Engineering Commons^™

Nano-Particles In Multi-Scale Composites And Ballistic Applications, Jason Gibson

Electronic Theses and Dissertations

Carbon nanotubes, graphene and nano sized core shell rubber particles have all been extensively researched for their capability to improve mechanical properties of thermoset resins. However, there has been a lack of research on their evaluation for energy absorption in high velocity impact scenarios, and the fundamental mechanics of their failure mechanisms during highly dynamic stress transfer through the matrix. This fundamental research is essential for laying the foundation for improvement in ballistic performance in composite armor. In hard armor applications, energy absorption is largely accomplished through delamination between plies of the composite laminate. This energy absorption is accomplished through …

Defining A Stakeholder-Relative Model To Measure Academic Department Efficiency At Achieving Quality In Higher Education, Federica Robinson-Bryant

Electronic Theses and Dissertations

In a time of strained resources and dynamic environments, the importance of effective and efficient systems is critical. This dissertation was developed to address the need to use feedback from multiple stakeholder groups to define quality and assess an entity’s efficiency at achieving such quality. A decision support model with applicability to diverse domains was introduced to outline the approach. Three phases, (1) quality model development, (2) input-output selection and (3) relative efficiency assessment, captured the essence of the process which also delineates the approach per tool applied. This decision support model was adapted in higher education to assess academic …

Non-Destructive Evaluation Of Concrete Structures Using High Resolution Digital Image And Infrared Thermography Technology, Azusa Watase

Electronic Theses and Dissertations

As existing bridge structures age, they are susceptible to the effects of deterioration, damage and other deleterious processes. These effects hamper the capacity and efficiency of transportation networks and adversely impact local, regional and national economic growth. As a result, bridge authorities and other professionals have become more sensitive to maintenance issues related to this aging infrastructure. While highway bridge condition have been monitored by visual inspection, non-destructive evaluation (NDE) technologies have also been developing and they are expected to be utilized for effective management of highway bridges or other civil infrastructure systems. Efficient use of these technologies saves time …

Geotechnical Technique To Strengthen Traditional I-Walls Through The Use Of Composite Material, Jimmy Irby Jackson

Electronic Theses and Dissertations

On Monday, August 29, 2005, Hurricane Katrina struck the southern gulf coast of the United States. Hurricane Katrina produced record high amounts of surge water along the coastal regions, that over topped and eroded levees and flood walls, inevitably flooding the entire city of New Orleans. After Hurricane Katrina, the Department of Homeland Security approved a research grant to The University of Mississippi to develop effective but economic technique of strengthening existing I-walls. Using composite materials, a new retrofitting technique was developed to increase the stability of existing I-walls by implementing composite caps. For economical and practical testing, scale models …

Design Of Fountain Codes With Error Control, Amrit Kharel

Electronic Theses and Dissertations

This thesis is focused on providing unequal error protection (uep) to two disjoint sources which are communicating to a comdestination via a comrelay by using distributed lt codes over a binary erasure channel (bec), and designing fountain codes with error control property by integrating lt codes with turbo codes over a binary input additive white gaussian noise (bi-awgn) channel. A simple yet efficient technique for decomposing the rsd into two entirely different degree distributions is developed and presented in this thesis. These two distributions are used to encode data symbols at the sources and the encoded symbols from the sources …

Enhanced Pvdf Film For Multi Energy Harvesting, Ranmunige Nadeeka Karunarathna

Electronic Theses and Dissertations

No abstract provided.

