Digital Commons Network^™

Multidimensional Waveform Shaping In Multicarrier Systems, Ertugrul Guvenkaya

USF Tampa Graduate Theses and Dissertations

Constantly increasing demand for wireless communications in various applications has always led to new ways of modulating the radio frequency (RF) carrier signal by advancing waveform structure throughout generations. Although communication data rates are limited by the theoretical capacity, specific signaling designs for the signal that experiences natural and artificial effects in the transmission medium such as multipath fading channel, hardware impairments and multiuser environment promised better solutions in providing improved wireless access to various type of users and networks. Besides communication capacity, broadcasting nature of radio signals poses the information security as another main concern in wireless communications. In …

Optical Communication Using Hybrid Micro Electro Mechanical Structures (Mems) And Commercial Corner Cube Retroreflector (Ccr), Sunny Kedia

USF Tampa Graduate Theses and Dissertations

This dissertation presents a free-space, long-range, passive optical communication system that uses electrostatically modulated microelectromechanical systems (MEMS) structures coupled with a glass total internal reflection (TIR)-type corner cube retroreflector (CCR) as a non-emitting data transmitter. A CCR consists of three mirrors orthogonal to each other, so that the incident beam is reflected back to the incident beam, source. The operational concept is to have a MEMS modulator fusion with TIR CCR, such that the modulators are working periodically to disrupt the evanescent waves at the air interface of one of the three back glass faces of a TIR CCR. The …

Near-Field Microwave Microscopy For Surface And Subsurface Characterization Of Materials, Maria Fernanda Cordoba Erazo

USF Tampa Graduate Theses and Dissertations

This dissertation presents an investigation on the capabilities of Near-Field Microwave Microscopy (NFMM) for the characterization of surface and subsurface materials. Subsurface characterization refers to the detection, differentiation and imaging of dielectric, and metallic features that are coated with an insulating layer. The design, simulation and modeling, and testing of a dielectric resonator (DR)-based NFMM and a coaxial transmission line resonator-based NFMM are discussed in detail in this work. Additionally, materials differentiation and imaging capabilities of each microscope are examined using several bulk samples, liquids, GaAs MMIC circuits, and gold/glass testing patterns.

The 5.7 GHz DR-based NFMM uses a microwave …

Operation And Monitoring Of Parabolic Trough Concentrated Solar Power Plant, Harsha Vardhan Amba

USF Tampa Graduate Theses and Dissertations

The majority of the power generated today is produced using fossil fuels,emitting carbon dioxide and other pollutants every second. Also, fossil fuels will eventually run out. For the increasing worldwide energy demand, the use f reliable and environmentally beneficial natural energy sources is one of the biggest challenges. Alongside wind and water, the solar energy which is clean, CO2-neutral and limitless, is our most valuable resource.

Concentrated solar power (CSP) is becoming one of the excellent alternative sources for the power industry. The successful implementation of this technology requires the efficient design of tracking and operation system of the CSP …

A Study Of Digital Rf Phase Shifters Fabricated With Additive Manufacturing, Yaniel Vega

USF Tampa Graduate Theses and Dissertations

Digital RF phase shifters fabricated using additive manufacturing processes are presented and studied. The purpose is to explain the performance differences between phase shifters fabricated using additive manufacturing and those fabricated with conventional subtractive techniques. All phase shifters are designed to operate at a center frequency of 2.45 GHz with a 100 MHz bandwidth. The 1-bit 45° switched line phase shifters have an average insertion loss of 1.3 dB and a 220 mm² footprint, while the 1-bit 180° high-pass low-pass phase shifters have an insertion loss 1.56 dB and a 180 mm² footprint. The 4-bit high-pass low-pass, switched …

Embedded System Design Of A Real-Time Parking Guidance System, Omkar Dokur

USF Tampa Graduate Theses and Dissertations

The primary objective of this work is to design a parking guidance system to reliably detect entering/exiting vehicles to a parking garage in a cost-efficient manner. Existing solutions (inductive loops, RFID based systems, and video image processors) at shopping malls, universities, airports etc., are expensive due to high installation and maintenance costs. There is a need for a parking guidance system that is reliable, accurate, and cost-effective. The proposed parking guidance system is designed to optimize the use of parking spaces and to reduce wait times. Based on a literature review we identify that the ultrasonic sensor is suitable to …

A Study Of Direct Digital Manufactured Rf/Microwave Packaging, John W.I. Stratton

USF Tampa Graduate Theses and Dissertations

Various facets of direct digital manufactured (DDM) microwave packages are studied. The rippled surface inherent in fused deposition modeling (FDM) fabricated geometries is modeled in Ansoft HFSS, and its effect on the performance of microstrip transmission lines is assessed via simulation and measurement. The thermal response of DDM microstrip transmission lines is analyzed over a range of RF input powers, and linearity is confirmed over that range.

