Engineering Commons^™

Characterization And Design Of A Completely Parameterizable Vhdl Digital Single Sideband Modulator Circuit For Quick Implementation In Fpga Or Asic Electronic Warfare Platforms, Harold Scott Axtell

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In this work we present the design and characterization of a parameterizable Digital Single Sideband Modulator (DSSM) circuit for use with a Digital Radio Frequency Memory (DRFM) or other signal processing circuits. Field Programmable Gate Arrays (FPGAs) can be used as a prototyping platform for quickly verifying and hardware testing a digital circuit or system. FPGAs can also be used as an implementation platform for a digital circuit or system. A main advantage of FPGAs over that of an Application Specific Integrated Circuit (ASIC) is that it can be quickly (and often dynamically) reprogrammed; whereas an ASIC can take months …

Impact Of Induced Defects On Rotor Life Assessment, Ashley Winfield Whitney-Rawls

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There is an economic need to reduce the conservatisms of current lifing methods and extend component life. Extending component usage increases the probability of failure during operation. Therefore, the risk of continued service must be quantified before life extension concepts can successfully be implemented. The current FAA approved software for the certification of new rotor designs, only accounts for defects present prior to service. Defects due to the handling of components during inspection and material fatigue will induce defects during service and need to be included in any analysis of component life extension. Component life extension analysis of an Inconel …

Fabrication And Analysis Of Compositionally Graded Functional Layers For Solid Oxide Fuel Cells, Jared Ray Mccoppin

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Solid Oxide Fuel Cell (SOFC) structures must be optimized for high performance, increased life, and low cost. Fabrication methods are an area of research interest in bringing down the total cost of SOFCs, and can also impact cell life and performance. Graded functional layers have been shown to enhance cell performance, but current fabrication methods require multiple fabrication steps. This thesis describes a novel fabrication method capable of compositional gradation of functional layers for SOFCs. Using colloidal spray deposition technology, a controlled co-deposition strategy was utilized to fabricate SOFC's with compositionally graded cathode and anode functional layers (CGCFL/CGAFL). In this …

High Frequency Vco And Frequency Divider In Vlsi 90nm Technology, Paesol Veerakitti

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A Voltage Controlled Oscillator (VCO) is essentially a tunable frequency generator. A VCO is used as a part in PLL system which is a system that generates a stable oscillating signal. As the digital electronic industry demands an ever increasing performance in speed, VCO's are required to create higher frequency signals. However, the phase noise performance of a VCO decreases as the operating frequency gets higher. The LC VCO is developed in this thesis to be used in with a tunable frequency divider as a part of a PLL system. The LC VCO structure design takes the advantage of a …

Stochastic Mistuning Simulation Of Integrally Bladed Rotors Using Nominal And Non-Nominal Component Mode Synthesis Methods, Joseph A. Beck

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Mistuning prediction in integrally bladed rotors is often done with reduced order models that minimize computational expenses. A common model reduction technique used for mistuning applications is the component mode synthesis method. In this work, two modern component mode synthesis methods are used to generate mistuned response distributions that will be used to determine if the two methods are statistically indistinguishable. The first method, nominal mode approximation, assumes an airfoil geometric perturbation alters only the corresponding substructure modal stiffnesses while its mode shapes remain unaffected. The mistuned response is then predicted by a summation of the nominal modes. The second …

Development Of An Efficient Super-Resolution Image Reconstruction Algorithm For Implementation On A Hardware Platform, Pestak Thomas C.

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There is a growing demand from numerous commercial and military applications for images with ever-improving spatial resolution. However, there are resolution-limiting factors inherent in all imaging systems. Decreasing pixel sizes and/or increasing sensor arrays are not always viable. Super-Resolution (SR) Image Reconstruction is an image processing technique that restores a high-resolution (HR) image from a series of low-resolution (LR) images of a particular scene. Recently, there has been extensive research on robust SR algorithms used for post-processing. The goal of this thesis is to explore the current SR research and design computationally efficient SR algorithms for real-time processing based on …

Experimental Studies Of Turbulent Boundary Layers Over A Rough Forward-Facing Step And Its Coarse Scale Resolution Approximations, Huiying Ren

