDs
Results presented here examine the effect of changing gas pressure on the radio frequency (RF) emissions of an ultrashort pulse laser filament plasma and how those emissions vary longitudinally in the laser focal region. We use a WR284 rectangular waveguide with a 1.5 cm hole that allows the beam through. A 3.2 GHz microwave signal is emitted in the waveguide, and signals are received through a waveguide-to-coax antenna connected to an HP8470B Schottky diode. By enabling and disabling the 3.2 GHz signal, we measure both the self-emitted RF from a USPL filament and subsequently the degree of attenuation a filament …
Subwavelength Engineering Of Silicon Photonic Waveguides,
2022
Clemson University
Subwavelength Engineering Of Silicon Photonic Waveguides, Farhan Bin Tarik
All Dissertations
The dissertation demonstrates subwavelength engineering of silicon photonic waveguides in the form of two different structures or avenues: (i) a novel ultra-low mode area v-groove waveguide to enhance light-matter interaction; and (ii) a nanoscale sidewall crystalline grating performed as physical unclonable function to achieve hardware and information security. With the advancement of modern technology and modern supply chain throughout the globe, silicon photonics is set to lead the global semiconductor foundries, thanks to its abundance in nature and a mature and well-established industry. Since, the silicon waveguide is the heart of silicon photonics, it can be considered as the core …
Study Of Single-Photon Wave-Packets With Atomically Thin Nonlinear Mirrors,
2022
University of Arkansas, Fayetteville
Study Of Single-Photon Wave-Packets With Atomically Thin Nonlinear Mirrors, Christopher Klenke
Graduate Theses and Dissertations
A novel controlled phase gate for photonic quantum computing is proposed by exploiting the powerful nonlinear optical responses of atomically thin transition metal dichalcogenides (TMDs) and it is shown that such a gate could elicit a π-rad phase shift in the outgoing electric field only in the case of two incident photons and no other cases. Firstly, the motivation for such a gate is developed and then the implementation of monolayer TMDs is presented as a solution to previous realization challenges. The single-mode case of incident photons upon a TMD is derived and is then used to constrain the more …
Atomic Gradiometry Based On The Interference Of Microwave Optical Sidebands,
2022
University of New Mexico - Main Campus
Atomic Gradiometry Based On The Interference Of Microwave Optical Sidebands, Kaleb L. Campbell
Optical Science and Engineering ETDs
We describe a novel pulsed magnetic gradiometer based on the optical interference of sidebands generated using two spatially separated alkali vapor cells. The sidebands are produced with high efficiency using parametric frequency conversion of a probe beam interacting with Rubiduim 87 atoms in a coherent superposition of magnetically sensitive hyperfine ground states. First, experimental evidence of the sideband process is described for both steady-state and pulsed operation. Then, a theoretical framework is developed that accurately models sideband generation based on density matrix formalism. The gradiometer is then constructed using two spatially separated vapor cells, and a beat-note is generated. The …
Neutron Interferometry Using A Single Modulated Phase Grating,
2022
Louisiana State University and Agricultural and Mechanical College
Neutron Interferometry Using A Single Modulated Phase Grating, Ivan J. Hidrovo Giler
LSU Master's Theses
Neutron grating interferometry provides information on phase and small-angle scatter in addition to attenuation. Previously, phase grating moiré interferometers (PGMI) with two or three phase gratings have been developed. These phase-grating systems use the moiré far-field technique to avoid the need for high-aspect absorption gratings used in Talbot-Lau interferometers (TLI) which reduce the neutron flux reaching the detector. We demonstrate through simulations a novel phase grating interferometer system for cold neutrons that requires a single modulated phase grating (MPG) for phase-contrast imaging, as opposed to the two or three phase gratings in previously employed PGMI systems. We compare the MPG …
Modelling Spherical Aberration Detection In An Analog Holographic Wavefront Sensor,
2022
Technological University Dublin
Modelling Spherical Aberration Detection In An Analog Holographic Wavefront Sensor, Emma Branigan, Suzanne Martin, Matthew Sheehan, Kevin Murphy
Conference Papers
The analog holographic wavefront sensor (AHWFS) is a simple and robust solution to wavefront sensing in turbulent environments. Here, the ability of a photopolymer based AHWFS to detect refractively generated spherical aberration is modelled and verified.
