Engineering Commons^™

Selective Free-Standing Through-Wafer Porous Silicon Membrane (Sftpsm) For Integrated Meta-Material Devices, Bella Liu Yao

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Meta-materials have attracted considerable attention due to their unique electromagnetic properties, such as negative permittivity (ε), negative magnetic permeability (μ), and negative index of refraction. These devices have shown broad flexibility in compact phase shifter, backward leaky-wave antenna, and high-directivity coupled-line coupler applications; however, integrated devices utilizing meta-material structures have not yet surfaced due to a lack of integration technology.

In this work, a novel concept of integrated meta-materials is presented, using free-standing porous silicon (PS) membranes of periodic magnetic wire arrays (PMWA). The free-standing PS membranes were fabricated on p-type silicon substrates through electrochemical anodization. Systematic investigations have been …

Stability Of A Fuzzy Logic Based Piecewise Linear Hybrid System, Aaron W. Seyfried

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Complex cyber-physical systems are difficult to model and control. However, humans are capable of accomplishing these tasks by constantly adapting and redefining the rules to control these complex systems. Fuzzy logic provides a means of encoding human inference into a control methodology. However, the fuzzy logic controllers are nonlinear and their stability is difficult to verify. Therefore, the widespread usefulness of fuzzy logic controllers is limited. It has been proven that fuzzy logic controllers can be implemented as piecewise linear switched controllers. It has also been shown that the piecewise linear system can be implemented as a hybrid system. Piecewise …

Non-Contact Probes For Characterization Of Thz Devices And Components, Mads Jacob Hedegaard Larsen

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One of the challenges in developing semiconductor devices and integrated circuits for the terahertz (THz) region is their electrical characterization. The most common technology for their characterization is presently metal-to-metal, DC-coupled contact probes, which operate up to 750 GHz but are expensive and fragile.

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In this Master's Thesis, we investigate through numerical simulation and analysis the electromagnetic properties of a novel, AC-coupled probe. The new probe couples radiation from the device or circuit-under-test (DUT) via polarization current, which is then transformed to conduction current in the probe and down-converted in frequency to baseband by an optically-pumped photomixer. Finite-element simulations …

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 …

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 …

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 …

Analysis Of Human Echolocation Waveform For Radar Target Recognition, Kandarp Patel

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Some blind humans have developed the remarkable capability of echolocation, similar to the type used by mammals such as the bat, dolphin and whale. This population of human has shown the ability to classify targets based on their location, size, shape and material in diverse environmental conditions simply by listening to the reflected echoes of tongue clicks generated by their mouth. To date, much of the research into human echolocation has been confined exclusively to behavioral science and the analysis is inconsistent with the approaches used in engineering. The waveforms used in current radar systems appear different to those typical …

Software-Defined Radio Based Blind Hierarchical Modulation Detector Via Second-Order Cyclostationary And Fourth-Order Cumulant, Yang Qu

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Modulation detection is very important to many communication and electronic warfare applications. Recent developments in cognitive radio (CR) and dynamic spectrum access (DSA) network have also brought much attention to modulation detection of unknown radio frequency (RF) signals. It is well known that using second-order cyclostationary features, e.g., spectral correlation function (SCF) and spectral coherent function (SOF), BPSK modulation can be easily distinguished from higher order modulations such as QPSK and QAM modulations. However, QPSK and higher order modulations exhibit similar second-order cyclostationary features, thus these features cannot be employed to distinguish among higher order modulations. To classify higher order …

Frequency Characterization Of Si, Sic, And Gan Mosfets Using Buck Converter In Ccm As An Application, Keshava Gopalakrishna

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Present day applications using power electronic converters are focusing towards improving the speed, efficiency, and robustness. This led to the implementation of new devices in such converters where speed and efficiency are of concern. As silicon (Si) based power devices are approaching their operational performance limits with respect to speed, it is essential to analyze the properties of new devices, which are capable of replacing silicon based devices. Wide band-gap (WBG) semiconductor materials such as silicon carbide (SiC) and gallium nitride (GaN) are such materials, whose material properties show promising advantages for power electronic applications.

This thesis focuses on the …

Timing And Power Optimization Using Mixed-Dynamic-Static Cmos, Hao Xue

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An effective approach to timing and power optimization for single clocking and multiple clocking dynamic CMOS designs is presented in this thesis. For the single-clocking scheme dynamic CMOS sub-blocks can be replaced by static CMOS and mixed-dynamic-static CMOS for power minimization. For the multiple-clocking scheme the delay of data ready for use plays more important role than its clock pulse in timing optimization. Power minimization can be achieved by implementing dynamic CMOS sub-blocks with static or mixed-dynamic-static CMOS. In comparison with the benchmark 16-bit carry select adder in dynamic CMOS, the critical path delay is reduced by 41.1% using the …

An Accuracy Improvement Method For Cricket Indoor Location System, Anall Vijaykumar Gandhi

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The effective deployment of Automated Guided Vehicles (AGV) in indoor hostile environment demands high precision localization for navigation purposes. The cricket system, based on Time Difference of Arrival (TDoA) approach, provides precise localization. It calculates TDoA between radio and ultrasonic signal to estimate distance between two cricket motes. The position, in the referenced coordinate system, is estimated by multilateration using estimated distances from multiple motes. Therefore, the position accuracy depends on the distance estimation which in turn depends on the TDoA calculation. Ultrasonic transducer, a component of cricket mote hardware, has highly directive radiation pattern which affects ultrasonic signal detection. …

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. …

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 …

Distributed Sensor Fault Diagnosis For Automated Highway Systems, Hui Chen

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Fault diagnosis problems for large-scale nonlinear systems have attracted significant attentions from researchers in recent years. Most fault detection and isolation (FDI) methods have been proposed based on a centralized architecture. However, due to the complexity of the system, most of these centralized fault detection and diagnosis schemes are not able to delivery effective fault detection and isolation performance for a large-scale nonlinear system, which contains subsystems interacting with neighboring subsystems.

In this thesis, a distributed fault detection and isolation method is developed for the automated highway systems (AHS). For each subsystem of AHS, a distributed fault detection and isolation …