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High spatial resolution PIV experiments are performed in the x-y plane at two different spanwise positions to compare the turbulent boundary layers over smooth and rough forward-facing-steps as well as the rough step's two coarse scale-resolution approximations. The Reynolds number based on the step's mean height, Re_h, is 3450 and the ratio of the boundary layer thickness to the step's height is δ/h = 8. The roughness topography on the top surface of the rough step is replicated from a realistic turbine blade and is intrinsically three-dimensional and highly irregular. The surface topographies of the coarse scale-resolution …

Hard-Switching And Soft-Switching Two-Switch Flyback Pwm Dc-Dc Converters And Winding Loss Due To Harmonics In High-Frequency Transformers, Dakshina S. Murthy Bellur

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The flyback pulse-width modulated (PWM) DC-DC power converter is a very important circuit in switching mode power supply (SMPS) converters for low power applications. The main drawback of the conventional single-switch flyback converter is the high turn-off voltage stress suffered by the switch. The high voltage transients are caused by the resonant behavior of the transformer leakage inductance and the transistor output capacitance, resulting in ringing superimposed on the steady-state switch voltage level. This requires a transistor with higher voltage rating. However, a transistor with higher voltage rating has higher on-resistance causing higher conduction loss. The high voltage ringing also …

Visualization Of Complex Unsteady 3d Flow: Flowing Seed Points And Dynamically Evolving Seed Curves With Applications To Vortex Visualization In Cfd Simulations Of Ultra Low Reynolds Number Insect Flight, Christopher M. Koehler

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Three dimensional integration-based geometric visualization is a very powerful tool for analyzing flow phenomena in time dependent vector fields. Streamlines in particular have many perceptual benefits due to their ability to provide a snapshot of the vectors near key features of complex 3D flows at any instant in time. However, streamlines do not lend themselves well to animation. Subtle changes in the vector field at each time step lead to increasingly large changes between streamlines with the same seed point the longer they are integrated. Path lines, which show particle trajectories over time suffer from similar problems when attempting to …

Population Fit Threshold: Fully Automated Signal Map Generation For Baseline Correction In Nmr-Based Metabolomics, Daniel C. Homer

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Baseline correction of NMR-based metabolomic spectra is a key step in data processing to elucidate biomarkers of diseased and toxic states. Automated baseline correction methods often use human-selected parameters. Presented is a method for automated baseline correction using parameters selected from and without manipulation of the spectrum. The focus is on generating an accurate signal map based on the differentiating characteristics of baseline noise and signal. The presented method of signal map generation and baseline correction was developed and tested on 13C and 1H NMR spectra. The spectra were as simple as chemical standards containing less than 25 signal peaks …

Ab Initio Simulations Of Hydrogen And Lithium Adsorption On Silicene, Tim H. Osborn

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The energies and temperature-dependent dynamics of hydrogen and lithium chemisorption on a silicon nanosheet, called silicene, were studied using density functional theory and molecular-dynamics (MD) simulations. Silicene has a buckled honeycomb structure, and has been fabricated as suspended monolayer sheets and nanoribbons in recent experiments. We calculated the adsorption energies of hydrogen and lithium on silicene for different adsorption ratios between 3.1% and 100%. The studies will clarify the characteristics of these novel and promising nanomaterials, and pave the way for their applications.

For Hydrogen, the adsorption energy had a maximum of 3.01 eV/H for complete hydrogenation, and decreased by …

Charaterization Of Chlorpyrifos Toxicity On The Pancreatic Beta Cell Line Rinm5f, Zhongyu Yan

