Engineering Commons^™

Pixel Qualification Methods In Attributed Scattering Center Extraction, Justin Tyler Farmer

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Recent work with the spectrum-parted linked image test (SPLIT) uses polarization with Fourier-based peak detection to qualify pixels for attributed scattering center (ASC) extraction from synthetic aperture radar (SAR) phase history data. SPLIT is a two-stage, non-linear technique to extract ASCs. The first stage qualifies pixels for ASC attribution, but suffers from imaging sidelobe energy. Error in pixel qualification propagates to stage two: pixel attribution. In this work, a new ASC extraction method is proposed. It is based on 2-D Prony method and motivated by SPLIT. Position estimation performance of SPLITs local peak detection is compared to the 2-D Prony …

Investigation Of Mirror Image Bias: Evidence For The Use Of Psychophysiological Measures As Indicators Of Cognitive Heuristics, Caroline R. Salchak

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The Mirror Imaging Bias (MIB) is gaining attention as a prominent quality factor in analysts' performance. MIB is an irrationality in which analysts perceive and process information through the filter of personal experience. As evidenced by notable historical events, the consequences of this bias can be dramatic. A way to understand MIB in humans is sought. How analysts analyze data, are trained, and interact with biases is explored. An experiment testing for the appearance of MIB was designed and completed. Measures from an eye tracker as well as physiological measures were collected. Results show a significant correlation between pupil diameter …

Hysteretic Controlled Dc-Dc Converters, Shweta Chauhan

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Switched-mode DC-DC converters are widely used in applications requiring step-up and step-down of DC voltages or currents. These converters find their use in portable applications such as laptops and smart phones, radio-frequency power amplifiers, as light emitting diode (LED) drivers, etc. The power converters consist of a switching network, energy storage elements such as inductors and capacitors, and a load resistor. Transformers are used in converters, which require isolation. The switching network comprises of MOSFETs and diodes. With improvement in the VLSI technology, smaller MOSFETs with increased power handling capability are pushing the speed of operation of these power converters …

Fluid-Structure Interaction Simulations Of A Flapping Wing Micro Air Vehicle, Alex W. Byrd

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Interest in micro air vehicles (MAVs) for reconnaissance and surveillance has grown steadily in the last decade. Prototypes are being developed and built with a variety of capabilities, such as the ability to hover and glide. However, the design of these vehicles is hindered by the lack of understanding of the underlying physics; therefore, the design process for MAVs has relied mostly on trial-and-error based production. Fluid-Structure Interaction (FSI) techniques can be used to improve upon the results found in traditional computational fluid dynamics (CFD) simulations. In this thesis, a verification of FSI is first completed, followed by FSI MAV …

Investigation Of Capabilities Of Observers In A Watch Window Study, Ositadimma Nnanna Eziolisa

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Due to an abundance of data and dynamic nature of tasks, challenges with information retrieval in surveillance and target identification tasks have risen in today's Intelligence, Surveillance, and Reconnaissance (ISR) community. In this study, two variables, Area of Coverage and Amount of Activity (AOC/ACT), are manipulated to study their effects on the number of Watch Windows an observer can monitor. This research describes the analyst's task model, and explains how the level of AOC/ACT and number of Watch Windows affects the analyst's cognitive load. Results showed a significant difference in performance and physiological indicators of workload between high AOC/ACT conditions …

Fatigue Based Structural Design Exploration Via Engineering Data Analytics, Hao Li

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In manufacturing industry, a successful machine development requires the durability of structure components to meet fatigue life targets. The typical way to obtain fatigue design loads for conceptual design exploration is based on hand calculations or historical data to capture envelopes of expected system responses, which may not guarantee to capture actual damaging loads. In this study, a new approach is developed to extract a fatigue design load set directly from measured load data for a conceptual design exploration. The proposed framework integrates the techniques from data analytics and physics based engineering mechanics to amplify and detect fundamental damaging load …

Dynamic Repeater With Booster Enhancement For Fast Switching Speed And Propagation In Long Interconnect, Kaushik Reddy Katpally

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A System-on-a-Chip (SoC) has millions of transistors connected by wires or so called Interconnects. As CMOS technologies scale down, SoC becomes more complex and denser. The delays of basic cells decrease, hereby improving logic gate and logic block delay. However, long wires connecting logic blocks still contribute significant delays, which limit SoC's speed performance.