Two IC packages are embedded into DDM printed circuit boards, and their performance is analyzed. The first is a low power RF switch, and the second is an RF front end device that …

Bio-Photoelectrochemical Solar Cells Incorporating Reaction Center And Reaction Center Plus Light Harvesting Complexes, Houman Yaghoubi

USF Tampa Graduate Theses and Dissertations

Harvesting solar energy can potentially be a promising solution to the energy crisis now and in the future. However, material and processing costs continue to be the most important limitations for the commercial devices. A key solution to these problems might lie within the development of bio-hybrid solar cells that seeks to mimic photosynthesis to harvest solar energy and to take advantage of the low material costs, negative carbon footprint, and material abundance. The bio-photoelectrochemical cell technologies exploit biomimetic means of energy conversion by utilizing plant-derived photosystems which can be inexpensive and ultimately the most sustainable alternative. Plants and photosynthetic …

Optimization And Control For Microgrid And Power Electronic Converters, Vahid Rasouli Disfani

USF Tampa Graduate Theses and Dissertations

The proposed dissertation research investigates Optimization and Control for Microgrid and Power Electronic Converters. The research has two major parts:

i- Microgrid Operation and Control,

ii- Power Electronic Converter Control and Optimization.

In the first part, three focuses are investigated. First, a completely distributed algorithm is developed for dc optimal power flow problem for power distribution systems as one of the necessary functions considered in unit-commitment problem in day-ahead markets. This method is derived based upon the partial primal-dual representation of the economic dispatch problem, which is finally translated to DC-OPF problem. Second, the optimal interaction between the utility and …

A Study On 2.45 Ghz Bandpass Filters Fabricated With Additive Manufacturing, Nicholas Christian Arnal

USF Tampa Graduate Theses and Dissertations

Square open loop resonator (SOLR) bandpass filters fabricated with additive manufacturing techniques are presented and studied. One filter contains novel 3D capacitive plates used to enhance resonator coupling. The filters are centered at 2.45 GHz and loaded with capacitors for miniaturization as low as 21% that of a conventional SOLR bandpass filter. The pass-band insertion loss of the filters ranges from 3.8 dB to 5.5 dB and the 3 dB bandwidth ranges from 180 MHz to 250 MHz. Also, degradation in the effective conductivity of printed ink as a function of substrate roughness is analyzed. Finally, a study of dielectric …

Improving System Performance In Cellular And Wban Networks Via User-Specific Qos And Mimo In Vivo Technologies, Chao He

USF Tampa Graduate Theses and Dissertations

This dissertation is composed of two independent studies: Cellular research and WBAN (Wireless Body Area Network) research. Both investigations are directed towards improving the system performance in wireless communication systems in terms of Quality of Service (QoS) and system capacity.

For the Cellular research part, this dissertation will present novel user-specific QoS requirements as defined by their respective Mean Opinion Score (MOS) formulas, and associated schedulers for wireless applications and systems that optimize spectral allocation. User-specific QoS requirements are defined and several methods to make use of such requirements to maximum the spectral utilization are presented. Five User-Specific QoS Aware …

Fabrication And Characterization Of Polycarbonate Polyurethane (Pcpu) Nanofibers Impregnated With Nanofillers, Hruday Chand Katakam

USF Tampa Graduate Theses and Dissertations

Polycarbonate polyurethane (PCPU) has been studied as a novel polymer impregnated with nanoparticles for improved mechanical, thermal and adhesion properties [4]. This study investigates the synthesis of polycarbonate polyurethane (PCPU) polymeric nanofiber membranes by the process of electrospinning. This study further examines all the parameters associated with electrospinning a novel PCPU polymeric solution impregnated with nanofillers, such as nanoparticles, to produce fiber membranes. Tetrahydrofuran (THF) and N, N dimethylformamide (DMF) are used as solvents to dissolve PCPU polymer. One percent (1%) of nanofillers like silver and silica nanoparticles are added to PCPU polymer solution to investigate the impact on polymer …

Investigation Of Opuntia Ficus-Indica Mucilage Nanofiber Membrane Filtration For Water Systems, Rasudha Muppaneni

