Engineering Commons^™

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 …

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. …

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 …

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 …

Decoding Complexity In Metabolic Networks Using Integrated Mechanistic And Machine Learning Approaches, Tolutola Timothy Oyetunde

McKelvey School of Engineering Graduate Student Theses & Dissertations

How can we get living cells to do what we want? What do they actually ‘want’? What ‘rules’ do they observe? How can we better understand and manipulate them? Answers to fundamental research questions like these are critical to overcoming bottlenecks in metabolic engineering and optimizing heterologous pathways for synthetic biology applications. Unfortunately, biological systems are too complex to be completely described by physicochemical modeling alone.

In this research, I developed and applied integrated mechanistic and data-driven frameworks to help uncover the mysteries of cellular regulation and control. These tools provide a computational framework for seeking answers to pertinent biological …

Investigating Cyanobacteria Metabolism And Channeling-Based Regulations Via Isotopic Nonstationary Labeling And Metabolomic Analyses, Mary Helen Abernathy

McKelvey School of Engineering Graduate Student Theses & Dissertations

Cyanobacteria have the potential to be low-cost and sustainable cell factories for bio-products; however, many challenges face cyanobacteria as biorefineries. This dissertation seeks to advance non-model photosynthetic organisms for biotechnology applications by characterizing central carbon metabolism and its regulations. Cyanobacteria phenotypes for bio-production are examined and their intracellular metabolism is quantified. Using isotopic labeling experiments, phenotypic relationships between biomass composition, central carbon fluxes, and metabolite pool sizes are investigated. Metabolic analyses of cyanobacteria led to new investigations of flux regulation mechanisms via protein spatial organizations or metabolite channeling. Metabolite channeling is further explored as a hypothesis to explain enigmatic labeling …

Graphene Oxides In Water: Characterization, Reactivity, And Application, Siyuan An

McKelvey School of Engineering Graduate Student Theses & Dissertations

Recently discovered, graphene and graphene oxide materials have drawn considerable research attention due to outstanding and novel properties, which underpin wide material potential for a number of advanced applications including supercapacitors, solar cells, sensors, catalysts, semiconductors, sorbents, and membranes, among others. Graphene oxides (GO), which are considered as a family of oxidized graphene materials (derivatives), is a key precursor to the synthesis of free-standing graphene via oxidation-exfoliation-reduction pathways. GO properties depend on the synthesis routes/conditions (i.e. derivatization), including partially maintaining graphene (i.e. sp2) properties. Further, oxygen-containing functionalities (epoxy, hydroxyl, carbonyl, and carboxyl groups) render GO hydrophilic – and correspondingly stability …

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, …

Parametric Design And Optimization Of A Pivoting S-Type Rudder For Containerships, Chen-Wei Chen, Tsung-Yueh Lin, Bo-Yen Chen, Jen-Shiang Kouh

Journal of Marine Science and Technology–Taiwan

This study proposes an energy-saving S-type rudder design to deal with the inhomogeneous inflow from a rotating propeller behind a containership. The S-type rudder was modelled parametrically using four-digit NACA foils as section profiles together with Non-uniform rational B-splines (NURBS) surface formulations. A three-stage optimization process is proposed to reduce the number of design iterations necessary to achieve an optimal design. The propulsion simulations were done via CFD software, which solves the hydrodynamics of viscous flow, as governed by the Reynold-averaged Navier-Stokes (RANS) equations. Validations were performed with experimental model tests, including hull resistance, propeller open-water performance, and propulsion in …

Collision Avoidance Path Planning For Ships By Particle Swarm Optimization, Yu-Tao Kang, Wei-Jiong Chen, Da-Qi Zhu, Jin-Hui Wang, Qi-Miao Xie

