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Southern Methodist University

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Full-Text Articles in Engineering

Multigrid For The Nonlinear Power Flow Equations, Enrique Pereira Batista Dec 2020

Multigrid For The Nonlinear Power Flow Equations, Enrique Pereira Batista

Mathematics Theses and Dissertations

The continuously changing structure of power systems and the inclusion of renewable
energy sources are leading to changes in the dynamics of modern power grid,
which have brought renewed attention to the solution of the AC power flow equations.
In particular, development of fast and robust solvers for the power flow problem
continues to be actively investigated. A novel multigrid technique for coarse-graining
dynamic power grid models has been developed recently. This technique uses an
algebraic multigrid (AMG) coarsening strategy applied to the weighted
graph Laplacian that arises from the power network's topology for the construction
of coarse-grain approximations ...


Advanced Thermal Characterization And Temperature Control To Enable The Next Generation Of Micro-Electronic Technologies, Assaad El Helou Dec 2020

Advanced Thermal Characterization And Temperature Control To Enable The Next Generation Of Micro-Electronic Technologies, Assaad El Helou

Mechanical Engineering Research Theses and Dissertations

In the electronics world, self-heating is an inevitable by-product of electrical activation that has a major impact on device performance and reliability. Thermal technologies have been in constant development to effectively dissipate the generated heat and keep device operation temperatures within reliable limits. Moreover, thermal characterization technologies have been implemented to understand the thermal performance within microelectronic sys- tems, but not without facing experimental and numerical challenges. This work presents ad- vanced thermal investigations, both experimental and numerical, that are adapted and most suited for emerging micro-electronic technologies. Initially, the main experimental and numerical modeling challenges faced in the thermal ...


On-Chip Nonreciprocal Components For Full-Duplex Communications And Gaussian Regulated Gate Driver For Electromagnetic Interference Reduction, Chang Yang Oct 2020

On-Chip Nonreciprocal Components For Full-Duplex Communications And Gaussian Regulated Gate Driver For Electromagnetic Interference Reduction, Chang Yang

Electrical Engineering Theses and Dissertations

This dissertation is comprised of two unrelated design endeavors. The first one is about two CMOS nonreciprocal components: 1) an isolator and 2) a circulator. To make the components compact enough for the next generation communication systems with wide bandwidth, both components operate at 100 GHz band for full-duplex transceivers for ultra-high-data-rate millimeter-wave wireless communication. The proposed nonreciprocal structures are based on a time-domain modulation by signals at around 1/6 of the RF frequencies and spatial duplexing over the RF signal paths, demonstrating over 45 dB isolation in a bandwidth of 1.5 GHz over the tuning range of ...


Blockchain And Its Transformational Impact To Global Business, Mohammed Qaudeer Aug 2020

Blockchain And Its Transformational Impact To Global Business, Mohammed Qaudeer

Engineering Management, Information, and Systems Research Theses and Dissertations

The advent of internet to the public back in 1994 resulted in the 4th industrial revolution disrupting and transforming business and communication models. As much as the transformation changed our lives and experiences, it has resulted in centralized models like Amazon and Facebook. It also resulted in exponential growth of Fraud, Identity theft, and lack of trust. Blockchain is considered an emerging technology of this era, which will trigger the 5th industrial revolution enabling another massive storm of disruptive transformation completely changing the current business models based on trust, security, collaboration and crypto currency. As the evolution of blockchain technology ...


Optimizing The Methanotrophic Production Of Polyhydroxyalkanoates Using Mixed Microbial Bacteria Cultures, Kai Cheng Aug 2020

Optimizing The Methanotrophic Production Of Polyhydroxyalkanoates Using Mixed Microbial Bacteria Cultures, Kai Cheng

Civil and Environmental Engineering Theses and Dissertations

The use of petroleum-based plastics has caused serious economic and environmental problems. It is imperative to develop sustainable ways to produce valuable and environmentally-friendly materials. Methanotrophic bacteria are known for assimilating methane while generating polyhydroxybutyrate (PHB) biopolymers, which are potential substitutes for conventional plastics. Additionally, biologically generated methane and volatile fatty acids (VFAs) are abundant and readily accessible through anaerobic digestion of organic wastes. Thus, optimizing the methanotrophic production will bring significant economic and environmental benefits.

