Engineering Commons^™

Automatic All-Hex Topology Operations Using Edge Valence Prediction With Application To Localized Coarsening, Timothy Ira Miller

Theses and Dissertations

In this work, we propose using edge valence as a quality predictor when used as a driver for adapting all hexahedral meshes. Edge valence, for hexahedra, is defined as the number of faces attached to an edge. It has shown to be a more reliable quality predictor than node valence for hexahedral meshes. An edge valence of 3, 4, or 5 within the volume of a hexahedral mesh has provided at least a positive scaled Jacobian for all observed meshes, without the presence of over constraining geometry. It is often desirable to adapt an existing mesh through sheet operations such …

Analysis Of Selected Factors Affecting Concrete Cover Measurements On Bridge Decks, Jeffrey Ryan Hoki

Theses and Dissertations

The objective of this research was to quantify the effects of selected parameters on the accuracy of concrete cover measurements on bridge decks. This research involved three full-factorial laboratory experiments each designed to investigate one of three primary variables. These primary variables included distance to a parallel adjacent bar, distance to a reinforcement intersection, and incorrect bar size input for the cover meter. Each experiment also involved four secondary variables known to affect cover readings. These secondary variables included actual cover depth, meter brand, antenna type, and bar size. Statistical analyses were performed to determine the significance of each factor. …

Temporal And Spatial Variability In Base Materials Treated With Asphalt Emulsion, Tyler James Quick

Theses and Dissertations

The first objective of this research was to investigate temporal trends in the mechanical properties of base materials stabilized with asphalt emulsion and to assess the rate at which emulsion-treated base (ETB) design properties are achieved. The second objective of this research was to identify construction and environmental factors most correlated to specific mechanical properties of ETB layers and to determine which construction factors exhibit the greatest variability. Additional statistical analysis was performed to determine if significant differences existed between different test sections on a given project. In this research, three experimental sections were established along a pavement reconstruction project …

A Gis-Based Data Model And Tools For Analysis And Visualization Of Levee Breaching Using The Gssha Model, Hoang Luu Tran

Theses and Dissertations

Levee breaching is the most frequent and dangerous form of levee failure. A levee breach occurs when floodwater breaks through part of the levee creating an opening for water to flood the protected area. According to National Committee on Levee Safety (NCLS), a reasonable upper limit for damage resulting from levee breaching is around $10 billion per year during 1998 and 2007. This number excludes hurricanes Katrina and Rita in 2005 which resulted in economic damages estimated to be more than $200 billion dollar and a loss of more than 1800 lives. In response to these catastrophic failures, the U.S. …

A Study Of The Cause Of Failure Of Rotationally Molded, High-Density Polyethylene, Sodium Hypochlorite Storage Tanks, Dixon Harold Abell

Theses and Dissertations

The topic of chemical oxidative degradation in rotational molded polyethylene (high-density cross-linked) chemical (sodium hypochlorite) storage tanks is an industry problem that ranks at the top of current business issues for manufacturers of chemical storage tanks. The degradation of these tanks not only compromises the physical and mechanical properties of the tank material, but reduces the life expectancy of the tank, eventually resulting in catastrophic tank failure. Premature tank failure comes at a hefty cost. The reputation of the manufacturer is questioned often resulting in immediate loss of customer satisfaction and future business. The leaking of the chemical from the …

Chemical Potential Perturbation: A Method To Predict Chemical Potentials In Periodic Molecular Simulations, Stan G. Moore, Dean R. Wheeler

Faculty Publications

A new method, called chemical potential perturbation (CPP), has been developed to predict the chemical potential as a function of density in periodic molecular simulations. The CPP method applies a spatially varying external force field to the simulation, causing the density to depend upon position in the simulation cell. Following equilibration the homogeneous (uniform or bulk) chemical potential as a function of density can be determined relative to some reference state after correcting for the effects of the inhomogeneity of the system. We compare three different methods of approximating this correction. The first method uses the van der Waals density …

Increasing Efficiency In Boundary Security With Wireless Sensor Networks And Geospatial Information Systems Using Homology Theory, Luis Berumen^, Eric Chaidez^, Hamide Dogan*, Jose Gerardo Rosiles**

