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Articles 1 - 30 of 405
Full-Text Articles in Engineering
Optimal Attitude Control Of Agile Spacecraft Using Combined Reaction Wheel And Control Moment Gyroscope Arrays, Cole C. Doupe
Optimal Attitude Control Of Agile Spacecraft Using Combined Reaction Wheel And Control Moment Gyroscope Arrays, Cole C. Doupe
Theses and Dissertations
This dissertation explores the benefits of combined control moment gyroscope (CMG) and reaction wheel array (RWA) actuation for agile spacecraft. Agile spacecraft are capable of slewing to multiple targets in minimum time. CMGs provide the largest torque capability of current momentum exchange actuation devices but also introduce singularity events in operation. RWAs produce less torque capability than CMGs but can achieve greater pointing accuracy. In this research, a combined RWA and CMG (RWCMG) system is evaluated using analytical simulations and hardware experiments. A closed-loop control scheme is developed which takes advantage of the strengths of each actuator set.The CMGs perform …
Effects Of Automation On Aircrew Workload And Situation Awareness In Tactical Airlift Missions, David R. Meyer
Effects Of Automation On Aircrew Workload And Situation Awareness In Tactical Airlift Missions, David R. Meyer
Theses and Dissertations
In tactical aviation, decision superiority brought upon by high situation awareness remains the arbiter of combat effectiveness. The advancement of sophisticated avionics and highly automated cockpits has allowed for the reduction of aircrew size, and in certain platforms, removal of the crew from the aircraft entirely. However, these developments have not reduced the complex and dynamic interaction between situation awareness and crew workload. While many predictive and experimental methods of evaluating workload exist, situation awareness can only be measured by conducting trials with human operators in a functional prototype. This thesis proposes an innovative methodology to predicatively determine situation awareness …
Application Of Executable Architectures In Early Concept Evaluation, Ryan M. Pospisal
Application Of Executable Architectures In Early Concept Evaluation, Ryan M. Pospisal
Theses and Dissertations
This research explores use of executable architectures to guide design decisions in the early stages of system development. Decisions made early in the system development cycle determine a majority of the total lifecycle costs as well as establish a baseline for long term system performance and thus it is vital to program success to choose favorable design alternatives. The development of a representative architecture followed the Architecture Based Evaluation Process as it provides a logical and systematic order of events to produce an architecture sufficient to document and model operational performance. In order to demonstrate the value in the application …
Comparison Of Novel Carboneous Structures To Treat Nitroaromatic Impacted Water, Benjamin M. Doane
Comparison Of Novel Carboneous Structures To Treat Nitroaromatic Impacted Water, Benjamin M. Doane
Theses and Dissertations
Carboneous materials such as carbon nanotube (CNT), granular activated carbon (GAC), and biochar are promising materials for the removal of organic contaminants from aqueous phase solutions. CNTs have astonishing mechanical strength, chemical and thermal stability and high surface area. While biochar, similar to GAC, having an extremely porous structure and high surface area, can be produced in more austere conditions with native materials. In this study, novel CNT-Hybrid structures (CNT-HS), hardwood pellet (HWP) Biochar and standard GAC (F-600 GAC) were used as adsorbents to treat water contaminated by a model nitroaromatic compound, 2,4-dinitrotoluene (DNT).