Autonomous Recovery Of Reconfigurable Logic Devices Using Priority Escalation Of Slack, Naveed Imran

Electronic Theses and Dissertations

Field Programmable Gate Array (FPGA) devices offer a suitable platform for survivable hardware architectures in mission-critical systems. In this dissertation, active dynamic redundancy-based fault-handling techniques are proposed which exploit the dynamic partial reconfiguration capability of SRAM-based FPGAs. Self-adaptation is realized by employing reconfiguration in detection, diagnosis, and recovery phases. To extend these concepts to semiconductor aging and process variation in the deep submicron era, resilient adaptable processing systems are sought to maintain quality and throughput requirements despite the vulnerabilities of the underlying computational devices. A new approach to autonomous fault-handling which addresses these goals is developed using only a uniplex …

A Dynamic Enrollment Simulation Model For Planning And Decision-Making In A University, Luis Robledo

Electronic Theses and Dissertations

Decision support systems for university management have had limited improvement in the incorporation of new cutting-edge techniques. Most decisionmakers use traditional forecasting methods to base their decisions in order to maintain financially affordable programs and keep universities competitive for the last few decades. Strategic planning for universities has always been related to enrollment revenues, and operational expenses. Enrollment models in use today are able to represent forecasting based on historical data, considering usual variables like student headcount, student credit, among others. No consideration is given to students’ preferences. Retention models, associated to enrollment, deal with average retention times leaving off …

Sustainability Analysis Of Intelligent Transportation Systems, Tolga Ercan

Electronic Theses and Dissertations

Commuters in urban areas suffer from traffic congestion on a daily basis. The increasing number of vehicles and vehicle miles traveled (VMT) are exacerbating this congested roadway problem for society. Although literature contains numerous studies that strive to propose solutions to this congestion problem, the problem is still prevalent today. Traffic congestion problem affects society’s quality of life socially, economically, and environmentally. In order to alleviate the unsustainable impacts of the congested roadway problem, Intelligent Transportation Systems (ITS) has been utilized to improve sustainable transportation systems in the world. The purpose of this thesis is to analyze the sustainable impacts …

Differential Games For Multi-Agent Systems Under Distributed Information, Wei Lin

Electronic Theses and Dissertations

In this dissertation, we consider differential games for multi-agent systems under distributed information where every agent is only able to acquire information about the others according to a directed information graph of local communication/sensor networks. Such games arise naturally from many applications including mobile robot coordination, power system optimization, multiplayer pursuit-evasion games, etc. Since the admissible strategy of each agent has to conform to the information graph constraint, the conventional game strategy design approaches based upon Riccati equation(s) are not applicable because all the agents are required to have the information of the entire system. Accordingly, the game strategy design …

Growth And Characterization Of Zno Based Semiconductor Materials And Devices, Ming Wei

Electronic Theses and Dissertations

Wide band gap semiconductors such as MgxZn1-xO represent an excellent choice for making optical photodetectors and emitters operating in the UV spectral region. High crystal and optical quality MgxZn1-xO thin films were grown epitaxially on c-plane sapphire substrates by plasma-assisted Molecular Beam Epitaxy. ZnO thin films with high crystalline quality, low defect and dislocation densities, and sub-nanometer surface roughness were achieved by applying a low temperature nucleation layer. The critical growth conditions were discussed to obtain a high quality film: the sequence of Zn and O sources for initial growth of nucleation layer, growth temperatures for both ZnO nucleation and …

Managing, Controlling And Improving The Treatment Of Produced Water Using The Six Sigma Methodology For The Iraqi Oil Fields, Maher T. Al-Shamkhani

Electronic Theses and Dissertations

Produced Water (PW) is the largest volume of waste that is normally generated during oil and gas production. It has large amounts of contaminants that can cause negative environmental and economic impacts. The management method for PW relies highly on types and concentrations of these contaminants, which are field dependent and can vary from one oil field to another. Produced water can be converted to fresh water if these contaminants are removed or reduced to the acceptable drinking water quality level. In addition, increasing oil production rate and reducing amounts of discharged harmful contaminants can be achieved by removing dissolved …

Bio-Inspired Cooperative Optimal Trajectory Planning For Autonomous Vehicles, Charles Remeikas

Electronic Theses and Dissertations

With the recent trend for systems to be more and more autonomous, there is a growing need for cooperative trajectory planning. Applications that can be considered as cooperative systems such as surveying, formation flight, and traffic control need a method that can rapidly produce trajectories while considering all of the constraints on the system. Currently most of the existing methods to handle cooperative control are based around either simple dynamics and/or on the assumption that all vehicles have homogeneous properties. In reality, typical autonomous systems will have heterogeneous, nonlinear dynamics while also being subject to extreme constraints on certain state …