Localized Surface Plasmon Resonance Of Copper Nanoparticles Using Finite Element Method,
2022
PhD Student, Faculty of Science, Beirut Arab University
Localized Surface Plasmon Resonance Of Copper Nanoparticles Using Finite Element Method, Samaya El Samad, Salem Marhaba
BAU Journal - Science and Technology
The aim of this paper is to study the interaction of the electromagnetic wave with plasmonic nanoparticles. Localized Surface Plasmon resonance (LSPR) characteristics are governed by the intrinsic properties of the nanoparticle (size, shape and dielectric environment). The extinction cross-section spectra of Cu nanoparticles are calculated using finite element method (FEM). By increasing both the size of the nanoparticle and the dielectric environment, the simulations show a red-shifting and broadening on the LSPR spectrum with enhancement of the spectral amplitude. The extinction cross section spectra are calculated using polarized light for non-spherical or assembled nanoparticles. We investigated the LSPR of …
Noncontact Liquid Crystalline Broadband Optoacoustic Sensors,
2022
Air Force Institute of Technology
Noncontact Liquid Crystalline Broadband Optoacoustic Sensors, Hengky Chandrahalim, Michael T. Dela Cruz
AFIT Patents
An optoacoustic sensor includes a liquid crystal (LC) cell formed between top and bottom plates of transparent material. A transverse grating formed across the LC cell that forms an optical transmission bandgap. A CL is aligned to form a spring-like, tunable Bragg grating that is naturally responsive to external agitations providing a spectral transition regime, or edge, in the optical transmission bandgap of the transverse grating that respond to broadband acoustic waves. The optoacoustic sensor includes a narrowband light source that is oriented to transmit light through the top plate, the LC cell, and the bottom plate. The optoacoustic sensor …
Improving On Atmospheric Turbulence Profiles Derived From Dual Beacon Hartmann Turbulence Sensor Measurements,
2022
Air Force Institute of Technology
Improving On Atmospheric Turbulence Profiles Derived From Dual Beacon Hartmann Turbulence Sensor Measurements, Alexander S. Boeckenstedt, Jack E. Mccrae, Santasri Bose-Pillai, Benjamin Wilson
Faculty Publications
Atmospheric turbulence is an inevitable source of wavefront distortion in all fields of long range laser propagation and sensing. However, the distorting effects of turbulence can be corrected using wavefront sensors contained in adaptive optics systems. Such systems also provide deeper insight into surface layer turbulence, which is not well understood. A unique method of profile generation by a dual source Hartmann Turbulence Sensor (HTS) technique is introduced here. Measurements of optical turbulence along a horizontal path were taken to create C2n profiles. Two helium-neon laser beams were directed over an inhomogeneous horizontal path and captured by the HTS. The …
Imnets: Deep Learning Using An Incremental Modular Network Synthesis Approach For Medical Imaging Applications,
2022
University of Dayton
Imnets: Deep Learning Using An Incremental Modular Network Synthesis Approach For Medical Imaging Applications, Redha A. Ali, Russell C. Hardie, Barath Narayanan Narayanan, Temesguen Messay
Electrical and Computer Engineering Faculty Publications
Deep learning approaches play a crucial role in computer-aided diagnosis systems to support clinical decision-making. However, developing such automated solutions is challenging due to the limited availability of annotated medical data. In this study, we proposed a novel and computationally efficient deep learning approach to leverage small data for learning generalizable and domain invariant representations in different medical imaging applications such as malaria, diabetic retinopathy, and tuberculosis. We refer to our approach as Incremental Modular Network Synthesis (IMNS), and the resulting CNNs as Incremental Modular Networks (IMNets). Our IMNS approach is to use small network modules that we call SubNets …