USF Tampa Graduate Theses and Dissertations

This work investigates the fabrication, characterization and testing of Opuntia ficus-indica mucilage nanofibers to be utilized in water filtration systems. These mucilage nanofibers are formed using different polymers through a process called electrospinning. The polymers used to promote the formation of nanofibers are poly vinyl alcohol (PVA) and polystyrene (PS). The mucilage is a jelly like substance extracted from the pads of the cactus plant. It is a mixture of proteins, complex polysaccharides and monosaccharaides. It is an inexpensive, non-toxic, biodegradable and biocompatible material which is present in abundance. The mucilage extracted from the pads is mixed with acetic acid …

Design, Fabrication And Characterization Of Mim Diodes And Frequency Selective Thermal Emitters For Solar Energy Harvesting And Detection Devices, Saumya Sharma

USF Tampa Graduate Theses and Dissertations

Energy harvesting using rectennas for infrared radiation continues to be a challenge due to the lack of fast switching diodes capable of rectification at THz frequencies. Metal insulator metal diodes which may be used at 30 THz must show adequate nonlinearity for small signal rectification such as 30 mV. In a rectenna assembly, the voltage signal received as an output from a single nanoantenna can be as small as ~30µV. Thus, only a hybrid array of nanoantennas can be sufficient to provide a signal in the ~30mV range for the diode to be able to rectify around 30THz. A metal-insulator-metal …

Rf Mems Resonators For Mass Sensing Applications, Ivan Fernando Rivera

USF Tampa Graduate Theses and Dissertations

Sensing devices developed upon resonant microelectromechanical and nanoelectromechanical (M/NEMS) system technology have become one of the most attractive areas of research over the past decade. These devices make exceptional sensing platforms because of their miniscule dimensions and resonant modes of operation, which are found to be extremely sensitive to added mass. Along their unique sensing attributes, they also offer foundry compatible microfabrication processes, low DC power consumption, and CMOS integration compatibility. In this work, electrostatically and piezoelectrically actuated RF MEMS bulk resonators have been investigated for mass sensing applications. The capacitively-transduced resonators employed electrostatic actuation to achieve desired resonance mode …

A Novel Update To Dynamic Q Algorithm And A Frequency-Fold Analysis For Aloha-Based Rfid Anti-Collision Protocols, Nikita Khanna

USF Tampa Graduate Theses and Dissertations

Radio frequency identification (RFID) systems are increasingly used for a wide range of applications from supply chain management to mobile payment systems. In a typical RFID system, there is a reader/interrogator and multiple tags/transponders, which can communicate with the reader. If more than one tag tries to communicate with the reader at the same time, a collision occurs resulting in failed communications, which becomes a significantly more important challenge as the number of tags in the environment increases. Collision reduction has been studied extensively in the literature with a variety of algorithm designs specifically tailored for low-power RFID systems.

In …

Synthesis And Fabrication Of Graphene/Conducting Polymer/Metal Oxide Nanocomposite Materials For Supercapacitor Applications, Mohamad Khawaja

USF Tampa Graduate Theses and Dissertations

The rising energy consumption worldwide is leading to significant increases in energy production with fossil fuels being the major energy source. The negative environmental impact of fossil fuel use and its finite nature requires the use of alternative sources of energy. Solar energy is a clean alternative energy source; however, its intermittent nature is a major impediment that needs to be reduced or eliminated by the development of cost effective energy storage. Thermal storage in tanks filled typically with molten salt at elevated temperatures is widely used in concentrating solar power plants to generate electricity during periods of low daytime …

Combinational Watermarking For Medical Images, Thrilok Chakravarthy Chinna Narayana Swamy

USF Tampa Graduate Theses and Dissertations

Digitization of medical data has become a very important part of the modern healthcare system. Data can be transmitted easily at any time to anywhere in the world using Internet to get the best diagnosis possible for a patient. This digitized medical data must be protected at all times to preserve the doctor-patient confidentiality. Watermarking can be used as an effective tool to achieve this.

In this research project, image watermarking is performed both in the spatial domain and the frequency domain to embed a shared image with medical image data and the patient data which would include the patient …

Region Of Interest Based Compression Of Grayscale Images, Adhokshaja Achar Budihal Prasad

USF Tampa Graduate Theses and Dissertations

Image compression based on Region of Interest (ROI) has been one of the hot topics of interest in image processing. There is not a single widely accepted method for detecting the ROI automatically form an image. To reduce the transmission bandwidth and storage space requirements of gray scale images, an algorithm is suggested for detecting the ROI automatically based on Tsallis entropy method.

Tsallis entropy method is used to segment the image into two segments, the ROI and the background. These two segments can then be compressed at different rates, to avoid losing information in the ROI while achieving a …