Electromagnetics and Photonics Commons^™

Modeling, Identification, Validation And Control Of A Hybrid Maglev Ball System, Ahmed Elhussein E. Mekky

Mechanical & Aerospace Engineering Theses & Dissertations

In this thesis, the electrodynamics of a single axis hybrid electromagnetic suspension Maglev system was modeled and validated by applying it to a single axis hybrid maglev ball experiment. By exploring its linearized model, it was shown that the single axis hybrid Maglev ball has inherently unstable dynamics. Three control scenarios were explored based on the linearized model; (1) Proportional, Deferential (PD) control, (2) Proportional, Deferential, Integral (PID) and (3) PID controller with pre-filtering. This thesis has shown that a PID controller with a pre-filtering technique can stabilize such a system and provide a well-controlled response.

A parametric system identification …

Application Of Chebyshev Formalism To Identify Nonlinear Magnetic Field Components In Beam Transport System, Michael Spata

Physics Theses & Dissertations

An experiment was conducted at Jefferson Lab's Continuous Electron Beam Accelerator Facility to develop a beam-based technique for characterizing the extent of the nonlinearity of the magnetic fields of a beam transport system. Horizontally and vertically oriented pairs of air-core kicker magnets were simultaneously driven at two different frequencies to provide a time-dependent transverse modulation of the beam orbit relative to the unperturbed reference orbit. Fourier decomposition of the position data at eight different points along the beamline was then used to measure the amplitude of these frequencies. For a purely linear transport system one expects to find solely the …

Reconfigurable Antenna And Rf Circuits Using Multi-Layer Stretchable Conductors, Riaz Ahmed -. Liyakath

USF Tampa Graduate Theses and Dissertations

The growth of flexible electronics industry has given rise to light-weight, flexible devices which have a wide range of applications such as wearable electronics, flexible sensors, conformal antennas, bio-medical applications, solar cells etc. Though several techniques exist to fabricate flexible devices, the limiting factors have been durability, cost and complexity of the approach. In this research, the focus has been on developing stretchable (flexible) conductors using a multi-layer structure of metal and conductive rubber. The stretchable conductors developed using this approach do not lose electrical connection when subjected to large strains up to 25%. Also, the conductivity of the conductive …

Novel Metamaterial Based Antennas For Flexible Wireless Systems, Haider Khaleel

Theses and Dissertations

Recent years have witnessed a great deal of interest from both academia and industry in the field of flexible electronic systems. This research topic tops the pyramid of research priorities requested by many national research agencies. Consistently, flexible electronic systems require the integration of flexible antennas operating in specific frequency bands to provide wireless connectivity which is highly demanded by today's information oriented society. On the other hand, metamaterials have become very popular in the design of contemporary antenna and microwave devices due to their wide range of applications derived from their unique properties which significantly enhances the performance of …

The Effect Of Polarization And Ingan Quantum Well Shape In Multiple Quantum Well Light Emitting Diode Heterostructures, Patrick M. Mcbride

Master's Theses

Previous research in InGaN/GaN light emitting diodes (LEDs) employing semi-classical drift-diffusion models has used reduced polarization constants without much physical explanantion. This paper investigates possible physical explanations for this effective polarization reduction in InGaN LEDs through the use of the simulation software SiLENSe. One major problem of current LED simulations is the assumption of perfectly discrete transitions between the quantum well (QW) and blocking layers when experiments have shown this to not be the case. The In concentration profile within InGaN multiple quantum well (MQW) devices shows much smoother and delayed transitions indicative of indium diffusion and drift during …

3d Electromagnetic Simulation Tool Exposure For Undergraduate Electrical Engineers: Incorporation Into An Analog Filters Course, Bobby B. Pheng

Master's Theses

With the growth of wireless communications, comes the need for engineers knowledgeable in 3D electromagnetic (EM) simulation of high-frequency circuits. To give electrical engineering students a better understanding of the behavior of electromagnetic fields, experiments including the use of 3D EM simulation software were proposed. Most students get lost in differential equations, curls, and divergences; this thesis aims to remedy that by exposing them to 3D EM simulation, which may motivate them toward further study in electromagnetics. Also, experience using EMPro is very beneficial for future RF/microwave/antenna engineers, as use of 3D EM simulation is becoming a requirement for this …

Pulsed Class-G Rf Amplifier System, Kevin Maulhardt, Kevin Haskett

Electrical Engineering

No abstract provided.

