Engineering Commons^™

Ku-Band Ag Channel Modeling, Albert Smith

Theses and Dissertations

With the rise in use of Unmanned Aerial Systems (UAS), there is a need for safe and reliable integration into existing infrastructure. A proposed system for beyond line of sight control links for UAS is a Ku-band air-to-satellite communication system. To ensure this proposed system does not interfere with existing terrestrial infrastructure that operates in the Ku band, an examination of the Ku-band air-to-ground channel is required. The focus of this thesis is the modeling of the Ku-band AG channel. Tests consisting of transmitting a single tone continuous wave signal were conducted with a signal generator onboard NASA’s Viking S-3 …

High Resolution Radiation Detectors Based On 4h-Sic N-Type Epitaxial Layers And Pixilated Cdznte Single Crystal Devices, Cihan Oner

Theses and Dissertations

Silicon Carbide (SiC) is an indirect wide bandgap semiconductor with high thermal conductivity, high breakdown electric field, high carrier saturation drift velocity, and large displacement energy making it a suitable candidate for replacing conventional radiation detectors based on Si, Ge, CdTe, and CdZnTe (CZT). In this dissertation, fabrication and characterization of high-resolution Schottky barrier detectors for alpha particles using 20 µm thick n-type 4H-SiC epitaxial layers are reported. Schottky barriers were obtained by depositing circular nickel contacts of ~10 mm2 area.

Room temperature current-voltage (I-V) measurements revealed Schottky barrier heights of the order of 1.7 eV, ideality factor of ~1.1, …

Role Of Mammary Microenvironment In Promoting Left-Right Differences In Tumor Progression, Metastasis, And Therapeutic Response, Huda Issa Atiya

Theses and Dissertations

Metastasis is the main cause of death in breast cancer patients; however, there are currently no treatments available to treat or prevent metastasis. This is in part because regulators of metastasis are not yet fully understood. Over the past century researchers began to study metastasis regulators by different hypotheses, such as the seed and soil hypothesis which focuses on studying the role of cancer cells, the seeds, and the tissue microenvironment, the soil, in regulating metastasis. Although lots of studies have focused on the microenvironment of metastatic sites and their roles in regulating metastasis, limited studies have focused on the …

Novel Topologies Based Rf Filtering Components And Methodologies For Wireless Communication System, Wei Jiang

Theses and Dissertations

Driven by the rapid progress of wireless communication technology in the past several decades, multiple generations of cellular technologies have been developed, deployed, and adopted to provide more convenient communication services to users. Nowadays, the personal hand-held devices, supporting multiple wireless standards, have been a multimedia terminal encompassing elements and functions such as video callers, Internet connectivity, home appliances remote controller, GPS, TV reception, and beyond. In order to accommodate a variety of wireless standards in a single device without imposing a substantial increase in cost and size, current and future RF transceiver front-ends should be designed with more attention. …

Photovoltaic Inverter Control To Sustain High Quality Of Service, Yan Chen

Theses and Dissertations

The increasing penetration of distributed solar photovoltaic (PV) generation presents both challenges and opportunities for distribution systems. The intermittent nature of solar irradiance may lead to power quality degradation. At the same time, PV inverters –if properly designed and operated– can be used to improve power quality. The goal of this dissertation is to develop power flow optimization methods for power distribution networks with high penetration of PV generation. The approaches proposed in this dissertation have been tested using the modified version of the IEEE 34-node distribution system and the IEEE 123-node distribution system, as well as the validated model …

Study Of 4h-Sic And Alxga1-Xn Based Heterojunction Devices For Ultraviolet Detection Applications, Venkata Surya Naga Raju Chava

Theses and Dissertations

Ultraviolet (UV) detectors are important for their applications in flame detection, furnace gas control systems, plume monitoring etc. Due to their wide band-gap, 4H-SiC (Eg=3.26eV) and III-V semiconductors such as GaN (Eg=3.4eV), AlxGa1-xN (Eg=3.4eV to 6.2eV) etc., are excellent candidates for visible(��cut-0ff=400nm) and solar blind(��cut-0ff=290nm) UV detectors. Conventional SiC UV detectors suffer from poor UV responsivities due to reflection/absorption/transmission losses caused by the metal electrodes used in those detectors.

