Electromagnetics and Photonics Commons^™

Magnetotelluric Analysis Of Central Kenya Kenyan Rift Volcanoes For Geothermal Development, Anna Wairimu Mwangi

Open Access Theses & Dissertations

Abstract

High temperature geothermal resources are vast along rift margins because of emplacement of magma in shallow crust. This is the case along the Kenyan Rift valley also known as the Gregory Rift. It is the Eastern arm of the East African rift and a chain of volcanoes along the rift graben characterizes it. We use (MT) magnetotelluric method to image beneath the peralkaline province of the Kenya Rift i.e. Olkaria, Eburru, Badlands, and Longonot volcanoes. The resistivity structure shows active geothermal activity happening at the upper 3km from the subsurface as evidenced by low resistivity cap rock comprised of …

Passive Self-Interference Suppression For Single Channel Full-Duplex Operation, Adam Narbudowicz, Giuseppe Ruvio, Max Ammann

Articles

Full duplex radios have become a topic of increased interest in the wireless communications community. As part of this development, many efforts were directed to passively decrease the self-interference level at the antenna outputs. However, in many proposed solutions transmission and reception occur through different propagation channels. This paper demonstrates and quantifies the negative impact of channel differentiation on pivotal applications of full-duplex radio, such as cognitive radio. Antenna designs used for self-interference suppression in full-duplex radio architectures are analyzed. In order to ensure that transmission and reception occur within the same propagation channel, the use of the envelope correlation …

Coexistence And Secure Communication In Wireless Networks, Saygin Bakşi

Electrical & Computer Engineering Theses & Dissertations

In a wireless system, transmitted electromagnetic waves can propagate in all directions and can be received by other users in the system. The signals received by unintended receivers pose two problems; increased interference causing lower system throughput or successful decoding of the information which removes secrecy of the communication. Radio frequency spectrum is a scarce resource and it is allocated by technologies already in use. As a result, many communication systems use the spectrum opportunistically whenever it is available in cognitive radio setting or use unlicensed bands. Hence, efficient use of spectrum by sharing users is crucial to increase maximize …

Developing A Methodology For Estimating The Growth Of Radiated Emission From Multi-Modular Systems, Kaustav Ghosh

Masters Theses

"The large multiscale problems are commonly faced in real-world applications such as analysis of electromagnetic interference for a printed circuit board installed on a large platform with connected cables, wires and other high speed interfaces. EMI problems are not uncommon in high speed systems which involve multiple modules of complex hardware. As the system clock frequency and data rate increases, so does the challenges in controlling the EMI in such systems. The costs to prototype and to develop networking equipment are growing as a result of increasing complexities and densities. EMC regulations require radiated emission testing to be done in …

Tvs Transient Behavior Modeling Method, And System-Level Effective Esd Design For Usb3.X Interface, Pengyu Wei

Masters Theses

"This research proposal presents a methodology whereby a protection device can be modeled in SPICE compatible platforms with respect to the transient behaviors during Electrostatic Discharge (ESD) events. This methodology uses an exclusively "black-box" approach to characterize the parameters of the protection device, thereby allowing it to be implemented without intimate knowledge of the DUT. Results of this methodology can be used to predict the transient response (conductivity modulation and snapback delay) of the ESD protection devices, and thereby predicts how much current could flow into the device (typically a digital IO pin) under protection. The transient behavior modeling methodology …

Development Of Hollow Coaxial Cable Fabry Perot Resonator For High Temperature Sensing Applications, Mohammed Farhan Ahmed

Masters Theses

"The thesis is comprised of two papers, the first paper presents the novel High-Quality Factor Coaxial Cable Fabry-Perot Resonator for sensing applications. The sensor is fabricated by creating two highly reflective mirrors in a coaxial cable. The temperature response of the sensor was tested, by monitoring the frequency shift of the reflection spectra as the temperature increased linearly from 35 °C to 80 °C in steps of 5 °C. The sensor exhibited high temperature sensitivity and good measurement resolution.

A high Q factor of 133 was recorded. The second paper in the thesis presents a low cost, robust, homemade hollow …

Speckle Effects In Target-In-The-Loop Laser Beam Projection Systems, Mikhail Vorontsov

Electro-Optics and Photonics Faculty Publications

In target-in-the-loop laser beam projection scenarios typical of remote sensing, directed energy, and adaptive optics applications, a transmitted laser beam propagates through an optically inhomogeneous medium toward a target, scatters off the target’s rough surface, and returns back to the transceiver plane. Coherent beam scattering off the randomly rough surface results in strong speckle modulation in the transceiver plane. This speckle modulation has been a long-standing challenge that limits performance of remote sensing, active imaging, and adaptive optics techniques. Using physics-based models of laser beam scattering off a randomly rough surface, we show that received speckle-field spatial and temporal characteristics …

Recursive Non-Local Means Filter For Video Denoising, Redha A. Ali, Russell C. Hardie

Electrical and Computer Engineering Faculty Publications

In this paper, we propose a computationally efficient algorithm for video denoising that exploits temporal and spatial redundancy. The proposed method is based on non-local means (NLM). NLM methods have been applied successfully in various image denoising applications. In the single-frame NLM method, each output pixel is formed as a weighted sum of the center pixels of neighboring patches, within a given search window.