Demonstration Of Inexact Computing Implemented In The Jpeg Compression Algorithm Using Probabilistic Boolean Logic Applied To Cmos Components, Christopher I. Allen
Demonstration Of Inexact Computing Implemented In The Jpeg Compression Algorithm Using Probabilistic Boolean Logic Applied To Cmos Components, Christopher I. Allen
Theses and Dissertations
Probabilistic computing offers potential improvements in energy, performance, and area compared with traditional digital design. This dissertation quantifies energy and energy-delay tradeoffs in digital adders, multipliers, and the JPEG image compression algorithm. This research shows that energy demand can be cut in half with noisesusceptible16-bit Kogge-Stone adders that deviate from the correct value by an average of 3 in 14 nanometer CMOS FinFET technology, while the energy-delay product (EDP) is reduced by 38 . This is achieved by reducing the power supply voltage which drives the noisy transistors. If a 19 average error is allowed, the adders are 13 times …
Collecting Unsolicited User-Generated Change Requests, Joseph W. Goldsmith
Collecting Unsolicited User-Generated Change Requests, Joseph W. Goldsmith
Theses and Dissertations
Unlike aircrew directly associated with acquisitions, line operators are not fully engaged in the methods to push materiel hardware or software change requests up the chain, to a decision maker, and then to the engineers. The Air Force trains these end users to logically apply expert systems knowledge to execute the mission but has not fully leveraged this resource for properly identifying and correcting operational shortfalls in an aircraft's design. Focusing on the Remotely Piloted Aircraft (RPA) community, the research goal is to determine if the Air Force should establish a formal program for collecting and prioritizing unsolicited user change …
Feature Selection And Classifier Development For Radio Frequency Device Identification, Trevor J. Bihl
Feature Selection And Classifier Development For Radio Frequency Device Identification, Trevor J. Bihl
Theses and Dissertations
The proliferation of simple and low-cost devices, such as IEEE 802.15.4 ZigBee and Z-Wave, in Critical Infrastructure (CI) increases security concerns. Radio Frequency Distinct Native Attribute (RF-DNA) Fingerprinting facilitates biometric-like identification of electronic devices emissions from variances in device hardware. Developing reliable classifier models using RF-DNA fingerprints is thus important for device discrimination to enable reliable Device Classification (a one-to-many looks most like assessment) and Device ID Verification (a one-to-one looks how much like assessment). AFITs prior RF-DNA work focused on Multiple Discriminant Analysis/Maximum Likelihood (MDA/ML) and Generalized Relevance Learning Vector Quantized Improved (GRLVQI) classifiers. This work 1) introduces a …
Design And Implementation Of A Unified Command And Control Architecture For Multiple Cooperative Unmanned Vehicles Utilizing Commercial Off The Shelf Components, Jeremy Gray
Theses and Dissertations
Small unmanned systems provide great utility to military applications due to their portable and expendable design. These systems are, however, costly to develop, produce, and maintain, making it desirable to integrate available commercial off the shelf (COTS) components. This research investigates the integration of COTS components through the development of a modular unified command and control (C2) architecture for heterogeneous and homogeneous vehicle teams to accomplish formation flocking and communication relay scenarios. A vehicle agnostic architecture was developed to be applied across different vehicle platforms, different vehicle combination, and different cooperative missions. COTS components consisting primarily of open source hardware …
Continuous Decision Support, Jeremy P. Hendrix
Continuous Decision Support, Jeremy P. Hendrix
Theses and Dissertations
Organizations are often faced with portfolio construction efforts that require them to select one or more alternatives, subject to resource constraints, with the aim of achieving the maximum value possible. This is a well-defined problem with a number of analytically defensible approaches, provided the entire set of alternatives is known when the decision event takes place. Less well treated in the literature is how to approach this problem when the entire set of alternatives is unknown, as when the alternatives arrive over time. This change in the availability of data shifts the problem from one of identifying an optimal subset …
Investigation Of Electromagnetic Signatures Of A Fpga Using An Aprel Em-Isight System, Karynn A. Sutherlin
Investigation Of Electromagnetic Signatures Of A Fpga Using An Aprel Em-Isight System, Karynn A. Sutherlin
Theses and Dissertations
Large military platforms have encountered major performance and reliability issues due to an increased number of incidents with counterfeit electronic parts. This has drawn the attention of Department of Defense (DOD) leadership making detection and avoidance of counterfeit electronic parts a top issue for national defense. More defined regulations and processes for identifying, reporting, and disposing of counterfeit electronic parts are being revised to raise awareness for this aggregating issue, as well as enhance the detection of these parts. Multiple technologies are currently employed throughout the supply chain to detect counterfeit electronic parts. These methods are often costly, time-consuming, and …
Creep And Oxidation Of Hafnium Diboride-Based Ultra High Temperature Ceramics At 1500°C, Anthony J. Degregoria
Creep And Oxidation Of Hafnium Diboride-Based Ultra High Temperature Ceramics At 1500°C, Anthony J. Degregoria
Theses and Dissertations
Ultra high temperature ceramics (UHTCs) are leading candidates for aerospace structural applications in high temperature environments, including the leading edges of hypersonic aircraft and thermal protection systems for atmospheric re-entry vehicles. Before UHTCs can be used in such applications, their structural integrity and environmental durability must be assured, which requires a thorough understanding and characterization of their creep and oxidation behavior at relevant service temperatures.
