Engineering Commons^™

Design And Validation Of A High-Lift Low-Pressure Turbine Blade, Mark W. Mcquilling

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This dissertation is a design and validation study of the high-lift low-pressure turbine (LPT) blade designated L2F. High-lift LPTs offer the promise of reducing the blade count in modern gas turbine engines. Decreasing the blade count can reduce development and maintenance costs and the weight of the engine, but care must be taken in order to maintain turbine section performance with fewer blades. For an equivalent amount of work extracted, lower blade counts increase blade loading in the LPT section. The high-lift LPT presented herein allows 38% fewer blades with a Zweifel loading coefficient of 1.59 and maintains the same …

Fpga Based Hardware Implementation Of Advanced Encryption Standard, Sowrirajan Sampath

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On October, 2, 2000, The National Institute of Standards and Technology (NIST) announced Rijndael as the new Advanced Encryption Standard (AES). The other competing algorithms were Mars, RC6, Serpent and Two-fish. The Predecessor to the AES was Data Encryption Standard (DES) which is considered to be insecure because of its vulnerability to brute force attacks. DES was a standard from 1977 and stayed until the mid 1990's. However, by the mid 1990s, it was clear that the DES's 56-bit key was no longer big enough to prevent attacks mounted on contemporary computers, which were thousands of times more powerful than …

Sic Schottky Diodes And Polyphase Buck Converters, Veda Prakash N. Galigekere

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The turn-on characteristics of a SiC Schottky diode are analyzed theoretically, by simulation, and by experiment. The static characteristics of SiC Schottky diodes and Si junction diodes are analyzed for normal and high temperatures. The effects of diffusion capacitance and junction capacitance on the turn-off transition of SiC Schottky diode have been analyzed theoretically. The turn-off transition of a SiC Schottky barrier diode is analyzed by modeling the metal-semiconductor junction capacitance considering the linear and the non-linear effects. Behavior of the linear and the non-linear metal-semiconductor junction capacitance models are evaluated exper- imentally. The performance of SiC Schottky diodes is …

On-Chip Signal Generation And Response Waveform Extraction For Analog Built-In-Self-Test, Brian Poling

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Built-In Self-Test (BIST) is a method of designing and creating an electronic chip or an electronic system that can self test for correct functionality and ensure no manufacturing defects. The reason for analog BIST is the testing of analog parts of analog and mixed-signal ICs is a costly process that traditionally requires the use of expensive high-end automatic test equipment. Due to the nature of the testing and length of the testing process, an efficient analog BIST scheme is in high demand for the ever increasing complexity of analog and mixed-signal circuits. This thesis presents a BIST scheme for generation …

Skin And Proximity Effects In Two Parallel Plates, Hamdi Eltayib Abdelbagi

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Time varying currents within winding and core conductors induce magnetic fields. When more than one conductor is present the resultant magnetic field can be found by adding the individual magnetic fields by superposition. The resultant magnetic field in turn induces eddy currents within each electrical component within the vicinity of the resultant magnetic field. Eddy currents flow in the opposite direction of the primary current and increase the resistance by reducing the area in which the primary current has to travel. Eddy currents also reduce the effectiveness of the conductors to conductor high frequency currents. Skin and proximity effects were …

Bezier Surface Generation Of The Patella, Dale A. Patrick

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A method to generate control points for a given collection of data points is developed. The shape characteristics of the patella are used as a case study. The developed computer graphic techniques are demonstrated using the given data of the 3-d patella model. Generation of curved surfaces in drafting has evolved over the years from draftsman who used tools such as French curves to today's drafting being well served by being able to apply numerical analysis on the ever increasing capabilities of computer. As an everyday observed example, nature very rarely produces two shapes that are equal to another. It …

Fpga-Based Implementation Of A Digital Processor For An Instantaneous Frequency Measurement Receiver, James M. Helton

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Digital wideband receivers are essential elements used in electronic warfare (EW) applications. Instantaneous Frequency Measurement (IFM) receivers are suitable for use in EW systems due to the ultrawide instantaneous radio-frequency (RF) bandwidth, fine-frequency resolution, and moderately high sensitivity and dynamic range. Conventional IFM receivers use analog components such as power dividers, crystal video detectors, and hybrids. This research presents the architecture and design implementation of a purely digital IFM receiver based on a patented algorithm courtesy of the United States Air Force. The invention is capable of detecting a short wave pulse with 1 MHz error for every 100 nsec. …

Characterization And Modeling Methodology Of Polytetrafluoroethylene Based Reactive Materials For The Development Of Parametric Models, Stephen D. Rosencrantz

