Engineering Commons^™

Contrast Adaptation In The Lateral Eye Of Limulus Polyphemus, Tchoudomira Valtcheva

USF Tampa Graduate Theses and Dissertations

Luminance and contrast adaptation are neuronal mechanisms that the retina applies for continuous adjustment to light sensitivity though a collection of cellular and synaptic mechanisms distributed across the retinal network, thus accommodating the wide input range of the visual system within the constricted output range of retinal ganglion cells. Luminance mean adaptation has been demonstrated in the output neurons of the invertebrate eye (eccentric cells), and the aim of the study was to investigate whether the homology in visual processing extends to luminance variance (contrast) adaptation as well. The spike trains of individual eccentric cells were recorded from live horseshoe …

Skeletal Muscle Contraction Simulation: A Comparison In Modeling, Jonathan M. Ford

USF Tampa Graduate Theses and Dissertations

Computer generated three-dimensional (3-D) models are being used at increasing rates in the fields of entertainment, education, research, and engineering. One of the aspects of interest includes the behavior and function of the musculoskeletal system. One such tool used by engineers is the finite element method (FEM) to simulate the physics behind muscle mechanics. There are several ways to represent 3-D muscle geometry, namely a bulk, a central line of action and a spline model. The purpose of this study is to exmine how these three representations affect the overall outcome of muscle movement. This is examined in a series …

Theory, Synthesis, And Application Of Adiabatic And Reversible Logic Circuits For Security Applications, Matthew Arthur Morrison

USF Tampa Graduate Theses and Dissertations

Programmable reversible logic is emerging as a prospective logic design style for implementation in modern nanotechnology and quantum computing with minimal impact on circuit heat generation. Adiabatic logic is a design methodology for reversible logic in CMOS where the current flow through the circuit is controlled such that the energy dissipation due to switching and capacitor dissipation is minimized. Recent advances in reversible logic using and quantum computer algorithms allow for improved computer architectures. Production of cost-effective Secure Integrated Chips, such as Smart Cards, requires hardware designers to consider tradeoffs in size, security, and power consumption. In order to design …

Future Engineering Professors' Conceptions Of Learning And Teaching Engineering, Ana Teresa Torres Ayala

USF Tampa Graduate Theses and Dissertations

Conceptions of learning and teaching shape teaching practices and are, therefore, important to understanding how engineering professors learn to teach. There is abundant research about professors' conceptions of teaching; however, research on the conceptions of teaching of doctoral students, the future professors, is scarce. Furthermore, there is a need to understand not just future engineering professors' conceptions of teaching but also their conceptions of learning. The purpose of this study was to explore qualitative variations in future engineering professors' conceptions of learning and teaching as well as understanding how they came to these conceptions.

The research questions that guided this …

Hydraulic Evaluation Of A Community Managed Wastewater Stabilization Pond System In Bolivia, Louis Lizima

USF Tampa Graduate Theses and Dissertations

This work explores the hydraulic performance of a wastewater lagoon system located in San Antonio, Bolivia. The system consists of one facultative pond and two maturation ponds in series and is managed through a locally elected water committee. A tracer study was performed on the primary facultative pond and an analysis of the solids accumulation on the bottom of the facultative lagoon was also performed. The results were used to generate residence time distribution curves and provide an estimate of mean residence time in the system. The data was used to examine hydraulic efficiency as it relates to short-circuiting and …

Environmental And Energy Saving Technologies Of Vinyl Chloride Production, Mykola Kurta

USF Tampa Graduate Theses and Dissertations

Recently, because of the increase of environmental concerns in process design, the need to enhance conversion to product and prevent generation of wasteful byproducts in the reactor network has become urgent. This prevents high cost treatment and separation costs downstream in the process. Therefore, in this thesis I focus on making production of vinyl chloride monomer (VCM) more efficient and on possible ways of industrial organochlorine waste (OCW) recycling. In particular, in the first experiment, we investigate how catalyst and its structure can affect product output.

