Engineering Commons^™

Lagrangian Visualization And Real-Time Identification Of The Vortex Shedding Time In The Wake Of A Circular Cylinder, Matthew Rockwood

Dissertations - ALL

The flow around a circular cylinder, a canonical bluff body, has been extensively studied in the literature to determine the mechanisms that cause the formation of vortices in the cylinder wake. Understanding of these mechanisms has led to myriad attempts to control the vortices either to mitigate the oscillating forces they cause, or to augment them in order to enhance mixing in the near-wake. While these flow control techniques have been effective at low Reynolds numbers, they generally lose effectiveness or require excessive power at Reynolds numbers commonly experienced in practical applications. For this reason, new methods for identifying the …

Delay Qos Provisioning And Optimal Resource Allocation For Wireless Networks, Yi Li

Dissertations - ALL

Recent years have witnessed a significant growth in wireless communication and networking due to the exponential growth in mobile applications and smart devices, fueling unprecedented increase in both mobile data traffic and energy demand. Among such data traffic, real-time data transmissions in wireless systems require certain quality of service (QoS) constraints e.g., in terms of delay, buffer overflow or packet drop/loss probabilities, so that acceptable performance levels can be guaranteed for the end-users, especially in delay sensitive scenarios, such as live video transmission, interactive video (e.g., teleconferencing), and mobile online gaming. With this motivation, statistical queuing constraints are considered in …

Computer Vision Algorithms For Mobile Camera Applications, Koray Ozcan

Dissertations - ALL

Wearable and mobile sensors have found widespread use in recent years due to their ever-decreasing cost, ease of deployment and use, and ability to provide continuous monitoring as opposed to sensors installed at fixed locations. Since many smart phones are now equipped with a variety of sensors, including accelerometer, gyroscope, magnetometer, microphone and camera, it has become more feasible to develop algorithms for activity monitoring, guidance and navigation of unmanned vehicles, autonomous driving and driver assistance, by using data from one or more of these sensors. In this thesis, we focus on multiple mobile camera applications, and present lightweight algorithms …

The Scalable And Accountable Binary Code Search And Its Applications, Qian Feng

Dissertations - ALL

The past decade has been witnessing an explosion of various applications and devices.

This big-data era challenges the existing security technologies: new analysis techniques

should be scalable to handle “big data” scale codebase; They should be become smart

and proactive by using the data to understand what the vulnerable points are and where

they locate; effective protection will be provided for dissemination and analysis of the data

involving sensitive information on an unprecedented scale.

In this dissertation, I argue that the code search techniques can boost existing security

analysis techniques (vulnerability identification and memory analysis) in terms of scalability and …

Investigating The Structures Of Turbulence In A Multi-Stream, Rectangular, Supersonic Jet, Andrew S. Magstadt

Dissertations - ALL

Supersonic flight has become a standard for military aircraft, and is being seriously reconsidered for commercial applications. Engine technologies, enabling increased mission capabilities and vehicle performance, have evolved nozzles into complex geometries with intricate flow features. These engineering solutions have advanced at a faster rate than the understanding of the flow physics, however. The full consequences of the flow are thus not known, and using predictive tools becomes exceedingly difficult. Additionally, the increasing velocities associated with supersonic flight exacerbate the preexisting jet noise problem, which has troubled the engineering community for nearly 65 years. Even in the simplest flows, the …

Restoration Of Historic Buildings In Zanzibar, John K. Makunza Jkm

Tanzania Journal of Engineering and Technology (TJET)

Looking at current state of most repaired historic buildings in Stone Town of Zanzibar, it is quite clear that the repair attempts made have not been very successful. Modern materials and techniques introduced in the repair works have often proven to be incompatible with the original materials causing accelerated deterioration of buildings fabric. This shows that, there is no comprehensive study undertaken so far on identifying the appropriate materials and restoration techniques. To solve this problem, a study has been made with the main objective of developing the means of restoring historic buildings by using materials existing in Stone Town …

Investigation Of The Multi-Physics Of Laser-Induced Ignition Of Transportation Fuels, Nathan Peters

Dissertations - ALL

Cleaner and more efficient combustion systems are expected to operate at conditions where successful spark ignition is difficult to achieve. Laser ignition is a proposed alternative ignition system capable of stable engine performance under these conditions. Fundamental studies are needed to fully characterize the complex, multi-physics nature of the laser ignition process. This thesis is a contribution in that direction, also characterizing the ignition and flame behavior of some engine-relevant fuels.