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Certain materials, when impacting a target at high velocity will chemically react due to the shock wave passing through them, thereby increasing the damage done by the material. In particular, the reactive materials of interest are capable of acting as both structure and explosive, allowing them to achieve an effect similar to a High Explosive Incindiary (HEI), without the complexity and added mass of fuses. There are a large number of materials/material combinations that could be used in reactive munitions. The purpose of this effort is to determine an efficient analytical characterization methodology that can be validated with a minimal …

Stability And Static Noise Margin Analysis Of Static Random Access Memory, Rajasekhar Keerthi

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The transistor mismatch can be described as two closely placed identical transistors have important differences in their electrical parameters as threshold voltage, body factor and current factor and make integrated circuit design and fabrication less predictable and controllable. Stability of a static random access memory (SRAM) is defined through its ability to retain the data at low-VDD. It is seriously affected by increased variability of transistor mismatch and decreased supply voltage and therefore becomes a major limitation of overall performance of low-voltage SRAM in nanometer CMOS process. The stability limitation is addressed through the design of a seven-transistor (7T) SRAM …

Comparative Microarray Data Mining, Shihong Mao

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As a revolutionary technology, microarrays have great potential to provide genome-wide patterns of gene expression, to make accurate medical diagnosis, and to explore genetic causes underlying diseases. It is commonly believed that suitable analysis of microarray datasets can lead to achieve the above goals. While much has been done in microarray data mining, few previous studies, if any, focused on multiple datasets at the comparative level. This dissertation aims to fill this gap by developing tools and methods for set-based comparative microarray data mining. Specifically, we mine highly differentiative gene groups (HDGGs) from given datasets/classes, evaluate the concordance of datasets …

A Hybrid Approach To Retrieving Web Documents And Semantic Web Data, Trivikram Immaneni

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The Semantic Web has been evolving into a property-linked web of RDF data, conceptually divorced from (but physically housed in) the World Wide Web of hyperlinked documents. Data Retrieval techniques are typically used to retrieve data from the Semantic Web while Information Retrieval techniques are used to retrieve documents from the Hypertext Web. Conceptually unifying the two webs enables the exploitation of their interconnections resulting in benefits to both data and document retrieval. Towards this end, we present the Unified Web model that integrates the two webs and formalizes the structure and the semantics of their interconnections. We present a …

Bibliography Tools In The Context Of Www And Latex, Munushree Thummala

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Preparation of academic papers involves not only the creative processes but also the more mechanical tasks such as adjusting the form and style to suit the demands of the publishing journal or conference. Among several packages that help in these rather tedious mechanical tasks, the TEX + LATEX + BibTEX combination is extremely popular. This thesis is about tools that help in the necessary task of citing related work accurately. It focuses on three aspects of this larger bibliography frame work: (i) a survey of existing bibliography formats and tools, (ii) a database view of BibTEX files and functionality that …

Particle Based Plasma Simulation For An Ion Engine Discharge Chamber, Sudhakar Mahalingam

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Design of the next generation of ion engines can benefit from detailed computer simulations of the plasma in the discharge chamber. In this work a complete particle based approach has been taken to model the discharge chamber plasma.This is the first time that simplifying continuum assumptions on the particle motion have not been made in a discharge chamber model. Because of the long mean free paths of the particles in the discharge chamber continuum models are questionable. The PIC-MCC model developed in this work tracks following particles: neutrals, singly charged ions, doubly charged ions, secondary electrons, and primary electrons. The …

Fabrication And Testing Of Scaffolds For Cell Growth From Ionic Liquid Solubilized Fibroin, Maneesh Kumar Gupta

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The advent of tissue engineering has spurred research into developing materials to act as scaffolds for tissue growth. These scaffolds require materials capable of mimicking the in vivo conditions so that tissues can be grown effectively in vitro. Silk is an attractive biomaterial for use in tissue engineering applications because of its slow degradation, excellent mechanical properties, and biocompatibility. The major objective of the research in this thesis is to demonstrate a simple method to cast films directly from silk fibroin dissolved in an ionic liquid. The films cast from the silk ionic liquid solution were found to support normal …

An Analog Evolvable Hardware Device For Active Control, Saranyan A. Vigraham

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The field of Evolvable Hardware (EH) has recently gained a lot of interest due to the novel methodology it offers for designing electrical circuits and machines. EH techniques involve configuring a reconfigurable hardware platform with the aid of learning engines such as evolutionary algorithms. The EH devices normally act as closed loop controllers with the capability of learning necessary control laws adaptively. Current EH practices have several shortcomings, which have restricted their use as reliable controllers. This dissertation will present an improved EH device based on behavioral reconfigurability that addresses the current open challenges in the field of analog Evolvable …

Non-Cooperative Modulation Recognition Via Exploitation Of Cyclic Statistics, Eric C. Like