Creep Of Hi-Nicalon™ S Ceramic Fiber Tows At 800°C In Air And In Silicic Acid-Saturated Steam, Scott J. Robertson
Creep Of Hi-Nicalon™ S Ceramic Fiber Tows At 800°C In Air And In Silicic Acid-Saturated Steam, Scott J. Robertson
Theses and Dissertations
A facility was demonstrated that successfully resolved problems highlighted by previous attempts to study SiC fibers in steam. Monotonic tension and creep tests were conducted to characterize the fibers. The tensile strength of the fibers showed little dependence on applied stress rate, indicating a resistance to environmentally assisted crack growth. Climb-controlled diffusion in air and grain boundary sliding in silicic acid-saturated steam were the dominant damage mechanisms. Silicic acid-saturated steam had a degrading effect on the mechanical performance of the fibers, but much less than unsaturated steam environments. The Monkman-Grant relationship was demonstrated for Hi-NicalonTM S fibers and may be …
Optimal Uas Assignments And Trajectories For Persistent Surveillance And Data Collection From A Wireless Sensor Network, Nidal M. Jodeh
Optimal Uas Assignments And Trajectories For Persistent Surveillance And Data Collection From A Wireless Sensor Network, Nidal M. Jodeh
Theses and Dissertations
This research developed a method for multiple Unmanned Aircraft Systems (UAS) to efficiently collect data from a Wireless Sensor Networks (WSN). WSN are composed of any number of fixed, ground-based sensors that collect and upload local environmental data to over flying UAS. The three-step method first uniquely assigns aircraft to specific sensors on the ground. Second, an efficient flight path is calculated to minimize the aircraft flight time required to verify their assigned sensors. Finally, sensors reporting relatively higher rates of local environmental activity are re-assigned to dedicated aircraft tasked with concentrating on only those sensors. This work was sponsored …
Guided Wave Based Integrated Structural Health Monitoring And Nondestructive Evaluation, Zhenhua Tian
Guided Wave Based Integrated Structural Health Monitoring And Nondestructive Evaluation, Zhenhua Tian
Theses and Dissertations
Damage detection and health monitoring are critical for ensuring the structural safety in various fields, such as aerospace, civil and nuclear engineering. Structural health monitoring (SHM) performs online nondestructive evaluation (NDE) and can predict the structural remaining life through appropriate diagnosis and prognosis technologies. Among various SHM/NDE technologies, guided ultrasonic waves have shown great potential for fast and large area SHM/NDE, due to their sensitivity to small defects and capability to propagate long distances. Recent advances in guided wave based SHM/NDE technologies have demonstrated the feasibility of detecting damage in simple structures such as metallic plates and pipes. However, there …
Experimental Study Of Longitudinal Sorting Of Particles Differing In Size And Density, Nabila Mahjabeen
Experimental Study Of Longitudinal Sorting Of Particles Differing In Size And Density, Nabila Mahjabeen
Theses and Dissertations
Transport, deposition and erosion of sediment particles differing in size, shape and density may result in particle segregation, which in geosciences applications is generally referred to as sediment sorting. A thorough understanding of sediment sorting processes is important to describe and model a wide variety of natural processes such as the decrease in particle size and/or density in a fluvial system (downstream fining and/or lightening), the formation of economic placers, concentration of heavy minerals, chemical and metal pollutants etc. Sorting of sediment grains associated with sediment transport in the streamwise direction results in the development of longitudinal sorting patterns. Vertical …
Industrial Robot Acceptance: Effects Of Workforce Demographics And Establishing A Culture Of Acceptance Within Manufacturing Industry, Melissa M. Henderson
Industrial Robot Acceptance: Effects Of Workforce Demographics And Establishing A Culture Of Acceptance Within Manufacturing Industry, Melissa M. Henderson
Theses and Dissertations
Industrial applications have not been extensively researched regarding human-robot interaction. This project investigated industrial robot acceptance in the context of one manufacturing site. Acceptance was examined in relation to the workforce and conditions of acceptance were identified using mixed methodology. Quantitative (surveys) and qualitative (interviews) data was used to measure and analyze the existing state of technology acceptance and site culture. Based on this exploratory study, it was found the manufacturing facility has a weak culture but would be generally accepting of industrial robots if the technology were easy to use and useful. The identified boundary conditions to acceptance included …
In Situ Ir Spectroscopic Investigation Of Noble Metal Catalysts Related To The Reduction Of Automotive Exhaust Emissions, Zhiyong Wang
In Situ Ir Spectroscopic Investigation Of Noble Metal Catalysts Related To The Reduction Of Automotive Exhaust Emissions, Zhiyong Wang