Journal of Marine Science and Technology–Taiwan

Ship collision avoidance is a key consideration in maritime systems. Collision avoidance maneuvers depend on navigators’ experience and skill levels. Because both maritime traffic densities and average ship speeds are increasing, the times available for decision-making are decreasing, which elevates the risk of human errors in the collision avoidance process. To reduce the effect of human factors and efficiently prevent collisions between ships navigating in open water with effective visibility, a particle swarm optimization (PSO) algorithm can be used to plan ship paths. An improved ship domain dynamic model can assess collision risks in close-range encounters. Several marine traffic scenarios …

Basis Vector Model Method For Proton Stopping Power Estimation Using Dual-Energy Computed Tomography, Shuangyue Zhang

McKelvey School of Engineering Graduate Student Theses & Dissertations

Accurate estimation of the proton stopping power ratio (SPR) is important for treatment planning and dose prediction for proton beam therapy. The state-of-the-art clinical practice for estimating patient-specific SPR distributions is the stoichiometric calibration method using single-energy computed tomography (SECT) images, which in principle may introduce large intrinsic uncertainties into estimation results. One major factor that limits the performance of SECT-based methods is the Hounsfield unit (HU) degeneracy in the presence of tissue composition variations. Dual-energy computed tomography (DECT) has shown the potential of reducing uncertainties in proton SPR prediction via scanning the patient with two different source energy spectra. …

Elevated Temperature Progressive Damage And Failure Of Duplex Stainless Steel, Darren P. Luke

Civil Engineering ETDs

Ductile failure of metals has been the focus of research efforts within academia and industry for many years since it is tremendously important for understanding the failure of structures under extreme loading conditions. However, limited research has been dedicated to elevated temperature ductile failure, which is critical for evaluating catastrophic events such as industrial, structural or shipping vessel fires. A detailed investigation was conducted on the structural response of Duplex Stainless Steel at elevated temperatures. The temperature dependence of elastic modulus, yield strength, ultimate strength, and ductility was measured up to 1000°C and a continuum damage plasticity model was developed. …

Chemically Modified Monolayer Surfaces Influence Valvular Interstitial Cell Attachment And Differentiation For Heart Valve Tissue Engineering, Matthew N. Rush

Nanoscience and Microsystems ETDs

As a cell mediated-process, valvular heart disease (VHD) results in significant morbidity and mortality world-wide. In the US alone, valvular heart disease VHD is estimated to affect 2.5% of the population with a disproportionate impact on an increasing elderly populous. It is well understood that the primary driver for valvular calcification is the differentiation of valvular interstitial cells (VICs) into an osteoblastic-like phenotype. However, the factors leading to the onset of osteoblastic-like VICs (obVICs) and resulting calcification are not fully understood and a more complete characterization of VIC differentiation and phenotypic change is required before treatment of valve disease or …

Stability Of A Spinning Triangle Tethered Spacecraft System In A Circular Orbit, Matthew James Heitstuman

Mechanical Engineering ETDs

Equations of motion are derived for a spinning triangle tethered spacecraft system and are used to analyze the stability of such systems. Floquet theory is applied to the linearized, periodic coefficient, equations of motion to analyze spin stability as a function of triangle geometry and the average spin rate of the satellite relative to the angular velocity of the spacecraft orbiting around a central body. The results of the Floquet analysis show that spin stability is achievable for many combinations of spacecraft geometry and spin rate. Spacecraft engineers or operators for a triangle-shaped tethered spacecraft can use this information for …

Effects Of Secondary Stall And Unsteady Free-Stream On Blade Drag And Pitching Moments, Michael Malick

McKelvey School of Engineering Graduate Student Theses & Dissertations

Dynamic stall is a complex aerodynamic phenomenon occurring in helicopter rotors, limiting the flight envelope and causing control linkage damage and instabilities. The Peters-Modarres semi-empirical dynamic stall model is extended to simulate pitching moment and drag in unsteady freestream and yawed flow, including the effects of secondary stall. The aerodynamics are implemented as a state-space model, suitable for time-marching or aeroelastic analyses. With small modifications to the original stall model, secondary stall effects and unsteady freestream can be simulated without adding additional states. An optimization routine determines sets of parameters that minimize the error between the modeled solution and experimental …