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This research proposes and evaluates a feature based modulation classification system designed to discriminate between AM, BFSK, OFDM, DS-CDMA, 4-ASK, 8-ASK, BPSK, QPSK, 8-PSK, 16- PSK, 16-QAM, and 64-QAM signals without a priori knowledge of critical signal parameters, including carrier frequency, symbol rate, or phase offset, among others. The classifier is based on the principles of cyclostationarity and leverages cyclic statistics to make its classification decision. The classification process is performed in a hierarchical process in order to exploit the lower variance of lower order cyclic statistics before making use of the higher order cyclic statistics. The initial classification is …

Functional Interplay Between Subthreshold Ion Channels In Preautonomic Neurons Of The Hypothalamic Paraventricular Nucleus In Health And Disease Conditions, Patrick M. Sonner

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Under normal conditions, blood pressure is tightly regulated through autonomic tonic and reflex mechanisms. However, when the set-point for blood pressure is chronically elevated, hypertension occurs. Hypertension if untreated can lead to further complications including heart failure, stroke and kidney failure. Elevated sympathetic outflow is known to contribute to the development and/or maintenance of hypertension, and while the hypothalamic paraventricular nucleus (PVN), a preautonomic center, has been implicated in the elevation of sympathetic activity during hypertension, the precise pathophysiological mechanisms underlying sympathoexcitation remain unclear. Subthreshold ion channels, including the A-type K ⁺(I _A) and the T-type Ca ^{2+ …}

On Optimal Survivability Design In Wdm Optical Networks Under Scheduled Traffic Models, Tianjian Li

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Wavelength division multiplexing (WDM) optical networks are widely viewed as the most appropriate choice for future Internet backbone with the potential to fulfill the ever-growing demands for bandwidth. WDM divides the enormous bandwidth of an optical fiber into many non-overlapping wavelength channels, each of which may operate at the rate of 10 Gigabit per second or higher. A failure in a network such as a cable cut may result in a tremendous loss of data. Therefore, survivability is a very important issue in WDM optical networks. The objective of this dissertation is to address the survivability provisioning problem in WDM …

An Initial Methodology For The Definition And Implementation Of Unmanned Aerial Vehicle Agent Behaviors, William Eric Marsh

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In many current agent-based modeling systems, it is difficult for a domain-expert user to define and implement agent behaviors without possessing extensive programming knowledge. MUAVES is an existing simulation environment that serves as a research testbed for examining command and control issues with unmanned aerial vehicle (UAV) systems containing many vehicle agents. In its previous form, defining agent behaviors required knowledge of the C# programming language that some MUAVES users did not have. This thesis presents a new methodology for the definition and implementation of UAV agent behaviors in MUAVES. The new methodology is based on diagramming an agent's controller …

An Evolutionary Programming Algorithm For Automatic Chromatogram Alignment, Bonnie Jo Schwartz

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Scientists use liquid chromatography/mass spectrometry (LC/MS) instruments to measure metabolic responses to external stimuli. The data from these instruments can be distorted due to changes in the testing environment. Automating the removal of distortions is crucial in processing the data. The purpose of this thesis is to develop an algorithm that will automate the process.

The data produced by the LC/MS instrument were treated as images and image registration techniques were applied. A polynomial transformation function was assumed. An evolutionary programming algorithm was used to determine the coefficients of the polynomial. The data was manipulated to determine the best registration …

Multilingual Articulatory Features For Speech Recognition, Brian M. Ore

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Articulatory features describe the way in which the speech organs are used when producing speech sounds. Research has shown that incorporating this information into speech recognizers can lead to an improvement in system performance. The majority of previous work, however, has been limited to detecting articulatory features in a single language. In this thesis, Gaussian Mixture Models (GMMs) and Multi-Layer Perceptrons (MLPs) were used to detect articulatory features in English, German, Spanish, and Japanese. The outputs of the detectors were used to form the feature set for a Hidden Markov Model (HMM)-based phoneme recognizer. The best overall detection and recognition …

Algan/Gan Hemt Topology Investigation Using Measured Data And Device Modeling, Derrick Langley

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Investigation has been done on procedure, development, and verification of transistor topology for Aluminum-Gallium Nitride/Gallium Nitride (AlGaN/GaN) High-Electron Mobility Transistor (HEMTs). To date various models have been published that address modeling issues dealing with AlGaN/GaN HEMTs. Many models rely on analytic parameter solutions to help define model behavior. In order to find an optimum transistor at X-band frequency, 8-12 Gigahertz (GHz), layout, testing, modeling and simulation was conducted on various transistor topologies. Theoretical and experimental analysis has been completed for device operating point selection in measurement and modeling to account for self-heating and radio frequency (RF) dispersion effects. The model …

