Engineering Commons^™

Bi-Directional Testing For Change Point Detection In Poisson Processes, Moinak Bhaduri

UNLV Theses, Dissertations, Professional Papers, and Capstones

Point processes often serve as a natural language to chronicle an event's temporal evolution, and significant changes in the flow, synonymous with non-stationarity, are usually triggered by assignable and frequently preventable causes, often heralding devastating ramifications. Examples include amplified restlessness of a volcano, increased frequencies of airplane crashes, hurricanes, mining mishaps, among others. Guessing these time points of changes, therefore, merits utmost care. Switching the way time traditionally propagates, we posit a new genre of bidirectional tests which, despite a frugal construct, prove to be exceedingly efficient in culling out non-stationarity under a wide spectrum of environments. A journey surveying …

The Combined Effect Of Photovoltaic And Electric Vehicle Penetration On Conservation Voltage Reduction In Distribution System, Narayan Bhusal

UNLV Theses, Dissertations, Professional Papers, and Capstones

Global conditions over the past dozen years have led to an expanded appetite for renewable energy sources: The diminishing fossil fuel supply, the political instability of countries producing these fossil fuels, the ever-more destructive effects of global warming, and the lowering of costs for renewable energy technologies have made countries around the world reconsider their sources of energy. The proliferation of photovoltaic (PV) systems especially has surged dramatically with the decreasing initial costs for installation, and increasing government support in the form of renewable energy portfolios, feed-in-tariffs,

tax incentives, etc. Furthermore, electric vehicles (EV) are also becoming widespread due to …

The Impact Of Waters Of Low Quality On Soiling Removal From Photovoltaic Panels, Alisson Luiz Boeing

UNLV Theses, Dissertations, Professional Papers, and Capstones

Soiling, bird droppings, or the accumulation of dust on the surface of photovoltaic cells, can significantly reduce the solar energy absorption and produce power losses. In solar plants where soiling is a problem, solar facilities use demineralized or distilled water for washing the panels to avoid mineral scale deposits that might interfere with solar irradiance absorption. However, in arid and dusty environments, water is normally scarce. For cleaning solar panels, the use of low quality water in lieu of the industry-standard demineralized water could conserve fresh water. The objectives of this research were as follows: evaluate the impacts of low …

Water-Energy Nexus Approaches For Solar Development And Water Treatment In The Southwestern United States, Syeda Saria Bukhary

UNLV Theses, Dissertations, Professional Papers, and Capstones

Water is crucial for energy production and conversion, and energy is crucial for various water related processes including water conveyance, treatment and distribution. Sustainability of water and energy are inextricably linked with each other. Over-utilization/ degradation of these resources may occur due to limited availability of water under the changing climate scenario, growing population, and increasing pollution due to the burning of fossil fuels. The goal of the current research was to study the water-energy nexus of the Southwestern U.S. and develop approaches for solar development and treatment of drinking water. To achieve the overall objective, the work was divided …

Evaluating The Feasibility And Sustainability Of Direct Potable Reuse In Las Vegas, Nv, Cory Dow

UNLV Theses, Dissertations, Professional Papers, and Capstones

Community water sources are becoming more and more strained due to several factors including severe drought, population growth, urbanization, and climate change. This has spurred several water agencies to evaluate alternative water supply options to extend their resources. One potential alternative is potable reuse. Potable reuse comes in two forms: indirect potable reuse (IPR) and direct potable reuse (DPR). IPR is the advanced treatment of wastewater effluent before discharging into an environmental buffer that is a drinking water supply such as a lake, river, or groundwater aquifer before extraction and use. DPR is the advanced treatment of wastewater effluent that …

Numerical Analysis Of An Electrical Transformer With Fins And Horizontal Pins, Sean Ferneyhough

UNLV Theses, Dissertations, Professional Papers, and Capstones

Three-dimensional numerical simulations are run on a cylindrical electrical transformer that is generating heat in order to study the resulting natural convection that is driven by density variation. The transformer generates a constant heat flux and is incased in a sleeve with radial fins. At first, the sleeve is analyzed without fins and compared to an analytical solution in order to validate the numerical simulations. Next, fins are added to the sleeve in order to maximize the heat transfer from the transformer. Heat transfer from the sleeve per number of fins is to be determined. Small pins are then added …

Detector Arrays For Nuclear Security And Safeguards Applications, Jessica Hartman

