Engineering Commons^™

A Novel Splitting Beam Laser Extensometer Technique For Kolsky Tension Bar Systems, Colin Loeffler

Mechanical Engineering Research Theses and Dissertations

The Kolsky (Split Hopkinson) Bar has become a well-known and established experimental technique for characterizing the mechanical behavior of materials subjected to dynamic loading conditions. Kolsky bar based experimental techniques facilitate the application of controlled and repeatable dynamic loading conditions to a specimen as well as the high resolution measurement of the resulting mechanical response. In recent decades the technique has been refined and adapted to provide more complex dynamic stress-states beyond uniaxial compression. However, the increasing complexity of the experimental apparatus introduces uncertainty to the traditional specimen deformation measurement techniques.

In this thesis, a direct non-contact optical measurement technique …

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 …

Spatial Exploration Of Trace Metals In Near-Surface Water And Soil In The Bolivian Altiplano, Lizzie Wilson

Civil and Environmental Engineering Theses and Dissertations

We analyzed soil and groundwater samples from the Bolivian Altiplano for trace metal concentrations, correlations and partitioning trends. Total digestion, sequential extraction and loss on ignition experiments were performed on soil samples. We ran aqueous samples on an ICP-MS. Results were analyzed to identify trace metal concentrations and find any significant correlations. We generated interpolated maps in ArcGIS to spatially analyze results. Results for elevated concentrations of interest were divided into sub-groups of organophilic metals, oxoanions and divalent metals and include vanadium, arsenic, selenium, zinc, nickel, lead, cobalt, uranium, copper and manganese. These elements are likely naturally sourced. We found …

Leveraging Grammars For Openmp Development In Supercomputing Environments, Samuel Hunter

Computer Science and Engineering Theses and Dissertations

This thesis proposes a solution to streamline the process of using supercomputing re- sources on Southern Methodist University’s ManeFrame II supercomputer. A large segment of the research community that uses ManeFrame II belong outside of the computer science department and the Lyle School of Engineering. While users know how to apply compu- tation to their field, their knowledge does not necessarily extend to the suite of tools and operating system that are required to use ManeFrame II. To solve this, the thesis proposes an interface for those who have little knowledge of Linux and SLURM to be able to use …

Non-Classical Plate Models Incorporating Microstructure And Surface Energy Effects: Their Variational Formulations And Applications, Gongye Zhang

Mechanical Engineering Research Theses and Dissertations

In this dissertation research, new non-classical models for Kirchhoff and Mindlin plates are developed and applied to study band gaps for flexural wave propagation in composite plate structures.

In Chapter 2, a new non-classical model for a Kirchhoff plate resting on an elastic foundation is developed using a modified couple stress theory, a surface elasticity theory and a two-parameter elastic foundation model. A variational formulation based on Hamilton’s principle is employed, which leads to the simultaneous determination of the equations of motion and the complete boundary conditions and provides a unified treatment of the microstructure, surface energy and foundation effects. …

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 …

Molecular Dynamics Studies On Nanoscale Confined Liquids, Alper Celebi

Mechanical Engineering Research Theses and Dissertations

Liquid transport in nanochannels have been attracting great interests, especially for last two decades, owing to its potential applicability in various fields including biochemistry, medical science and engineering. For exploring and generating new ideas in the field of nanofluidics, molecular simulation techniques have become an ideal way due to the experimental challenges impeding the field of nanofluidics in fabrication and measurements.

In this dissertation, we perform molecular dynamics simulations to investigate liquid transport behavior in nanoscale channels. The expanse of this dissertation concerns several fundamental topics in nanoscale liquid transport phenomena such as liquid properties in nanoscale confinements, interfacial flows …

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 …

Flexural Rigidity Estimation Using Noisy Static Influence Lines, Yasha Hajizeinalibiouki

Civil and Environmental Engineering Theses and Dissertations

Society depends on critical infrastructure to support everyday activities. Even as critical components of civil infrastructure approach and exceed their design lives, demand on these structures continues to increase. In light of the need for managing aging infrastructure, several opportunities exist for research that can aid infrastructure managers in significant the challenge of detecting, classifying, and mitigating structural impairments. This dissertation presents a novel framework for impairment detection through the capture and utilization of deformation influence lines for flexural rigidity estimation on Euler-Bernoulli beams. In this research study, mechanical theory, a computer-vision algorithm, and multiple numerical methods are integrated to …

Network Design For In-Motion Wireless Charging Of Electric Vehicles: Models And Algorithms, Mamdouh Mubarak

Operations Research and Engineering Management Theses and Dissertations

The aim of this research is to study the optimal deployment of wireless charging stations (WCS) in urban transportation networks. It is widely acknowledged that the relatively short driving range of EV and the long battery charging times collectively lead to a phenomenon known as "range anxiety" of EV drivers. This phenomenon remains to be the major factor that hampers EV adoption. Thus, in this dissertation, we study a cost-effective deployment plan of WCSs that facilitates EV adoption by alleviating the two major causes of the “range anxiety” phenomenon.