In the first part, a novel bipolar transistor with epitaxial graphene(EG)/p-SiC (30μm)/n+-SiC substrate was fabricated and characterized. The 2-3 ML thick, transparent and conducting, EG used in this work was grown …

Enhancements In Alginate Microencapsulation Technology & Impacts On Cell Therapy Development, Marwa Belhaj

Theses and Dissertations

Biodegradable alginate microcapsules (MC) are recently becoming widely used in the biomedical field, and have shown effectiveness as a drug delivery system. Alginate has been used in microencapsulation due to its simple gelling process, biodegradability, excellent biocompatibility, and its stability under in-vivo conditions. Alginate polymer is a natural polysaccharide derived from brown seaweed and has the ability to polymerize rapidly in the presence of cations to form a porous matrix. In order to advance the previous system for efficient protein and peptide delivery, we further lyophilized the peptide-filled microcapsules and we were able to rehydrate, and test them for sustained …

Novel Wideband Ebg Structures For Isolation Improvement Between Cosite Antennas, Paul John Czeresko Iii

Theses and Dissertations

As the number of installed antennas increases on a structure, the available real estate to do so without each antenna interfering with the others diminishes. Electromagnetic band gap (EBG) structures are one way to mitigate this cosite interference with compact antenna installations. While a host of EBG structures and types (3-D, planar etc.) have been proposed and studied historically, it has been found that planar EBG structures tend to provide very narrow bandwidths for both antenna design and cosite interference reduction. This research focuses on the design of EBG structures intended to achieve greater than 20 dB of isolation improvement …

Quantifying Time Retarded Electromagnetic Fields And Their Applications In Transmission Lines, Brandon Thomas Gore

Theses and Dissertations

Modern baseband signaling that facilitates the passing of information over high speed interconnects such as copper twin-ax cable and printed circuit boards supports single line data rates of 100 Gbps. Next generation bandwidth requirements of electrical links are approaching frequencies up to 50 GHz. Yet, signal integrity engineers that analyze these interconnects rely on models with underlying assumptions and limited extensions beyond those proposed in the 19th century to describe per unit length characteristics of Resistance, Inductance, Conductance, and Capacitance (RLGC) for transatlantic telegraph cable. An excluded phenomenon is the time retarded behavior of electromagnetic fields. The aim of this …

Structurally Integrated Reconfigurable Wideband Array For Conformal Applications, Michael Damon Wright

Theses and Dissertations

Structurally integrated conformal antennas offer significant advantages over traditional bolt on antennas, especially for air vehicle applications. The ability to leverage the entire structure allows for unconventionally large antennas and arrays to be implemented in a manner which does not detract from the aerodynamic, structural or aesthetic qualities of the vehicle. Works along this line have included Slotted Waveguide Antenna Stiffened Structures (SWASS), conformal helix and spiral antennas, Log Periodic Dipole Arrays (LPDA), and other antennas.

An area which has not been investigated to date is the possibility of implementing reconfigurable antennas in a structural environment. There are inherent challenges …

Multifunction Radio Frequency Composite Structures, David L. Zeppettella

Theses and Dissertations

There has been recent interest in the development of multifunction structures for weight-critical applications. A multifunction structure is a load-bearing structure that also allows one or more additional functions such as RF communication, energy storage, sensing etc. The focus of this dissertation is to analyze, design, develop, and test new high performance (broadband, high gain, circularly polarized) internal antennas that are structural and integral to the aircraft. It is demonstrated that antennas with more bandwidth and higher efficiency could be developed if the space and materials available in an aircraft structure could be judiciously exploited for multifunctional usage. This is …