Engineering Commons^™

High-Efficiency Wideband Class-F Power Amplifier With Electronically Tunable Resonant Network, Alex D. Compton

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This thesis presents a high-efficiency Class-F power amplifier (PA) operating from 30-88 MHz through the use of an electronically tunable resonant network. While conventional Class-F designs are limited to operation over less than an octave, the proposed design utilizes reconfigurable reactive elements in order to cover the entire VHF-FM frequency range. A real circuit implementation using GaN HEMT is designed and simulated, with the notable design considerations examined in detail. A minimum power added efficiency (PAE) of 71.7% is achieved across the band, at output powers = 49.2 dBm. This combination of high output power and high-efficiency operation across a …

Large Scene Sar Image Formation, Leroy A. Gorham

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With new advances in digital signal processing technology, Synthetic Aperture Radar (SAR) systems are capable of collecting high resolution data over very large scenes. Well known image formation algorithms such as the polar format algorithm (PFA) create image artifacts in large images due to phase errors introduced by the algorithm. In this dissertation, we analyze the nature of these artifacts by comparing PFA to an exact imaging algorithm, the backprojection algorithm (BPA). First, we perform a novel phase error analysis by decomposing the PFA phase errors into constant, linear, and quadratic terms for arbitrary flight paths. Second, we utilize the …

Direct Optimization For Classification With Boosting, Shaodan Zhai

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Boosting, as one of the state-of-the-art classification approaches, is widely used in the industry for a broad range of problems. The existing boosting methods often formulate classification tasks as a convex optimization problem by using surrogates of performance measures. While the convex surrogates are computationally efficient to globally optimize, they are sensitive to outliers and inconsistent under some conditions. On the other hand, boosting's success can be ascribed to maximizing the margins, but few boosting approaches are designed to directly maximize the margin. In this research, we design novel boosting algorithms that directly optimize non-convex performance measures, including the empirical …

Contrast Pattern Aided Regression And Classification, Vahid Taslimitehrani

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Regression and classification techniques play an essential role in many data mining tasks and have broad applications. However, most of the state-of-the-art regression and classification techniques are often unable to adequately model the interactions among predictor variables in highly heterogeneous datasets. New techniques that can effectively model such complex and heterogeneous structures are needed to significantly improve prediction accuracy. In this dissertation, we propose a novel type of accurate and interpretable regression and classification models, named as Pattern Aided Regression (PXR) and Pattern Aided Classification (PXC) respectively. Both PXR and PXC rely on identifying regions in the data space where …

Feature Extraction Using Dimensionality Reduction Techniques: Capturing The Human Perspective, Ashley B. Coleman

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The purpose of this paper is to determine if any of the four commonly used dimensionality reduction techniques are reliable at extracting the same features that humans perceive as distinguishable features. The four dimensionality reduction techniques that were used in this experiment were Principal Component Analysis (PCA), Multi-Dimensional Scaling (MDS), Isomap and Kernel Principal Component Analysis (KPCA). These four techniques were applied to a dataset of images that consist of five infrared military vehicles. Out of the four techniques three out of the five resulting dimensions of PCA matched a human feature. One out of five dimensions of MDS matched …

A Workload Balanced Mapreduce Framework On Gpu Platforms, Yue Zhang

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The MapReduce framework is a programming model proposed by Google to process large datasets. It is an efficient framework that can be used in many areas, such as social network, scientific research, electronic business, etc. Hence, more and more MapReduce frameworks are implemented on different platforms, including Phoenix (based on multicore CPU), MapCG (based on GPU), and StreamMR (based on GPU). However, these MapReduce frameworks have limitations, and they cannot handle the collision problem in the map phase, and the unbalanced workload problems in the reduce phase. To improve the performance of the MapReduce framework on GPGPUs, in this thesis, …

Improved Spare Part Forecasting For Low Quantity Parts With Low And Increasing Failure Rates, Albert Frank Lowas Iii

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Part demand forecasting methods assume that the demand for a part over time follows a predictable pattern, and that the patterns observed in historical data provide a reliable indication of future demands. Generally, forecasting studies focus on topics such as: the span of time from which to sample the historical data, an assessment of data in order to find weekly or annual patterns, and the assignment of probabilities of different demand quantities in any given time period. Using the demand models derived from these forecasting methods, inventory decisions are made--decisions which directly impact operating cost and equipment availability.