UNLV Theses, Dissertations, Professional Papers, and Capstones

Over the last two decades it has become increasingly apparent that there is a need for new technologies capable of reliable and efficient fast neutron detection. As national and international stockpiles of 3He continue to dwindle, the need to find a new gold standard of neutron detection becomes more critical. Moreover, neutrons are generated typically in the MeV energy range. The use of 3He detectors for fast neutron measurements requires the use of moderators. Detector arrays capable of fast neutron detection are one solution to this problem. To this end, the focus of this work was the study of detector …

Preliminary Investigation Of Tensile Strength And Impact Characterization Of Cementitious Composite Incorporating Carbon Nanotubes, Robabeh Jazaei

UNLV Theses, Dissertations, Professional Papers, and Capstones

Cement has been largely used in the construction industry, specifically as a matrix for concrete. Recently, a new generation of cement-based composite that greatly increases mechanical properties is replacing conventional concrete. With periodic advances in the field, researchers considered particles with high-aspect ratios such as Carbon Nanotubes (CNTs) to reinforce cement matrices. Although there is not much literature to draw upon in research, some research on improving the tensile strength of cementitious composite incorporating with CNTs does exist. However, there had been no evidence of investigation into impact strength until this study.

Most papers presented examined the effect of multi-walled …

Fundamental Tradeoffs In Estimation Of Finite-State Hidden Markov Models, Justin Le

UNLV Theses, Dissertations, Professional Papers, and Capstones

Hidden Markov models (HMMs) constitute a broad and flexible class of statistical models that are widely used in studying processes that evolve over time and are only observable through the collection of noisy data. Two problems are essential to the use of HMMs: state estimation and parameter estimation. In state estimation, an algorithm estimates the sequence of states of the process that most likely generated a certain sequence of observations in the data. In parameter estimation, an algorithm computes the probability distributions that govern the time-evolution of states and the sampling of data. Although algorithms for the two problems are …

Design Optimization And Control Of A Fully Actuated Hexrotor Uav For Use In Aerial Manipulation Applications, Jameson Yau Sung Lee

UNLV Theses, Dissertations, Professional Papers, and Capstones

This work addresses the issue of controller complexity in the application of a special class of multirotor in aerial manipulation tasks. Much of the current research concerning aerial manipulation involves the modeling and control of highly coupled multirotor and manipulator systems. This is a consequence of the platform’s under-actuation condition. To accommodate the rejection of arbitrary wrench disturbances brought about by the environment, multirotor must perform deliberate attitude tracking to affect forward and lateral maneuvers mid-flight. The manipulator end-effector tracking is highly affected by this, thus, their performance in general aerial manipulation is limited. To address these limitations, a special …

Morphological And Energy Transport Optimization Of Spectrally-Selective Solar Absorber Coatings At Mesoscale, Dale Karas

UNLV Theses, Dissertations, Professional Papers, and Capstones

A special class of cuprous-based inorganic oxide materials, synthesized as nanoparticles via hydrothermal and co-precipitation methods, are portable to spectrally-selective absorber coatings with high solar-thermal energy conversion efficiency. Operating reliably at elevated temperatures when used in tandem with solar concentrators, these materials enable cost-competitive solar energy conversion technology that can be incorporated with thermal energy storage systems, supporting the viability of novel renewable power generation; notably, optimizing absorptive performance while mitigating thermal losses through re-radiated waste heat motivates sustainable energy production particular to desert climates, where water conservation and ecological sensitivity needs are paramount.

This work targets the chemical synthesis …

Linear And Nonlinear Adaptive Attitude Control Of Asteroid-Orbiting Spacecraft Using State Feedback And Output Feedback, Nicholas Moya

UNLV Theses, Dissertations, Professional Papers, and Capstones

This thesis presents the derivation of both a linear and nonlinear adaptive control law for the attitude states of a spacecraft in orbit around rotating asteroids. The asteroid is assumed to be irregularly shaped and in an elliptical orbit around the sun. The linearized, time-varying spacecraft model will assume to include unknown parameters and will have external disturbances present. The objective is to control the roll, pitch, and yaw angle trajectories of the spacecraft such that they track desired reference trajectories. To achieve this, the control law will be composed of (1) a feedback controller, sufficiently robust to disturbance such …

A Numerical Model Of An Axial Wind Turbine, Andrew Liam Poland

UNLV Theses, Dissertations, Professional Papers, and Capstones

Since the beginning of the industrial revolution, there has never been more of a constant in the world than that of the demand for energy. For years a stable source has been fossil fuels, but with the growing impacts of global warming, it is important to look for renewable sources. Wind energy’s use has become more and more prevalent throughout the world.