COURI Symposium Abstracts, Spring 2011

As part of an institutional investigation, we attempt to address the challenges the US customs and Border protection agency faces in the El Paso region. Our research focuses on defining a system for the surveillance application, and the use of mathematical models employed to achieve a greater efficiency of such architecture. With the use of the defined system, we apply homology theory through the algebraic process of topology, to accomplish an independent coordinate-free based system, which covers the surveillance area, with lesser quantity of sensor nodes. Our architecture makes the use of an operating system for wireless sensor networks; TinyOS, …

Pyrolysis Kinetics And Chemical Structure Considerations Of A Green River Oil Shale And Its Derivatives, James L. Hillier

Theses and Dissertations

This work had the objective of determining both the kinetic parameters for the pyrolysis of oil shale and kerogen as well as using analytical techniques coupled with pyrolysis to shed light on the structure of a specific Green River oil shale. Because of the problems with linearized methods and disagreement among literature values and methods, a new method was developed tofit kinetic parameters to non linearized data. The method was demonstrated to determine the "correct" answer for mathematically generated data within a few percent error and was shown to have a lower sum squared error than the linearized methods. The …

A Proteolytic Process To Simulate The Mechanics Of Disc Dengeration In Bovine Cadaveric Tissue, Timothy A. Bishop

Theses and Dissertations

Purpose. The present work hypothesized that proteolytic dissolution of intervertebral discs could induce biomechanical change comparable to the change observed in natural disc degeneration. A method to do such could be utilized for in vitro research where intersample differences in geometry and chemical makeup render it difficult to compare and aggregate results into generalized conclusions.
Methods. Forty-one bovine coccygeal intervertebral discs were isolated with individual functional spinal units. Samples were loaded in three modes: compression/tension, flexion/extension, and axial rotation. The anulus fibrosus of each disc was injected with 200µl trypsin or fetal bovine serum (control) and incubated for an allotted …

Developing Methods To Assess The Potential Effects Of Global Climate Change On Deer Creek Reservoir Using Water Quality Modeling, Reed Earl Chilton

Theses and Dissertations

To evaluate the potential impacts of future climate change on a temperate reservoir, I used a calibrated water quality and hydrodynamic model validated using three years of data (2007-2009) from Deer Creek Reservoir (Utah). I evaluated the changes due to altered air temperatures, inflow rates, and nutrient loads that might occur under Global Climate Change (GCC). I developed methods to study GCC on reservoirs. I produced Average Water Temperature Plots, Stratification Plots, and Total Concentration Plots. Average Water Temperature Plots show the sensitivity of the water temperature to various parameters. Stratification Plots quantify stratification length and strength as well as …

Automated Delay Estimation At Signalized Intersections: Phase I Concept And Algorithm Development, Taylor R. Forbush

Theses and Dissertations

Currently there are several methods to measure the performance of surface streets, but their capabilities in dynamically estimating vehicle delay are limited. The objective of this research is to develop a method to automate traffic delay estimation in real-time using existing field traffic data collection technologies. This research has focused on method and algorithm development that can be applied to existing technologies. Two algorithms were developed to run automatically using Microsoft Excel and Visual Basic to calculate traffic delay from data collected from existing vehicle detection. The algorithms were developed using computer modeling software to simulate different lane configurations. The …

Culvert Roughness Elements For Native Utah Fish Passage: Phase I, Lindsay D. Esplin

Theses and Dissertations

Culverts can increase stream velocities as a result of reduced waterway areas and prevent upstream passage of small non-salmonid fish such as the Native Utah Leatherside chub (Gila copei) and Longnose dace (Rhinichthyscataractae). To mitigate this problem, current culvert design standards for fish passage match sustained fish swim speeds with average cross sectional velocity through the culvert. Such policies dictate relatively large barrels and do not recognize the role of reduced velocity zones near culvert boundaries. Obstacles and streambed substrate create turbulent regions with lower velocity zones that can increase upstream fish passage. A comparison of …

