Electromagnetics and Photonics Commons^™

A Reconfigurable Stretchable Liquid Metal Antenna, Phase Shifter, And Array For Wideband Applications, David M. Hensley

Electrical and Computer Engineering ETDs

While liquid metals, such as mercury, have been used in electronics for quite some time, the non-toxic gallium based liquid metals have caused an increase in research for liquid metal applications. Some of the potential applications that have been previously presented range from reconfigurable antennas, strain and pressure sensors, and speakers and microphones to name a few. The focus of this work is to provide further research into the use of gallium based liquid metals as a reconfigurable antenna, a phase shifter, and an array. This is done by designing, constructing, and characterizing each of these reconfigurable liquid metal (LM) …

Experimental Validation Of A 3d-Printed Millimeter Wave/Thz Power Combiner, Jacob C. Giese

Electrical and Computer Engineering ETDs

The terahertz band (THz) in the electromagnetic spectrum is an untapped resource that possesses unique features for nondestructive methods of material imaging and detection. However, little advancements have been made in regard to a practical long range portable THz device. The solution proposed is an oversized cylindrical waveguide termed Power Combiner, designed to combine 12 azimuthally aligned rectangular waveguides to produce power levels suitable for threat detection at secure distances. This paper explores the physical parameters of the power combiner and the power distribution network and creates the 12 signals that allow for modification at the input of the power …

On The Dynamic Generation Of Megagauss-Level Magnetic Fields On 100-Ns Timescales To Stabilize And Magnetize Pulsed-Power-Driven Liner Implosions, Gabriel A. Shipley

Electrical and Computer Engineering ETDs

This dissertation presents analysis of experiments and simulations executed to develop the auto-magnetizing liner concept (AutoMag) for use as an alternative premagnetization mechanism for MagLIF. Tests of each stage of AutoMag (magnetization, dielectric breakdown, and implosion) were executed on the Mykonos accelerator and the Z accelerator. Experiments demonstrate strong peak axial magnetic field production (20 – 150 T), dielectric breakdown initiation that depends on global induced electric field across the target, and a level of cylindrical implosion uniformity high enough to be useful for prospective fusion-fuel-filled (auto-magnetized MagLIF) experiments.

This dissertation also presents detailed simulations of the Solid Liner Dynamic …

Computational_Electromagnetic Modeling (Cem) Of Foliage Penetration (Fopen), Monica R. Jaramillo

Electrical and Computer Engineering ETDs

Foliage penetration (FOPEN) radar at lower frequencies (UHF, VHF) is a well-studied area with a wide set of contributions. However, there is growing interest in using higher Ku-band frequencies (12-18 GHz frequency range) for FOPEN. In particular, the reduced wavelength sizes (centimeters range) provide some key saliencies for developing more optimized foliage detection solutions. The disadvantage is that exploiting Ku-band for FOPEN is complicated because higher frequencies have much more pronounced scattering effects due to their smaller wavelengths. Despite these challenges, certain foliage characteristics and signal parameters can help improve electromagnetic (EM) wave penetration in the Ku-band such as foliage …

Twisted Spatiotemporal Optical Vortex Random Fields, Milo W. Hyde Iv

Faculty Publications

We present twisted spatiotemporal optical vortex (STOV) beams, which are partially coherent light sources that possess a coherent optical vortex and a random twist coupling their space and time dimensions. These beams have controllable partial coherence and transverse orbital angular momentum (OAM), which distinguishes them from the more common spatial vortex and twisted beams (known to carry longitudinal OAM) in the literature and should ultimately make them useful in applications such as optical communications and optical tweezing. We present the mathematical analysis of twisted STOV beams, deriving the mutual coherence function and linear and angular momentum densities. We simulate the …

Specification, Control, And Applications Of Z-Source Circuit Breakers For The Protection Of Dc Power Networks, Sagar Bhatta

Electrical & Computer Engineering Theses & Dissertations

There is a highly-increasing demand for the DC power transmission and distribution in modern power systems for the integration of newly-installed renewable energy resources and storage systems to the existing utilities. Application of DC power systems in electric ships, battery energy devices, high-voltage DC networks, smart grids, electric vehicles, microgrids, and wind farms is a recent trend that is being highly investigated. The fault protection of DC systems is an essential but challenging issue that needs careful attention to maintain system operation reliability and device safety. In this research, the specification, control, and application of Z-source breakers (ZCBs) are investigated …

Color-Compressive Bilateral Filter And Nonlocal Means For High-Dimensional Images, Christina Karam, Kenjiro Sugimoto, Keigo Hirakawa