Day/Night Band Imager For A Cubesat, Eric Stanton

Electrical Engineering

Day/Night Band (DNB) earth sensing and meteorological systems like the Defense Meteorological Satellite Program (DMSP) Operational Linescan System (OLS) provide visible wavelength imagery 24 hours a day that is used primarily for cloud imaging in support of weather forecasting. This paper describes a compact push-broom imager that meets low light imaging requirements for DMSP OLS and the NOAA/NASA Joint Polar Satellite System (JPSS) as documented in the Integrated Operational Requirements Document [1] (IORD) including the imager design, system level concepts of operation for data collection, radiometric and spatial calibration, and data transmission to Earth. This small, lightweight imager complies with …

Inductive Metal Identification, Paul Maggi

Electrical Engineering

This project focuses on creating a device to differentiate between various types of metals via magnetic induction. Magnetic induction is used because it is both non-optical and non-contact. It achieves this by generating a varying magnetic field, which induces eddy currents in the metal. These eddy currents produce small disturbances in the surrounding magnetic field, which can be sensed with Hall Effect Sensors (HES). The primary challenge in this project was generating a sufficiently strong magnetic field to detectable disturbances. In order to achieve better results, a stronger magnetic field must be used as well as more sensitive Hall Effect …

Light Extraction Enhancement Of Gan Based Leds Using Top Gratings, Patterned Sapphire Substrates, And Reflective Surfaces, Greg Chavoor

Master's Theses

In the last 15 years, an immense amount of research has gone into developing high efficiency Gallium Nitride based light emitting diodes (LED). These devices have become increasingly popular in LED displays and solid state lighting. Due to the large difference in refractive index between GaN and Air, a significant amount of light reflects at the boundary and does not escape the device. This drawback decreases external quantum efficiency (EQE) by minimizing light extraction. Scientists and engineers continue to develop creative solutions to enhance light extraction. Some solutions include surface roughening, patterned sapphire substrates, and reflective layers.

This study proposes …

Design, Modeling And Fabrication Of Shear Mode Bulk Acoustic Wave Sensor As A Potential Biosensor, Chi-Jung Cheng

Dissertations

There has been an increasing interest in development of thin film bulk acoustic wave resonator (FBAR) devices for chemical and biological sensing applications in the environmental and biomedical industries. The zinc oxide (ZnO) thin film based FBAR devices provides attractive advantages, such as high resonant frequency, small size, and rapid response. Typically, the ZnO-based FBAR devices are operated in the longitudinal wave mode where the ZnO crystallites are perpendicular to the substrate. In gaseous environments, the longitudinal mode FBAR device provides high sensitivity for mass sensing. However, the longitudinal wave mode is adversely affected when used in liquid environments because …

A Linear Sampling Multiple Frequency Method For Target Detection, Tyler Bowman

Electrical Engineering Undergraduate Honors Theses

In the field of inverse scattering problems of electromagnetic imaging, there are many techniques that can be used to detect unknown objects. Generally these methods maintain a direct relationship between the precision of the target shape and the amount of time required to obtain the solution. However, it has been shown that hybridization, or a combination of techniques, can be used to obtain the shape reconstruction that is accurate and less expensive computationally. Previous research in the Computational Electromagnetics Group of Professor El-Shenawee at the University of Arkansas has looked into the use of hybridization by combining the Level Set …

Development Of Micro-Hall Sensors For High Power Electronics Applications, Thomas Rembert

Electrical Engineering Undergraduate Honors Theses

In this project, we are looking to explore the characteristics of GaAs/InGaAs/AlGaAs and GaAs/AlGaAs Hall Effect sensors for use in power electronics monitoring circuitry. Hall sensors have the ability to detect the presence of magnetic fields orthogonal to the sensor surface. In order to fully understand the response of such a sensor, I performed complete micro-Hall sensor fabrication and characterization, which includes (i) fabrication of Greek cross sensors with lateral dimensions of 120 µm (ii) contact optimization (iii) sensitivity measurements (iv) noise spectra measurements. Basic studies of sensor response to high current circuit board traces were also performed on the …

Antipodal Vivaldi Antenna For Water Pipe Sensor And Telemetry, Giuseppe Ruvio, Domenico Gaetano, Max Ammann, Patrick Mcevoy

Articles

An antipodal Vivaldi antenna operates simultaneously for telemetry and sensing when placed conformally onto PVC pipes. Good radiation efficiency is realised and the antenna impedance matching remains stable when the pipe is empty or contains water. The Fidelity Factor performance based on an input Ultra Wideband Gaussian pulse is a suitable figure of merit to detect water presence. Different water levels and pipe conditions correspond to Fidelity Factors between 90% and 96%, which are a suitable dynamic range for sensing and the appropriate quality for pulse communications for remote monitoring.