This work investigates experimentally the early stages of the laser ignition process, characterizing breakdown and laser-induced shock waves. It then explores self-sustained flame behavior from early flame emergence to …

Ict Adoption And Use In Tanzania Smes, Cuthbert Msuya

Tanzania Journal of Engineering and Technology (TJET)

The purpose of this paper was to establish the status of ICTs adoption and use in Tanzania SMEs. Previously, it was shown that there is a shortage of comprehensive, accurate and up to date data on many aspects of the SMEs sector including the level of ICT adoption and use. This has affected government efforts aimed at development of this important sector in the economic development of the country. Results show that: (i) By year 2014, adoption of ICTs in SMEs had grown from almost non-existence in year 2004 to 80.1% computer technology use, and over 56.6% for use of …

Economic Returns To Clean Water: Evidence From Us Historical Records., Joseph Price

Journal of Undergraduate Research

The purpose of this project was to use linked census records to evaluate the long-run effects of access to clean water. By linking individuals across census years we can specifically determine where they lived during their childhood and also have information about their educational attainment and earnings later in life (using the 1940 census). The project was designed to use a time period when the US was a developing country and beginning to use chlorination to clean its water to assess the economic returns to clean water.

Design And Manufacture Of A Waste Compactor Prototype: A Step Towards Implementing A Non-Burn Health Care Waste Disposal In Developing Countries, Tito Mwinuka

Tanzania Journal of Engineering and Technology (TJET)

Non-burn technology is the only safe way of handling and disposing infectious healthcare waste. It involves steam treatment of infectious waste at temperatures higher than 121 o C for a minimum of 30 minutes before disposing them just like other municipal waste. Infectious healthcare waste is normally only about 10 25% of all healthcare waste. In this paper, design, manufacturing and testing of a waste compactor for reducing waste volume to facilitate its handling is discussed. Preliminary tests show that the waste volume can be reduced to less than 10% of its original volume using the developed compactor. Waste compactors …

1900 - Conceptual And Historical 1900 Land Use And Development In Salinas Valley And Vicinity [Draft]

Groundwater Basin Maps

A digitized map created in 2017 representing land use and development in the Salinas Valley and vicinity in 1900. The map reflects private rancho; high probability of harming and Irrigation areas; land suitable for grazing cattle, sheep and horses with some agriculture; California native habitat (least developed lands); canals; railroads; pump houses, oil seep, population centers; 1898 USGS Monterey County Road & Historic El Camino Real; Salinas River Watershed; Township and Range; County boundary; historic Mission sites; springs; wetland, sloughs and lakes; intermittent stream or slough; Salinas River; as well as rivers and streams. Data sources include Bureau of Land …

Design, Material And Surgical Assembly Effects On Fretting Corrosion Behavior Of Modular Tapers In Orthopedic Implants, David Pierre

Dissertations - ALL

Mechanically assisted crevice corrosion (MACC) has become a significant problem in the orthopedic device industry, particularly in modular devices with metal-on-metal (MoM) tapered interfaces. Oxide film abrasion, leading to fretting corrosion in the presence of a crevice, accelerates the corrosion process and in some instances may lead to failure of the implant. Failure is defined as the need for revision surgery. The basic processes of oxide film abrasion and repassivation, and the associated effects (chemical, transport, mechanical and electrical) of these processes have been well described and studied over time.