Towards Engineering Advanced Nanomaterials: Elucidating Fundamental Particle Behavior In Water And Critical Sorption Dynamics, Changwoo Kim

McKelvey School of Engineering Graduate Student Theses & Dissertations

As advanced nanomaterials, inorganic-organic nano composites have received great interest as potential platform (nano) structures for sensor, catalyst, sorbent, and environmental applications. Here, my Ph.D. research has focused on the design, synthesis, and characterization of advanced water-stable engineered metal-oxide nanoparticles functionalized by organic frames for environmental applications. For the environmental applications, I have evaluated particleoptimized sorption processes for the remediation and separation of arsenic, chromium, and uranium under environmentally relevant conditions. More specifically, I have explored the critical role of organic coating on sorption mechanisms and performances using engineered iron oxide -based, manganese oxide -based, and manganese ferrite -based (core) …

Multifunctional Nanocomposites Based On Bacterial Cellulose, Qisheng Jiang

McKelvey School of Engineering Graduate Student Theses & Dissertations

Cellulose is biodegradable, renewable, and abundant in nature thus cellulose (or paper)-based products can be inexpensively produced and recycled. Among cellulosic materials, bacterial nanocellulose (BNC) draws a special research attention due to the inherent three-dimensional nanofibrous structure, excellent mechanical flexibility, high purity and well-defined surface chemistry, and cost-efficient, scalable and environment-friendly synthesis. BNC can be biosynthesized by Gluconacetobacter xylinus, which is the most characterized BNC producer among various microorganisms. BNC is composed of highly pure cellulose nanofibrils, produced from well-defined dextrose through biochemical steps and subsequent self-assembling of the secreted cellulose fibrils which has the dimension ranges from 25 to …

Brand Loyalty In The Cruise Sector: Age Cohorts, Gender, And Travel Attributes As Key Moderators For Relationship Marketing Theory, Stephen Wen-Hung Wang, Maxwell Kuo-Hsuan Hsu, Angeline Close Scheinbaum, Feng-Ming Tsai

Journal of Marine Science and Technology–Taiwan

Testing established theory in relationship marketing, we examine the impact of customer relationship management on customer satisfaction and brand loyalty in the context of the cruise industry. Individual differences such as age cohort (e.g., millennials, Gen X, baby boomers), gender, and consumers’ desired travel attributes are examined as moderators. Cruise vacation consumers at an international cruise harbor were approached to complete an in-person survey (n = 226). Empirical findings support extant theory in relationship marketing in that consumers’ perception of relationship investment raises satisfaction and, in turn, brand loyalty. Notably, when customer relationship investment is degenerated into a second order …

A Simplified Two-Switching-Based Model-Free Predictive Current Controller For An Interior Permanent Magnet Synchronous Motor Drive System, Cheng-Kai Lin, Jen-Te Yu, Jyun-Ting Wang, Yen-Shin Lai, Hsing-Cheng Yu, Hao-Qun Huang

Journal of Marine Science and Technology–Taiwan

This paper presents a simplified two-switching-based modelfree predictive current control (STSB-MFPCC) method as well as its application to interior permanent magnet synchronous motor (IPMSM) drive systems. Unlike existing model predictive current controller (MPCC) that uses 7 basic voltage vectors, STSB-MFPCC employs 19 synthesized ones, with each of which consisting of two basic voltage vectors. The new method does not require any information about the load parameters, back electromotive force, nor the system model. Compared to modelbased controllers, the proposed one has a distinctive and appealing nature in that it is much less sensitive to system parameter variations. A digital signal …

Cfd Modeling Of Smoke Movement In An Atrium, Robin Wu

UNLV Theses, Dissertations, Professional Papers, and Capstones

The purpose of this paper is to better understand the behavior of smoke movement in an atrium. Thus gives first responders and civilians in and out of building a better understanding

With the advancements of modern technology, computers and softwares make simulation models possible such as fire models to simulate fire and smoke movements. In this paper, a computational fluid dynamic (CFD) software Fire Dynamic Simulator (FDS) is used to conduct a series of atrium tests to investigate the effectiveness of smoke exhaust systems. FDS solves the Navier-Stokes equations appropriate for low speed flows (Ma < 0.3) with an emphasis on smoke, heat transport and CO2 concentrations from fires. The default turbulence model used in FDS simulation is the Large Eddy Simulation (LES), which is the solution of Navier-Stokes equations at low speed.