In section one, a feast-famine based cultivation system was adopted to produce PHAs using Hyphomicrobium, and Methylocysits dominated bacterial culture. The mixed bacterial culture ...


A Modeling Framework For Urban Growth Prediction Using Remote Sensing And Video Prediction Technologies: A Time-Dependent Convolutional Encoder-Decoder Architecture, Ahmed Hassan Jaad Aug 2020

A Modeling Framework For Urban Growth Prediction Using Remote Sensing And Video Prediction Technologies: A Time-Dependent Convolutional Encoder-Decoder Architecture, Ahmed Hassan Jaad

Civil and Environmental Engineering Theses and Dissertations

Studying the growth pattern of cities/urban areas has received considerable attention during the past few decades. The goal is to identify directions and locations of potential growth, assess infrastructure and public service requirements, and ensure the integration of the new developments with the existing city structure. This dissertation presents a novel model for urban growth prediction using a novel machine learning model. The model treats successive historical satellite images of the urban area under consideration as a video for which future frames are predicted. A time-dependent convolutional encoder-decoder architecture is adopted. The model considers as an input a satellite ...


Model-Based And Data-Driven Situational Awareness For Distribution System Monitoring And Control, Ying Zhang Aug 2020

Model-Based And Data-Driven Situational Awareness For Distribution System Monitoring And Control, Ying Zhang

Electrical Engineering Theses and Dissertations

Electric power systems are undergoing a dramatic change. The penetration of distributed energy resources (DERs) such as wind turbine generators and photovoltaic panels is turning a traditional power system into the active distribution network. Power system situational awareness, which provides critical information for system monitoring and control, is being challenged by multiple sources of uncertainties such as random meter errors, stochastic power output of DERs, and imprecise network parameters. On the other hand, cyber-physical power system operation is vulnerable to cyberattacks against effective state estimation, such as false data injection attacks (FDIAs). To construct next-generation smart grids, this dissertation develops ...


A 2.56 Gbps Serial Wireline Transceiver That Supports An Auxiliary Channel And A Hybrid Line Driver To Compensate Large Channel Loss, Xiaoran Wang Aug 2020

A 2.56 Gbps Serial Wireline Transceiver That Supports An Auxiliary Channel And A Hybrid Line Driver To Compensate Large Channel Loss, Xiaoran Wang

Electrical Engineering Theses and Dissertations

Serial transceiver links are widely used for high-speed point-to-point communications. This dissertation describes two transceiver link designs for two different applications.

In serial wireline communications, security is an increasingly important factor to concern. Securing an information processing system at the application and system software layers is regarded as a necessary but incomplete defense against the cyber security threats. In this dissertation, an asynchronous serial transceiver that is capable of transmitting and receiving an auxiliary data stream concurrently with the primary data stream is described. The transceiver instantiates the auxiliary data stream by modulating the phase of the primary data without ...


Learning Deep Architectures For Power Systems Operation And Analysis, Mahdi Khodayar Aug 2020

Learning Deep Architectures For Power Systems Operation And Analysis, Mahdi Khodayar

Electrical Engineering Theses and Dissertations

With the rapid increase in size and computational complexities of power systems, the need for powerful computational models to capture strong patterns from energy datasets is emerged. In this thesis, we provide a comprehensive review on recent advances in deep neural architectures that lead to significant improvements in classification and regression problems in the area of power engineering. Furthermore, we introduce our novel deep learning methodologies proposed for a large variety of applications in this area. First, we present the interval deep probabilistic modeling for wind speed forecasting. Incorporating the Rough Set Theory into deep neural networks, we create an ...


Machine Learning Applications In Power Systems, Xinan Wang Jul 2020

Machine Learning Applications In Power Systems, Xinan Wang

Electrical Engineering Theses and Dissertations

Machine learning (ML) applications have seen tremendous adoption in power system research and applications. For instance, supervised/unsupervised learning-based load forecasting and fault detection are classic ML topics that have been well studied. Recently, reinforcement learning-based voltage control, distribution analysis, etc., are also gaining popularity. Compared to conventional mathematical methods, ML methods have the following advantages: (i). better robustness against different system configurations due to its data-driven nature; (ii). better adaption to system uncertainties; (iii). less dependent on the modeling accuracy and validity of assumptions. However, due to the unique physics of the power grid, many problems cannot be directly ...