Infrared spectroscopy and X-ray diffraction analysis were utilized to investigate the structure of the …

Location And Capacity Modeling Of Network Interchanges, Aldo D. Fabregas

USF Tampa Graduate Theses and Dissertations

Network design decisions, especially those pertaining to urban infrastructure, are made by a central authority or network leader, and taking into consideration the network users or followers. These network decision problems are formulated as non-linear bi-level programming problems. In this work, a continuous network design problem (CNDP) and discrete network design problem (DNDP) bi-level optimization programs are proposed and solved in the context of transportation planning. The solution strategy involved reformulation and linearization as a single-level program by introducing the optimality conditions of the lower level problem into the upper level problem. For the CNDP, an alternative linearization algorithm (modified …

Effects Of Solvent Composition And Hydrogen Pressure On The Catalytic Conversion Of 1,2,4,5-Tetrachlorobenzene To Cyclohexane, Margaret Elizabeth Cone

USF Tampa Graduate Theses and Dissertations

Halogenated hydrophobic organic compounds (HHOCs) such as 1,2,4,5-tetrachlorobenzene (TeCB) present a threat to both human health and the environment. The common occurrence and recalcitrant nature of HHOCs as soil contaminants necessitate an effective soil remediation method. Wee and Cunningham (2008, 2011, 2013) proposed a clean-up technology called Remedial Extraction and Catalytic Hydrodehalogenation (REACH), which pairs solvent extraction of HHOC contaminants from soil with catalytic hydrodehalogenation to destroy contaminants. Wee and Cunningham (2008, 2011, 2013) utilized a palladium (Pd) catalyst to hydrodehalogenate TeCB to benzene. However, benzene is still a toxic contaminant. Prior research has demonstrated that Pd-catalyzed hydrodehalogenation (HDH) can …

Reconfigurable Low Profile Antennas Using Tunable High Impedance Surfaces, David Cure

USF Tampa Graduate Theses and Dissertations

This dissertation shows a detailed investigation on reconfigurable low profile antennas using tunable high impedance surfaces (HIS). The specific class of HIS used in this dissertation is called a frequency selective surface (FSS). This type of periodic structure is fabricated to create artificial magnetic conductors (AMCs) that exhibit properties similar to perfect magnetic conductors (PMCs). The antennas are intended for radiometric sensing applications in the biomedical field. For the particular sensing application of interest in this dissertation, the performance of the antenna sub-system is the most critical aspect of the radiometer design where characteristics such as small size, light weight, …

Design Of A Highly Portable Data Logging Embedded System For Naturalistic Motorcycle Study, Noureddine Elmehraz

USF Tampa Graduate Theses and Dissertations

According to Motorcycle Industrial Council (MIC), in USA the number of owned

motorcycle increased during last few years and most likely will keep increasing. However, the

number of the deadly crash accidents associated with motorcycles is on the rise. Although MIC

doesn't explain why the accident rate has increased, the unprotected motorcyclist gear can be one

of the reasons. The most recent National Highway Traffic Safety Administration (NHTSA)

annual report stated that its data analyses are based on their experiences and the best judgment is

not based on solid scientific experiment [3]. Thus, building a framework for the data acquisition …

Development Of Catalytic Technology For Producing Sustainable Energy, Syed Ali Z Gardezi

USF Tampa Graduate Theses and Dissertations

This dissertation explores catalyst technology for the production of renewable liquid fuels via thermo-chemical conversion of biomass derived syngas. Fischer-Tropsch synthesis is a process for converting syngas, i.e. a mixture of CO and H2, into energy rich long chain hydrocarbons and oxygenated compounds. This synthesis process involves a number of elementary reactions leading to an array of polymeric products. The economic operation of an FTS process lie in the interplay of both catalyst and reactor design. In relation to catalysis, the nature of chemisorbed species, and the fractional availability of active metal sites determines rate, conversion and yield. Similarly, reactor …

Multidimensional Signal Analysis For Wireless Communications Systems, Ali Gorcin

USF Tampa Graduate Theses and Dissertations

Wireless communications systems underwent an evolution as the voice oriented applications evolved to data and multimedia based services. Furthermore, current wireless technologies, regulations and the un-

derstanding of the technology are insufficient for the requirements of future wireless systems. Along with the rapid rise at the number of users, increasing demand for more communications capacity to deploy multimedia applications entail effective utilization of communications resources. Therefore, there is a need for effective spectrum allocation, adaptive and complex modulation, error recovery, channel estimation, diversity and code design techniques to allow high data rates while maintaining desired quality of service, and reconfigurable …