Subband Engineering For P-Type Silicon Ultra-Thin Layers For Increased Carrier Velocities: An Atomistic Analysis, Neophytos Neophytou, Gerhard Klimeck

Birck and NCN Publications

Ultra-thin-body (UTB) channel materials of a few nanometers in thickness are currently considered as candidates for future electronic, thermoelectric, and optoelectronic applications. Among the features that they possess, which make them attractive for such applications, their confinement length scale, transport direction, and confining surface orientation serve as degrees of freedom for engineering their electronic properties. This work presents a comprehensive study of hole velocities in p-type UTB films of widths from 15 nm down to 3 nm. Various transport and surface orientations are considered. The atomistic sp3d5s*-spin-orbit-coupled tight-binding model is used for the electronic structure, and a semiclassical ballistic model …

Subband Engineering For P-Type Silicon Ultra-Thin Layers For Increased Carrier Velocities: An Atomistic Analysis, Neophytos Neophytou, Gerhard Klimeck, Hans Kosina

Other Nanotechnology Publications

Ultra-thin-body (UTB) channel materials of a few nanometers in thickness are currently considered as candidates for future electronic, thermoelectric, and optoelectronic applications. Among the features that they possess, which make them attractive for such applications, their confinement length scale, transport direction, and confining surface orientation serve as degrees of freedom for engineering their electronic properties. This work presents a comprehensive study of hole velocities in p-type UTB films of widths from 15 nm down to 3 nm. Various transport and surface orientations are considered. The atomistic sp3d5s*-spin-orbit-coupled tight-binding model is used for the electronic structure, and a semiclassical ballistic model …

A High-Gain, Low-Power Cmos Operational Amplifier Using Composite Cascode Stage In The Subthreshold Region, Rishi Pratap Singh

Theses and Dissertations

This thesis demonstrates that the composite cascode differential stage, operating in the subthreshold region, can form the basis of a high gain (113 dB) and low-power op amp (28.1 µW). The circuit can be fabricated without adding a compensation capacitance. The advantages of this architecture include high voltage gain, low bandwidth, low harmonic distortion, low quiescent current and power, and small chip area. These advantages suggest that this design might be well-suited for biomedical applications where low power, low noise bio-signal amplifiers capable of amplifying signals in the millihertz-to-kilohertz range is required.

Relocatable Field Programmable Gate Array Bitstreams For Fault Tolerance, David P. Montminy, Rusty O. Baldwin, Paul D. Williams

AFIT Patents

A Field Programmable Gate Array (FPGA) circuit capable of operating through at least one fault. The FPGA circuit includes a configuration memory and an embedded microprocessor. The embedded microprocessor having access to the configuration memory, static modules, at least one relocatable module, and at least one spare module. The relocatable module being relocatable from a first target area to a second target area. The relocatable module being relocatable by manipulating a partial bitstream with the embedded microprocessor. The microprocessor calculating a plurality of bitstream changes, to relocate the at least one relocatable module using at least triple modular redundancy (TMR).

Shaped Mems Contact, Ronald A. Coutu Jr., Paul E. Kladitis, Robert L. Crane

AFIT Patents

A MEMS switch fabrication process and apparatus inclusive of a bulbous rounded surface movable contact assembly that is integral with the switch movable element and achieving of long contact wear life with low contact electrical resistance. The disclosed process is compatible with semiconductor integrated circuit fabrication materials and procedures and includes an unusual photoresist reflow step in which the bulbous contact shape is quickly defined in three dimensions from more easily achieved integrated circuit mask and etching-defined precursor shapes. A plurality of differing photoresist materials are used in the process. A large part of the contact and contact spring formation …

System Identification, State Estimation, And Control Of Unmanned Aerial Robots, Caleb H. Chamberlain

Theses and Dissertations

This thesis describes work in a variety of topics related to aerial robotics, including system identification, state estimation, control, and path planning. The path planners described in this thesis are used to guide a fixed-wing UAV along paths that optimize the aircraft's ability to track a ground target. Existing path planners in the literature either ignore occlusions entirely, or they have limited capability to handle different types of paths. The planners described in this thesis are novel in that they specifically account for the effect of occlusions in urban environments, and they can produce a much richer set of paths …