Electrical and Computer Engineering Faculty Publications

We propose accelerated implementations of bilateral filter (BF) and nonlocal means (NLM) called color-compressive bilateral filter (CCBF) and color-compressive nonlocal means (CCNLM). CCBF and CCNLM are random filters, whose Monte-Carlo averaged output images are identical to the output images of conventional BF and NLM, respectively. However, CCBF and CCNLM are considerably faster because the spatial processing of multiple color channels are combined into a single random filtering process. This implies that the complexity of CCBF and CCNLM is less sensitive to color dimension (e.g., hyperspectral images) relatively to other BF and NLM methods. We experimentally verified that the execution time …

Studying The Conditions For Magnetic Reconnection In Solar Flares With And Without Precursor Flares, Seth H. Garland

Theses and Dissertations

Forecasting of solar flares remains a challenge due to the limited understanding of the triggering mechanisms associated with magnetic reconnection, the primary physical phenomenon connected to these events. Consequently, methods continue to rely on the climatology of solar flare events as opposed to the underlying physics principles. Models of magnetic reconnection in the solar atmosphere places the null point of the reconnection within the corona. Though as of now the coronal magnetic field cannot be directly measured, the field is tied to the photospheric magnetic field, which can be. This study utilized data from the Solar Dynamics Observatory Helioseismic and …

Modeling Aircraft Disturbance Fields For Magnetic Navigation Using Dense Anns And The Novel Manntl Architecture, Kyle A. Emery

Theses and Dissertations

The ability to use GPS for navigation is becoming increasingly limited in certain areas of the world. Knowing this, the Air Force Research Labs is constantly looking for ways to improve alternate navigation methods such as magnetic navigation. In the interest of making advancements in aircraft disturbance field modelling, Lieutenant Emery recreates models from previous works to prove results. Lieutenant Emery also introduces a novel model architecture that attempts to mix the filtering properties of Tolles-Lawson with the non-linear capabilities of an artificial neural network. The introduction of this model could present better aircraft disturbance field modelling and in turn, …

Real-Time Aerial Magnetic And Vision-Aided Navigation, Daniel J. Clarke

Theses and Dissertations

Aerial magnetic navigation has shown to be a viable alternative navigation method that has the potential for world-wide availability, to include over oceans. Obtaining GPS-level accuracy using magnetic navigation alone is challenging, but magnetic navigation can be combined with other alternative navigation methods that are more posed to obtaining GPS-level accuracy in their current state. This research presents an aerial navigation solution combining magnetic navigation and vision-aided navigation to aid an inertial navigation system (INS). The navigation solution was demonstrated in real-time playback using simulated magnetic field measurements and flight-test captured visual imagery. Additionally, the navigation solution was flight-tested on …

Computational Electromagnetic Modeling Of Metasurface Optical Devices With Defect Study, Carlos D. Diaz

Theses and Dissertations

One of the first fabricated metasurface optical devices, the in-plane V-antenna lenses, were plagued by a fundamental transmission limit (<25 >). Two distinct sets of Out-of-Plane phase elements were designed with improved transmission (~60 ). These were fabricated as beamsteerers and characterized in terms of their Bidirectional Transmittance Distribution Function measured as a function of scatter angle. Experimental data from the beamsteerers was analyzed via simulations using a finite element method (FEM). The measurements showed the designed beamsteering, but also a strong zero-order diffraction not present in the simulations, which motivated this study to understand what was causing these differences. …

Source Localization With Machine Learning, Arjun Gupta

Electrical and Computer Engineering ETDs

Source localization with sensor arrays have found applications across domains beginning with radar and sonar, astronomy, acoustics, bio-medical devices and more recently in autonomous cars and adaptive communication systems. The knowledge of the spatial spectrum not only provide information about the source and interference but also assists in increasing signal integrity and avoid interference. This provides an added degree of freedom in the form of spatial diversity. This research investigates spatial spectrum estimation of waveforms from the signals sampled by arbitrarily distributed sensors. Conventional high resolution algorithms such as root-MuSiC fails to perform accurate source localization due to the reliance …

On-Chip Silicon Photonic Controllable 2 × 2 Four-Mode Waveguide Switch, Cao Dung Truong, Duy Nguyen Thi Hang, Hengky Chandrahalim, Minh Tuan Trinh

Faculty Publications

Multimode optical switch is a key component of mode division multiplexing in modern high-speed optical signal processing. In this paper, we introduce for the first time a novel 2 × 2 multimode switch design and demonstrate in the proof-of-concept. The device composes of four Y-multijunctions and 2 × 2 multimode interference coupler using silicon-on-insulator material with four controllable phase shifters. The shifters operate using thermo-optic effects utilizing Ti heaters enabling simultaneous switching of the optical signal between the output ports on four quasi-transverse electric modes with the electric power consumption is in order of 22.5 mW and the switching time …

Design, Development, And Evaluation Of Customized Electronics For Controlling A 5-Dof Magneto-Rheological Actuator Collaborative Robot, Ziqi Yang