Supply Chain Optimization Of Blood Products, Serkan Gunpinar

USF Tampa Graduate Theses and Dissertations

Major challenges in the management of blood supply chain are related to the shortage and wastage of the blood products. Given the perishability characteristics of blood which can be stored up to a limited number of days, if hospitals and blood centers keep an excessive number of blood units on inventory, wastages may occur. On the other hand, if sufficient number of blood units are not stored on inventory, shortages of this resource may cause the cancellations of important activities and increase the fatality rates at hospitals. Three mathematical models have been developed with the goal to improve the efficiency …

An Acoustic-Based Microfluidic Platform For Active Separation And Mixing, Myeong Chan Jo

USF Tampa Graduate Theses and Dissertations

Particle separation is of great interest to many biological and biomedical applications. Flow-based methods have been used to sort particles and cells. However, the main challenge with flow based particle separation systems is the need for a sheath flow for successful operation. Existence of the sheath liquid dilutes the analyte, necessitates precise flow control between sample and sheath flow, requires a complicated design to create sheath flow and separation efficiency depends on the sheath liquid composition. In addition, current gold standard active separation techniques are only capable of separation based on particle size; hence, separation cannot be achieved for same-size …

Biomechanics Of Patient Handling Slings Associated With Spinal Cord Injuries, Julie Kahn

USF Tampa Graduate Theses and Dissertations

Pressure ulcers and related skin integrity threats are a significant problem in current transfer/transport systems used for spinal cord injury patients. To understand this problem twenty-three different slings with varying type, material, and features were analyzed in hopes to identify at-risk areas for skin integrity threats such as pressure ulcers. Population samples included non-disabled (otherwise referred to as "healthy") volunteers as well as SCI patients from the James A. Haley Veterans Hospital. High resolution pressure interface mapping was utilized to directly measure the interface pressures between the patient and sling interface. Overall results provide relevant feedback on the systems used …

Synthesis, Characterization And Applications Of Barium Strontium Titanate Thin Film Structures, Supriya Ashok Ketkar

USF Tampa Graduate Theses and Dissertations

Barium Strontium Titanate (BST) based ferroelectric thin film devices have been popular over the last decade due to their versatile applications in tunable microwave devices such as delay lines, resonators, phase shifters, and varactors. BST thin films are promising candidates due to their high dielectric constant, tunability and low dielectric loss. Dielectric-tunable properties of BST films deposited by different deposition techniques have been reported which study the effects of factors, such as oxygen vacancies, film thickness, grain size, Ba/Sr ratio, etc. Researchers have also studied doping concentrations, high temperature annealing and multilayer structures to attain higher tunability and lower loss. …

Fabricating And Characterizing Physical Properties Of Electrospun Polypeptide-Based Nanofibers, Dhan Bahadur Khadka

USF Tampa Graduate Theses and Dissertations

This dissertation has aimed to fabricate polypeptide based biomaterial and characterize physical properties. Electrospinning is used as a tool for the sample fabrication. Project focused on determining the feasibility of electrospinning of certain synthetic polypeptides and certain elastin-like peptides from aqueous feedstocks and to characterize physical properties of polymer aqueous solution, cast film and spun fibers and fiber mats. The research involves peptide design, polymer electrospinning, fibers crosslinking, determining the extent of crosslinking, fibers protease degradation study, fibers stability and self-organization analysis, structure and composition determination by various spectroscopy and microscopy techniques and characterization of mechanical properties of individual suspended …

Continuous Electrowetting In Passivating And Non-Passivating Systems, Mehdi Khodayari

USF Tampa Graduate Theses and Dissertations

Electrowetting is an electromechanical response that can be used to change the equilibrium

shape of droplets on a surface through the application of an electric potential. By applying this potential asymmetrically to a droplet, the droplet can be moved. Typical electrowetting devices use an electrode covered by a dielectric to reduce electrochemical interactions. Successful electrowetting requires electrodes and dielectric layers that can resist damage through many cycles of voltage.

