Physical Sciences and Mathematics Commons^™

Hierarchy Of Supramolecular Synthons In The Of Design Multi-Component Crystals, Padmini Kavuru

USF Tampa Graduate Theses and Dissertations

Most of the biological systems in nature are sustained by molecular self-assemblies which are the finest examples of supramolecular architectures. Non-covalent interactions are key concepts which govern these molecular assemblies. Inspired by these examples crystal engineering emerged as an important tool in supramolecular chemistry which aids in the invention of new molecular structures with desired properties. Understanding of how the molecules interact at the molecular levels enables one to rationally design novel solid forms with modulated physicochemical properties. This feature of crystal engineering has heightened its position in materials chemistry and is currently one of the most well studied fields …

A Location-Aware Architecture Supporting Intelligent Real-Time Mobile Applications, Sean J. Barbeau

USF Tampa Graduate Theses and Dissertations

This dissertation presents LAISYC, a modular location-aware architecture for intelligent real-time mobile applications that is fully-implementable by third party mobile app developers and supports high-precision and high-accuracy positioning systems such as GPS. LAISYC significantly improves device battery life, provides location data authenticity, ensures security of location data, and significantly reduces the amount of data transferred between the phone and server. The design, implementation, and evaluation of LAISYC using real mobile phones include the following modules: the GPS Auto-Sleep module saves battery energy when using GPS, maintaining acceptable movement tracking (approximately 89% accuracy) with an approximate average doubling of battery life. …

Surface Mass Transfer In Large Eddy Simulation (Les) Of Langmuir Turbulence, Cigdem Akan

USF Tampa Graduate Theses and Dissertations

Over the past century the study of gas exchange rates between the atmosphere and the ocean has received increased attention because of concern about the fate of greenhouse gases such as CO₂ released into the atmosphere. Of interest is the oceanic uptake of CO₂ in shallow water coastal regions as biological productivity in these regions is on average about three times larger than in the open ocean. It is well-known that in the absence of breaking surface waves, the water side turbulence controls gas transfer of sparingly soluble gases such as CO₂ from the air to the …

Innovative Desalination Systems Using Low-Grade Heat, Chennan Li

USF Tampa Graduate Theses and Dissertations

Water and energy crises have forced researchers to seek alternative water and energy sources. Seawater desalination can contribute towards meeting the increasing demand for fresh water using alternative energy sources like low-grade heat. Industrial waste heat, geothermal, solar thermal, could help to ease the energy crisis.

Unfortunately, the efficiency of the conventional power cycle becomes

uneconomically low with low-grade heat sources, while, at the same time, seawater desalination requires more energy than a conventional water treatment process. However, heat discarded from low-grade heat power cycles could be used as part of desalination energy sources with seawater being used as coolant …

Functional Magnetic Nanoparticles, James Gass

USF Tampa Graduate Theses and Dissertations

Nanoparticle system research and characterization is the focal point of this research and dissertation. In the research presented here, magnetite, cobalt, and ferrite nanoparticle systems have been explored in regard to their magnetocaloric effect (MCE) properties, as well as for use in polymer composites. Both areas of study have potential applications across a wide variety of interdisciplinary fields.

Magnetite nanoparticles have been successfully dispersed in a polymer. The surface chemistry of the magnetic nanoparticle proves critical to obtaining a homogenous and well separated high density dispersion in PMMA. Theoretical studies found in the literature have indicated that surface interface energy …

Algorithms For Visual Maritime Surveillance With Rapidly Moving Camera, Sergiy Fefilatyev

USF Tampa Graduate Theses and Dissertations

Visual surveillance in the maritime domain has been explored for more than a decade. Although it has produced a number of working systems and resulted in a mature technology, surveillance has been restricted to the port facilities or areas close to the coastline assuming a fixed-camera scenario. This dissertation presents several contributions in the domain of maritime surveillance. First, a novel algorithm for open-sea visual maritime surveillance is introduced. We explore a challenging situation with a camera mounted on a buoy or other floating platform. The developed algorithm detects, localizes, and tracks ships in the field of view of the …

Investigation And Synthesis Of Novel Graphene-Based Nanocomposites For Hydrogen Storage, Anthony Joseph D'Angelo

USF Tampa Graduate Theses and Dissertations

It is of great interest to develop and utilize a high surface area material with optimized hydrogen sorption properties. The need for a renewable energy source to replace automobile gasoline has become more critical in the past decade. Hydrogen is a viable fuel source for automobile usage; however, the question of how hydrogen will be safely and efficiently stored still remains. Critical factors for optimum hydrogen storage include ambient conditions and low activation temperature for adsorption and desorption phenomena. In order for optimum hydrogen adsorption to be achieved, the properties of (1) high surface area, (2) optimum hydrogen adsorption energy, …