Theses and Dissertations
The reduction of automotive exhaust emissions has been one of the hottest topics in catalysis community since 1970s. Thanks to the development of three-way catalysts, main auto-exhaust pollutants, such as carbon monoxide, nitrogen oxides and unburned hydrocarbons, can be removed simultaneously. Nowadays, diesel engines and lean-engines become more and more popular due to their high fuel-efficiency and low CO2 emissions. Unfortunately, conventional three-way catalysts are not effective at reducing the NOx emissions from these engines due to the excess oxygen in the exhaust stream. Platinum catalysts were found to be highly active for selective NO reduction with hydrocarbons in excess …
Development Of Highly Active And Stable Hybrid Cathode Catalyst For Pemfcs, Won Suk Jung
Development Of Highly Active And Stable Hybrid Cathode Catalyst For Pemfcs, Won Suk Jung
Theses and Dissertations
Polymer electrolyte membrane fuel cells (PEMFCs) are attractive power sources of the future for a variety of applications including portable electronics, stationary power, and automobile application. However, sluggish cathode kinetics, high Pt cost, and durability issues inhibit the commercialization of PEMFCs. To overcome these drawbacks, research has been focused on alloying Pt with transition metals since alloy catalysts show significantly improved catalytic properties like high activity, selectivity, and durability. However, Pt-alloy catalysts synthesized using the conventional impregnation method exhibit uneven particle size and poor particle distribution resulting in poor performance and/or durability in PEMFCs. In this dissertation, a novel catalyst …
Wavelet Analysis Of Periodic Error In Heterodyne Interferometry, Chao Lu
Wavelet Analysis Of Periodic Error In Heterodyne Interferometry, Chao Lu
Theses and Dissertations
Heterodyne displacement measuring interferometry provides important metrology for applications requiring high resolution and accuracy. Heterodyne Michelson interferometers use a two-frequency laser source and separate the two optical frequencies into one fixed length and one variable length path via polarization. Ideally these two beams are linearly polarized and orthogonal so that only one frequency is directed toward each path. An interference signal is obtained by recombining the light from the two paths; this results in a measurement signal at the heterodyne (split) frequency of the laser source. This measurement signal is compared to the optical reference signal. Motion in the measurement …
Supported Group Ib-Pd Bimetallic Catalysts Prepared By Electroless Deposition And Galvanic Displacement For Selective Hydrogenation Of Acetylene, Yunya Zhang
Theses and Dissertations
Ethylene is the building block for many chemical intermediates in the petrochemical industry. The current worldwide ethylene production is over 150 million tons per year and demand increases by 3-5% annually. However, ethylene produced from steam cracking of light naptha contains up to 2% acetylene which acts as a poison for the downstream ethylene polymerization catalysts. Selective hydrogenation of acetylene in the ethylene stream using supported Pd catalysts is the industrially preferred method of lowering acetylene to acceptable ppm levels (< 5 ppm). Due to inferior selectivity at high acetylene conversion and the formation of “green oil”, or ethylene/acetylene oligomers, during reaction, small amounts of Group IB metals have been added to improve the performance of current generation catalysts. However, the bimetallic effects of the above additives have not been experimentally confirmed, possibly because the conventional methods of catalyst preparation result in both monometallic and bimetallic particles with varying compositions. This in turn makes it difficult to determine the position of the two metallic components, and bimetallic interactions typically occur only when the two metals form proximal contact instead of separate particles. In this study, a series of Ag- and Au-Pd/SiO2 bimetallic catalysts were prepared by electroless deposition (ED) with incremental and controlled coverages of Ag and Au on Pd. The selectivity of acetylene to ethylene and turnover frequencies of acetylene conversion were enhanced at high coverages of Ag and Au on Pd surfaces due to the transition of acetylene adsorption modes, which was further confirmed by the kinetics of acetylene hydrogenation. The similar performance trends for Ag- and Au-Pd/SiO2 suggest that the bimetallic effect for these catalysts was likely geometric and not electronic in nature. For comparison, a series of reverse Pd-Ag/SiO2 bimetallic catalysts where variable coverages of Pd were deposited onto Ag surfaces was prepared using galvanic displacement (GD) of Ago by Pd2+ to further explore the nature of bimetallic effects for selective acetylene hydrogenation. Unlike for the earlier case for Ag on Pd surfaces using ED, for samples prepared by GD there was considerably diffusion of Pd into the Ag lattice to give greater electronic interactions between these two metals, which limited selectivity of acetylene hydrogenation to form ethylene.