Continuous Electrowetting (CEW) is performed on high resistivity silicon wafers. In this process, when an electric potential difference is applied between the substrate ends, the droplet on the substrate moves towards …

Optimized Correlation Of Geophysical And Geotechnical Methods In Sinkhole Investigations: Emphasizing On Spatial Variations In West-Central Florida, Henok Gidey Kiflu

USF Tampa Graduate Theses and Dissertations

Abstract

Sinkholes and sinkhole-related features in West-Central Florida (WCF) are commonly identified using geotechnical investigations such as standard penetration test (SPT) borings and geophysical methods such as ground penetrating radar (GPR) and electrical resistivity tomography (ERT). Geophysical investigation results can be used to locate drilling and field testing sites while geotechnical investigation can be used to ground truth geophysical results. Both methods can yield complementary information. Geotechnical investigations give important information about the type of soil, groundwater level and presence of low-density soils or voids at the test location, while geophysical investigations like GPR surveys have better spatial coverage and …

A Wearable Motion Analysis System To Evaluate Gait Deviations, Amanda Lynn Martori

USF Tampa Graduate Theses and Dissertations

A Wearable Motion Analysis System (WMAS) was developed to evaluate gait, particularly parameters that are indicative of mild traumatic brain injury. The WMAS consisted on six Opal IMUs attached on the sternum, waist, left and right thigh and left and right shank. Algorithms were developed to calculate the knee flexion angle, stride length and cadence parameters during slow, normal and fast gait speeds. The WMAS was validated for repeatability using a robotic arm and accuracy using the Vicon motion capture system, the gold standard for gait analysis. The WMAS calculated the gait parameters to within a clinically acceptable range and …

Design, Manufacturing, And Assembly Of A Flexible Thermoelectric Device, Christopher Anthony Martinez

USF Tampa Graduate Theses and Dissertations

This thesis documents the design, manufacturing, and assembly of a flexible thermoelectric device. Such a device has immediate use in haptics, medical, and athletic applications. The governing theory behind the device is explained and a one dimensional heat transfer model is developed to estimate performance. This model and consideration for the manufacturing and assembly possibilities are the drivers behind the decisions made in design choices. Once the design was finalized, manufacturing methods for the various components were explored. The system was created by etching copper patterns on a copper/polyimide laminate and screen printing solder paste onto the circuits. Thermoelectric elements …

Shield Design For Maximum Deformation In Shape-Shifting Surfaces, Daniel Eduardo Perez

USF Tampa Graduate Theses and Dissertations

This research presents the initial studies and results on shield design for Shape-Shifting Surfaces (SSSs) seeking maximum compression and maximum expansion of a unit-cell. Shape-Shifting Surfaces (SSSs) are multilayered surfaces that are able to change shape while maintaining their integrity as physical barriers. SSSs are composed of polygonal unit-cells, which can change side lengths and corner angles. These changes are made possible by each side and corner consisting of at least two different shields, or layers of material. As the layers undergo relative motion, the unit-cell changes shape. In order for the SSS to retain its effectiveness as a barrier, …

Thermal Infrared Reflective Metal Oxide Sol-Gel Coatings For Carbon Fiber Reinforced Composite Structures, Brandon Demar Richard

USF Tampa Graduate Theses and Dissertations

Recent trends in composite research include the development of structural materials with multiple functionalities. In new studies, novel materials are being designed, developed, modified, and implemented into composite designs. Typically, an increase in functionality requires additional material phases within one system. The presence of excessive phases can result in deterioration of individual or overall properties. True multi-functional materials must maintain all properties at or above the minimum operating limit. In this project, samples of antimony and cobalt-doped tin oxide (ATO(Co2O3)) sol-gel solutions are used to coat carbon fibers and are heat treated at a temperature range of 200 - 500 …

Robotic Swarming Without Inter-Agent Communication, Daniel Jonathan Standish

USF Tampa Graduate Theses and Dissertations

Many physical and algorithmic swarms utilize inter-agent communication to achieve advanced swarming behaviors. These swarms are inspired by biological swarms that can be seen throughout nature and include bee swarms, ant colonies, fish schools, and bird flocks. These biological swarms do not utilize inter-agent communication like their physical and algorithmic counterparts. Instead, organisms in nature rely on a local awareness of other swarm members that facilitates proper swarm motion and behavior. This research aims to pursue an effective swarm algorithm using only line-of-sight proximity information and no inter-agent communication. It is expected that the swarm performance will be lower than …