Ultrasensitive Biosensing On The Zepto-Molar Level, Yongki Choi, Siu-Tung Yau

Electrical and Computer Engineering Faculty Publications

Detection of analytes on the zepto-molar (10^-^2^1M) level has been achieved using a field-effect bio-detector. By applying a gating voltage to enzymes immobilized on the working electrode of the detector, amplification of the biocatalytic current was observed. The amplification is attributed to the modification of the tunnel barrier between the enzyme and the electrode by the gating voltage-induced electric field which exists at the solution-electrode interface. The detection was demonstrated with the glucose oxidase (GOx)-glucose and alcohol dehydrogenase (ADH)-ethanol biocatalytic systems. Glucose at zepto-molar level was detected with zepto-molar detection resolution. Equivalently, 30 glucose …

Integrated Home Server, Santiago John Rose

Computer Science and Engineering Master's Theses

Since the advent of the microprocessor in the 1970s, the market for consumer electronics has exploded with new devices changing the way we live and do business. Today, mobile phones, cameras, PCs, iPads, mp3 players, network media players, security systems, automation and IT systems, all have common functionality and there is an increasing need for unification of access to all these devices around a common server based architecture to unlock the benefits of smart integration and to simplify access for the end user.

IHS project is designed to provide to its business and home owners a unified network for all …

Disturbance Attenuation In A Magnetic Levitation System With Acceleration Feedback, Feng Tian, Craig Kevin, Mark L. Nagurka

Mechanical Engineering Faculty Research and Publications

The objective of this work is to demonstrate the use of acceleration feedback to improve the performance of a maglev system, especially in disturbance attenuation. In the single degree-of-freedom (DOF) system studied here, acceleration feedback has the effect of virtually increasing inertia, damping and stiffness. It is shown that it can be used to increase disturbance rejection without sacrificing tracking performance. Both analytical and experimental results demonstrate that disturbance rejection can be improved with acceleration feedback.

Seismic Response Of Peaty Organic Soils As A Levee Foundation Material, Robb E.S. Moss, Justin C. Hollenback

Civil and Environmental Engineering

The dynamic response of peaty organic soils is not well understood but its poor competency as an engineering material is well known. Its use as a foundation material is generally avoided through careful selection of project location, or removal and replacement with more suitable material. In certain situations peaty organic soils are unavoidable because of prior land use and subsequent development of infrastructure. In a delta environment levees are often found to be overlying peaty organic deposits, the California Bay Delta and New Orleans levee systems are two important examples. The Bay Delta is in a seismically active area and …

Shake Table Testing Of Seismic Soil-Foundation-Structure-Interaction, Robb E.S. Moss, Steven Kuo, Victor Crosariol

Civil and Environmental Engineering

This research involves shake table testing of 1g scale models that mimic the coupled seismic response of a structure on a shallow mat foundation and the foundation soil (termed soil‐foundation‐structure‐interaction or SFSI). In previous research, SFSI effects have been quantified through analytical models, numerical analyses, and limited field data. This research is working towards increasing the amount of empirical data through scale model shake table testing. A suite of earthquake times histories are considered in evaluating a 10^th scale soil‐structure model using a flexible wall barrel on a 1‐D shake table. San Francisco Young Bay Mud (YBM) is used …

Characterization And In Vitro Toxicity Of Copper Nanoparticles (Cu-Nps) In Murine Neuroblastoma (N2a) Cells, Sitao Veronica Brownheim

Theses and Dissertations

Nanomaterials, classified as materials within the 1 - 100 nanometer range, have seemingly endless applications. It is very important to the Air Force to increase the understanding of Cu-NPs and the possible health impacts from nanomaterial exposure prior to wide-spread industry and military use. Therefore, the purpose of this research is to thoroughly characterize the properties of three different copper samples upon suspension into aqueous solutions over time: Cu-NPs (Cu 25 nm), CuO-NPs (CuO 40 nm), and Cu-MSP (Cu 500nm). Additionally, this research seeks to observe in vitro effects upon murine neuroblastoma cells (N2A) by these three types of particles …