The compartment tested was 9 …

Effect Of Curing Conditions On Mechanical Properties And Durability Of Concrete, Edgar Lazaro Salas-Borrero

UNLV Theses, Dissertations, Professional Papers, and Capstones

This thesis presents the results for three different concrete mix designs with compression strengths of 4500 psi. The experiment was conducted in the Las Vegas area during the summer, from August 16th to October 12th, 2018, where temperatures and relative humidity was recorded daily, three times a day. In total, 135 concrete specimens (4” x 8”) were taken on site and were subjected to five different curing conditions.

For each concrete mix design, three concrete samples (4” x 8”) were taken and submitted for each curing condition, resulting in 45 cylinders for each concrete mix design. The same number of …

Calculation Of Access Charge For High Speed Rail Xpresswest Of Nevada, Sameeksha Sapkota

UNLV Theses, Dissertations, Professional Papers, and Capstones

XpressWest is a High Speed Rail (HSR) system that plans to connect Las Vegas with California at Palmdale. It will utilize the railway network of the California High Speed Rail (CAHSR) to connect Las Vegas with California destinations that include Los Angeles and San Francisco. For sharing the railway network of CAHSR, XpressWest will pay certain charge known as an access charge. The access charge is the fee paid by the train operator to the infrastructure owner for the addition of trains in a track. There are several access charge systems in the world. However, there is no study that …

Surface Resistivity For Concrete Quality Assurance, Stanley Tat

UNLV Theses, Dissertations, Professional Papers, and Capstones

The goal of this study was to determine the effectiveness of SRT for concrete quality assurance and to evaluate the relationship between SRT and the three chloride ion ingress methods currently used by various State DOTs. Additionally, the influence of binder type and content, concrete age, and water-to cementitious materials ratio on the experimental results were also examined.

In this study, Type V Portland and three SCMs; namely fly ash, slag, and silica fume were used. Fine and coarse, aggregates were supplied by a local quarry. To evaluate the transport properties of the studied concretes, RMT, RCPT, and ACT were …

Monitoring The Impact Of Groundwater Pumping On Infrastructure Using Geographic Information System (Gis) And Persistent Scatterer Interferometry (Psi), Kirsten Deprekel, El Hachemi Bouali, Thomas Oommen

Department of Geological and Mining Engineering and Sciences Publications

Transportation infrastructure is critical for the advancement of society. Bridges are vital for an efficient transportation network. Bridges across the world undergo variable deformation/displacement due to the Earth’s dynamic processes. This displacement is caused by ground motion, which occurs from many natural and anthropogenic events. Events causing deformation include temperature fluctuation, subsidence, landslides, earthquakes, water/sea level variation, subsurface resource extraction, etc. Continual deformation may cause bridge failure, putting civilians at risk, if not managed properly. Monitoring bridge displacement, large and small, provides evidence of the state and health of the bridge. Traditionally, bridge monitoring has been executed through on-site surveys. …

Analysis And Design Of Analog Front-End Circuitry For Avalanche Photodiodes (Apd) And Silicon Photo-Multipliers (Sipm) In Time-Of-Flight Applications, Vikas Vinayaka

UNLV Theses, Dissertations, Professional Papers, and Capstones

This thesis reports the analysis and design of analog front-end circuitry for reading out signals from avalanche photodiodes (APD) or silicon photomultiplier (SiPM) in time-of-flight (ToF) applications. An integrated circuit was designed using AMS SiGe 0.35 um BiCMOS process. The chip measured 2 mm x 2 mm (2000 umx2000 um). The chip mainly contains the following circuits: an APD with photoactive area measuring 24 umx24 um, an SiPM with 8x8 APDs with 236 k ohm quench resistors, a transimpedance amplifier (TIA), a comparator and a R-2R digital to analog converter (DAC). The TIA is based on the shunt-shunt feedback topology. …