In this thesis, we take a practical approach towards reducing propagation delay in long wire (Interconnect). A dynamic repeater with Booster enhancement circuit is presented and analyzed in this regard. Both switching speed and Interconnect propagation delay are significantly improved upon locally enabling the Booster to …

Development Of The Academic Performance-Commitment Matrix (Apcm): Understanding The Effects Of Motivation And An Engineering Mathematics Curricular Intervention On Student Self-Efficacy And Success In Engineering, Anthony Bourne

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The latest push to encourage workforce growth in science, technology, engineering and math (STEM) disciplines has generated varying results. Overall, demand for STEM graduates is outpacing the numbers available. This has motivated a wide range of proposed solutions to increase the number of people trained to work in these fields. While a focus on college recruitment in these areas is a necessity for increasing numbers of STEM graduates, the expanding variety of students admitted to university programs in STEM disciplines creates a new series of issues in higher education. Most prominently, retention and graduation rates are low in STEM disciplines. …

16-Bit Digital Adder Design In 250nm And 64-Bit Digital Comparator Design In 90nm Cmos Technologies, Naga Venkata Vijaya Krishna Boppana

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High speed, low power, and area efficient adders and comparators continue to play a key role in hardware implementation of digital signal processing applications. Adders based on Complimentary Pass Transistor Logic (CPL) are power and area efficient, but are slower compared to Square Root Carry Select (SQRT-CS) based adders. This thesis demonstrates a unique custom designed 16-bit adder in 250-nm CMOS technology to obtain fast and power/area efficient features by combining CPL and CS logic. Comparing the results obtained for proposed 16-bit Linear CPL/CS adder with the BEC (Binary Excess-1 Code) based low power SQRT-CS adder, the delay is reduced …

Influence Of Curved Geometries On The Fatigue Life Of Laser Peened Components, Anoop Vasu

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Generating compressive residual stresses at the critical stress locations can prevent or delay structural component failure. Laser peening is a well-known method for inducing compressive residual stresses. The plastic deformation created by the planar shock waves near the surface regions is the major cause for the generation of compressive residual stresses. Apart from the planar waves, release waves at the border of impact are generated that act against the plastic deformation created by planar waves. This decrease of plastic deformation reduces the compressive residual stress generated near the surface regions of peened components. Laser peening of curved geometries creates compressive …

Computational Design And Characterization Of Silicene Nanostructures For Electrical And Thermal Transport Applications, Tim H. Osborn

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Novel silicene-based nanomaterials are designed and characterized by first principle computer simulations to assess the effects of adsorptions and defects on stability, electronic, and thermal properties. To explore quantum thermal transport in nanostructures a general purpose code based on Green's function formalism is developed.

Specifically, we explore the energetics, temperature dependent dynamics, phonon frequencies, and electronic structure associated with lithium chemisorption on silicene. Our results predict the stability of completely lithiated silicene sheets (silicel) in which lithium atoms adsorb on the atom-down sites on both sides of the silicene sheet. Upon complete lithiation, the band structure of silicene is transformed …

Adapting Linguistic Deception Cues For Malware Detection, Stacie Noel Severyn

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People verbally express themselves in a variety of ways, yet the same patterns consistently appear within the words of a person who is being deceptive. This research provides insight and demonstrates that similar patterns exist within malicious software that do not commonly exist within benign software, and can be used to help determine that the software is malicious or untrustworthy.