Sawdust Pyrolysis And Petroleum Coke Co2 Gasification At High Heating Rates, Aaron D. Lewis

Theses and Dissertations

Clean and efficient electricity can be generated using an Integrated Gasification Combined Cycle (IGCC). Although IGCC is typically used with coal, it can also be used to gasify other carbonaceous species like biomass and petroleum coke. It is important to understand the pyrolysis and gasification of these species in order to design commercial gasifiers and also to determine optimal conditions for operation. High heating-rate (100,000 K/s) pyrolysis experiments were performed with biomass (sawdust) in BYU's atmospheric flat-flame burner reactor at conditions ranging from 1163 to 1433 K with particle residence times ranging from 23 to 102 ms. Volatile yields and …

Spear Phishing Attack Detection, David T. Merritt

Theses and Dissertations

This thesis addresses the problem of identifying email spear phishing attacks, which are indicative of cyber espionage. Spear phishing consists of targeted emails sent to entice a victim to open a malicious file attachment or click on a malicious link that leads to a compromise of their computer. Current detection methods fail to detect emails of this kind consistently. The SPEar phishing Attack Detection system (SPEAD) is developed to analyze all incoming emails on a network for the presence of spear phishing attacks. SPEAD analyzes the following file types: Windows Portable Executable and Common Object File Format (PE/COFF), Adobe Reader, …

Characterization Of Noise Technology Radar Signal Detectability Using A Non-Cooperative Receiver, Daniel V. Atienza

Theses and Dissertations

As Noise Technology Radar (NTR) systems emerge, there is a need for non-cooperative, non-matched filter detection and exploitation. This work is based on that need and AFIT's Noise Network (NoNET) radar system. These signals are associated with Low Probability of Detection/ Intercept (LPD/LPI) signals. Quadrature Mirror Filter Banks (QMFB) has been effectively used for non-cooperatively detecting structured LPD/LPI signals and extracting various waveform characteristics. However, the QMFB process performance with unstructured NTR signals was challenging and motivated a need for a transformed QMFB. This transform was based on AFIT research by Gronholz and Mims (G-M), who used a multi-channel receiver …

An Investigation Of Cavity Resonance And Its Relationship To Store Force And Moment Loading, Christopher J. Coley

Theses and Dissertations

A store which is released from an internal bay is subjected to a highly unsteady flowfield which influences the release characteristics for the store. Pressure transducer information is often used to estimate store loading, although no direct correlation between the observed frequencies from the pressure transducers and the store loading has been developed. The relationship between the acoustic modes present in the cavity and the force and moment loading on a store released from a bay are investigated through a CFD study using the OVERFLOW 2.1 solver. The acoustic modes of the cavity are calculated from the pressure fluctuation histories …

Perimeter Security And Intruder Detection Using Gravity Gradiometry: A Feasibility Study, Jared D. Tuinstra

Theses and Dissertations

Changes in the mass distribution around some point on the Earth’s surface induce corresponding changes to the magnitude and direction of the gravity vector at that location. The nine-tensor derivative of the gravity vector, or gravity gradient, is sensitive to very small changes in the gravity vector. With some assumptions, continuous measurement of the gravity gradient using a gravity gradiometer (GGI) is used to determine the location of a mass change in the local area near the instrument. This investigation sought to determine the effectiveness, operating characteristics, and limitations of a physical perimeter security system that uses an array of …

Software And Critical Technology Protection Against Side Channel Analysis Through Dynamic Hardware Obfuscation, John R. Bochert

Theses and Dissertations

Side Channel Analysis (SCA) is a method by which an adversary can gather information about a processor by examining the activity being done on a microchip though the environment surrounding the chip. Side Channel Analysis attacks use SCA to attack a microcontroller when it is processing cryptographic code, and can allow an attacker to gain secret information, like a crypto-algorithm's key. The purpose of this thesis is to test proposed dynamic hardware methods to increase the hardware security of a microprocessor such that the software code being run on the microprocessor can be made more secure without having to change …