The weights are based on the patch intensity vector distances. The process requires computing vector distances for all of the patches in the search window. Direct extension of this method from 2D to 3D, for video …

Generalized Ellipsometry On Complex Nanostructures And Low-Symmetry Materials, Alyssa Mock

Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research

In this thesis, complex anisotropic materials are investigated and characterized by generalized ellipsometry. In recent years, anisotropic materials have gained considerable interest for novel applications in electronic and optoelectronic devices, mostly due to unique properties that originate from reduced crystal symmetry. Examples include white solid-state lighting devices which have become ubiquitous just recently, and the emergence of high-power, high-voltage electronic transistors and switches in all-electric vehicles. The incorporation of single crystalline material with low crystal symmetry into novel device structures requires reconsideration of existing optical characterization approaches. Here, the generalized ellipsometry concept is extended to include applications for materials with …

Modeling And Simulation Of Iii-Nitride-Based Solar Cells Using Nextnano®, Malak Refaei

Graduate Theses and Dissertations

Nextnano³ software is a well-known package for simulating semiconductor band-structures at the nanoscale and predicting the general electronic structure. In this work, it is further demonstrated as a viable tool for the simulation of III-nitride solar cells. In order to prove this feasibility, the generally accepted solar cell simulation package, PC1D, was chosen for comparison. To critique the results from both PC1D and Nextnano3, the fundamental drift-diffusion equations were used to calculate the performance of a simple p-n homojunction solar cell device analytically. Silicon was picked as the material for this comparison between the outputs of the two simulators as …

Free-Space Measurements Of Dielectrics And Three-Dimensional Periodic Metamaterials, Clifford E. Kintner

Graduate Theses and Dissertations

This thesis presents the free-space measurements of a periodic metamaterial structure. The metamaterial unit cell consists of two dielectric sheets intersecting at 90 degrees. The dielectric is a polyetherimide-based material 0.001” thick. Each sheet has a copper capacitively-loaded loop (CLL) structure on the front and a cut-wire structure on the back. Foam material is used to support the unit cells. The unit cell repeats 40 times in the x-direction, 58 times in the y-direction and 5 times in the z-direction. The sample measures 12” × 12” × 1” in total. We use a free-space broadband system comprised of a pair …

A High Accuracy Microwave Radiometric Thermometer To Measure Internal Body Temperature, Michael D. Grady

USF Tampa Graduate Theses and Dissertations

The Center for Disease Control and Prevention (CDC) released heat illness data which highlighted that ~29 heat stress hospitalizations and ~3 heat-related deaths occurred every day during the summer months within the US from years 2000 to 2014. Heatstroke- the most severe form of heat illness which oftentimes lead to death- has been cited to be entirely preventable if a timely intervention is introduced. This dissertation uses microwave radiometric thermometry to perform wireless non-invasive internal body temperature monitoring which can enable intervention methods that help to prevent deaths associated with heat-illness.

Overall, this dissertation develops a comprehensive closed-form analytical radiometric …

Direct Digital Manufacturing Of Multi-Layer Wideband Ku-Band Patch Antennas, Merve Kacar

USF Tampa Graduate Theses and Dissertations

Design and performance of fully-printed Ku-band aperture coupled patch antennas fabricated by a direct digital manufacturing (DDM) approach that integrates fused deposition modeling (FDM) of acrylonitrile butadiene styrene (ABS) thermoplastic with in-situ micro-dispensing of conductive silver paste (CB028) are reported. Microstrip line characterizations are performed and demonstrate that misalignment of ABS substrate deposition direction with microstrip line micro-dispensing direction can degrade the effective conductivity up to 60% within the Ku-band, and must be taken into consideration in antenna array feed network designs. Specically, over 125 µm thick ABS substrate, RF loss of 0.052 dB/mm is obtained at 18 GHz, demonstrating …

Design And Simulation Of A Miniature Cylindrical Mirror Auger Electron Energy Analyzer With Secondary Electron Noise Suppression, Jay A. Bieber

