Engineering Commons^™

Optical Micro-Seismometer Based On Evanescent Field Perturbation Of Whispering Gallery Modes, Jaime Da Silva

Mechanical Engineering Research Theses and Dissertations

This thesis proposes a light-weight, compact, and accurate optical micro-seismometer that could be used in many applications, such as planetary exploration. The sensor proposed here is based on the principle of whispering gallery optical mode (WGM) resonance shifts of a dielectric micro-resonator due to disturbances of its evanescent field. The micro-seismometer could be used in place of the traditional bulky seismometers. The design of a waveguide-resonator and mechanical structure to disturb the evanescent field are presented. A proof-of-concept a seismometer model that uses a 5µm ring resonator is numerically tested with actual seismic data. The results show that a WGM-based …

Accurate Vehicle Detection Using Multi-Camera Data Fusion And Machine Learning, Hao Wu

Electrical Engineering Theses and Dissertations

Computer-vision methods have recently been extensively used in intelligent transportation systems for vehicle detection. However, the detection of severely occluded or partially observed vehicles due to the limited camera fields of view remains a significant challenge. This paper presents a multi-camera vehicle detection system that significantly improves the detection performance under occlusion conditions. The key elements of the proposed method include a novel multi-view region proposal network that localizes the candidate vehicles on the ground plane. We also infer the vehicle occupancies by leveraging multi-view cross-camera context. Experiments are conducted on a dataset captured from a roadway in Richardson, TX, …

A Novel Ultrasound Imaging Technique Using Random Signals, Anahita Khalilzadeh

Electrical Engineering Theses and Dissertations

Ultrasound imaging has been used extensively because of its benign nature and relatively low cost implementation. The most common approach for forming an image is Brightness Mode (B-Mode), which uses an array with dynamic focusing. Focus is performed through Phase Shifters that are bulky and complicated components which increases the device cost.

This research describes a new method to form an Ultrasound image, without relying on phase shifting. The proposed method offers a lower cost solution compared to the B-Mode systems and overcomes some of their inherent limitations.

Using Gs/S Adc To Evaluate The Emi Of Gan-Based Power Devices, Chi Zhang

Electrical Engineering Theses and Dissertations

As the silicon-based power devices are gradually reaching their performance limits, new power transistors such as Silicon Carbide (SiC) and Gallium Nitride (GaN) FETs have been rapidly developed in recent years. GaN devices have been widely accepted by researchers for its higher speed and efficiency than silicon power devices. However, despite all its merits, the GaN device faces a more severe problem of electromagnetic interference (EMI) than the silicon device due to its high performance. Various control techniques of EMI have been studied so far and many of them require the evaluation of EMI. Research shows that the EMI level …

Standing-Wave Dielectric Array Antennas, Ayman Althuwayb

Electrical Engineering Theses and Dissertations

Due to the evolutions in wireless communication systems, antenna engineers have been confronting a number of challenges regarding improving the performance of antennas, miniaturizing the size as well as considering the fabrication simplicity. Although dielectric resonator antennas typically suffer from exhibiting low gain, they have been thoroughly under investigating as they are being excellent candidates to be utilized to fulfill contemporary communication systems requirements and specifications, especially at high-frequency ranges. The reason behind this solicitude is because they have several advantageous features, including but not limited to the simplicity of the used excitation mechanism and fabrication easiness.

One of the …

Indirect Imaging Using Computational Imaging Techniques, Aparna Viswanath

Electrical Engineering Theses and Dissertations

The work describes various methods employed towards solving the problem of indirect imaging. Computational techniques are employed to indirectly decipher information about an object hidden from view of a camera. Notion of virtualizing the source of illumination and detectors on real world rough surfaces was exploited to construct a non line of sight computational imager. Diversity was explored from the stand point of both illumination of the object and imaging of light reflected from the object. To understand the impact of scattering by real world rough surfaces, an instrument was developed that allows characterization of isoplanatic angle for different surface …

Investigating The Effect Of Detecting And Mitigating A Ring Oscillator-Based Hardware Trojan, Lakshmi Ramakrishnan

Electrical Engineering Theses and Dissertations

The outsourcing of the manufacturing process of integrated circuits to fabrications plants all over the world has exposed these chips to several security threats, especially at the hardware level. There have been instances of malicious circuitry, such as backdoors, being added to circuits without the knowledge of the chip designers or vendors. Such threats could be immensely powerful and dangerous against confidentiality, among other vulnerabilities.