This preliminary work runs through the creation of a three-dimensional numerical model of a conventional wind turbine that was created using ANSYS-Fluent© commercial software. This work provides the base wind turbine and a blade element and momentum theory …

A Novel Approach To Analyzing Strain Heterogeneity In Polycrystalline Quartz Specimens Deformed At High Pressure And Temperature, Nolan Ambrose Regis

UNLV Theses, Dissertations, Professional Papers, and Capstones

Rheological studies of rocks and minerals allow researchers to study the grain-scale deformation mechanisms that govern large-scale geologic processes from mountain building to mantle mixing. Deforming rock samples with high pressure and temperature apparatuses similar to the Griggs piston cylinder apparatus allows us to simulate deformation at depth. However, many apparatuses are limited to “cook-and-look” analysis and require modeling techniques to determine the evolution of deformation patterns found in experimental samples. A previous study used two-dimensional finite element models to analyze the development of stress and strain patterns in polycrystalline rocks. The study suggested rhythmic patterns in deformed rocks develop …

Design On High Performance Nanoscale Cmos Circuits With Low Temperature Sensitivity, Ming Zhu

UNLV Theses, Dissertations, Professional Papers, and Capstones

With the rapid development of integrated circuit (IC) design and manufacturing technology, the transistor size now can be shrunk into only couple of nanometers whereas billions of transistors can be squeezed into a square millimeter, providing unprecedented computation power. However, accompanied with continuous device miniaturization and increased integration density is the explosive growth of on-chip power dissipation and a wide range of temperature fluctuation, which can heavily and negatively affect the delay performance of the circuit, or in the worst case, the circuit may malfunction and the system can be unreliable. Therefore, improved performance resilience against temperature variations has become …

Effect Of Driver, Vehicle, And Road Related Factors On Crashes At Intersections And Non-Intersections: A Naturalistic Driving Study, Grace Naa Ashley

LSU Master's Theses

Traffic accidents in the U.S. have declined over the last two decades but continue to cost the country billions of U.S. dollars each year. Intersection accidents alone account for 23% of the 32,675 deaths that occurred by motor vehicle crashes in 2014. In light of this, the first part of this study sought to identify driver behavior and secondary tasks that influenced the occurrence of a crashes at controlled, uncontrolled and non-intersections with multiple logistic regression. The second part of the study used decision tree which applied machine learning algorithms to identify significant factors that influenced the occurrence of crashes …

Ozone Removal Efficiency And Surface Analysis Of Green And White Roof Hvac Filters, Omed A. Abbass, David Sailor, Elliott T. Gall

Mechanical and Materials Engineering Faculty Publications and Presentations

Heating, ventilation, and air-conditioning ( HVAC ) system filters from a commercial building were tested for their ability to remove ozone from intake air. Filters were taken from rooftop HVAC systems installed for two months: one located on a white membrane roof and the other on a vegetated green roof. One new, unused filter sample was tested as a reference. Samples from these filters were exposed to ozonated air streams at 40 and 120 ppb and relative humidity levels of 30% and 70%. Filter surfaces were analyzed with a scanning electron microscope to observe the structure and composition of the …

Design & Delivery Of Automated Winston-Lutz Test For Isocentric & Off-Axis Delivery Stability Utilizing Truebeam Developer Mode & Electronic Portal Imaging Device, Mahmoud Mohammad Yaqoub

UNLV Theses, Dissertations, Professional Papers, and Capstones

The uncertainties in treatment delivery cannot be ignored in radiation therapy. Thus, the quality assurance QA tests are very important task of the medical physicist in clinical practice. Assuring the coincidence between the mechanical isocenter of the Linear Accelerator (LINAC) and its radiation beams isocenter is one of the most important qualities need to be tested, and the Winston Lust (WL) test is the

most popular technique to perform this task, especially for the treatment modalities which need high precision in beam delivery such as the stereotactic radiosurgery/stereotactic body radiotherapy (SRS/SBRT). The linear accelerator-based SRS/SBRT is a well-established method in …

Development And Optimization Of Alumina Fine Fibers Utilizing A Centrifugal Spinning Process, Mandana Akia, Dulce Capitanachi, Misael E. Martinez, Carlos Hernandez, Hector De Santiago, Yuanbing Mao, Karen Lozano

Mechanical Engineering Faculty Publications

Highlights

• Successful synthesis of AIP/PVA composite fibers using Forcespinning® techniques.

• Optimization of the operating parameters applying response surface methodology (RSM).