Space And Depth-Resolved Naturally Occurring Toxic Groundwater Species In Bangladesh And Rwanda: Origination And Risk Analysis, Kenneth Hamilton May 2020

Space And Depth-Resolved Naturally Occurring Toxic Groundwater Species In Bangladesh And Rwanda: Origination And Risk Analysis, Kenneth Hamilton

Civil and Environmental Engineering Theses and Dissertations

Access to safe potable water is a necessity for all. Groundwater is a commonly relied upon drinking water source for many areas around the world. This is especially true for communities in high density, rural settings. Such is the case for populations near Cox’s Bazaar, Bangladesh, and in the Bugesera region of Rwanda. Sediment and groundwater contamination, through toxic dissolved species, represents a significant public health risk to exposed populations. Tropical soils, such as the soil profiles in Bangladesh and Rwanda, often contain higher concentrations of heavy metals (Rieuwerts, 2007). Additionally, nitrate from fertilizers, are widely used on the ...


Control And Locomotion Of Inertially And Magnetically Actuated Multi-Scale Robotic Systems, Ehab Al Khatib May 2020

Control And Locomotion Of Inertially And Magnetically Actuated Multi-Scale Robotic Systems, Ehab Al Khatib

Mechanical Engineering Research Theses and Dissertations

In this research, two actuation systems were introduced, inertial and magnetic actuation. In the inertial actuation, the robot used the transfer of momentum to navigate, and this momentum could be generated by spinning masses and wheels. Recent studies in our System Laboratory proved that a wide range of inertially actuated locomotion systems could be generated. This can be achieved by using a family tree approach, starting from a very simple system, and progressively evolving it to more complex ones. The motion diversity of these robots inspired us to extend their locomotion from a macro scale to millimeter and micro scales ...


Application Of Optimal Switching Using Adaptive Dynamic Programming In Power Electronics, Ataollah Gogani Khiabani May 2020

Application Of Optimal Switching Using Adaptive Dynamic Programming In Power Electronics, Ataollah Gogani Khiabani

Mechanical Engineering Research Theses and Dissertations

In this dissertation, optimal switching in switched systems using adaptive dynamic programming (ADP) is presented. Two applications in power electronics, namely single-phase inverter control and permanent magnet synchronous motor (PMSM) control are studied using ADP. In both applications, the objective of the control problem is to design an optimal switching controller, which is also relatively robust to parameter uncertainties and disturbances in the system. An inverter is used to convert the direct current (DC) voltage to an alternating current (AC) voltage. The control scheme of the single-phase inverter uses a single function approximator, called critic, to evaluate the optimal cost ...


Design Of A Drone-Flight-Enabled Wireless Isolation Chamber, John Wensowitch May 2020

Design Of A Drone-Flight-Enabled Wireless Isolation Chamber, John Wensowitch

Electrical Engineering Theses and Dissertations

The next wave of drone applications is moving from repeatable, single-drone activities such as evaluating propagation environments to team-based, multi-drone objectives such as drone-based emergency services. In parallel, testbeds have sought to evaluate emerging concepts such as highly-directional and distributed wireless communications. However, there is a lack of intersection between the two works to characterize the impact of the drone body, antenna placement, swarm topologies, and multi-dimensional connectivity needs that require in-flight experimentation with a surrounding testbed infrastructure. In this work, we design a drone-flight-enabled isolation chamber to capture complex spatial wireless channel relationships that drone links experience as applications ...


A Data-Driven Framework For Decision Making Under Uncertainty: Integrating Markov Decision Processes, Hidden Markov Models And Predictive Modeling, Hossein Kamalzadeh May 2020

A Data-Driven Framework For Decision Making Under Uncertainty: Integrating Markov Decision Processes, Hidden Markov Models And Predictive Modeling, Hossein Kamalzadeh

Engineering Management, Information, and Systems Research Theses and Dissertations

The problem of decision making under uncertainty can be broken down into two parts. First, how do we learn about the world? This involves the problem of modeling the system and its uncertainty. Secondly, given what we currently know about the world, how should we decide what to do, taking into account uncertainty of future events and observations that may change our conclusions. Many systems evolve over time and often the next state of the system is not known with certainty, often modeled as a probability distribution over system states. Dealing with such systems especially when we can make a ...