Fiber Reinforcement Compaction In Resin Injection Pultrusion Process, Neerad Shakya

Electronic Theses and Dissertations

Resin injection pultrusion is a cost-effective continuous manufacturing process to produce composites of constant cross-section. In this process, fiber reinforcements are continuously pulled through the injection chamber where liquid resin is injected to cause complete wetout of the fibers before exit. The fiber-resin combination obtained from the injection chamber is then cured to obtain the desired pultruded composite. There are various processing and geometric parameters affecting the wetout process. The main objective of this study is to present a numerical model to simulate the resin flow through the fiber reinforcement when compaction of the fibers is also taken into account. …

The Manufacturing And Ballistic Testing Of Tri-Axial Quasi Three Dimensional Woven Composites Layered In Polyurea, Brandon Saint

Electronic Theses and Dissertations

The protection of important infrastructure and vital resources of the United States is essential to the Nation's security. Attacks using the Nation's infrastructure as weapons of mass destruction could have a disturbing physical and psychological consequences. Work needs to be done to enhance the protection of the Nation's infrastructure to prevent, deter, or mitigate the effects of deliberate attacks by terrorist. Toxic inhalation hazard (TIH) chemicals such as chlorine gas and anhydrous ammonia are very dangerous hazardous materials. Rail transportation of TIH creates risk that exposes highly populated areas across the country to this threat. This study investigates the ballistic …

Subsurface Discontinuity Analysis & Modeling For The Federal Waste Disposal Facility And Compact Waste Disposal Facility Landfills, Shuang Cao

Electronic Theses and Dissertations

This research considers discontinuities mapped by Waste Control Specialists LLC to support the site conditions and performance analysis of the Compact Waste Disposal Facility and the Federal Waste Disposal Facility excavations constructed near Andrews, Texas. Discontinuities observed in excavation walls contain a limited number of discontinuities shoevidence of previous fluid movement. While no networks of such discontinuities were observed in the field, the potential for such networks may exist. This research is significant in understanding the performance of these waste facilities by modeling multiple realizations of possible fracture configurations in three-dimensional spatial models of the type of discontinuities observed in …

Mode-Division Multiplexed Transmission In Few-Mode Fibers, Neng Bai

Electronic Theses and Dissertations

As a promising candidate to break the single-mode fiber capacity limit, mode-division multiplexing (MDM) explores the spatial dimension to increase transmission capacity in fiberoptic communication. Two linear impairments, namely loss and multimode interference, present fundamental challenges to implementing MDM. In this dissertation, techniques to resolve these two issues are presented. To de-multiplex signals subject to multimode interference in MDM, Multiple-InputMultiple-Output (MIMO) processing using adaptive frequency-domain equalization (FDE) is proposed and investigated. Both simulations and experiments validate that FDE can reduce the algorithmic complexity significantly in comparison with the conventional time-domain equalization (TDE) while achieving similar performance as TDE. To further …

Development Of Thulium Fiber Lasers For High Average Power And High Peak Power Operation, Robert Sims

Electronic Theses and Dissertations

High power thulium fiber lasers are useful for a number of applications in both continuous-wave and pulsed operating regimes. The use of thulium as a dopant has recently gained interest due to its large bandwidth, possibility of high efficiency, possibility of high power and long wavelength ~1.8 – 2.1 μm. The longer emission wavelength of Tm-doped fiber lasers compared to Yb- and/or Er-doped fiber lasers creates the possibility for higher peak power operation due to the larger nonlinear thresholds and reduced nonlinear phase accumulation. One primary interest in Tm-doped fiber lasers has been to scale to high average powers; however, …

Investigating The Universality And Comprehensive Ability Of Measures To Assess The State Of Workload, Julian Abich