• Fabrication of mesostructured gamma alumina and highly crystalline alpha alumina fine fibers.

Abstract

Aluminum isopropoxide and poly(vinylalcohol) fine fibers were successfully fabricated and optimized utilizing the response surface methodology. The optimized composite fibers showed mean fiber diameter of 304 nm. The fiber samples were calcined at different temperatures to attain both gamma and alpha phases of alumina. Various characterization methods including scanning electron microscopy, thermogravimetric analysis, x-ray diffraction and nitrogen adsorption/desorption analysis were conducted. The BET analysis …

Fundamental Studies Of Solid-Fuel Combustion Using A Two-Stage Flat-Flame Burner, Adewale Ayodeji Adeosun

McKelvey School of Engineering Graduate Student Theses & Dissertations

Innovative coal technologies are essential for addressing concerns about air pollution and global climate change. A key pathway to advancing these technologies is through developing a thorough understanding of the fundamental physical and chemical processes that occur during coal combustion. Ignition influences many aspects of coal combustion, including flame stability, submicron aerosol evolution, and char burnout. As important as ignition and these associated processes are, they are challenging to study because they depend on many factors, such as the combustion environment, particle size, and particle-particle interactions.

While there have been many studies of coal ignition, none have studied the process …

Developing Wavefront Shaping Techniques For Focusing Through Highly Dynamic Scattering Media, Ashton Hemphill

McKelvey School of Engineering Graduate Student Theses & Dissertations

One of the prime limiting factors of optical imaging in biological applications is the diffusion of light by tissue, which prevents focusing at depths greater than the optical diffusion limit of ~1 mm in soft tissue. This greatly restricts the utility of optical diagnostic and therapeutic techniques, such as optogenetics, microsurgery, optical tweezing, and phototherapy of deep tissue, which require focused light in order to function. Wavefront shaping extends the depth at which optical focusing may be achieved by compensating for phase distortions induced by scattering, allowing for focusing through constructive interference.

However, due to physiological motion, scattering of light …

Fluorescence Guided Tumor Imaging: Foundations For Translational Applications, Jessica P. Miller

McKelvey School of Engineering Graduate Student Theses & Dissertations

Optical imaging for medical applications is a growing field, and it has the potential to improve medical outcomes through its increased sensitivity and specificity, lower cost, and small instrumentation footprint as compared to other imaging modalities. The method holds great promise, ranging from direct clinical use as a diagnostic or therapeutic tool, to pre-clinical applications for increased understanding of pathology. Additionally, optical imaging uses non-ionizing radiation which is safe for patients, so it can be used for repeated imaging procedures to monitor therapy, guide treatment, and provide real-time feedback. The versatile features of fluorescence-based optical imaging make it suited for …

Increasing Ph In Cancer: Enabling A New Therapeutic Paradigm Using Novel Carbonate Nanoparticles, Avik Som

McKelvey School of Engineering Graduate Student Theses & Dissertations

Enormous progress has been made to treat cancer, and yet the mortality rate of cancer remains unacceptably high. High clinical resistance to molecularly targeted therapeutics has pushed interest again towards inhibiting universal biochemical hallmarks of cancer. Recent evidence suggests that malignant tumors acidify the local extracellular environment to activate proteases for degrading the tumor matrix, which facilitates metastasis, and explains why more aggressive tumors are more acidic. Current therapies have only focused on using the low pH for enhancing drug release in tumors, thereby still relying on the traditional paradigm of intracellular inhibition of pathways, a method that continues to …

Transcriptional Regulation Of Arrhythmia: From Mouse To Human, Yun Qiao

McKelvey School of Engineering Graduate Student Theses & Dissertations

In the last two decades, our understanding of cardiac arrhythmias has been accelerated immensely by the development of genetically engineered animals. Transgenic and knockout mice have been the “gold standard” platforms for delineating disease mechanisms. Much of our understanding of the pathogenesis of atrial and ventricular arrhythmias is gained from mouse models that alter the expression of specific ion channels or other proteins. However, cardiac arrhythmias such as atrial fibrillation are heterogeneous diseases with numerous distinct conditions that could not be explained exclusively by the disruption of ionic currents. Increasing evidence suggests disruption of signaling pathways in the pathogenesis of …

Functional Electrical Stimulation Of Peripheral Nerve Tissue Via Regenerative Sieve Microelectrodes, Matthew Reagan Macewan