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Chlorpyrifos (CPF) is a well-known organophosphate (OP) insecticide that inhibits acetylcholinesterase (AChE). Organophosphates have been shown to induce hyperglycemia in both humans and animals that cannot be explained by AChE inhibition alone. Pancreatic β-cells are responsible for secreting insulin and playing a fundamental role in glucose homeostasis. The aim of this research was to investigate CPF toxicity on the insulin secreting β-cell line RINm5f (RIN). In the first part of this dissertation, we determined that cytotoxic concentrations of CPF between 50 µM and 200 µM induced a dose-dependent increase in RIN cell apoptotic and necrotic death (p<0.05). Lower doses, i.e., 5-25 µM did not induce apoptosis or necrosis. In further mechanistic studies, inhibitors of c-Jun N-terminal kinase (JNK) and P38 pathways, i.e., SP600125 and SB202190, successfully attenuated CPF-induced apoptosis (p<0.05), suggesting cell death is mediated by JNK and/or p38. In addition, N-Acetyl-L-cysteine (NAC), an antioxidant, inhibited apoptosis suggesting that oxidative stress is also involved in RIN cell death. In the second part of this dissertation, low dose CPF's effects on insulin synthesis and secretion was studied. Our results showed that RIN cells treated with CPF for 4 hr exhibited a dose-dependent decrease in insulin secretion in response to stimulation by 50 mM potassium (p<0.05). Insulin secretion stimulated by 25 mM glucose also showed significant decreases upon incubation with various doses of CPF (p<0.05). Insulin synthesis involves proteolytic cleavage of proinsulin at two specific sites. The enzymes responsible for promoting proinsulin cleavage, i.e, prohormone convertase (PC) 1/3 and 2 (PC2), contain a serine hydrolase catalytic triad, His-Asp-Ser, similar to AChE. CPF modification of PC enzymes similar to AChE, could potentially interrupt the conversion of proinsulin to insulin and disrupt insulin secretion. PC2 enzyme activity was significantly inhibited by CPF at concentrations as low as 10 µM (p<0.01). RIN cells, for the first time, were found to secrete proinsulin was through a constitutive instead of a regulated pathway. In summary, our results show that CPF not only exerts a direct cytotoxic effect at concentrations above 50 µM, but also significantly impairs insulin secretion at lower doses. Low dose CPF could potentially affect endocrine function in vivo by inhibiting the proinsulin processing enzyme PC2.

Extent And Effects Of Selection To Reduce Synthetic Cost Of Highly Expressed Proteins, Esley Marvin Heizer Jr

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Organisms that preferentially utilize less biosynthetically expensive amino acids in highly expressed genes exhibit metabolic efficiency. Exploration of this phenomenon has been limited to six prokaryotes.

I present a large scale analysis of metabolic efficiency in prokaryotic organisms and analysis of two eukaryotes (Saccharomyces cerevisiae and humans). Examination of 73 bacteria reveals the presence of metabolic efficiency in 66 organisms. The average correlation between amino acid biosynthetic cost and CAI scores in these organisms is -0.21. The seven organisms that did not exhibit metabolic efficiency are all Lactobacilli and highly auxotrophic. Saccharomyces cerevisiae exhibits significant trends between average amino acid …

Radio Frequency Controlled Stimulation Of Intracellular Gold Or Silver Nanoparticle Conjugates For Use As Potential Sensors Or Modulators Of Biological Function, Richard Craig Murdock

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The objective of this investigation was to further explore the ability of a radio frequency (RF) signal to interact with metal nanoparticles (NPs) for the purposes of remote stimulation or control of cellular processes. Gold and silver NPs have shown the ability to be heated by electromagnetic frequencies, especially for the purpose of deactivating abnormal cells. However, the heating of the NPs in these previous studies was constant and uncontrolled. For this study, our hypothesis was by investigating the RF heating characteristics of NPs and its impact on surface functionalizations, a remotely stimulated control mechanism can be developed at the …

Algorithmic Techniques Employed In The Quantification And Characterization Of Nuclear Magnetic Resonance Spectroscopic Data, Paul Edward Anderson

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Nuclear magnetic resonance (NMR) based metabolomics is a developing research field with broad applicability, including the identification of biomarkers associated with pathophysiologic changes, sample classification based on the mechanism of toxicity, and clinical diagnosis. Intrinsic to these applications is the need for statistical and computational techniques to facilitate the associated data analysis. Further, a typical 1H NMR spectrum of pure proteins, biofluids, or tissue may contain thousands of resonances (i.e., peaks), thus, a pure visual inspection is insufficient to fully utilize the spectral information.

Common practice within the NMR-based metabolomics community is to evaluate and validate novel algorithms on empirical …

A Human-Computer Integrated Approach Towards Content Based Image Retrieval, Phani Nandan Kidambi

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Digital photography technologies permit quick and easy uploading of any image to the web. Millions of images being are uploaded on the World Wide Web every day by a wide range of users. Most of the uploaded images are not readily accessible as they are not organized so as to allow efficient searching, retrieval, and ultimately browsing. Currently major commercial search engines utilize a process known as Annotation Based Image Retrieval (ABIR) to execute search requests focused on retrieving an image. Even though the information sought is an image, the ABIR technique primarily relies on textual information associated with an …

Design Of Hf Forward Transformer Including Harmonic Eddy Current Losses, Dhivya Ammanambakkam Nagarajan