Heuristic-Based Threat Analysis Ofregister-Transfer-Level Hardware Designs, Wesley Layton Ellington Apr 2020

Heuristic-Based Threat Analysis Ofregister-Transfer-Level Hardware Designs, Wesley Layton Ellington

Electrical Engineering Theses and Dissertations

The development of globalized semiconductor manufacturing processes and supply chains has lead to an increased interest in hardware security as new types of hardware based attacks, called hardware Trojans, are being observed in industrial and military electronics. To combat this, a technique was developed to help analyze hardware designs at the register-transfer-level (RTL) and locate points of interest within a design that might be vulnerable to attack. This method aims to eventually enable the creation of an end-to-end design hardening solution that analyzes existing designs and suggests countermeasures for potential Trojan attacks. The method presented in this work uses a ...


Hybrid Vehicle-Drone Routing Problem For Pick-Up And Delivery Services Mathematical Formulation And Solution Methodology, Aline Karak Apr 2020

Hybrid Vehicle-Drone Routing Problem For Pick-Up And Delivery Services Mathematical Formulation And Solution Methodology, Aline Karak

Civil and Environmental Engineering Theses and Dissertations

The fast growth of online retail and associated increasing demand for same-day delivery have pushed online retail and delivery companies to develop new paradigms to provide faster, cheaper, and greener delivery services. Considering drones’ recent technological advancements over the past decade, they are increasingly ready to replace conventional truck-based delivery services, especially for the last mile of the trip. Drones have significantly improved in terms of their travel ranges, load-carrying capacity, positioning accuracy, durability, and battery charging rates. Substituting delivery vehicles with drones could result in $50M of annual cost savings for major U.S. service providers.

The first objective ...


Critical Point Identification In 3d Velocity Fields, Mohammadreza Zharfa Apr 2020

Critical Point Identification In 3d Velocity Fields, Mohammadreza Zharfa

Mechanical Engineering Research Theses and Dissertations

Classification of flow fields involving strong vortices such as those from bluff body wakes and animal locomotion can provide important insight to their hydrodynamic behavior. Previous work has successfully classified 2D flow fields based on critical points of the velocity field and the structure of an associated weighted graph using the critical points as vertices. The present work focuses on extension of this approach to 3D flows. To this end, we have used the Gauss-Bonnet theorem to find critical points and their indices in the 3D velocity vector field, which functions similarly to the Poincare-Bendixon theorem in 2D flow fields ...


Wireless Wearable System For The Assessment Of Gait, Abdallah Jabr Jan 2020

Wireless Wearable System For The Assessment Of Gait, Abdallah Jabr

Mechanical Engineering Research Theses and Dissertations

This work investigates the development and use of a wireless wearable system for the assessment of gait. The system proposed consists of a sensor module that is attached to the foot. The sensor proposed is an inertial measurement unit, often abbreviated as IMU - a 9-axis System in Package (SiP) including a 3-axis accelerometer, a 3-axis gyroscope, and a 3-axis magnetometer, as well as a fusion engine for signal processing. While the focus of this work is on evaluating gait metrics, the performance of the proposed IMU in evaluating orientation is quantified. In doing this work, we try to address the ...


Reducing The Production Cost Of Semiconductor Chips Using (Parallel And Concurrent) Testing And Real-Time Monitoring, Qutaiba Khasawneh Dec 2019

Reducing The Production Cost Of Semiconductor Chips Using (Parallel And Concurrent) Testing And Real-Time Monitoring, Qutaiba Khasawneh

Electrical Engineering Theses and Dissertations

Consumer electronics changed the semiconductor industry by developing many new challenges for consumer products. One of the main challenges in the consumer product is that it propelled the volume of production to massive production, e.g. hundreds of millions of cell phones are produced yearly. Combined with the overproduction of consumer products, price pressure is another challenge for consumer products. Many of the new techniques used in the design and fabrication enabled the integration of more devices in the same chips. This reduced the cost of the chips, lowered the power consumption, increased the circuit operation speed, enabled more reliable ...