Like most …

Gallium Nitride: Analysis Of Physical Properties And Performance In High-Frequency Power Electronic Circuits, Dalvir K. Saini

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Gallium nitride (GaN) technology is being adopted in a variety of power electronic applications due to their high efficiencies even at high switching speeds. In comparison with the silicon (Si) transistors, the GaN-based devices exhibit lower on-state resistance and parasitic capacitances. The thermal performance of the GaN transistors are also better than the Si counterparts due to their higher junction temperature and lower temperature-coefficient of on-resistance. These unique properties make the gallium-nitride power transistors an appropriate selection for power electronic converters and radio-frequency power amplifiers, where size, efficiency, power density, and dynamic performance are major requirements.

Foreseeing the immense capabilities …

Unsteady Physics And Aeroelastic Response Of Streamwise Vortex-Surface Interactions, Caleb J. Barnes

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Streamwise vortex-surface interactions can occur in aviation intentionally in the context of formation flight as an energy saving mechanism, unintentionally in wake crossings when aircraft fly in close proximity, and as a consequence of aircraft design through the interaction of fluid dynamics between different aerodynamic surfaces. The bulk of past work on streamwise vortex-surface interactions has focused on steady inviscid analysis for optimizing aerodynamic loads in the context of formation flight or experimental analysis on fin buffeting problems. A fundamental understanding of the viscous and unsteady effects that may occur is both important and currently lacking in the literature. This …

A Computational Study Of A Photovoltaic Compound Parabolic Concentrator, William M. Vance

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Routines have been written and added to the Wright State developed solar system simulation program called Solar_PVHFC to model incident solar radiation for a compound parabolic concentrator (CPC) that uses solar panels (photovoltaic panels) to produce electrical energy. Solar_PVHFC is a program that models a solar energy system composed of solar panels to produce electricity from the sun, hydrogen storage tanks to chemically store the energy produced by the solar panels, and fuel cells to convert between electrical and chemical energy when required. Solar_PVHFC features several adjustable parameters to model a solar panel, hydrogen storage, and fuel cell system. Now …

Direction Of Arrival Estimation Using Wideband Spectral Subspace Projection, Majid Shaik

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Many areas such as Wireless Communication, Oil Mining, Radars, Sonar, and Seismic Exploration require the direction of arrival estimation (DOA) of wideband sources. Most existing wideband DOA estimation algorithms decompose the wideband signals into several narrowband frequency bins, followed by either focusing or transforming to a reference frequency bin, before estimating the DOAs. The focusing based methods are iterative and their performance is affected by the choice of preliminary DOA estimates and the number of source DOAs to be estimated. The existing method requiring transformation to a reference frequency bin exhibits spurious peaks in the spatial spectrum and is not …

An Experimental Investigation On Friction And Scuffing Failure Of Lubricated Point Contacts, Sai Goutham Soma

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Scuffing failure is a catastrophic thermal failure mode induced by the extreme surface temperature of the contacting components. As two mechanical elements roll against each other with high sliding motion, the frictional heat flux elevates the surface temperature to exceed the critical limit, resulting in the welding of the surfaces. The relative motion then tears the welded surfaces apart, causing the damage. Scuffing failure has been an important failure mode for rolling machine elements such as bearings and gears in aerospace applications, owing to the very high operating speeds. Recently, this failure mode has extended to the automotive field, where …

Vitamin D Receptor And 1Α, 25-Dihydroxyvitamin D3 Mediated Regulation Of Δnp63Α, Hill Tremayne Natasha