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Pulse Width Modulated (PWM) Forward DC-DC converter is a buck-derived isolated power converter which is used extensively in low power to medium power applications. Satisfactory operation of the transformer utilized in forward converter plays a crucial role in the overall operation of the forward converter. Hence detailed analysis pertaining to design of forward transformer is important. The forward transformer is unique as the magnetizing inductance is not required to store magnetic energy. Additionally, the forward transformer has a tertiary winding, which is required to reset the core and to prevent core saturation. This adds to the complexity of design and …

An Improved Genetic Algorithm For Knapsack Problems, Taskiran, Gamze Kilincli

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In this study, an improved genetic algorithm (GA) is presented to solve the multidimensional 0-1 knapsack problem (MKP). The MKP is a well-known combinatorial optimization problem and has received wide attention from the operations research community for decades. Although recent advances in computing and optimization technologies have made the solution of small and medium size instances possible, this NP-hard problem, in general, still remains one of the challenging problems yet to be solved.

Of the various algorithms developed to solve the MKP, GA seems to be one of the best methods pointed out in the literature. A GA is an …

A Biomechanical Comparison Of Locking Compression Plate Constructs With Plugs/Screws In Osteoporotic Bone Model, Krishna P. Desai

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Locking compression plates are proven to be safe for use in open reduction and internal fixation (ORIF) especially in osteoporotic bones. Because of various combinations of holes, the system provides more options for clinicians to use either locking screws or non-locking screws. This clinical research introduces screw like plugs which can be used along with the screws in case of locking compression plates. Experimental work was performed to determine the effectiveness of the plugs. The results showed that there is not a significant difference between the groups which used plugs and did not use the plugs, both in case of …

Electromagnetic Fields, Power Losses, And Resistance Of High-Frequency Magnetic Devices, Daniel Joseph Whitman

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The operation of dc-dc PWM converters requires magnetic components that operate at high frequencies and carry large currents. At such frequencies the skin and proximity effects cause a substantial increase in power losses and ac resistance. This thesis reviews existing one dimensional analytical work on the prediction of these losses and, beginning with an inductor, derives expressions for the electromagnetic fields and power losses within the winding as well as the ac resistance of the device. The results of the inductor analysis are then extended to examine these quantities in transformers of various winding configurations. It is shown that proximity …

The Harmonic Distortion Reduction Of Phase-Angle Fired Scrs Feeding A Resistive Load Using Fuzzy Logic, Matthew A. Clark

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High power silicon controlled rectifiers (SCR) are used in the application of infrared radiation testing. A case study has been performed on a department of defense facility utilizing SCRs to transfer electrical energy to thermal energy. The facility is capable of generating up to 5000 °F across large cross-sectional areas, requiring tens of megawatts of power. The combination of high power, unbalanced loads, and SCR switching generate high harmonic disturbances that offer significant challenges for conventional linear control systems. In addition, unbalanced three-phase distribution systems are difficult to model, specifically during switching transients. Fuzzy logic is used to characterize the …

Mining Shared Decision Trees Between Datasets, Qian Han

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This thesis studies the problem of mining models, patterns andstructures (MPS) shared by two datasets (applications), a well understood dataset, denoted as WD, and a poorly understood one, denoted as PD. Combined with users' familiarity with WD, the shared MPS can help users better understand PD, since they capture similarities between WD and PD. Moreover, the knowledge on such similarities can enable the users to focus attention on analyzing the unique behavior of PD. Technically, this thesis focuses on the shared decision tree mining problem. In order to provide a view on the similarities between WD and PD, this thesis …

Induction Of P53 Dependent Cellular Senescence Through Hdmx Inhibition Or Ypel3 Expression, Kelly Lynn Robbins Miller

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Mutations in p53 that compromise its function have been reported in approximately half of all human cancers (Vousden et al., 2002). The other half of human tumors that retain wild-type p53 have a dysfunctional p53 pathway through other mechanisms (Wade et al., 2009). Activation of p53 leads to cell cycle arrest, DNA repair, apoptosis and senescence, however, the pathway leading to cellular senescence is the focus of this study. Cellular senescence is a process leading to irreversible arrest of cell division. Under normal physiologic conditions, the activity of p53 is kept in check by its negative regulators, Mdm2 and MdmX. …

A Direction Finding System Using Log Periodic Dipole Antennas In A Sparsely Sampled Linear Array, Jonathan Andrew Weldon

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This thesis explores the use of wide band log periodic dipole array (LPDA) antennas in direction finding systems. A wide band log periodic antenna will be constructed and tested to ensure hardware capability. A novel approach utilizing non-uniform spacing in a linear array will be used to improve the spatial resolution of the direction finding system. These specialized linear arrays are known as minimum redundancy or non-redundant linear arrays.