Performance-Based Economical Seismic Design Of Multistory Reinforced Concrete Frame Buildings And Reliability Assessment, Chunyu Zhang

UNLV Theses, Dissertations, Professional Papers, and Capstones

As the next generation of seismic design methodology, performance-based seismic design (PBSD) method requires a structure satisfy multiple preselected performance levels under different hazard levels. Optimal PBSD methods provide different strategies to design the numerous variables, including strength, stiffness and ductility of each structural component. The overall goal of this study is to develop a new optimal PBSD method for multi-story RC moment frames. This method is capable of overcoming the deficiencies of existing optimal PBSD methods and can be implemented by the U.S. design practice. The proposed method minimizes construction cost and takes the limit of member plastic rotation …

A Distributed Real-Time Short-Term Solar Irradiation Forecasting Network For Photovoltaic Systems, Michael Adelbert Gacusan

UNLV Theses, Dissertations, Professional Papers, and Capstones

Solar irradiation forecasting is essential for PV connected electrical grids to maintain reliability, stability, and effective matching of real-time demand to power distribution. This research paper develops and evaluates proposed forecasting methods using wireless sensor networks. Each node of the network is capable of monitoring illuminance data and communicate it through RF and/or WiFi. The nodes are calibrated with respect to irradiance data from an industry-standard pyranometer. Power consumption of each node type is also collected at different operating states. The proposed sensor network can estimate a cloud motion vector or a cloud shadow’s speed and direction from the data …

Fluid Structure Interaction Study Of The Obstructive Sleep Apnea And Surgical Treatment Using Suture-Patch Device On The Patient’S Tongue, Yang Liu

UNLV Theses, Dissertations, Professional Papers, and Capstones

Up to 14% of the U.S. population is estimated to have obstructive sleep apnea (OSA) related to obesity, and there is increased incidence occurring worldwide. While treatment with continuous positive airway pressure (CPAP) resolves airway obstruction, patient compliance is relatively low. Alternative interventions are available to treat OSA patients; however, their outcomes have had variable results. For example, current technologies have demonstrated an inability to define and treat the specific anatomical site(s) causing the obstruction, resulting in suboptimal modifications of the airway and poor control of OSA.

In the current study, a three-dimensional (3-D) fluid-structure interaction (FSI) numerical simulation has …

Biodegradable And Biocompatible Silk Fibroin For Optical Applications, Corey Bryce Malinowski

UNLV Theses, Dissertations, Professional Papers, and Capstones

This study presents nanopatterned silk fibroin films that were fabricated using soft lithography and nanoimprinting to replicate patterns from diffraction gratings. These film’s optics were analyzed based on their light scattering potential as well as their transmittance and transmission haze using a laser light, spectrometer, and UV-Vis spectrophotometer, respectively. The patterned fibroin films all displayed similar light scattering patterns to their master patterns with some transmission haze. When using the spectrometer to measure samples, those made without any nanostructure displayed transmission of 90% and over, while those with patterns depended on the structure used. The denser a structure, like the …

Design And Preliminary Evaluation Of A Supercritical Carbon Dioxide Brayton Cycle For Solar Dish Concentrator Clean Energy Production, Danielle Nobles-Lookingbill

UNLV Theses, Dissertations, Professional Papers, and Capstones

As we move toward energy independence and more ambitious clean energy goals, solar energy research must push the efficiency limits of traditional energy generation systems. Increases in efficiency can be achieved by increasing the hot temperature of the power cycle. Recent research demonstrates the potential for increased efficiency and a vastly smaller component size when supercritical carbon dioxide Brayton power cycles are used. Concentrated solar and nuclear heat sources are capable of achieving the high working fluid temperatures needed for significant efficiency gains. This NSF EPSCoR funded, experimental research system is designed to exploit the uniquely immense solar irradiance of …