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1alpha, 25-dihydroxyvitamin D3 (VD3), the ligand for the Vitamin D Receptor (VDR), functions to both inhibit cell growth and promote cell survival. High-dose VD3 is being utilized as a cancer preventive therapy for melanoma, breast and colorectal cancers, without a complete understanding of VD3/VDR signaling. DeltaNp63alpha, considered to be a proto-oncogene, is overexpressed in non-melanoma skin cancers (NMSCs), induces VDR gene expression and promotes keratinocyte proliferation, and may serve to exacerbate non-melanoma skin cancer. The objective of this dissertation was to determine whether VDR/VD3 signaling promotes keratinocyte proliferation by up-regulating DeltaNp63alpha. I showed that VDR increases DeltaNp63alpha expression at both …

Whole-Lake Primary Production Calculator, Colin D. Leong

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This work describes an implementation of a model for estimation of both benthic and phytoplanktonic primary production in lakes. The web application makes use of interpolation techniques to allow estimates of primary production using values for photosynthesis/irradiance parameters at only 5 depths. These estimates compare favorably in accuracy with estimates using values listed at over one hundred depths. Validation of the implementation was done by comparison with primary production results from the Northern Temperate Lakes Long Term Ecological Research database.

Left Ventricle Volume Reconstruction To Minimize Scanning Time: Slice-Fitting Method, Prateek Kalra

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Assessment of left ventricle volume is usually done for diagnosis and prognosis of heart diseases. Slice-summation method is a standard method used to compute left ventricle volume where region of interest from several short axis (SA) slices are added. There are some limitations to this method, however. It requires short-axis slices to be taken parallel to the mitral valve plane from the base to apex. Moreover, scanning several short-axis slices is a tedious and time consuming process especially for studies that require several hundreds datasets. There are some existing methods to reconstruct left ventricle volume but most of them depend …

Split Ring Resonator Design For Agricultural Based Applications, Joshua David Compaleo

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Recent advances with manufactured electromagnetic materials known as metamaterials are paving the way to use microwave technology in agricultural development and harvesting. It has been proposed that split ring resonators could be placed on the surface of fruit or vegetables such that the resonant behavior may be monitored and used to estimate the ripeness level. The method is non-destructive and could enable monitoring of large quantities of produce or even be tailored to hand-held devices for consumers. However, the understanding of corresponding changes in the proposed device's resonant behaviors and ripeness levels are limited. In addition, fruit and vegetables are …

Reducing Error Rates In Intelligence, Surveillance, And Reconnaissance (Isr) Anomaly Detection Via Information Presentation Optimization, Donald Glen Church

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In the ISR domain, time-critical decision-making and dealing with multiple information feeds places high demands on the human. When designing aids and tools, the decision maker must be taken into account. This research looks toward designing a decision aid based the personality type of the operator. The BFI is used to determine the impact of personality and decision aid type (graphical vs. textual) on performance. Results show Openness and Agreeableness to be the strongest single factors for decision aid impact on performance. A model was also developed to show how the human takes the information and relates it to a …

Manipulation Of Gold Nanorod Physicochemical Properties To Enhance Biocompatibility, Uptake And Intracellular Preservation Of Optical Properties For Bio-Imaging And Plasmonic Photo-Therapeutic Applications, Anthony B. Polito

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Gold nanorods (GNRs) due to their tunable optical properties within the near infrared (NIR) region have been identified as strong candidates for new nano-based biomedical applications. Unfortunately, many have reported GNR cytotoxicity and it is still unclear how GNR aspect ratio (AR), surface charge and surface chemistry contribute to cellular association and cytotoxicity. GNR surface chemistry modifications have been reported to reduce cytotoxicity, however they can result in poor cellular uptake and loss of NIR optical properties preventing efficiency with bio-imaging and photo-thermal applications. The aim of this study was to determine if manipulation of GNR physicochemical properties could enhance …