The patterns that have been shown to exist within deceptive language were investigated to determine whether similar patterns exist within malware. Tests were performed to determine whether malware is more likely to consistently contain a higher or lower frequency of …

6 Ghz Rf Cmos Active Inductor Band Pass Filter Design And Process Variation Detection, Shuo Li

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A 90nm CMOS active inductor band pass filter with automatic peak detection is demonstrated in this thesis. The active inductor band pass filter has a better performance than the passive band pass filter in on-chip circuit design, due to small area, larger gain and tunable frequency. However, process variation makes the active inductor band pass filter hard to be used widely in many applications. To settle this issue, an automatic voltage peak detector is introduced to detect the process variation direction and hope to be used to control the active inductor band pass filter center frequency and gain. The designed …

Multi-Finger Mosfet Low Noise Amplifier Performance Analysis, Xiaomeng Zhang

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Multi-finger layout technique has been extensively used in Nano-scale CMOS circuit design due to the increased circuit performance compared to a single finger layout. However choosing a finger width (W_f) and number of fingers (N_f) to optimize circuit performance is a challenging problem. In this thesis, the performances of 2.4GHz and 6.0GHz single ended low noise amplifiers (LNA) with fixed total transistor widths in 90nm CMOS technology are analyzed as function of number of fingers, bias voltage (V_bias) and channel length (L). The results show that the drain to source current, transconductance and effective gate capacitance increase with increasing number …

End-To-End Classification Process For The Exploitation Of Vibrometry Data, Ashley Nicole Smith

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Laser vibrometry provides a method to identify running vehicles' unique signatures using non-contact measurements. A vehicle's engine, size, materials, shape, and other attributes affect its vibration signature. To develop the capability to classify and identify these signatures, a robust aided target recognition (AiTR) end-to-end process is evaluated and expanded. The main challenge in classifying a vehicle's vibration signatures is presented by the operating conditions and parameters that vary as a function of sensor, environment, and collection locations on the target, among others. Some of the parameters affecting the vibration signatures include weather, terrain, sensor location, sensor type, and engine speed. …

Modern Statistical Methods And Uncertainty Quantification For Evaluating Reliability Of Nondestructive Evaluation Systems, Jeremy Scott Knopp

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The reliability of Nondestructive Evaluation (NDE) is an important input for risk analysis for sustainment of aging infrastructure. Reliability has typically been quantified via probability of detection (POD) studies. There are three problems with POD modeling methodologies provided in the most recent guidance on the subject:

1) Current models do not estimate the extremes of a POD curve very well because of the assumption that the POD curve approaches zero as flaw size goes to zero, and the POD curve approaches one as the flaw size goes to infinity.

2) The existing 2-parameter logit/probit models can be misused since there …

Evaluation And Application Of Lte, Dvb, And Dab Signals Of Opportunity For Passive Bistatic Sar Imaging, Aaron S. Evers

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Due to the many advantages of passive radar and ubiquity of commercial broadcast transmitters, interest in passive bistatic radar (PBR) applications has continued to grow. More specifically, sources studying commercial orthogonal frequency division multiplexing (OFDM) waveforms for passive bistatic synthetic aperture radar (SAR) imaging have become more common. This work evaluates and applies long term evolution (LTE), digital video broadcast (DVB), and digital audio broadcast (DAB) signals of opportunity for passive bistatic SAR imaging.

First, implications of the structure and properties of each of the signal of opportunity's transmitted waveform are characterized by examining the waveform's self- and cross-ambiguity functions …

Fragment Association Matching Enhancement (Fame) On A Video Tracker, Andrew Johnson

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In the field of surveillance, algorithms are developed to extract meaningful information out of a video feed captured via a camera. One type of algorithm used in the field of surveillance is a tracking algorithm. A tracking algorithm allows a user to watch the movement of an object in the camera's field of view. The tracker used in this thesis research is a feature aided tracker (FAT). The FAT uses both features and kinematics to generate tracks. However, camera movement will affect the tracker's ability to accurately track an object which poses a problem to the tracker. Specifically, the camera …