In the first part of this dissertation, we propose a deployment …

Maximizing Financial Benefit Of Lean Six Sigma Projects Through Optimized Selection Criteria, Colin Wasiloff

Operations Research and Engineering Management Theses and Dissertations

As evolving threats across the globe keep pace with increasing budget constraints, the US Army’s major subordinate commands and their sub-organizations are constantly challenged to do more with less. Resources such as human capital, information technology, facilities, and budgeted funding are stretched as thin as ever, while requirements to serve the Warfighter remain paramount. Each dollar of financial benefit gained through cost reduction efforts at the US Army can affect the Warfighter directly. Budgeted money saved or avoided is reprogrammed both locally and atop the hierarchy at the Department of Treasury to serve the Warfighter better.

Ordinal Logistic Regression was …

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 …

Text Enhanced Recommendation System Model Based On Yelp Reviews, Peter Kouvaris, Ekaterina Pirogova, Hari Sanadhya, Albert Asuncion, Arun Rajagopal

SMU Data Science Review

In this paper, we introduce a useful natural language model for improving recommendation systems using collaborative filtering algorithms on ordinal ratings data. Since their inception, recommendation systems have evolved from simple user-business-rating matrices to complex systems that can consume multiple dimensions. Using Yelp's competition data set, we explore extending these dimensions to include natural language by leveraging a dual neural network architecture to produce a new and improved star rating system which offers potential improvements to collaborative filtering based recommendation systems.

Enhancing Trust In The Cryptocurrency Marketplace: A Reputation Scoring Approach, Dan Freeman, Tim Mcwilliams, Sudip Bhattacharyya, Craig Hall, Pablo Peillard

SMU Data Science Review

Trust is paramount for the effective operation of any monetary system. While the distributed architecture of blockchain technology on which cryptocurrencies operate has many benefits, the anonymity of users on the blockchain has provided criminal users an opportunity to hide both their identities and illicit activities. In this paper, we present a scoring mechanism for cryptocurrency users where the scores represent users’ trustworthiness as safe or risky transactors in the cryptocurrency community. In order to distinguish law-abiding users from potential threats in the Bitcoin marketplace, we analyze historical thefts to profile transactions, classify them into risky and non-risky categories using …

Yelp’S Review Filtering Algorithm, Yao Yao, Ivelin Angelov, Jack Rasmus-Vorrath, Mooyoung Lee, Daniel W. Engels

SMU Data Science Review

In this paper, we present an analysis of features influencing Yelp's proprietary review filtering algorithm. Classifying or misclassifying reviews as recommended or non-recommended affects average ratings, consumer decisions, and ultimately, business revenue. Our analysis involves systematically sampling and scraping Yelp restaurant reviews. Features are extracted from review metadata and engineered from metrics and scores generated using text classifiers and sentiment analysis. The coefficients of a multivariate logistic regression model were interpreted as quantifications of the relative importance of features in classifying reviews as recommended or non-recommended. The model classified review recommendations with an accuracy of 78%. We found that reviews …

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 …

How Much Privacy Do We Have Today? A Study Of The Life Of Marc Mezvinsky, Miguel Mares, Salomon Gilles, Brian D. Gobran, Dan Engels

SMU Data Science Review

In this paper, we present a case study evaluating the level of information available about an individual through public, Internet-accessible sources. Privacy is a basic tenet of democratic society, but technological advances have made access to information and the identification of individuals much easier through Internet-accessible databases and information stores. To determine the potential level of privacy available to an individual in today’s interconnected world, we sought to develop a detailed history of Marc Mezvinsky, a semi-public figure, husband of Chelsea Clinton, and son of two former members of the United States House of Representatives. By utilizing only publicly and …

Fuel Flow Reduction Impact Analysis Of Drag Reducing Film Applied To Aircraft Wings, Damon Resnick, Chris Donlan, Nimish Sakalle, Cody Pinkerman

SMU Data Science Review

In this paper, we present an analysis of flight data in order to determine whether the application of the Edge Aerodynamix Conformal Vortex Generator (CVG), applied to the wings of aircraft, reduces fuel flow during cruising conditions of flight. The CVG is a special treatment and film applied to the wings of an aircraft to protect the wings and reduce the non-laminar flow of air around the wings during flight. It is thought that by reducing the non-laminar flow or vortices around and directly behind the wings that an aircraft will move more smoothly through the air and provide a …

Enhanced Coupling Strength Gratings For Outcouplers In Optical Waveguides, Ruo-Hua He