Multidimensional Spectroscopy Of Semiconductor Quantum Dots, Jason Michael Bylsma

USF Tampa Graduate Theses and Dissertations

The coherent properties of semiconductor nanostructures are inherently difficult to measure and one-dimensional spectroscopies are often unable to separate inhomogeneous and homogeneous linewidths. We have refined and improved a method of performing multidimensional Fourier transform spectroscopy based on four-wave

mixing (FWM) experiments in the box geometry. We have modified our system with broadband beamsplitters in all interferometer arms, high-resolution translation stages and the ability to work in reflection geometry. By improving the phase-stability of our setup and scanning pulse delays with sub-optical cycle precision, we are able to

reproduce 2DFT spectra of GaAs multiple quantum wells. With the FWM signal …

Willingness-To-Pay For Maintenance And Improvements To Existing Sanitation Infrastructure: Assessing Community-Led Total Sanitation In Mopti, Mali, Justin Vern Meeks

USF Tampa Graduate Theses and Dissertations

In recent years, much focus has been put on the sustainability of water and sanitation development projects. Experts in this field have found that many of the projects of the past have failed to achieve sustainability because of a lack of demand for water and sanitation interventions at a grassroots level. For years projects looked to create this demand through various subsidy schemes, with the "software" of behavior change and education taking a backseat to the "hardware" of infrastructure provision. Community-Led Total Sanitation (CLTS) is a fairly new way of looking at the issues of increasing basic sanitation coverage, promoting …

Overcoming Limitations Of Serial Audio Search, Isabela Cordeiro Ribeiro Moura Hidalgo

USF Tampa Graduate Theses and Dissertations

The typical approach for finding audio recordings, such as music and sound effects, in a database is to enter some textual information into a search field. The results appear summarized in a list of textual descriptions of the audio files along with a function for playing back the recordings. Exploring such a list sequentially is a time-consuming and tedious way to search for sounds. This research evaluates whether searching for audio information can become more effective with a user interface capable of presenting multiple audio streams simultaneously.

A prototype audio player was developed with a user interface suitable for both …

Synthesis And Characterization Of Nanocomposites For Electrochemical Capacitors, Farah Alvi

USF Tampa Graduate Theses and Dissertations

Presently there are deep concerns over the environmental consequences and the consumption of non-renewable energy sources, with the accelerated greenhouse effect, triggered enormous interest in the use of renewable energy sources e.g., solar, hydropower, wind and geothermal. However the intermittent nature of harvesting renewable energy sources has recently gained considerable attention in the alternative reliable, cost effective, and environmentally friendly energy storage devices. The supercapacitor and lithium ion batteries are considered more efficient electrical energy storage devices than conventional energy storage systems.

Both devices have many useful and important applications; they could be an excellent source for high power and …

Theory And Modeling Of Graphene And Single Molecule Devices, Lyudmyla Adamska

USF Tampa Graduate Theses and Dissertations

This dissertation research is focused on first principles studies of graphene and single organic molecules for nanoelectronics applications. These nanosized objects attracted considerable interest from the scientific community due to their promise to serve as building blocks of nanoelectronic devices with low power consumption, high stability, rich functionality, scalability, and unique potentials for device integration. Both graphene electronics and molecular electronics pursue the same goal by using two different approaches: top-down approach for graphene devices scaling to smaller and smaller dimensions, and bottom-up approach for single molecule devices. One of the goals of this PhD research is to apply first-principles …

Aggregation Of Sediment And Bacteria With Mucilage From The Opuntia Ficus-Indica Cactus, Audrey Lynn Buttice

USF Tampa Graduate Theses and Dissertations

Flocculants are commonly used in industrial settings where solid-liquid separations are desired including industrial and municipal wastewater management and potable water production facilities. Conventional flocculants include inorganic metal salts and synthetic organic polymers. The cost, availability, and harmful effects of the non-biodegradable nature of these flocculants have led to the widespread study of natural flocculants. Current natural flocculants being studied include polysaccharides cultivated from microbial extracellular matrix products and plant based materials. In this study, the mucilage of Opuntia ficus-indica cactus was evaluated as a natural flocculant for sediments and bacteria. The O. ficus-indica cactus is also known as the …

Design Of Colloidal Composite Catalysts For Co2 Photoreduction And For Co Oxidation, Bijith D. Mankidy