Removel Of Polluntants From Aqueous Solution Via Graphene Oxide/Magnesium Oxide Nanocomposites, Mahdi Heidarizad Dec 2019

Removel Of Polluntants From Aqueous Solution Via Graphene Oxide/Magnesium Oxide Nanocomposites, Mahdi Heidarizad

Civil and Environmental Engineering Theses and Dissertations

In this study, a series of graphene oxide/magnesium oxide nanocomposites (GO/MgO NCs) were synthesized and applied for the removal of Methylene Blue (MB) from aqueous solutions. The prepared NCs were characterized using scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and thermogravimetric analysis. The results showed that MgO particles were successfully layered on GO. The impacts of different experimental variables on the removal of MB including GO/MgO NCs dosage, pH, contact time, and initial MB concentration were investigated.

Thereafter, we investigate the mechanism and kinetics of ozonation processes in the presence of GO/MgO ...


Evaluation Of The Mechanisms And Effectiveness Of Nano-Hydroxides, Wood And Dairy Manure-Derived Biochars To Remove Fluoride And Heavy Metals From Water, Anna Rose Wallace, Wenjie Sun Dr, Chunming Su Dr Dec 2019

Evaluation Of The Mechanisms And Effectiveness Of Nano-Hydroxides, Wood And Dairy Manure-Derived Biochars To Remove Fluoride And Heavy Metals From Water, Anna Rose Wallace, Wenjie Sun Dr, Chunming Su Dr

Civil and Environmental Engineering Theses and Dissertations

The development of effective treatment processes for the removal contaminants, such as fluoride and heavy metals, from polluted water have been urgently needed due to serious environmental health and safety concerns. In this dissertation, a variety of materials including various (hydro)oxide nanomaterials, biochars and surface modified biochar were studied to evaluate their effectiveness and mechanism on removing fluoride or mixed heavy metals from water.

In the Chapter 2, this study investigated the adsorptive removal of fluoride from water using various (hydro)oxide nanomaterials, focusing on ferrihydrite, hydroxyapatite (HAP) and brucite, which have the potential to be used as sorbents ...


Failure Of High Strength Concrete Under Dynamic Uniaxial Compression, Colin Loeffler Dec 2019

Failure Of High Strength Concrete Under Dynamic Uniaxial Compression, Colin Loeffler

Mechanical Engineering Research Theses and Dissertations

The failure strength of concrete materials has been widely shown to be dependent on experimental parameters such as specimen geometry and strain-rate. The effects of specimen geometry have been shown both theoretically and experimentally to be a result of the quasi-brittle nature of concrete. While the failure strength of concrete has been widely reported to increase significantly when deformed at high strain-rates, the physical mechanisms driving this phenomenon remain the source of debate amongst researchers. This means that constitutive models designed to predict this rate dependent behavior are not based on the real physical mechanisms that drive this behavior but ...


Technology-Dependent Quantum Logic Synthesis And Compilation, Kaitlin Smith Dec 2019

Technology-Dependent Quantum Logic Synthesis And Compilation, Kaitlin Smith

Electrical Engineering Theses and Dissertations

The models and rules of quantum computation and quantum information processing (QIP) differ greatly from those that govern classical computation, and these differences have caused the implementation of quantum processing devices with a variety of new technologies. Many platforms have been developed in parallel, but at the time of writing, one method of quantum computing has not shown to be superior to the rest. Because of the variation that exists between quantum platforms, even between those of the same technology, there must be a way to automatically synthesize technology-independent quantum designs into forms that are capable of physical realization on ...


Resource Allocation And Task Scheduling Optimization In Cloud-Based Content Delivery Networks With Edge Computing, Yang Peng Dec 2019

Resource Allocation And Task Scheduling Optimization In Cloud-Based Content Delivery Networks With Edge Computing, Yang Peng

Engineering Management, Information, and Systems Research Theses and Dissertations

The extensive growth in adoption of mobile devices pushes global Internet protocol (IP) traffic to grow and content delivery network (CDN) will carry 72 percent of total Internet traffic by 2022, up from 56 percent in 2017. In this praxis, Interconnected Cache Edge (ICE) based on different public cloud infrastructures with multiple edge computing sites is considered to help CDN service providers (SPs) to maximize their operational profit. The problem of resource allocation and performance optimization is studied in order to maximize the cache hit ratio with available CDN capacity.

