Electrical and Computer Engineering Commons^™

Verification And Validation Of A Transient Heat Exchanger Model, Jayme Lee Carper

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A statistical based verification and validation process is applied to the transient modeling of a shell and tube heat exchanger. A generic model of a heat exchanger was developed based on first principles as a sub-system of a larger thermal system model. This model was originally created without any experimental data, as it was not readily available. To provide the data necessary to apply the validation process, a thermal emulator was designed and built that allowed control of all system inputs to the heat exchanger, while also providing the instrumentation to record all required data. A wide test matrix was …

Steady-State Analysis Of Pwm Z-Bridge Source Dc-Dc Converter, Lokesh Kathi

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A PWM Z-bridge source dc-dc converter has a potential to play a prominent role in renewable energy applications, as it provides boosted and regulated output voltage and also behaves as an intermediate buffer between the source and the load. A complete circuit analysis of the Z-bridge source converter is needed to understand the operation of this converter. Steady-state analysis of pulse-width modulated (PWM) Z-bridge source dc-dc converter operating in continuous conduction mode (CCM) is given. Expressions describing waveforms of voltages across and currents through the all components of the PWM Z-bridge source dc-dc converter to operate in steady-state condition are …

Automatic Pmg Controller For Small Applications, William Scott Adkins

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This thesis is used to describe the proof of concept and design for a much needed answer to a major flight time limitation in smaller application drones. All small electric drones and small electric vehicles have the same major problem, short run-times. The average time a multi-rotor helicopter runs is for approximately 20 minutes. The concept idea of the combination of a permanent magnet generator (PMG) and a controller can extend this flight time. The basic idea is to add the similar function an automobile has, which is the alternator. This thesis will include, but not limited to the following …

Average Current-Mode Control, Ankit Chadha

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In this thesis, an average current-mode controller is analyzed for controlling power electronic converters. This controller consists of two loops. An inner loop, which senses and controls the inductor current and an outer loop, which is used to control the output voltage and provide reference voltage for the inner current loop. An average current-mode controller averages out high frequency harmonics it senses from the inductor current to provide a smooth DC component. This can be used as a control voltage for a pulse width modulator and produce switching pulses for the power electronic converters. An average current-mode controller can also …

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.

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 …

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 …

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 …

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 …

Testing Of Two Novel Semi-Implicit Particle-In-Cell Techniques, Trenton J. Godar

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PIC (Particle-in-cell) modeling is a computational technique which functions by advancing computer particles through a spatial grid consisting of cells, on which can be placed electric and magnetic fields. This method has proven useful for simulating a wide range of plasmas and excels at yielding accurate and detailed results such as particle number densities, particle energies, particle currents, and electric potentials. However, the detailed results of a PIC simulation come at a substantial cost of computational requirement and the algorithm can be susceptible to numerical instabilities. As processors become faster and contain more cores, the computational expense of PIC simulations …

Biaxial Material Design Method For The Reduced Aperture Waveguide Model, Jason M. Brand

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The design and characterization of metamaterials has emerged as a field of great interest in electromagnetics in recent years. The characterization has been accomplished primarily by means of fabrication, measurement, and parameter estimation. Previous work by Knisely and Havrilla [8] has shown that biaxial anisotropy can be created by machining air vias uniaxially into a homogeneous, isotropic material. This research project proposes a design method for manufactured biaxial materials. Full wave modeling and simulation is used for samples with varying via size, separation and pose to obtain the scattering parameters S11 and S21. To compare the simulated S-parameters to theoretical …

Adaptive I/Q Mismatch Compensation For Wideband Receiver, Linda Zhu

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Wide working bandwidth is one of the main concerns in digital wideband receiver. The traditional digital receiver covers only one Nyquist zone, which bandwidth range is from DC to half of the sampling frequency. By utilizing in-phase/quadrature (I/Q) channels, wideband receiver is able to double the working bandwidth, which covers from DC to half of the sampling frequency and also from negative half of the sampling frequency to DC. However, I/Q mismatch in reality introduces unwanted signals, which significantly reduce the system performance and the quality of the received signals. In this thesis, an adaptive I/Q mismatch compensation technique is …