Electrical Engineering Theses and Dissertations

Gratings used for silicon photonic waveguides were demonstrated with outcoupling efficiency greater than 60% in a short grating length of 13 µm at a wavelength of 1550 nm. Due to problems of generating light from silicon, light has to be generated by either growing III-V material, wafer bonding III-V material to silicon, or externally generated light has to be coupled into and out of silicon photonic waveguides. Gratings have been used in semiconductor lasers to obtain single frequency operation. Some applications such as telecommunications require a narrow and single spectral line. And such single frequency lasers are typically distributed Bragg …

Soft-Microrobotics: The Manipulation Of Alginate Artificial Cells, Samuel Sheckman

Mechanical Engineering Research Theses and Dissertations

In this work, the approach to the manipulation of alginate artificial cell soft-microrobots, both individually and in swarms is shown. Fabrication of these artificial cells were completed through centrifugation, producing large volumes of artificial cells, encapsulated with superparamagnetic iron oxide nanoparticles; these artificial cells can be then externally stimulated by an applied magnetic field. The construction of a Permeant Magnet Stage (PMS) was produced to manipulate the artificial cells individually and in swarms. The stage functionalizes the permanent magnet in the 2D xy-plane. Once the PMS was completed, Parallel self-assembly (Object Particle Computation) using swarms of artificial cells in complex …

A Microresonator-Based Laser Doppler Velocity Sensor For Interplanetary Atmospheric Re-Entry, Benjamin Wise

Mechanical Engineering Research Theses and Dissertations

In this thesis, a laser velocity sensor concept based on optical microresonators is presented and the application to spacecraft atmospheric entry is explored. The concept is based on the measurement of Doppler shift of back-scattered laser light. Specifically, the Doppler shift is detected by observing the whispering gallery optical modes (WGM) of a dielectric microresonator excited by the back scattered light from particulates and gas molecules. The microresonator replaces the typical Fabry-Perot interferometer and CCD camera system, thereby significantly reducing the size and weight of the overall detection system. This thesis presents proof-of-concept results for this measurement approach. The Doppler …

Blunt And Ballistic Impacts On Human Head Models: An Analytical And Numerical Study, Yongqiang Li

Mechanical Engineering Research Theses and Dissertations

Head injuries, as a leading cause of death, have become a major health care issue for civilians and soldiers. There has been an urgent need to understand mechanisms of such injuries. The objective of this dissertation research is to study some head injuries and related mechanisms using analytical and computational models.

In Chapter 2, a new analytical (non-linear) model for the impact of a solid sphere on a fluid-filled spherical shell is developed by including the stress wave propagation effect in addition to the Hertzian contact deformations and the shell membrane and bending actions. A simplified (linearized) model incorporating the …

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 …

Improving System-On-Chip Test Networks For: Bandwidth, Security, And Power, Saurabh Gupta

Computer Science and Engineering Theses and Dissertations

Modern System-on-Chips (SoCs) provide benefits such as reduction in overall system cost, and size, increased performance, and lower power consumption. Increasing complexity of these Integrated Circuits (ICs) has resulted in a higher probability of manufacturing defects. Manufacturing defects can result in the faulty operation of a system. Thus, it is essential to test an IC after it is manufactured to detect any possible faults in it. These SoCs include on-chip embedded instruments that can be used for test, debug, diagnosis, validation, monitoring, characterization, configuration, or functional purposes. IEEE 1687 Std. (IJTAG) provides a standard interface for the reconfigurable access and …

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 …

Investigation Of The Effects Of Harmful Radiation On Type-Ii Strained Layer Superlattice Focal Plane Arrays Operated In The Long Wave Infrared, Patrick Fumo

Electrical Engineering Theses and Dissertations

In-situ exposure of InAs/InAsSb strained layer superlattice focal plane arrays to gamma-rays revealed the possibility of a detector capable of imaging through a total ionizing dose event. Two long wave infrared focal plane arrays were exposed to a Co⁶⁰ source at dose rates of 60 Rads/s and 70 Rads/s in incremental steps up to a total accumulated dose of 30 kRads. The first device showed no degradation in dark current density with accumulated dose while the second device tested showed a small increase up to 1 kRad and minimal increases with subsequent dose steps. The primary imaging defect in …

Modeling Kidney Transplantation Decisions: Regulatory Oversight, Information Sharing, And Post-Transplant Drug Choice, Zahra Gharibi

Operations Research and Engineering Management Theses and Dissertations

The United States and many other nations are encountering a disturbing obstacle: A shortage of available organs for patients who are in need of kidney transplantation. This dissertation strives to analyze this trend and present potential solution by focusing on three different aspects, namely regulatory oversight, information sharing, and post-transplant immunosuppressant drug choice. In my first essay, I propose a stochastic model that identifies a socially-optimal kidney transplant choice given the inherent trade-off between the expected wait time (driven by supply and demand) and the quality of received donor kidney.

I modify the model to account for changes made by …