A Validation Study Of Sc/Tetra Cfd Code, Hongtao Yu

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The goal of this study is to validate the accuracy of the SC/Tetra CFD code by modeling four cases: a 2D zero pressure gradient flat plate, an axisymmetric separated boundary layer, flow over an NACA 0012 airfoil, and flow over an NACA 4412 airfoil trailing edge separation. The results will be compared to experimental data and CFL3D results. This study also investigates the sensitivity of SC/Tetra results to different set up details such as mesh resolution, turbulence model, and under-relaxation settings. Automation using the Visual Basic programming language was used to vary these set up details and efficiently process a …

Null Convention Logic Asynchronous Register Full Path Completion Feedback Loop Using Two Stage Voltage Divider, Christopher P. Taylor

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As fabrication technologies improve logic densities increase. It becomes harder to mitigate clock skew and jitter. Higher clock rates combined with increased numbers of sinks increase mixed-system substrate noise. An increasingly popular approach to address these problems is clockless logic. One technique is Null Convention Logic (NCL). However, traditional NCL feedback loops have large area overhead and require many gate delays. This makes NCL impractical in many applications. In this paper we propose to replace the feedback logic with a two-stage voltage divider. Using our technique we show up to 50% area reduction and require only one unit gate delay.

A Comparison Of Monocular Camera Calibration Techniques, Richard L. Van Hook

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Extensive use of visible electro-optical (visEO) cameras for machine vision techniques shows that most camera systems produce distorted imagery. This thesis investigates and compares several of the most common techniques for correcting the distortions based on a pinhole camera model. The methods being examined include a common chessboard pattern based on (Sturm 1999), (Z. Zhang 1999), and (Z. Zhang 2000), as well as two "circleboard" patterns based on (Heikkila 2000). Additionally, camera models from the visual structure from motion (VSFM) software (Wu n.d.) are used. By comparing reprojection error from similar data sets, it can be shown that the asymmetric …

Novel Devices And Components For Thz Systems, John Raymond Middendorf

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Since the first demonstration of the generation of terahertz (THz) pulses from photoconductive (PC) antennas, research has pushed toward the development of smaller, cost efficient, and faster THz systems. This dissertation presents the work accomplished in order to realize these more practical terahertz (THz) photoconductive (PC) systems.

First, this work will present a novel ErAs:GaAs photoconductive switch used to make a THz source excited by 1550 nm laser pulses. It will be shown that the excitation process taking place in the material relies on extrinsic (rather than intrinsic) photoconductivity. Then, several experiments will be presented that aim to improve the …

Impact Of Sar Image Formation Quality On Target Separability, Cody A. Lawyer

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The polar format algorithm (PFA) allows the use of computationally efficient fast Fourier transforms in synthetic aperture radar (SAR) image formation, but introduces phase errors when making the far-field approximations that facilitate this approach. The phase errors cause spatially variant distortion and defocus in the formed image. These effects may complicate target recognition applications. To limit the impact of defocus, scene size is usually limited such that the maximum quadratic phase error within an image falls below some threshold. This thesis looks at how distortion and defocus affects the classification of targets, with the hope of developing an application-driven scene …

Analysis Of A Fuel Cell Combustor In A Solid Oxide Fuel Cell Hybrid Gas Turbine Power System For Aerospace Application, Ryan R. Sinnamon

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Over the last few years, fuel cell technology has significantly advanced and has become a mode of clean power generation for many engineering applications. Currently the dominant application for fuel cell technology is with stationary power generation. Very little has been published for applications on mobile platforms, such as unmanned aerial vehicles. With unmanned aerial vehicles being used more frequently for national defense and reconnaissance, there is a need for a more efficiency, longer endurance power system that can support the increased electrical loads onboard. It has already been proven by others that fuel cell gas turbine hybrid systems can …