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 …

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 …

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 …

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 …

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 …

Non-Contact, Antenna-Free Probes For Characterization Of Thz Integrated-Devices And Components, Prasanna Kumar Daram

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The most common technology for electrical characterization of THz devices is DC-coupled contact probes. In this Masters thesis, a non-contact, antenna-free probe is analyzed for characterizing THz devices and integrated circuits. The probe consists of on-chip receiving or transmitting THz photomixers in a co-planar waveguide environment. Our probes are coupled to a CPW-embedded DUT by polarization current rather than conduction current and then down converted in frequency to baseband by an optically pumped photomixer. We investigated probe performance through numerical simulations using High Frequency Structure Simulator (HFSS) carried up to 1 THz and yielded a broadband design with DUT to …

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. …

Large-Signal Analysis Of Buck And Interleaved Buck Dc-Ac Converters, Sourav Dey

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With the improvement in the present day technology, power electronic engineers are more focused on systems which are fast and have better performance. Closed-loop systems with a fast response and better performance have been a priority these days. PWM converters are self-regulating voltage regulators with high efficiency. Depending upon the voltage level and the type of power conversion, different converters are used to meet the necessary demands. One such PWM converter is the, buck DC-AC converter which plays an important role in the applications related to high-frequency and low-power. Large-signal analysis of buck and buck-derived converters for both open-loop and …

A Probabilistic Technique For Open Set Recognition Using Support Vector Machines, Matthew Scherreik

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Classification algorithms trained using finite sets of target and confuser data are limited by the training set. These algorithms are trained under closed set assumptions and do not account for the infinite universe of confusers found in practice. In contrast, classification algorithms developed under open set assumptions label inputs not present in the training data as unknown instead of assigning the most likely class. We present an approach to open set recognition, the probabilistic open set SVM, that utilizes class posterior estimates to determine probability thresholds for classification. This is accomplished by first training an SVM in a 1-vs-all configuration …

Hierarchical Modulation Detection Of Underwater Acoustic Communication Signals Through Maximum Likelihood Combining, Josh Sanderson

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Modulation detection is important to many communication applications. Much research has been done in this area for radio frequency (RF) signals, but until recently little has carried over to the underwater communication world. Traditional methods include the use of fourth order cumulants or second order cyclostationary features to determine the modulation scheme being used. Many of these methods fail due to the complex and varying nature of the underwater channel. This thesis proposes a new form of hierarchy modulation detection for underwater acoustic communication signals using maximum likelihood combining. The proposed method for hierarchical modulation detection for this research is …

Java Implementation Of Grounded Circumscription For Owl, Ali Akhavan Karbasi

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The semantic web is a new development in the World Wide Web (WWW) supporting machine-readable and machine-understandable data in order to add the "understanding" aspect to current capabilities. This technology involves the use of semantic reasoners, which are software that can infer logical consequences from a set of facts or axioms. Inference can be done in different ways, e.g. based on what is called the open world assumption in which what is not known to be true is simply unknown, and its closed world assumption opposite, which considers what is not known to be true as false. Each of these …

Dynamic Cmos Mimo Circuits With Feedback Inverter Loop And Pull-Down Bridge, Duo Zhang

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Two novel techniques, feedback inverter loop and pull-down bridge, adopted for multiple-input multiple-output (MIMO) dynamic CMOS circuits have been proposed in this thesis. The pull-down bridge technique optimizes the area and power of a single stage MIMO dynamic CMOS circuits, and the feedback inverter loop (FIL) technique improves the speed of multiple-stage dynamic CMOS circuits. Applying the pull-down bridge to the MIMO dynamic CMOS seven segment decoder, it is shown that common paths of different outputs are shared and optimized, which accounts for 12% speed improvement, 48% power reduction, and 73% area saving, as compared to the conventional logic design. …