Pwm Buck Converter As A Dynamic Power Supply For Envelope Tracking And Amplitude Modulation, Thomas R. Salvatierra

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Modern energy transmission and signal reproduction techniques rely upon power amplifier (PA) architectures that must operate with high efficiency. Current-source PAs are linear but inherently inefficient; switch-mode PAs are efficient-yet-nonlinear systems, often lacking an efficient means of amplitude modulation (AM) for power transmission. A promising technique for addressing these problems involves replacing the fixed PA supply voltage V_dd with a controlled, variable voltage provided by a dynamic power supply. High-efficiency envelope tracking and amplitude modulation can thereby be provided to both current-source and switch-mode PAs, respectively. This work presents a pulse-width modulated (PWM) dc-dc buck converter for use as the …

Analysis Of The Tapered Transition Waveguide, Ryan J. Shaver

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The tapered transition waveguide is used in waveguide measurement systems for characterizing biaxial electromagnetic properties of materials, but its complex geometry does not support an analytic field solution. To ensure single-mode field behavior, the system includes sections of standard waveguides that only support the dominant mode. As a result, full-wave modeling and simulation of the system is exceedingly large.

Using the finite-element method to analyze the high-order modes at the junctions and to explore field configurations within the transition altering geometry, it is shown that besides the TE10 mode, the TE11 mode is significant. Then, two methods are proposed for …

The Organization Of Kv2.1 Channel Proteins In The Membrane Of Spinal Motoneurons: Regulation By Injury And Cellular Activity, Shannon Hunt Romer

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The intrinsic membrane properties of neurons in the central nervous system are controlled by the tight regulation of membrane-bound ion channels. Rather than existing as static entities operating only in opened or closed states in fixed locations, ion channels are dynamic molecules with the capacity to adopt multiple functional states through conformational changes and/or post-translational modification - enabling flexibility in their activity. Furthermore, the location of ion channels within certain membrane compartments and/or signaling ensembles is critical to synaptic integration and shaping of firing properties, and can also be dynamically modified by changes in neuronal activity and pathology. In mammalian …

Integrated Magnetic Components For Rf Applications, Sheena Hussaini

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Integrated r-f passive components such as inductors, transmission lines, transformers etc, form the basic building blocks in r-f integrated circuits (RFICs) such as matching networks, low noise amplifiers (LNAs), synthesizers and r-f mixers. One main challenge faced by current technology developers in integrating r-f components on integrated chip (IC) are related to operation and size. Tremendous efforts were made for overcoming challenges of r-f integrated circuits to meet growing technology demands.

In general, r-f devices utilize magnetic materials such as ferrites for their operation for improving device performance and scaling. However, due to material properties and size ferrite materials are …

Strain-Induced Energy Band-Gap Opening Of Silicene, Zhonghang Ji

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Inspired by the success of graphene, various two dimensional (2D) structures on different substrates have been proposed. Among others, an allotropic form of silicon, coined "silicene" was shown to exhibit similar properties with graphene of a zero band gap and a Dirac cone shape at the K point in the Brillouin zone. Similar to its counterpart graphene, one of the main obstacles to applying silicene in modern electronics is the lack of an energy band gap. In this work, a systematic study was presented on the structural and electronic properties of single and bi-layered silicon films under various in-plane biaxial …

Virtual Agent Interaction - Improving Cognitive Abilities And Trust For A Complex Visual Search Task, Heather H. Milecki

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Introduction: This thesis research examined a novel decision support aid ("Spatial Cue + Virtual Agent") on human performance in a simulated complex visual search task. Method: Participants in the "Control" condition did not receive support from an aid. Participants in the "Spatial Cue" condition received support from an aid in the form of a bounding box. Participants in the "Spatial Cue + Virtual Agent" condition received support from an aid in the form of a bounding box and a virtual agent. The aids' reliability was held constant at one level, 70 percent. Image difficulty was based on clutter; clutter was …

Design And Performance Analysis Of Magnetic Adder And 16-Bit Mram Using Magnetic Tunnel Junction Transistor, Surya Kiran Akkaladevi