Surface Modification Of Nanodiamond And Its Incorporation In Nanodiamond/Peek Nanocomposites, Zahidul Wahab
Surface Modification Of Nanodiamond And Its Incorporation In Nanodiamond/Peek Nanocomposites, Zahidul Wahab
Theses and Dissertations
The continued miniaturization of electronic device components requires new lightweight polymers with high thermal stability, high thermal conductivity, low electrical conductivity, and low dielectric constant. Composites of nanodiamond (ND) and poly(ether ether ketone) (PEEK) are candidates for these applications due their unique combination of properties. The objectives of this research are to explore new routes for surface functionalization of nanodiamond (ND), develop methods for maximizing dispersion of ND as a nano-scale filler in PEEK, and characterize the effect of dispersed ND on the mechanical, thermal and dielectric properties of ND/PEEK composites. Initial attempts to disperse different kinds of commercially available, …
Preparation And Characterization Of Pt-Ru Bimetallic Catalysts Using Electroless Deposition Methods And Mechanistic Study Of Re And Cs Promoters For Ag-Based, High Selectivity Ethylene Oxide Catalysts, Weijian Diao
Theses and Dissertations
Pt-Ru bimetallic catalysts are widely used for direct methanol fuel cells, biomass upgrading and hydrocarbon refining and offer unique properties compared to Pt or Ru monometallic catalysts due to ensemble effects, electronic effects, and/or bifunctional effects. To achieve better performance, strong metal-metal interactions and true bimetallic surface are needed. Electroless deposition (ED) methods are used in our laboratory to synthesize such bimetallic catalysts. In this study, two series of Ru@Pt/C (Pt deposited on Ru surfaces) and Pt@Ru/C (Ru deposited on Pt surfaces) catalysts have been synthesized. Characterization data from temperature programmed reduction (TPR), selective chemisorption, X-ray photoelectron spectroscopy (XPS), and …
Impact Of Formulation And Processing Parameters On Mechanical Properties Of Magadiite/Elastomer Composites, Yating Mao
Impact Of Formulation And Processing Parameters On Mechanical Properties Of Magadiite/Elastomer Composites, Yating Mao
Theses and Dissertations
This work seeks a better understanding of mechanical reinforcement and energy dissipation in elastomer composites containing the layered silicate magadiite (MGD, Na2Si14O29·nH2O). We characterized the elastomer’s accessibility into MGD interlayer spaces and studied the factors that influence the composite mechanical properties. We also compare the mechanical reinforcement of MGD with montmorillonite (MMT, a layered aluminosilicate clay mineral), which is widely used as filler in other kinds of nanocomposites. The study explores the grafting chemistry, vulcanization, and reinforcement mechanism in MGD/elastomer composites, which may help us to formulate the platelet/elastomer composites with superior mechanical properties and performance in the future. We …
A Multiphysics Modeling Of Solid Oxide Metal-Air Redox Battery, Md Ahsan Uddin
A Multiphysics Modeling Of Solid Oxide Metal-Air Redox Battery, Md Ahsan Uddin
Theses and Dissertations
Cost-effective and large scale energy storage is essential for the growth of the future’s ‘‘green energy’’ infrastructure. Among the energy storage technologies currently being used, rechargeable batteries represent a class of advanced electrical energy storage (EES) mechanisms that can be valuable for the future renewable integration and smart grid. Rechargeable batteries have innumerous advantages over the conventional pumped hydro and compressed-air energy storage system. Now days, There are various types of rechargeable batteries available to work as an energy storage device in a smart grid but it still needs many breakthroughs to become commercially viable for stationary energy storage. First …
Effects Of Cell Adhesion Peptides, Ph, And Matrix Shape On Maintenance Of Breast Cancer Stem Cells In An Engineered Hydrogel Matrix, Leily Daneshian
Effects Of Cell Adhesion Peptides, Ph, And Matrix Shape On Maintenance Of Breast Cancer Stem Cells In An Engineered Hydrogel Matrix, Leily Daneshian
Theses and Dissertations
Metastasis, resistance to chemo- and radiotherapy, and eventual relapse has been attributed to a tumor subpopulation known as cancer stem cells (CSCs). CSCs are regulated in their tumor microenvironment by various factors. Synthetic hydrogels can be used to investigate the effects of individual environmental factors on CSCs by providing inert 3D matrices. In this thesis, poly ethylene glycol diacrylate (PEGDA) hydrogel with 5kpa modulus has been used as a culture system to study the effect of; I) integrin and heparin binding peptides, 2) pH, and 3) the shape of the microenvironment on breast CSCs maintenance and tumorsphere formation in PEGDA. …