Dynamical Model Of Harmonic Generation In Centrosymmetric Semiconductors At Visible And Uv Wavelengths, Michael Scalora, Maria Antonietta Vincenti, Domenico De Ceglia, N. Akozbek, Vito Roppo, M. J. Bloemer, Joseph W. Haus

Electrical and Computer Engineering Faculty Publications

We study second and third harmonic generation in centrosymmetric semiconductors at visible and UV wavelengths in bulk and cavity environments. Second harmonic generation is due to a combination of spatial symmetry breaking, the magnetic portion of the Lorentz force, and quadrupolar contributions from inner core electrons. The material is assumed to have a nonzero, third-order nonlinearity that gives rise to most of the third harmonic signal. Using the parameters of bulk silicon we predict that cavity environments modify the dependence of second harmonic generation on incident angle, while improving third harmonic conversion efficiency by several orders of magnitude relative to …

High Frequency Characterization Of Carbon Nanotube Networks For Device Applications, Emmanuel Decrossas

Graduate Theses and Dissertations

This work includes the microwave characterization of carbon nanotubes (CNTs) to design new CNTs-based high frequency components. A novel developed method to extract the electrical properties over a broad microwave frequency band from 10 MHz to 50 GHz of carbon nanotubes (CNTs) in a powder form is performed. The measured scattering parameters (S-parameters) with a performance network analyzer are compared to the simulated one obtained from an in-house computed mode matching technique (MMT). An optimized first order gradient method iteratively changes the unknown complex permittivity parameters to map the simulated S-parameters with the measured one until convergence criteria are satisfied. …

Rfid And The Millennium: Item Status Api, Wilson Chu

Hong Kong Innovative Users Group Meetings

No abstract provided.

Information Encryption And Retrieval In Mid-Rf Range Using Acousto-Optic Chaos, Monish Ranjan Chatterjee, Abhinay Kundur

Electrical and Computer Engineering Faculty Publications

In recent work, low-frequency AC signal encryption, decryption and retrieval using system-parameter based keys at the receiver stage of an acousto-optic (A-O) Bragg cell under first-order feedback have been demonstrated [1,2]. The corresponding nonlinear dynamics have also been investigated using the Lyapunov exponent and the so-called bifurcation maps [3]. The results were essentially restricted to A-O chaos around 10 KHz, and (baseband) signal bandwidths in the 1-4 KHz range. The results have generally been satisfactory, and parameter tolerances (prior to severe signal distortion at the output) in the ±5% - ±10% range have been obtained.

Periodic AC waveforms, and a …

Numerical Simulation Of Nanopulse Penetration Of Biological Matter Using The Adi-Fdtd Method, Fei Zhu

Doctoral Dissertations

Nanopulses are ultra-wide-band (UWB) electromagnetic pulses with pulse duration of only a few nanoseconds and electric field amplitudes greater than 105 V/m. They have been widely used in the development of new technologies in the field of medicine. Therefore, the study of the nanopulse bioeffects is important to ensure the appropriate application with nanopulses in biomedical and biotechnological settings. The conventional finite-difference time-domain (FDTD) method for solving Maxwell's equations has been proven to be an effective method to solve the problems related to electromagnetism. However, its application is restricted by the Courant, Friedrichs, and Lewy (CFL) stability condition that confines …

Low-Loss Meta-Atom For Improved Resonance Response, Derrick Langley, Ronald Coutu Jr., Peter J. Collins

Faculty Publications

Measurements of a meta-atom integrated with a low noise amplifier into the split-ring resonator are presented. A comparison is made between baseline meta-atoms and one integrated with a GaAs low noise amplifier. S-parameter measurements in a RF strip-line show the resonant frequency location. The resonance null is more prominent for the integrated meta-atom. Biasing the low noise amplifier from 0 to 7 VDC showed that the resonant null improved with biasing voltage. As the biasing voltage increases, the transmission null reduced from -11.82 to -23.21 dB for biases from 0 to 7 VDC at resonant frequency.