McKelvey School of Engineering Graduate Student Theses & Dissertations

Functional electrical stimulation (FES) of peripheral nervous tissue offers a promising method for restoring motor function in patients suffering from complex neurological injuries. However, existing microelectrodes designed to stimulate peripheral nerve are unable to provide the type of stable, selective interface required to achieve near-physiologic control of peripheral motor axons and distal musculature. Regenerative sieve electrodes offer a unique alternative to such devices, achieving a highly stable, selective electrical interface with independent groups of regenerated nerve fibers integrated into the electrode. Yet, the capability of sieve electrodes to functionally recruit regenerated motor axons for the purpose of muscle activation remains …

Developing Photoacoustic Tomography Devices For Translational Medicine And Basic Science Research, Tsz Wai Wong

McKelvey School of Engineering Graduate Student Theses & Dissertations

Photoacoustic (PA) tomography (PAT) provides volumetric images of biological tissue with scalable spatial resolutions and imaging depths, while preserving the same imaging contrast—optical absorption. Taking the advantage of its 100% sensitivity to optical absorption, PAT has been widely applied in structural, functional, and molecular imaging, with both endogenous and exogenous contrasts, at superior depths than pure optical methods. Intuitively, hemoglobin has been the most commonly studied biomolecule in PAT due to its strong absorption in the visible wavelength regime.

One of the main focuses of this dissertation is to investigate an underexplored wavelength regime—ultraviolet (UV), which allows us to image …

Numerical Study Of Oxidation In Stainless Steel Alloy Ep-823 By Liquid Lead-Bismuth Eutectic, Rajyalakshmi Palaparty

UNLV Theses, Dissertations, Professional Papers, and Capstones

The oxidation of stainless steel is influenced by the presence of oxygen in the surrounding medium; the oxygen reacts with the alloy to form an oxide. In certain environments, such as nuclear reactor coolant systems, minimal oxidation of the stainless steel containment functions as a protective shield from corrosive coolants such as liquid lead-bismuth eutectic.

In the current study, this minimal oxidation is evaluated for a system in which corrosion-resistant stainless steel alloy EP-823 is subject to an environment of flowing oxygenated liquid lead-bismuth eutectic at a temperature of 743 K, whereby the thickness of the forming oxide layer is …

The Design, Modeling, And Optimization Of A Biomimetic Soft Robot For Fluid Pumping And Thrust Generation Using Electroactive Polymer Actuators, Zakai Jedidiah Olsen

UNLV Theses, Dissertations, Professional Papers, and Capstones

Nature is a constant source of inspiration for engineers and scientists through its simple, effective, and elegant solutions to many complex problems. Smart materials and soft robotics have been seen to be particularly well suited for developing biomimetic devices and are active fields of research. In this study, the design, modeling, and optimization of a new biomimetic soft robot is described. Preliminary work was made in the modeling of a biomimetic robot based on the locomotion and kinematics of jellyfish. Modifications were made to the governing equations for jellyfish locomotion that accounted for geometric differences between biology and the robotic …

Numerical Study Of Biopolymer Implants For Distal Femoral Condyles– Finite Element Simulations, Luke Olsen

UNLV Theses, Dissertations, Professional Papers, and Capstones

Approximately 12% of the adult population in the United States is affected by

Osteoarthritis (OA) [1, 2]. Because of this, OA is the considered the most chronic degenerative joint disease, and is subject to continuous research into treatment. OA mainly manifests itself by degrading the articular cartilage in joints, such as the knee, and can eventually lead to complete loss of cartilage and potentially bone damage, leading to pain and discomfort for the patient [3]. For severe OA, the most common treatment is total knee arthroplasty (TKA) [4]. This procedure includes removing portions of the femur and tibia, and replacing …

N-Nitrosodimethylamine Formation And Mitigation In Potable Reuse Treatment Trains Employing Ozone Nd Biofiltration, Fernanda Bacaro

UNLV Theses, Dissertations, Professional Papers, and Capstones

Potable reuse has been growing as a strategy to augment water supplies, especially in highly populated and water-scarce regions. Ozone and chloramines have emerged as important disinfectants and oxidants in potable reuse applications, but reactions with wastewater-derived constituents can lead to the formation of potentially carcinogenic disinfection byproducts (DBPs). One DBP that has received considerable attention is the nitrogenous DBP N-nitrosodimethylamine (NDMA). NDMA is a potential human carcinogen and mutagen at trace concentrations — even at the sub-ng/L level. Several studies have reported successful attenuation of NDMA in biofiltration systems at wastewater treatment plants, but the associated mechanisms and design …