USF Tampa Graduate Theses and Dissertations

In the nanoscale metrology industry, there is a need for low-cost instruments, which have the ability to probe the structrure and elemental composition of thin films. This dissertation, describes the research performed to design and simulate a miniature Cylindrical Mirror Analyzer, (CMA), and Auger Electron Spectrometer, (AES). The CMA includes an integrated coaxial thermionic electron source. Electron optics simulations were performed using the Finite Element Method, (FEM), software COMSOL. To address the large Secondary Electron, (SE), noise, inherent in AES spectra, this research also included experiments to create structures in materials, which were intended to suppress SE backgound noise in …

Design Of Post-Consumer Modification Of Standard Solar Modules To Form Large-Area Building-Integrated Photovoltaic Roof Slates, Joshua M. Pearce, Jay Meldrum, Nolan Osborne

Department of Materials Science and Engineering Publications

Building-integrated photovoltaic (BIPV) systems have improved aesthetics but generally cost far more than conventional PV systems because of small manufacturing scale. Thus, in the short and medium term, there is a need for a BIPV mounting system that utilizes conventional modules. Such a design is provided here with a novel modification of conventional photovoltaic (PV) modules to allow them to act as BIPV roofing slates. The open-source designs for the mechanical components necessary to provide the post-consumer conversion for a conventional PV module are provided, and prototypes are fabricated and installed on a mock roof system along with control modules …

Design And Modeling Of A High-Power Periodic Spiral Antenna With An Integrated Rejection Band Filter, Jonathan M. O'Brien

USF Tampa Graduate Theses and Dissertations

This work details the design and fabrication of an ultra-wideband periodic spiral antenna (PSA) with a notch filter embedded directly into the radiating aperture. Prototype fabrication of the PSA reveals long assembly time due to forming the antenna element, therefore modifications are made to allow fabricating the antenna elements on a thin, flexible, Polyimide substrate. A transmission line model is develop to support the updated configuration of the antenna elements. In addition, a symmetric spurline filter is integrated into the arms of the spiral antenna in order to address the common problem of interference in ultra-wideband systems. For the first …

Analysis Of The Joint Impact Of Atmospheric Turbulence And Refractivity On Laser Beam Propagation, Victor A. Kulikov, Mikhail Vorontsov

Electro-Optics and Photonics Faculty Publications

A laser beam propagation model that accounts for the joint effect of atmospheric turbulence and refractivity is introduced and evaluated through numerical simulations. In the numerical analysis of laser beam propagation, refractive index inhomogeneities along the atmospheric propagation path were represented by a combination of the turbulence-induced random fluctuations described in the framework of classical Kolmogorov turbulence theory and large-scale refractive index variations caused by the presence of an inverse temperature layer. The results demonstrate that an inverse temperature layer located in the vicinity of a laser beam’s propagation path may strongly impact the laser beam statistical characteristics including the …

Electrostatic Sail - Tether Deployment Testbed, Davis Hunter

Von Braun Symposium Student Posters

No abstract provided.

Nanowire-Based Light-Emitting Diodes: A New Path Towards High-Speed Visible Light Communication, Mohsen Nami

Physics & Astronomy ETDs

Nano-scale optoelectronic devices have gained significant attention in recent years. Among these devices are semiconductor nanowires, whose dimeters range from 100 to 200 nm. Semiconductor nanowires can be utilized in many different applications including light-emitting diodes and laser diodes. Higher surface to volume ratio makes nanowire-based structures potential candidates for the next generation of photodetectors, sensors, and solar cells. Core-shell light-emitting diodes based on selective-area growth of gallium nitride (GaN) nanowires provide a wide range of advantages. Among these advantages are access to non-polar m-plane sidewalls, higher active region area compared to conventional planar structures, and reduction of threading …

Spin-Imbalance In A 2d Fermi-Hubbard System, Peter Brown, Debayan Mitra, Elmer Guardado-Sanchez, Peter Schauß, Stanimir Kondov, Ehsan Khatami, Thereza Paiva, Nandini Trivedi, David Huse, Waseem Bakr

Faculty Publications

The interplay of strong interactions and magnetic fields gives rise to unusual forms of superconductivity and magnetism in quantum many-body systems. Here, we present an experimental study of the two-dimensional Fermi-Hubbard model—a paradigm for strongly correlated fermions on a lattice—in the presence of a Zeeman field and varying doping. Using site-resolved measurements, we revealed anisotropic antiferromagnetic correlations, a precursor to long-range canted order. We observed nonmonotonic behavior of the local polarization with doping for strong interactions, which we attribute to the evolution from an antiferromagnetic insulator to a metallic phase. Our results pave the way to experimentally mapping the low-temperature …