Xml Integrated Environment For Service-Oriented Data Management, Marwan Younes Maarouf

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The proliferation of XML as a family of related standards including a markup language (XML), formatting semantics (XSL style sheets), a linking syntax (XLINK), and appropriate data schema standards have emerged as a de facto standard for encoding and sharing data between various applications. XML is designed to be simple, easily parsed and self-describing. XML is based on and support the idea of separation of concerns: information content is separated from information rendering, and relationships between data elements are provided via simple nesting and references. As the XML content grows, the ability to handle schemaless XML documents becomes more critical …

Parameterizable Channelized Wideband Digital Receiver For High Update Rate, Peter E. Buxa

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Wideband digital receivers are important components used prevalently by the United States Air Force for many modern electronic warfare systems. Currently, many digital receiver architectures are designed for a specific mission requirement and are not parameterizable, modular, or reusable for varying mission requirements. Also, many designs are technology, platform, and vendor dependent which make upgrading existing fielded systems costly and difficult. Additionally, current wideband FFT-based digital receivers must wait until a number of samples equal to the size of the FFT are collected before spectral information can be updated. Achieving a high spectral update rate is important for the accurate …

Design Of A Controller To Control Light Level In A Commercial Office, Saeid Javidbakht

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Proper amount of light in a business office is important for health and productivity of the employees. On a sunny day, there may be more than enough light entering the office from outside to carry out the necessary tasks. Presently, the main source of light in most offices is the fluorescent lamp. Thus, It is possible to save energy by dimming the fluorescent lamp. Dimming of the fluorescent lamp is possible by changing the frequency of the sinusoidal voltage or current. Hence, there is a need of a control system to adjust the light from the fixtures based on the …

Manipulation Of Polystyrene Microparticles On A Microchannel Glass, Ravi Mamillapalli, Henry D. Young

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Bulk quantities of spherical microbeads have various applications in research and industrial fields. Simple techniques are required to be developed in order to manipulate and modify large numbers of these beads simultaneously. In our experiment, a microchannel glass-based microfluidic device is used to actuate large numbers of microbeads in parallel. The microchannel glass used in these experiments contains channels 4.1 μm in diameter. The microbeads are polystyrene beads which are superparamagnetic in nature and 5-6 μm in diameter. An aqueous suspension of microbeads is injected into a 2-chamber fluid cell that contains a separator, microchannel glass. The beads are reversibly …

Multi-Attribute Optimization Based On Conjoint Analysis, Hemanth K. Amarchinta

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Over the last thirty years, there were tremendous advances in multidisciplinary design optimization in reducing computational cost, developing algorithms for efficient sensitivity analysis in reaching an optimum. Most of these efforts assumed a single objective (attribute) function and a multitude of constraints. Very little work has been done in including the designer's preferences as part of the optimization scheme and in addressing the ability to handle multiple attributes simultaneously. This need to develop a systematic method for including designer's preferences is the main focus of this research work. The concept of modeling preferences among multi-attribute alternatives is prevalent in consumer …

Cognitively-Engineered Multisensor Data Fusion Systems For Military Applications, Amanda Christine Muller

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The fusion of imagery from multiple sensors is a field of research that has been gaining prominence in the scientific community in recent years. The technical aspects of combining multisensory information have been and are currently being studied extensively. However, the cognitive aspects of multisensor data fusion have not received so much attention. Prior research in the field of cognitive engineering has shown that the cognitive aspects of any human-machine system should be taken into consideration in order to achieve systems that are both safe and useful. The goal of this research was to model how humans interpret multisensory data, …

Flexible Sigma Delta Time-Interleaved Bandpass Analog-To-Digital Converter, Ryan Edward Mcginnis

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Conversion of analog signals to their digital equivalent earlier in a circuit’s topology facilitates faster and more efficient exploitation of the information contained within. Analog-to-digital converters (ADCs) form the link between the analog and digital realms. In high frequency circuits ADCs must often be implemented further downstream after several stages of down-conversion, or through the use of more expensive technologies such as Bi-polar Junction Transistors or Gallium Arsenide. This thesis presents a technique to utilize Complimentary Metal Oxide Semiconductor technology in a parallel time-interleaved architecture. This will reduce circuit complexity and allow the ADC to be placed further upstream reducing …

Robust Shape Design Techniques For Steady-State Metal Forming Processes, Jalaja Repalle

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Metal forming is a process that transforms a simple shape of a workpiece into a predetermined complex shape through the application of compressive/tensile forces exerted by dies. In the design of a forming process, the only factors that are known are the final component shape and the material with which it is to be made. Then the engineer has to design a process to make defect-free product, subject to limitations of shape, material properties, cost, time, and other such factors. The design cycle can be enhanced if performance sensitivity information is available that could be used with any commercially available …