Defense mechanisms against such attacks have been probed and defense techniques have been developed. But with the passage of time, attack techniques have improved immensely as well. From directly observing the inputs or outputs, adversaries …

Indirect Imaging Using Heterodyne Remote Digital Holography, Muralidhar Madabhushi Balaji

Electrical Engineering Theses and Dissertations

Conventional line-of-sight imaging techniques rely on detecting light paths bouncing from the object and reaching directly to the detector. Absence of any such direct light paths from object to detector results in a failure to recover any useful information using conventional techniques. The absence of direct light paths from object to detector can be observed in several real-world scenarios such as looking around a corner, imaging through turbid media, imaging through tissue etc.

The focus of this thesis is pertaining to the problem of looking around corners (or) imaging object hidden from line of sight at macroscopic scales. This thesis …

A Comparative Analysis Of Integrated Optical Waveguide Isolators With Magneto-Optic Layers, Reyhane Oztekin

Electrical Engineering Theses and Dissertations

The objective of this study is to theoretically devise an on-chip optical isolator which is monolithically integrated with a semiconductor waveguide layer yielding low loss. The optical properties of iron are modeled for the use of optical waveguide isolators by improving the Brendel-Bormann model. Our model for iron shows excellent fit with the optical data up to 30 electronvolts (eV). The semiconductor optical waveguide isolator with magneto-optic layers based on non-reciprocal loss shift is developed in this study. Fe, Co, and Ni metals as well as cerium-substituted yttrium iron garnet (Ce:YIG) have been used as magneto-optic layers. We have shown …

Subspace Averaging Of Auditory Evoked Potentials, Xiaoliang Wang

Electrical Engineering Theses and Dissertations

The auditory evoked potential (AEP) is an electric potential generated in the brain in response to auditory stimuli. It has clinical importance in the detection of newborn infant hearing loss. The signal to noise ratio (SNR) of the AEP is low, so signal averaging is typically employed to estimate it. Often, thousands of trials must be averaged before a sufficiently high SNR estimate is obtained.

In this research, we have developed a new AEP averaging method called subspace averaging. The subspace averaging method projects onto the signal subspace: the span of the principal eigenvectors of the signal correlation matrix. The …

Linear Phase Multi-Frequency Notch Filter Via Quadratic Programming, Yueran Ma

Electrical Engineering Theses and Dissertations

Discrete-time notch filters can be divided into infinite impulse response (IIR) and finite impulse response (FIR) notch filters. Infinite impulse response notch filters are easy to design and implement but suffer from nonlinear phase characteristics and unacceptable startup transients. Finite impulse response filters on the other hand can be designed to have linear phase but require more coefficients to achieve narrow notch widths. Multiple frequency FIR notch filters that can effectively reject several selected spectral regions while providing high transmission at frequencies outside the rejected regions have applications in communication systems, radar systems and biomedical signal processing.

A new multi-frequency …

Cell-Aware Fault Analysis And Test Set Optimization In Digital Integrated Circuits, Fanchen Zhang, Jennifer Dworak

Computer Science and Engineering Theses and Dissertations

Structural tests have many advantages over functional patterns. The fault coverage of structural patterns is generally higher and easier to quantify, well-known algorithms are available to generate them, and they are often a much easier choice for debugging and diagnosis. However, depending on the fault models used, traditional structural patterns can still miss many defects, such as the defects that may occur inside the standard cells, and when chips are placed on a board, they may fail in functional mode even if they pass all structural tests. This can happen even if those same structural tests are applied in-system on …