Electronic Theses and Dissertations

Measures of workload have been developed on the basis of the various definitions, some are designed to capture the multi-dimensional aspects of a unitary resource pool (Kahneman, 1973) while others are developed on the basis of multiple resource theory (Wickens, 2002). Although many theory based workload measures exist, others have often been constructed to serve the purpose of specific experimental tasks. As a result, it is likely that not every workload measure is reliable and valid for all tasks, much less each domain. To date, no single measure, systematically tested across experimental tasks, domains, and other measures is considered a …

Sediment Control In Alluvial Rivers Using Simulation-Based Optimization, Moustafa Abdelkader Elgohry

Electronic Theses and Dissertations

During storm events in rivers and watersheds, the peak runoff may creates excess erosion and deposition in channels or river reaches and cause changes in flow characteristics and fluvial geomorphology. Severe sediment erosion such as in-stream sever bed and bank erosion or gullying can threaten the stability of in-stream hydraulic structures, river banks, levees, and underground utilities. On the other hand, large amounts of sediment deposition can significantly reduce the flow capacity of channel or reservoir and increases further possibility of flooding. Therefore, sediment control is generally required for rivers and watersheds conservation purposes to maintain stable flow systems in …

An Implicit Finite-Volume Depth-Integrated Model For Coastal Hydrodynamics And Multiple-Sized Sediment Transport, Alejandro Sanchez

Electronic Theses and Dissertations

A two-dimensional depth-integrated model is developed for simulating wave-averaged hydrodynamics and nonuniform sediment transport and morphology change in coastal waters. The hydrodynamic model includes advection, wave-enhanced turbulent mixing and bottom friction; wave-induced volume flux; wind, atmospheric pressure, wave, river, and tidal forcing; and Coriolis-Stokes force. The sediment transport model simulates nonequilibrium total-load transport, and includes flow and sediment transport lags, hiding and exposure, bed material sorting, bed slope effects, nonerodible beds, and avalanching. The flow model is coupled with an existing spectral wave model and a newly developed surface roller model. The hydrodynamic and sediment transport models use finite-volume methods …

A Gis-Based Watershed Impact Management Model, Chioma Nneamaka Udeze

Electronic Theses and Dissertations

Assessment of land use changes on hydrological processes is essential for the planning and development of sustainable land management practices and water resources. Understanding how land management practices influence hydrological components is essential for the prediction of hydrological consequences of changes in land use. Given the plethora of hydrological models, digital data sources, and the limited availability of observed data, it is difficult to quantify the impacts of land use changes on hydrology. In this study, a Watershed Impact Management (WIM) model framework was conceptualized. A case study of the Yocona River basin, Mississippi, was implemented with the soil and …

Cavitation In Pharmaceutical Manufacturing And Shipping, Donn Sederstrom

Electronic Theses and Dissertations

Therapeutic proteins are used to successfully treat hemophilia, Crohn's Disease, diabetes, and cancer. Recent product recalls have occurred because of sub-visible particle formation resulting from the inherent instability of proteins. It has been suggested that particle formation is associated with late stage processing steps of filling, shipping, and delivery. Previous work at the University of Denver demonstrated that fluid cavitation can generate a large number of sub-visible protein particles in ultra clean formulations, but that mitigation can be achieved with fluid property manipulation. The goal of this research was to (1) assess the risk of cavitation under common pharmaceutical manufacturing …

Biomechanical Comparison Of Lower Limb Unloading Between Common Modalities Of Ankle Foot Orthoses, Andrea Blake Wanamaker

Electronic Theses and Dissertations

Tibial stress fractures and other lower extremity injuries can be treated using an ankle foot orthosis (AFO). AFOs are popular because they allow the patient to ambulate somewhat naturally while reducing weight bearing on the injured limb. Despite their popularity, it is currently unclear how well AFOs reduce lower extremity weight bearing.