The considered problem is formulated as a multi-stage stochastic linear ...


Development Of A Robotized Laser Directed Energy Deposition System And Process Challenges, Meysam Akbari Oct 2019

Development Of A Robotized Laser Directed Energy Deposition System And Process Challenges, Meysam Akbari

Mechanical Engineering Research Theses and Dissertations

Metal additive manufacturing (AM) is a disruptive technology, enabling fabrication of complex and near net shaped parts by adding material in a layer-wise fashion. It offers reduced lead production time, decreased buy-to-fly ratio, and repair and remanufacturing of high value components. AM processes are finding applications in many industrial sectors such as aerospace, automotive, biomedical and mold tooling. However, beside tremendous advantages of AM, there are still some challenges that prevent the adoption of this technology into high standard applications. Anisotropy and inhomogeneity in mechanical properties of the as-built parts and existence of pores and lack-of-fusion defects are considered as ...


Graphene-Based Water Desalination Using Atomistic Simulations, Thanh Chinh Nguyen Oct 2019

Graphene-Based Water Desalination Using Atomistic Simulations, Thanh Chinh Nguyen

Mechanical Engineering Research Theses and Dissertations

My research focused on investigating saltwater transport through nanoporous graphene membranes using molecular dynamics (MD) simulations. Particularly, in this dissertation, we focused on pressure-driven flows of salt water through uncharged and charged nanoporous graphene membranes for water desalination applications. In the first study, desalination performance of uncharged single-layer nanoporous graphene membranes was observed based on volumetric flow rate, required pressure drop, and salt rejection efficiency. A functional relationship between the volumetric flow rate, pressure drop, pore diameter, and the dynamic viscosity of saltwater was also examined. In further studies, transport of salt ions through positively and negatively charged single-layer nanoporous ...


Leveraging Geographical And Spectral Information For Efficient Cellular Systems, Matthew Tonnemacher Oct 2019

Leveraging Geographical And Spectral Information For Efficient Cellular Systems, Matthew Tonnemacher

Electrical Engineering Theses and Dissertations

With the unprecedented increase in mobile data demand and limited usable spectrum to provide for it, a paradigm shift towards spectrum sharing is a promising solution. However, there are many challenges that limit current spectrum sharing practices. One challenge is that proper spectrum sharing requires engaging devices to have an understanding of the impact they have on the ecosystem while transmitting in terms of spacial interference footprint and the implications to devices in their interference range. Another is that operators, especially licensed ones, have strict quality of service requirements for their subscribers, discouraging them from allowing unlicensed access of their ...


Feedback Mechanisms For Centralized And Distributed Mobile Systems, Yan Shi Oct 2019

Feedback Mechanisms For Centralized And Distributed Mobile Systems, Yan Shi

Electrical Engineering Theses and Dissertations

The wireless communication market is expected to witness considerable growth in the immediate future due to increasing smart device usage to access real-time data. Mobile devices become the predominant method of Internet access via cellular networks (4G/5G) and the onset of virtual reality (VR), ushering in the wide deployment of multiple bands, ranging from TVWhite Spaces to cellular/WiFi bands and on to mmWave. Multi-antenna techniques have been considered to be promising approaches in telecommunication to optimize the utilization of radio spectrum and minimize the cost of system construction. The performance of multiple antenna technology depends on the utilization ...


Big-Data Talent Analytics In The Public Sector: A Promotion And Firing Model Of Employees At Federal Agencies, Rabih Neouchi Oct 2019

Big-Data Talent Analytics In The Public Sector: A Promotion And Firing Model Of Employees At Federal Agencies, Rabih Neouchi

Engineering Management, Information, and Systems Research Theses and Dissertations

Talent analytics is a relatively new area of focus to researchers working in analytics and data science. Talent Analytics has the potential to help companies make many informed critical decisions around talent acquisition, promotion and retention. This work investigates data science to predict “shiny star” employees in the U.S. public sector, defined as top-notch performers over the years of a given time span. Its scope falls within talent analytics, also called people analytics, a relatively new research area.

We clean a data set made available by the U.S. Office of Personnel Management (OPM) and present two models to ...