A Structured Asic Approach To A Radiation Hardened By Design Digital Single Sideband Modulator For Digital Radio Frequency Memories, Thomas B. Pemberton

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Digital Radio Frequency Memories (DRFM) are widely used as modules in digital signal processing. These modules can provide several forms of signal manipulation and storage capabilities. With single event effects caused by environmental radiation the need for a radiation hardened DRFM is increased. Typical radiation hardening involves the use of specialized foundries utilizing proprietary CMOS libraries that are expensive to build or adding lead packages around a chip that is expensive and add weight to the chip. An alternative radiation hardening technique is to utilize a radiation hardened by design library. This library includes digital gates that have been hardened …

Frequency Domain Processing Based Chaos Communication For Cognitive Radio, Daniel Y. Sundersingh

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Chaotic systems are deterministic non-linear dynamical systems which have intrinsic properties such as: irregularity, aperiodicity, and are impossible to predict over long periods of time. Cognitive radio on the other hand, has emerged recently as a powerful means to tackle the spectrum congestion problem. The goal of this thesis is to combine the benefits of the chaos communication system with the cognitive radio to create a robust, highly secure, flexible chaotic cognitive radio system. We first begin with a short survey of chaotic communication and cognitive radio technology. Then we compare chaotic waveforms to other conventional PN sequences and show …

Fuzzy Logic Learning For Predictive Feedback Estimation In A Radiant Heat System, Matthew R. Rickey

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High temperature thermal testing is used to validate the effectiveness of thermal protection systems (TPS) and to simulate aerodynamic heating in high speed flight vehicle structures. Silicon controlled rectifiers (SCR) are utilized to drive resistive heating elements and producing temperatures up to 5000 degrees Fahrenheit. Thermocouples used to provide feedback to the control system have a high probability of failure at extreme temperatures. Traditional solutions include switching to redundant thermocouples, changing to an open-loop control scheme, or using power as the control signal. The first methods is limited in that redundant thermocouples are also not completely reliable. Both open-loop control …

Development Of A Remote Medical Image Browsing And Interaction System, Wei Ye

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In this thesis a new capability - remote image browsing built upon our existing music telepresence platform is introduced. The implementation of this new image capability has two parts: one part is the local image viewing and the other part is distributed image-view interaction. Image viewing part is realized using the foundation of Linux GTK+ library. Most popular lossless and lossy image coding formats such as GIF, PNG, BMP and JPEG are supported currently. Image viewing part also provides several image operations such as: zoom in and zoom out, image information display and moreover users can select their own regions …

A Study Of Evolvable Hardware Adaptive Oscillators For Augmentation Of Flapping-Wing Micro Air Vehicle Altitude Control, Bharath Venugopal Chengappa

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The control of insect-sized flapping-wing micro air vehicles is fraught with difficulties. Even when adequate control laws are known, limits on computational precision and floating-point processing can render it difficult to field implementations that provide sufficiently accurate and precise vehicle body placement and pose. Augmentation of an existing altitude controller with an Evolvable Adaptive Hardware (EAH) oscillator has been proposed as a means for an on-board altitude controller to correct control precision and accuracy difficulties during normal flight. This thesis examines a range of setting of the internal learning algorithms for the EAH oscillator and provides empirical evidence about which …

Cytochrome C Oxidase From Rhodobacter Sphaeroides: Oligomeric Structure In The Phospholipid Bilayer And The Structural And Functional Effects Of A C-Terminal Truncation In Subunit Iii, Teresa L. Cvetkov

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Cytochrome c oxidase (COX) of the mitochondrial electron transport chain catalyzes the reduction of oxygen to water while concomitantly translocating protons across the inner mitochondrial membrane. This two part dissertation is a structural and functional investigation of COX using the bacterial model system from Rhodobacter sphaeroides (R.sph.).

First, the oligomeric structure of R.sph. COX within the lipid bilayer was investigated using discontinuous sucrose gradient ultracentrifugation. Utilizing this technique, liposomes containing R.sph. COX (pCOV) were separated from liposomes lacking enzyme (COV). The net buffering capacity and degree of light scattering per COX molecule were reduced in pCOVs, making them well suited …