The first objective of this investigation was to examine the ability of three commonly used ankle foot orthoses to reduce weight bearing within the lower limb by comparing the ground reaction force measured from a force platform to the force measured from an insole pressure measurement device inside …

Computational Representation Of The Patellofemoral Joint, Abraham Wright

Electronic Theses and Dissertations

Many people suffer from knee pain due to abnormal function of the patellofemoral joint and are not able to enjoy normal activities of daily living. Surgical treatments are available and new methods are being developed by the medical industry. However, computational tools to efficiently evaluate the effects of the intervention on patellofemoral function are lacking.

Therefore, a validated and efficient computational model of the patellofemoral joint was developed. The subject specific finite element model was validated against the patellar kinematics recorded during cadaveric patellofemoral laxity experiments of the natural knee. The development involved a sequential process in which the soft-tissue …

Representing Intersubject Variability With A Statistical Shape And Alignment Model Of The Knee, Chandreshwar Rao

Electronic Theses and Dissertations

Prior statistical shape models have not considered multiple structures in the knee joint to characterize anatomic variation which are required to investigate joint mechanics further for the successful knee replacement. Accordingly, the study's objective was to develop statistical shape and alignment model (SSAM) to capture intersubject variability and demonstrate the ability to generate realistic instances for use in finite element analysis (FEA). SSAM described the variability in the training set of 20 subjects with a series of modes of variation obtained by performing principal component analysis (PCA). PCA produced modes of variation with the first 3 modes representing 70% and …

X-Ray Scattering Investigations Of Metallic Thin Films, Andrew Warren

Electronic Theses and Dissertations

Nanometric thin films are used widely throughout various industries and for various applications. Metallic thin films, specifically, are relied upon extensively in the microelectronics industry, among others. For example, alloy thin films are being investigated for CMOS applications, tungsten films find uses as contacts and diffusion barriers, and copper is used often as interconnect material. Appropriate metrology methods must therefore be used to characterize the physical properties of these films. Xray scattering experiments are well suited for the investigation of nano-scaled systems, and are the focus of this doctoral dissertation. Emphasis is placed on (1) phase identification of polycrystalline thin …

Robust Subspace Estimation Using Low-Rank Optimization. Theory And Applications In Scene Reconstruction, Video Denoising, And Activity Recognition., Omar Oreifej

Electronic Theses and Dissertations

In this dissertation, we discuss the problem of robust linear subspace estimation using low-rank optimization and propose three formulations of it. We demonstrate how these formulations can be used to solve fundamental computer vision problems, and provide superior performance in terms of accuracy and running time. Consider a set of observations extracted from images (such as pixel gray values, local features, trajectories . . . etc). If the assumption that these observations are drawn from a liner subspace (or can be linearly approximated) is valid, then the goal is to represent each observation as a linear combination of a compact …

Similarity Of Climate Control On Base Flow And Perennial Stream Density In The Budyko Framework, Liuliu Wu

Electronic Theses and Dissertations

Streams are classified into perennial, intermittent, and ephemeral streams based on flow durations. Perennial stream is the basic network, while intermittent or ephemeral stream is the expanded network. Connection between perennial stream and base flow at the mean annual scale exists since one of the hydrologic functions of perennial stream is to deliver runoff even in low flow seasons. The partitioning of precipitation into runoff and evaporation at the mean annual scale, on the first order, is captured by the ratio of potential evaporation to precipitation (Ep/P called climate aridity index) based on the Budyko hypothesis. The primary focus of …

Development And Characterization Of Nanoparticlee Enhancements In Pyrolysis-Derived High Temperature Composites, James Mckee

Electronic Theses and Dissertations

Thermal protection systems, which are commonly used to protect spacecraft during atmospheric entry, have traditionally been made of materials which are traditionally high in manufacturing costs for both the materials needed and the manufacturing complexity, such as carbon-carbon composites and aerogels. [1] In addition to their manufacturing costs, these materials are also limited in their strength, such as PICA, in a way that necessitate the use of tiles as opposed to single structures because they are not capable of supporting larger structures. [2] The limitations of polymer reinforced composites have limited their entry into these applications, except for pyrolyzed composite …