Computational Theories For Human Stereo Vision, Han Gao

Electrical Engineering Theses and Dissertations

Binocular stereopsis refers to the ability to perceive depth, which has always been a central problem in perception since the time of da Vinci. The foremost theoretical difficulty that arises when attempting to understand how the visual system computes disparity is known as the correspondence or matching problem. Decades of research upon macaque primary visual cortex has shown that in each layer of the primary visual cortex (V1) long-range horizontal connections among striate cortex cells exist which integrate information from different parts of the visual field. Inspired by long-range horizontal connections in V1 and the Jeffress model, a time-delay neural …

High-Speed Single-Channel Sar Adc Using Coarse And Fine Comparators With Background Comparator Offset Calibration, Guanhua Wang

Electrical Engineering Theses and Dissertations

A 1-GS/s 8-bit single-channel successive-approximation-register (SAR) analog-to-digital converter (ADC) using coarse and fine comparators with fully background comparator offset calibration is presented. Low-power coarse comparators and low-noise fine comparators are both employed to improve the comparator power efficiency. Non-binary digital-to-analog converter (DAC) with redundancy is employed to tolerate possible errors in the most-significant-bit (MSB) decisions. A novel comparator offset calibration scheme is proposed to remove the offsets between the different comparators, without slowing down the speed of the SAR conversion. The prototype ADC is simulated in a 28 nm CMOS technology and achieves an SNDR of 42.13 dB near Nyquist …

Designing Smart-Grid Telecommunications Systems Via Interval Flow Network Optimization, Anthony J. Klinkert

Operations Research and Engineering Management Theses and Dissertations

One of the first major, widespread deployments of an Internet of Things (IoT) system is an electric utility’s smart-grid communications network. Communication networks support utility smart-grids for an electrical power provider by linking industrial IoT devices on the grid, such as residential and commercial customers’ electric meters to the utility’s data center. A new solution methodology and software tool is applied to the optimization of an electric utility smart-grid communications network. This research provides utilities with a technique to reduce cost of new and current communications networks for smart-grid programs. This research introduces the use of a new advanced optimization …

Microgrids: Resilience, Reliability, And Market Structure, Saeed Dehghan Manshadi

Electrical Engineering Theses and Dissertations

This dissertation addresses several challenges corresponding to the operation and planning of microgrids in distribution networks including the formation, energy supply resilience, the contribution of microgrids in the short-term and mid-term operation of bulk power networks and the computational challenges in operation of interdependent infrastructure systems.

An approach to transforming the active distribution network with distributed energy resources into multiple autonomous microgrids is presented in the first section. The distribution network consists of several generation resources and demand entities that could be clustered into autonomous microgrids. Eigen decomposition in the graph spectra of the distribution network is leveraged to determine …

Near-Optimal Control Of Switched Systems With Continuous-Time Dynamics Using Approximate Dynamic Programming, Tohid Sardarmehni

Mechanical Engineering Research Theses and Dissertations

Optimal control is a control method which provides inputs that minimize a performance index subject to state or input constraints [58]. The existing solutions for finding the exact optimal control solution such as Pontryagin’s minimum principle and dynamic programming suffer from curse of dimensionality in high order dynamical systems. One remedy for this problem is finding near optimal solution instead of the exact optimal solution to avoid curse of dimensionality [31]. A method for finding the approximate optimal solution is through Approximate Dynamic Programming (ADP) methods which are discussed in the subsequent chapters.

In this dissertation, optimal switching in switched …

Circularly Polarized Two-Dimensional Microstrip Standing-Wave Array Antenna, Yang Fan

Electrical Engineering Theses and Dissertations

This dissertation reviews current designs of single-fed circularly polarized microstrip antennas and proposes a novel design concept with improved performance. The structure is similar to a regular microstrip patch antenna and the design procedure is relatively simple. By extending this SF scheme to an array structure based on the standing-wave array concept, a novel circular polarized array antenna can be realized by using one SF CP patch with standing-wave feeding networks. The standing-wave array antenna developed at SMU has a low-profile planar configuration and a simple feeding network structure and thus can be fabricated easily and cheaply with relatively high …