Tool Material Degradation Due To Friction Stir Welding Of Aluminum Alloys, Corbin T. Collier
Tool Material Degradation Due To Friction Stir Welding Of Aluminum Alloys, Corbin T. Collier
Theses and Dissertations
The purpose of this study is to investigate the friction stir welding (FSW) tool material degradation factors due variation in tool material properties and the effect of an aluminum diffusion wear mechanism on three different FSW tool material when exposed to various welding temperatures and times. The degradation factors are essential to FSW tool design due to the effect of the tool pin and shoulders on the heat generation and material flow which directly correlated to the weld quality created during the FSW process. For this investigation the three materials used are H13, TSP1, and MP159. To determine degradation factors …
Confluence Of Density Currents Over An Erodible Bed, Hassan Ismail
Confluence Of Density Currents Over An Erodible Bed, Hassan Ismail
Theses and Dissertations
Results from laboratory experiments on conservative density current confluence are reported. Hydraulic characteristics and morphodynamic consequences of the confluence of two continuous release density currents in a horizontal, 45 degree asymmetrical junction are examined and compared to those of terrestrial river junctions. It was observed that density current confluence is markedly different than those in river junctions primarily due to the ease of the dense fluid to convect into the ambient fluid in the junction zone. Upward convection in the junction resulted in low horizontal velocity and shear stresses on the bed of the junction zone, followed by re-plunging to …
Development Of Ultra-Low Loading Of Compressive Pt Lattice Cathode Catalyst On Highly Stable Support For Pemfc Automotive Applications, Tianyuan Xie
Theses and Dissertations
The major barriers in the commercialization of the fuel cell technology for automotive applications are the cost and durability of the Pt catalyst and the support stability at high potentials. The U.S. Department of Energy (DOE) targets direct hydrogen fuel cell systems for transportation to meet 65% peak-efficiency, 5,000 hour durability with a mass production cost of $40/kW by 2020. Currently in 2015, the system can be operated at peak energy efficiency of 60% for 3,900 hours with cost of $55/kW. To meet these targets, precious metal loadings must be greatly reduced without altering the catalyst stability. The primary objective …
Bio-Inspired Design Of Mechanical Band Pass Sensor With The Ability To Scavenge Energy, Md Riaz Uddin Ahmed
Bio-Inspired Design Of Mechanical Band Pass Sensor With The Ability To Scavenge Energy, Md Riaz Uddin Ahmed
Theses and Dissertations
Primary objective of this work is to introduce the multi-scale computational model for the bio-inspired acousto-ultrasonic band pass sensor that are capable of mechanically sense and/or filter wide range user defined frequencies. Selecting a particular and/or a distinct band of frequencies is essential for many applications in science engineering and technologies. For example design of sensors in chemical, biomedical and biological applications; device application for acoustic modulation by breaking the acoustic reciprocity and the sensors used in precision manufacturing applications requires sensing and/or filtering of wide range of acousto-ultrasonic frequencies. Presently, electronic devices are widely employed in commercial applications for …
Numerical And Experimental Investigations Of Dam And Levee Failure, Ezzat Youssef Elhassan Mohamed Elalfy
Numerical And Experimental Investigations Of Dam And Levee Failure, Ezzat Youssef Elhassan Mohamed Elalfy
Theses and Dissertations
Both numerical and experimental investigations are conducted to study the failure of earthen dams and levees. Boussinesq equations describing one-dimensional unsteady flow including non-hydrostatic pressure distribution are solved numerically along with Exner equation for the sediment mass conservation to include the effects of the streamline curvature on the failure of non-cohesive earthen embankments. In addition, the effects of the steep bottom slope on the flow variables during the failure are studied by solving the Saint- Venant equations modified for steep bed slope along with the Exner equation to simulate non-cohesive earthen embankment failure due to overtopping. The Boussinesq equations are …