Despite these advancements, there is much that is still not …

The Effects Of Simulated Inflammatory Conditions On The Corrosion And Fretting Corrosion Of Cocrmo Alloy, Yangping Liu

Dissertations - ALL

In vivo corrosion of CoCrMo alloy and its potential adverse effects on the body have been recognized as major concerns in recent years. While the underlying concepts of general and mechanically-assisted corrosion have been well documented, recent report of inflammatory cell-induced corrosion (ICIC) of CoCrMo alloy challenged traditional understanding of the relationship between biology and corrosion of hip implants. To better understand the role biology may play in the corrosion of CoCrMo-based implants, this study explored the mechanism of ICIC on CoCrMo alloy and investigated how simulated inflammatory (SI) conditions affected the electrochemistry, oxide film and fretting corrosion behavior of …

Cytotoxicity Of Galvanically Coupled Magnesium And Titanium Particles For Therapeutic Effect, Jua Kim

Dissertations - ALL

This dissertation characterized how galvanic coupling of magnesium (Mg) with titanium (Ti) via sputtering enhanced the cytotoxicity of Mg particles due to increased corrosion rate. Mg and Mg-Ti particles were characterized using scanning electron microscopy (SEM), which showed that Mg and Mg-Ti particles have the average diameter of 50 µm, which makes them slightly larger than an average mammalian cell. Therefore, the cytotoxicity of the particles is not due to the ingestion of the particles by cells via phagocytosis, but solely due to electrochemical effects. Sputtering of Ti to partially cover Mg particles results in a very thin layer, in …

Quantitative Optical Measurement Of Mitochondrial Superoxide Dynamics In Pulmonary Artery Endothelial Cells, Zahra Ghanian, Girija G. Konduri, Said H. Audi, Amadou K.S. Camara, Mahsa Ranji

Biomedical Engineering Faculty Research and Publications

No abstract provided.

Intensive Mentoring And Micro-Electronics Research For Students In Engineering (Immerse) 2014, Stephen Schultz

Journal of Undergraduate Research

The MEG funds used for this projects supported undergraduate students working in the IMMERSE program starting in the Summer of 2015. IMMERSE employed a total of 35 students, with 14 of them being supervised directly by Dr. Aaron Hawkins and Stephen Schultz. The students working for Drs. Hawkins and Schultz were paid hourly wages for their research work from this MEG grant.

Validation Of Adaptive Control Laws Using Optimization And Trajectory Sensitivity, Mario Luca Fravolini, Antonio Ficola, Fabio Radicioni, Tansel Yucelen, Ehsan Arabi

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In this paper it is proposed an easy-to-use verification and validation method for adaptive control laws that relies on time domain simulations. The problem is set as a trajectory falsification problem that is the search of closed loop trajectories that, starting from a set of admissible initial conditions, reach a set of unsafe states. The falsification is placed as a nonlinear optimization problem whose decision variables are the initial condition of the states and the uncertain parameters of the system. The falsification is performed iteratively using the local gradient of the sensitivity function derived from a linearized model of the …

Laser Machining And Near Field Microwave Microscopy Of Silver Inks For 3d Printable Rf Devices, Anthony J. Ross Iii

USF Tampa Graduate Theses and Dissertations

3D printable materials for RF devices need improvement in order to satisfy the demand for higher frequency and lower loss performance. Characterization of materials that have shown improvements of conductor conductivity have been performed. By using a laser machining technique the loss of a 3D printed 2.45 GHz microstrip Square Open Loop Resonator (SOLR) bandpass filter has been shown to improve by 2.1dB, along with an increase in bandwidth from 10% to 12.7% when compared to a SOLR filter that has not been laser machined. Both laser machined and microwaved silver inks have been mapped for conductivity using a Near …

A Decentralized Adaptive Control Architecture For Large-Scale Active-Passive Modular Systems, Benjamin C. Gruenwald, Ehsan Arabi, Tansel Yucelen, Animesh Chakravarthy, Drew Mcneely

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Decentralized control of large-scale active-passive modular systems is considered. These systems consist of physically interconnected and generally heterogeneous modules, where local control signals can be only applied to a subset of these modules (i.e., active modules) and the rest are not subject to any control signals (i.e., passive modules). Using a set-theoretic adaptive control approach predicated on restricted potential functions, we design decentralized command following control architectures for each active module such that they can effectively perform their tasks with strict performance guarantees in the presence of unknown physical interconnections between modules and module-level system uncertainties. The efficacy of the …