Development And Application Of An Analyst Process Model For A Search Task Scenario, Hendrickson K. Karl

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A key intelligence analyst role in open source search is the transformation of data into understanding. Better comprehension is needed of how new tools impact the analyst search process. The use of function analysis, heuristic analysis, and a usability study combine to provide the basis for developing an analyst process model, which affords the researcher with a structure to measure the impact of tools and expertise in performing a search task. The experiment utilized representative analyst scenario tasks in comparing baseline tools with the Geospatial Open Search Toolkit (GOST). The results show error rates increase when using a new toolset …

Relating Microstructure To Process Variables In Beam-Based Additive Manufacturing Of Inconel 718, John Ryan Thompson

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The advancement of laser or electron beam-based additive manufacturing requires the ability to control solidification microstructure. Previous work combined analytical point source solutions and nonlinear thermal finite element analysis (FEA) to explore the effects of deposition process variables on Ti-6Al-4V solidification microstructure. The current work seeks to extend the approach to Inconel 718, with the addition of Cellular Automaton-Finite Element (CAFE) models. Numerical data from finite element results are extracted in order to calculate accurate melt pool geometry, thus leading to corresponding cooling rates and thermal gradients. The CAFE models are used to simulate grain grown and nucleation, providing a …

Study On The Vortex Wake Of An Airfoil Equipped With Flexible Trailing Edge Fringes, Zhengkai He

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With the inspiration of owl's silent flight, a traditional airfoil S833 equipped with flexible fringes on the trailing edge is investigated through numerical simulation and experiments in a wind tunnel. The newly constructed airfoil is modeled and numerically investigated. An incompressible, 2D and viscous flow solver in the Computational Fluid Dynamics (CFD) software FLUENT is utilized to conduct the numerical simulation on the vortex flow feature in the wake of the airfoil. A User Defined Function code was applied to generate the defined motion of flexible fringes. The effects of the flapping frequency of the fringe and the deformation pattern …

Hierarchical Porous Structures Functionalized With Silver Nanoparticles: Adaptation For Antibacterial Applications, Anil Kumar Karumuri

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For a large number of applications involving surface interactions, there is an ever growing demand for materials with high specific surface area (surface area to volume ratio). Porous materials and nanomaterials offer higher specific surface area (SSA) each with their respective advantages and disadvantages. This research program is focused on bringing the two approaches together to create truly "hierarchical" materials that combine advantages of both while minimizing their disadvantages. In this study, various carbon based porous geometries were fabricated by grafting carbon nanotubes (CNT) onto highly porous reticulated carbon foams. These structures were further modified by functionalizing metal nanoparticles such …

Imperfect Situation Analysis: Representing The Role Of Error And Uncertainty In Modeling, Simulation And Analysis, Victor Eaton Middleton

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Much of traditional modeling, simulation and analysis (MS&A) is supported by engineering models - deterministic, Newtonian physics-based representations of closed systems. Such approaches are not well-suited to represent the intricacies of human behavior. This research advocates and seeks to articulate the concept of a more human- centric approach to MS& A, one that better represents decision-making and other cognitive aspects of human behavior as well as it does physical activity.

It starts with a view of individuals and groups as complex adaptive systems, which are best represented using agent-based modeling. Representation of human behavior through intelligent agents incorporates models of …

Two-Speed Control Of Compressors In Residentlial Air-Conditioning Systems, George Joseph Ramayya

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Residential air-conditioning systems pre-dominantly have single phase compressors and the new technology in use is Ultratech scroll compressors capable of running at partial and full capacity levels using electro-mechanical controls allowing for staged and more efficient operation based on system load conditions. This project is to look at electronic methods to obtain two-speed control to duplicate the Ultratech compressor and evaluate the performance of the control options. A triac control scheme is designed for worst case assuming maximum load conditions of compressor in an air-conditioning system. The control schemes are prototype tested on single phase motor and compressor motor for …