Non-Equilibrium Melting And Sublimation Of Graphene Simulated With Two Interatomic Potentials, Brad Steele

USF Tampa Graduate Theses and Dissertations

The mechanisms of the sublimation of graphene at zero pressure and the condensation of carbon vapor is investigated by molecular dynamics (MD) simulations. The interatomic interactions are described by the Reactive Empirical Bond Order potential (REBO). It is found that graphene sublimates at a temperature of 5,200 K. At the onset of sublimation, defects that contain several pentagons and heptagons are formed, that are shown to evolve from double vacancies and stone wales defects. These defects consisting of pentagons and heptagons act as nucleation sites for the gaseous phase. The influence of the interatomic interactions on the sublimation process are …

Flexible Urban Water Distribution Systems, Seneshaw Amare Tsegaye

USF Tampa Graduate Theses and Dissertations

With increasing global change pressures such as urbanization and climate change, cities of the future will experience difficulties in efficiently managing scarcer and less reliable water resources. However, projections of future global change pressures are plagued with uncertainties. This increases the difficulty in developing urban water systems that are adaptable to future uncertainty.

A major component of an urban water system is the distribution system, which constitutes approximately 80-85% of the total cost of the water supply system (Swamee and Sharma, 2008). Traditionally, water distribution systems (WDS) are designed using deterministic assumptions of main model input variables such as water …

Full 3d Reconstruction From Multiple Rgb-D Cameras, Owen Watson

USF Tampa Graduate Theses and Dissertations

This thesis describes a novel procedure for achieving full 3D reconstruction from multiple RGB-D cameras configured such that the amount of overlap between views is low. Overlap is used to describe the portion of a scene that is common in a pair of views, and is considered low when at most 50% of the scene is common. Compatible systems are configured such that interpreting cameras as nodes and overlap as edges, a connected undirected graph can be constructed. The fundamental goal of the proposed procedure is to calibrate a given system of cameras. Calibration is the process of finding the …

Environmental Implications Of Pavements: A Life Cycle View, Bin Yu

USF Tampa Graduate Theses and Dissertations

Environmental aspect of pavement, unlike its economic counterpart, is seldom considered in the theoretical study and field practices. As a highly energy and material intensive infrastructure, pavement has great potential to contribute to the environment protection, which, in root, depends on the in-depth understanding of the environmental impacts, holistically and specifically. A life cycle assessment (LCA) model is used to fulfill the goal.

This research firstly carried out extensive literature review of LCA studies on pavement to identify the major research gaps, including: incompleteness of the methodology, controversy of the functional unit, and unawareness of feedstock energy of asphalt, etc. …

Algorithms And Data Structures For Efficient Timing Analysis Of Asynchronous Real-Time Systems, Yingying Zhang

USF Tampa Graduate Theses and Dissertations

This thesis presents a framework to verify asynchronous real-time systems based on model checking. These systems are modeled by using a common modeling formalism named Labeled Petri-nets(LPNs).

In order to verify the real-time systems algorithmically, the zone-based timing analysis method is used for LPNs. It searches the state space with timing information (represented by zones). When there is a high degree of concurrency in the model, firing concurrent enabled transitions in different order may result in different zones, and these zones may be combined without affecting the verification result. Since the zone-based method could not deal with this problem efficiently, …

Determining The Benefit Of Human Input In Human-In-The-Loop Robotic Systems, Christine Elizabeth Bringes

USF Tampa Graduate Theses and Dissertations

This work analyzes human-in-the-loop robotic systems to determine where human input can be most beneficial to a collaborative task. This is accomplished by implementing a pick-and-place task using a human-in-the-loop robotic system and determining which segments of the task, when replaced by human guidance, provide the most improvement to overall task performance and require the least cognitive effort.

The first experiment entails implementing a pick and place task on a commercial robotic arm. Initially, we look at a pick-and-place task that is segmented into two main areas: coarse approach towards a goal object and fine pick motion. For the fine …