An Algorithm For Enlarging The Region Of Attraction Using Trajectory Reversing, Nilay Kant, Dhrubajit Chowdhury, Ranjan Mukherjee, Hassan K. Khalil

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Trajectory reversing is a method commonly used for estimating the region of attraction of stabilized equilibria. Using a discrete set of points obtained by trajectory reversing, this paper presents an algorithm for estimation and mathematical representation of the region of attraction using convex hulls. Several two-dimensional examples are presented to illustrate the usefulness of the algorithm. The method provides larger estimates compared to that obtained by existing algorithms, but its main advantage lies in its applicability to higher-order systems. The mathematical representation of the region of attraction is useful in applying the Impulse Manifold Method, which was developed for stabilization …

Enlarging The Region Of Attraction Of Equilibria Of Underactuated Systems Using Sum Of Squares And Impulse Manifold Method, Dhrubajit Chowdhury, Nilay Kant, Ranjan Mukherjee, Hassan K. Khalil

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This paper presents an algorithm to enlarge the estimate of the Region of Attraction of stable equilibria of underactuated systems. To achieve this, we use a combination of the Sum of Squares (SOS) method and the Impulse Manifold Method (IMM). Initially, the SOS method is used to optimize the control input u(x) in order to obtain an enlarged Region of Attraction. The IMM is then applied on enlarged Region of Attraction obtained using SOS to further enlarge it. The IMM is implemented using high gain feedback and to demonstrate the efficacy of our algorithm, we present simulation results where an …

Spatial Variability Of Co < Inf> 2 Uptake In Polygonal Tundra: Assessing Low-Frequency Disturbances In Eddy Covariance Flux Estimates, Norbert Pirk, Jakob Sievers, Jordan Mertes, Frans Jan W. Parmentier, Mikhail Mastepanov, Torben R. Christensen

Michigan Tech Publications, Part 1

The large spatial variability in Arctic tundra complicates the representative assessment of CO2 budgets. Accurate measurements of these heterogeneous landscapes are, however, essential to understanding their vulnerability to climate change. We surveyed a polygonal tundra lowland on Svalbard with an unmanned aerial vehicle (UAV) that mapped ice-wedge morphology to complement eddy covariance (EC) flux measurements of CO2. The analysis of spectral distributions showed that conventional EC methods do not accurately capture the turbulent CO2 exchange with a spatially heterogeneous surface that typically features small flux magnitudes. Nonlocal (low-frequency) flux contributions were especially pronounced during snowmelt and introduced a large bias …

Dissipative Elastic Metamaterial With A Lowfrequency Passband, Yongquan Liu, Jianlin Yi, Zheng Li, Xianyue Su, Wenlong Li, Mehrdad Negahban

Department of Mechanical and Materials Engineering: Faculty Publications

We design and experimentally demonstrate a dissipative elastic metamaterial structure that functions as a bandpass filter with a low-frequency passband. The mechanism of dissipation in this structure is well described by a mass-spring-damper model that reveals that the imaginary part of the wavenumber is non-zero, even in the passband of dissipative metamaterials. This indicates that transmittance in this range can be low. A prototype for this viscoelastic metamaterial model is fabricated by 3D printing techniques using soft and hard acrylics as constituent materials. The transmittance of the printed metamaterial is measured and shows good agreement with theoretical predictions, demonstrating its …

Vertical Axis Wind Turbine Wake Model Development, Andrew Ning

Journal of Undergraduate Research

The objective of this research was to develop an aerodynamic wake model for a vertical axis wind turbine (VAWT), and to better understand vertical axis wind turbine performance. We were successful in developing a wake model. Additional work went in to understand trade-offs in power performance with acoustic constraints. The results were two conference papers, two journal papers, and open-source data and code. Additional work in ongoing to extended the wake mode’s usefulness for wake interactions and closely-spaced turbines.