USF Tampa Graduate Theses and Dissertations

In this doctoral dissertation, novel colloidal routes were used to synthesize nanomaterials with unique features. We have studied the impact of nanoparticle size of catalyst, role of high surface area of a photocatalyst, and the effect of varying elemental composition of co-catalytic nanoparticles in combination with core-shell plasmonic nanoparticles. We have demonstrated how physical and chemical characteristics of nanomaterials with these unique features play a role in catalytic reactions, specifically the oxidation of CO and the photoreduction of CO2. The first objective of this doctoral dissertation involved the preparation of CoO nanoparticles with discrete nanoparticles sizes (1-14 nm) using a …

Encapsulation Of High Temperature Phase Change Materials For Thermal Energy Storage, Rupa Nath

USF Tampa Graduate Theses and Dissertations

Thermal energy storage is a major contributor to bridge the gap between energy demand (consumption) and energy production (supply) by concentrating solar power. The utilization of high latent heat storage capability of phase change materials is one of the keys to an efficient way to store thermal energy. However, some of the limitations of the existing technology are the high volumetric expansion and low thermal conductivity of phase change materials (PCMs), low energy density, low operation temperatures and high cost. The present work deals with encapsulated PCM system, which operates at temperatures above 500°C and takes advantage of the heat …

Novel Blends Of Sulfur-Tolerant Water-Gas Shift Catalysts For Biofuel Applications, Timothy Michael Roberge

USF Tampa Graduate Theses and Dissertations

As traditional sources of energy become depleted, significant research interest has gone into conversion of biomass into renewable fuels. Biomass-derived synthesis gas typically contains concentrations of approximately 30 to 600 ppm H2S in stream. H2S is a catalyst poison which adversely affects downstream processing of hydrogen for gas to liquid plants. The water-gas shift reaction is an integral part of converting CO and steam to H2 and CO2. Currently, all known water-gas shift catalysts deactivate in sulfur concentrations typical of biomass-derived synthesis gas. Novel catalysts are needed to remain active in the presence of sulfur concentrations in order to boost …

Catalytic Tri-Reforming Of Biomass-Derived Syngas To Produce Desired H2:Co Ratios For Fuel Applications, Devin Mason Walker

USF Tampa Graduate Theses and Dissertations

This study focuses on upgrading biomass derived syngas for the synthesis of liquid fuels using Fischer-Tropsch synthesis (FTS). The process includes novel gasification of biomass via a tri-reforming process which involves a synergetic combination of CO2 reforming, steam reforming, and partial oxidation of methane. Typical biomass-derived syngas H2:CO is 1:1 and contains tars that deactivate FT catalyst. This innovation allows for cost-effective one-step production of syngas in the required H2:CO of 2:1 with reduction of tars for use in the FTS. To maximize the performance of the tri-reforming catalyst, an attempt to control oxygen mobility, thermal stability, dispersion of metal, …

Shelf-Scale Mapping Of Fish Distribution Using Active And Passive Acoustics, Carrie Christy Wall

USF Tampa Graduate Theses and Dissertations

Fish sound production has been associated with courtship and spawning behavior. Acoustic recordings of fish sounds can be used to identify distribution and behavior. Passive acoustic monitoring (PAM) can record large amounts of acoustic data in a specific area for days to years. These data can be collected in remote locations under potentially unsafe seas throughout a 24-hour period providing datasets unattainable using observer-based methods. However, the instruments must withstand the caustic ocean environment and be retrieved to obtain the recorded data. This can prove difficult due to the risk of PAMs being lost, stolen or damaged, especially in highly …

Basal Graph Structures For Geometry Based Organization Of Wide-Baseline Image Collections, Aveek Shankar Brahmachari

USF Tampa Graduate Theses and Dissertations

We propose algorithms for organization of images in wide-area sparse-view datasets. In such datasets, if the images overlap in scene content, they are related by wide-baseline geometric transformations. The challenge is to identify these relations even if the images sparingly overlap in their content. The images in a dataset are then grouped into sets of related images with the relations captured in each set as a basal (minimal and foundational) graph structures. Images form the vertices in the graph structure and the edges define the geometric relations between the images. We use these basal graphs for geometric walkthroughs and detection …

Crack Analysis In Silicon Solar Cells, Maria Ines Echeverria Molina

USF Tampa Graduate Theses and Dissertations

Solar cell business has been very critical and challenging since more efficient and low costs materials are required to decrease the costs and to increase the production yield for the amount of electrical energy converted from the Sun's energy. The silicon-based solar cell has proven to be the most efficient and cost-effective photovoltaic industrial device. However, the production cost of the solar cell increases due to the presence of cracks (internal as well as external) in the silicon wafer. The cracks of the wafer are monitored while fabricating the solar cell but the present monitoring techniques are not sufficient when …