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The scaling down of IC's based on CMOS technology faces significant challenges due to technology advancing factors. The stand-by power becomes comparable to active power due to the increasing leakage current. Power gating and various low-power schemes have been proposed in the past to reduce the stand-by power in CMOS designs. As most random access memory (RAM) used for primary storage in personal computers is volatile memory, which needs constant voltage (power on) to store the data and results in a higher stand-by power. Magnetic Tunnel Junctions (MTJ) transistor has feature of non-volatility, endurance and high density, which makes it …

Theoretical Throughput Capacity: Capabilities Of Human Information Processing During Multitasking, Aerial N. Camden

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Technological advancements in automation have allowed humans to collect data at exorbitant rates. As a result, human multitasking as become an integral part of many government, industrial, and routine activities. However, multitasking can be difficult to study, primarily due to the lack of objective metrics. The Human Operator Informatic Model (HOIM) is an information-theory based model that has been recently developed to combat these difficulties. The HOIM is based on Shannon information theory and can provide an objective, meaningful measure to describe system complexity and overall multitasking performance. The main goal of this work was to validate the HOIM as …

An Improved Adaptive Filtering Approach For Removing Artifact From The Electroencephalogram, Justin Ronald Estepp

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The biophysics of volume conduction that enable electrophysiological data acquisition also result in the mixing of data sources including possible, undesirable noise sources at the electrode interface. This work specifically focuses on improving the performance of the recursive least-squares (RLS) adaptive filtering method for removing eye movement artifact from the electroencephalogram. In biophysically-inspired simulated data, the RLS algorithm is verified to produce results that are inferior to extended infomax independent component analysis (ICA), the most widely used artifact correction approach in this problem space, due to its non-linear filter phase response and the presence of bidirectional contamination, or cross-talk, resultant …

Anterior Cruciate Ligament Biomechanics, Computational Modeling Of Mechanical Behavior And Injury Risk, Bharadwaj Cheruvu

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Knee joint involves interactions from various structures such as cartilage, bone, muscles, ligaments, tendon, as well as neural control. Anterior cruciate ligament (ACL) tears are one of the most frequent soft tissue injuries of the knee. A torn ACL leaves the joint unstable and at risk for further damage to other soft tissues manifested as pain, dislocation, and osteoarthritis. This injury is quite common in sports such as basketball, soccer and football. Females often tear their ACL 2-8 times more frequently than their male counterparts. An ACL injury can be devastating and significantly increases the athlete's risk for osteoarthritis long …

Hierarchical Porous Structures With Aligned Carbon Nanotubes As Efficient Adsorbents And Metal-Catalyst Supports, Hema Vijwani

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The overall goal of this study is two-fold: synthesis of multiscale nanostructures by growing aligned carbon nanotubes on porous foam substrates and investigation of their applicability as adsorbents and catalyst supports for environmental remediation applications. High purity, vertically-aligned arrays of carbon nanotubes (CNT) are grown on open-cell interconnected porous carbon foams by pre-activating them with an oxide buffer layer followed by chemical vapor deposition (CVD). This type of hierarchical morphology provides the capability of increasing surface area by several orders of magnitude, while tuning its morphology for targeted applications. Analytical models are also proposed in this study for specific surface …

Signal Subspace Processing In The Beam Space Of A True Time Delay Beamformer Bank, Nathan Allen Wilkins

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A number of techniques for Radio Frequency (RF) source location for wide bandwidth signals have been described that utilize coherent signal subspace processing, but often suffer from limitations such as the requirement for preliminary source location estimation, the need to apply the technique iteratively, computational expense or others. This dissertation examines a method that performs subspace processing of the data from a bank of true time delay beamformers. The spatial diversity of the beamformer bank alleviates the need for a preliminary estimate while simultaneously reducing the dimensionality of subsequent signal subspace processing resulting in computational efficiency. The pointing direction of …