Synthesis And Characterization Of Graphene Oxide/Sulfur Nanocomposite For Lithium-Ion Batteries, Aaron Joseph Blake

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The growing need for clean and efficient energy storage systems has recently peaked due to concerns of climate change and increased global energy consumption. However, efficiently integrating renewable resources such as solar and wind energy into society will require a complex electrical energy storage (EES) system capable of storing and expending significant amounts of energy. A battery based on the lithium/sulfur couple can yield a theoretical specific energy of 2600Wh/kg, which is about five times higher than that offered by present Li-ion batteries, and hence, is a promising and attractive technology. Despite recent developments in addressing various issues inherent to …

Design And Implementation Of A 16-Bit Flexible Rom-Less Direct Digital Synthesizer In Fpga And Cmos 90nm Technology, Sunny Raj Dommaraju

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A ROM-less direct digital synthesizer architecture is presented in this thesis. This architecture eliminates the ROM-based phase to sine wave amplitude converter, which is a bottleneck for pushing clock frequencies into the gigahertz range. The design consists of a 16-bit phase accumulator, a set of 18 band pass finite impulse response filters, a 12-bit digital to analog converter and a low pass filter to produce a sine wave with output frequencies ranging from 36 MHz to 72 MHz with a resolution of 3.05 kHz and a 55 dB spur free dynamic range. The same hardware can be used to achieve …

Monolithically Integrated Non-Reciprocal Devices Based On Magnetic Thin Films, Gregory Hartman

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For years technology developers have been reassessing current technology for ways to cut size and cost while maintaining or improving performance. One particular area that continues to grow in importance, yet remains difficult to reassess, are nonreciprocal devices. Components such as isolators and circulators are typically constructed using ferrite materials and permanent magnets; unfortunately, due to size and material properties, those materials are poor choices when attempting to scale down.

The following experiments investigate the ferromagnetic material NiFe and various patterning methods as potential solutions to the scaling and cost questions driven by modern technology requirements. NiFe is of interest …

Provable Run Time Safety Assurance For A Non-Linear System, Cory Firmin Snyder

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Systems that are modeled by non-linear continuous-time differential equations with uncertain parameters have proven to be exceptionally difficult to formally verify. The past few decades have produced a number of useful verification tools which can be applied to such systems but each is applicable to only a subset of possible verification scenarios. The Level Sets Toolbox (LST) is one such tool which is directly applicable to non-linear systems, however, it is limited to systems of relatively small continuous state space dimension. Other tools such as PHAVer and the SpaceEx invariant of the Le Guernic-Girard (LGG) support function algorithm are specifically …

Computational Modeling Of Graphene Oxide Exfoliation And Lithium Storage Characteristics, Reza Mortezaee

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Graphene oxide is a two dimensional material obtained by adsorption of oxygen or oxygen-containing groups on graphene. Stacked layers of graphene oxide constitute graphite oxide. These materials have various applications such as a source material for graphene production, transport support for electron microscopy, flexible organic photovoltaic cells and use in Li-ion batteries. Generation of exfoliated graphene oxide from a graphite oxide precursor is achieved relatively easily in solution as compared to graphene exfoliation. In this study we investigate the details of the graphene oxide exfoliation procedure in solution by calculating the Gibb's free energies and reaction rates. We consider two …

Piezoelectric-Based, Self-Sustaining Artificial Cochlea, Jared Evans

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Hearing loss is a prevalent issue, affecting all ages in innumerable occupations. Cochlear implants are one solution to sensorineural hearing complications; and though they are commonly used, the electronic devices have limitations in power consumption and external equipment. Piezoelectric films emulate the relationship between the basilar membrane and inner hair cell structures of the human cochlear epithelium, inducing a potential difference in response to sound pressure. Through proper MEMS fabrication and material selection, an artificial cochlear can be developed utilizing piezoelectrics, which is self-sustainable and functions naturally with the mechanisms of the human ear. This research investigates the feasibility of …