Rebuilding Kidneys, Alonzo D. Cook, Deverly L. Roeder, Jonathan J. Wisco

Journal of Undergraduate Research

The motivation for this work was the tremendous need for replacement kidneys. End-stage renal disease (ESRD) affects over 500,000 patients in the U.S. and costs Medicare $30 Billion annually for dialysis and transplant procedures. Our overall objective was to engineer kidneys from decellularized porcine extracellular matrix (DPECM) scaffolds and cell cultures grown from human progenitor cells. The primary reason for using human cells was to develop non-immunogenic kidneys that can be used to treat the more than 100,000 chronic kidney disease (CKD) patients awaiting a transplant, thus obviating the need for post-transplant immunosuppressive therapy and the associated risks of acute …

Space-Time Transportation System Modelling: From Traveler’S Characteristics To The Network Design Problem, Mohsen Parsafard

USF Tampa Graduate Theses and Dissertations

Traditional network design problems only consider the long-term stationary travel patterns (e.g., fixed OD demand) and short-term variations of human mobility are ignored. This study aims to integrate human mobility characteristics and travel patterns into network design problems using a space-time network structure. Emerging technologies such as location-based social network platforms provide a unique opportunity for understanding human mobility patterns that can lead to advanced modeling techniques. To reach our goal, at first multimodal network design problems are investigated by considering safety and flow interactions between different modes of transport. We develop a network reconstruction method to expand a single-modal …

Loss Model For Gallium Nitride Dc-Dc Buck Converter, Rushi P. Patel

Pursuit - The Journal of Undergraduate Research at The University of Tennessee

In recent years, more research has been done on Enhancement Mode Gallium Nitride (eGaN) converters, as the world is moving towards more power efficient converters. Power converters play a major role in efficiently controlling and converting electric energy used by machines, systems, and everyday products. The process to make converters more efficient was complicated and slow in the twentieth century. One of the important aspects in power electronics is to evaluate different losses and minimize losses to achieve high efficiency of the converter. With help of simulation tools such as MATLAB and LTspice, this process has become much faster and …

Evaluation Of Foldable Tractor Roll-Over Protective Structures (Rops) Clearance, Luke Martin

Pursuit - The Journal of Undergraduate Research at The University of Tennessee

Tractor rollovers are a leading cause of death in the agricultural industry. While rollovers continue to happen, Roll-Over Protective Structures (ROPS) have shown great ability to prevent or reduce the casualties and injuries associated with rollover events. One authority on the subject even goes so far as to claim that “that fatality rates due to tractor overturns could be reduced by a minimum of 71% if all tractors in the U.S. were equipped with ROPS,” (NIOSH, 2009). The potential of this promising statistic has been devalued slightly due to the misapplication of foldable ROPS by leaving the ROPS in the …

Streambank Erosion Mapping On The Nottoway River Using Gps-Based Above-Water Video, Emine Fidan

Pursuit - The Journal of Undergraduate Research at The University of Tennessee

This project concerns the development of streambank erosion maps on military installations utilizing GPS-based above-water video mapping and image georeferencing techniques. The river mapped was the Nottoway River at the Fort Pickett military installation on October 10-11, 2015. Kayak-mounted above-water cameras were utilized to capture georeferenced images of streambank erosion. These GIS-based erosion classifications were utilized to develop erosion maps for determining streambank erosion conditions along the river. Areas of high erosion were identified as about two percent of the river (2167 ft. of streambank length). These maps allow for the opportunity to revisit the sites to determine changes in …

Identification Of Key Drivers For Municipal Utility Performance, Jasmin Alsaied

Pursuit - The Journal of Undergraduate Research at The University of Tennessee

This report explores the various performance indicators for municipal electric utilities and the greatest impact financial investments can make for improving these indicators. A literature search provided key detail about performing an analysis that would prove useful to utilities. The analysis identifies key performance indicators that allowed for the most prudent of investments. Data mining techniques and statistical analyses were performed on data sets concerning the 51 North Carolina municipal electric utilities to identify several key ratios and performance indicators that have the greatest impact on cost of service, system reliability, and customer satisfaction. Statistical analyses were used to determine …