Development Of Interatomic Potentials For Large Scale Molecular Dynamics Simulations Of Carbon Materials Under Extreme Conditions, Romain Perriot

USF Tampa Graduate Theses and Dissertations

The goal of this PhD research project is to devise a robust interatomic potential for large scale molecular dynamics simulations of carbon materials under extreme conditions. This screened-environment dependent reactive empirical bond order potential (SED-REBO) is specifically designed to describe carbon materials under extreme compressive or tensile stresses. Based on the original REBO potential by Brenner and co workers, SED-REBO includes reparametrized pairwise interaction terms and a new screening term, which serves the role of a variable cutoff. The SED-REBO potential overcomes the deficiencies found with the most commonly used interatomic potentials for carbon: the appearance of artificial forces due …

Growth And Characterization Of Functional Nanoparticulate Films By A Microwave Plasma-Assisted Spray Deposition Process, Ted Wangensteen

USF Tampa Graduate Theses and Dissertations

Nanoparticle and nanoparticulate films have been grown by a unique approach combining a microwave and nebulized droplets where the concentration and thus the resulting particle size can be controlled. The goal of such a scalable approach was to achieve it with the least number of steps, and without using expensive high purity chemicals or the precautions necessary to work with such chemicals. This approach was developed as a result of first using a laser unsuccessfully to achieve the desired films and particles. Some problems with the laser approach for growing desired films were solved by substituting the higher energy microwave …

Assessment Of Methods To Manipulate Thermal Emission And Evaluate The Quality Of Thermal Radiation For Direct Energy Conversion, Samantha Wijewardane

USF Tampa Graduate Theses and Dissertations

ABSTRACT

Control of spectral thermal emission from surfaces may be desirable in some energy related applications, such as nano-scale antenna energy conversion and thermophotovoltaic conversion. There are a number of methods, from commercially available paints to advanced surface gratings that can be used to modify the thermal emission from a surface. To find out the proper emission controlling technique for a given energy conversion method all the surface emission controlling methods are comprehensively reviewed regarding the emission control capabilities and the range of possible applications. Radiation with high degree of coherence can be emitted using advanced surface emission controlling techniques. …

Precipitation Of Phosphate Minerals From Effluent Of Anaerobically Digested Swine Manure, Alex Y. Lin

USF Tampa Graduate Theses and Dissertations

Swine production represents approximately 40% of the world's meat production, and its wastes contain high concentrations of organic carbon, nitrogen (N), and phosphorus (P). Anaerobic digestion is an increasingly popular technology for treating animal wastes while simultaneously generating energy. Its propagation and ability to solubilize organic N and P make adding a struvite recovery process attractive. Recovering struvite (MgNH4PO4) from anaerobically digested swine waste can address global P shortages, meet P discharge guidelines, and produce slow-release fertilizer, which can be sold for revenue.

Anaerobic digesters were operated with at organic loading rates of 3.4-3.9 g volatile solids per liter per …

Field And Laboratory Comparison Of The Hydraulic Performance Of Two Ceramic Pot Water Filters, Duncan Peabody

USF Tampa Graduate Theses and Dissertations

Currently 884 million people worldwide are living without access to an improved source of drinking water (WHO/UNICEF, 2011). Piped-water on premises is the ultimate goal of World Health Organization (WHO) due to the ability to treat all of the water and distribute it safely in pressurized pipes. However, Household Water Treatment and Safe Storage (HWTS) is an option for improving the quality of drinking water where that infrastructure is not yet developed, especially where there is a risk of recontamination between point of collection and point of use (Clasen, 2006).

This study analyzed one such HWTS, the ceramic pot water …

Water's Dependence On Energy: Analysis Of Embodied Energy In Water And Wastewater Systems, Weiwei Mo

USF Tampa Graduate Theses and Dissertations

Water and wastewater treatment is a critical service provided for protecting human health and the environment. Over the past decade, increasing attention has been placed on energy consumption in water and wastewater systems for the following reasons: (1) Water and energy are two interrelated resources. The nexus between water and energy can intensify the crises of fresh water and fossil fuel shortages; (2) The demand of water/wastewater treatment services is expected to continue to increase with increasing population, economic development and land use change in the foreseeable future; and (3) There is a great potential to mitigate energy use in …