Electronic Thesis and Dissertation Repository

In recent years, Magneto-Rheological (MR) fluids has been used in various fields such as robotics, automotive, aerospace, etc. The most common use of the MR fluids is within a clutch-like mechanism, namely an MR clutch. When mechanical input is coupled to the input part of the MR clutch, the MR clutch provides a means of delivering this mechanical input to its output, through the MR fluids. The combination of the mechanical input device and the MR clutch is called an MR actuator. The MR actuator features inherently compliance owing to the characteristic of the MR fluids while also offering higher …

Optical Metasurfaces, Fatih Balli

Theses and Dissertations--Physics and Astronomy

Traditional optical elements, such as refractive lenses, mirrors, phase plates and polarizers have been used for various purposes such as imaging systems, lithographic printing, astronomical observations and display technology. Despite their long-term achievements, they can be bulky and not suitable for miniaturization. On the other hand, recent nanotechnology advances allowed us to manufacture micro and nanoscale devices with ultra-compact sizes. Metasurfaces, 2D engineered artificial interfaces, have emerged as candidates to replace traditional refractive lenses with ultra-thin miniaturized optical elements. They possess sub-wavelength unit cell structures with a specific geometry and material selection. Each unit cell can uniquely tailor the phase, …

Novel Liquid Crystal Photonic Devices Enabled By Liquid Crystal Alignment Engineering, Ziqian He

Electronic Theses and Dissertations, 2020-

Liquid crystals (LCs) are self-assembled soft materials composed of certain anisotropic molecules with orientational orders. Their widespread applications include information displays and photonic devices, such as spatial light modulators for laser beam steering and tunable-focus lens, where achieving desired LC alignment is pivotal. In general, LC alignment is influenced by several factors, including chemical bonding, dipolar interactions, van der Waals interactions, surface topographies, and steric factors. Here, we focus on three alignment techniques for aligning rod-like LC molecules and highlights the photonic devices enabled by these techniques: 1) Two-photon polymerization direct-laser writing-induced alignment, 2) Weigert effect-based reversible photoalignment, and 3) …

Development Of Quantitative Intensity-Based Single-Molecule Assays, Benjamin Croop

Electronic Theses and Dissertations, 2020-

Fluorescence microscopy has emerged as a popular and powerful tool within biology research, owing to its exceptional signal contrast, specificity, and the versatility of the various microscope designs. Fluorescence microscopy has been used to study samples across orders of magnitude in physical scale ranging from tissues to cells, down to single-molecules, and as such has led to breakthroughs and new knowledge in a wide variety of research areas. In particular, single-molecule techniques are somewhat unique in their ability to study biomolecules in their native state, which enables the visualization of short-lived interactions and rare events which can be highly relevant …

Directional Link Management Using In-Band Full-Duplex Free Space Optical Transceivers For Aerial Nodes, A F M Saniul Haq

Electronic Theses and Dissertations, 2020-

Free-space optical (FSO) communication has become very popular for wireless applications to complement and, in some cases, replace legacy radio-frequency for advantages like unlicensed band, spatial reuse, and enhanced security. Even though FSO can achieve very high bit-rate (tens of Gbps), range limitation due to high attenuation and weather dependency has always restricted its practical implementation to indoor application like data centers and outdoor application like Project Loon. Building-to-building communication, smart cars, and airborne drones are potential futuristic wireless communication sectors for mobile ad-hoc FSO networking. Increasing social media usage demands high-speed mobile connectivity for applications like video call and …

Ultraviolet Solar Blind Ga2o3-Based Photodetectors, Isa Hatipoglu

Electronic Theses and Dissertations, 2020-

Detection within the deep ultraviolet (DUV) region (˜200-280 nm) offers unique fundamental advantages to probe certain optical traces. Therefore, many applications have emerged including flame and missile detection, and non-line of sight and space-to-space communication. Ga2O3 has become a natural choice for DUV detection owing to its intrinsic ultra-wide optical bandgap (˜4.85 eV), extrinsic n-type dopability, and excellent chemical and physical stability. However, Ga2O3 has no viable p-type doping to date, and fabricated photodetectors show only partial coverage of the entire solar-blind region (˜200-245nm). Furthermore, there is a limited understanding of how various growth parameters for ß-Ga2O3 and its alloys …

Tunable Optical Filter Using Phase Change Materials For Smart Ir Night Vision Applications, Remona Heenkenda, Keigo Hirakawa, Andrew Sarangan

Electro-Optics and Photonics Faculty Publications

In this paper we present a tunable filter using Ge2Sb2Se4Te1 (GSST) phase change material. The design principle of the filter is based on a metal-insulator-metal (MIM) cavity operating in the reflection mode. This is intended for night vision applications that utilize 850nm as the illumination source. The filter allows us to selectively reject the 850nm band in one state. This is illustrated through several daytime and nighttime imaging applications.