Engineering Commons^™

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 …

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 …

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 …

The Effect Of Titanium Dioxide On Nucleate Pool Boiling Using An Aluminum Substrate, Kevin Yim

UNLV Theses, Dissertations, Professional Papers, and Capstones

Nucleate pool boiling is a mode of pool boiling that tends to transfer heat more efficiently than the other modes of pool boiling. Many studies have been done to augment the heat transferred during nucleate pool boiling. Various methods of heat transfer augmentation in

boiling can be performed through active treatments (mechanical aids, surface/fluid vibrations, etc.) or passive treatments (functional coating, surface roughening, etc.). This study focuses primarily on a passive treatment, specifically TiO2 coating, which involves testing a substrate coated with TiO2 using NeverWetTM base coating as a coupling agent and coated using a method outlined by Wu et …

Investigations Into The Airside Cooling Of A Heat Exchanger, David Vallet

UNLV Theses, Dissertations, Professional Papers, and Capstones

In this study we investigate the air-side cooling of a flat-plate fin and tube heat transfer condenser with numerical simulations. A new design is proposed which utilises vortex generators to direct the flow in such a way as to remove some of the stagnant heated air that collects in the wake of the pipes. A comparative study of the proposed design and a standard tube and fin condenser is conducted by varying the air side entrance velocities. The Shear Stress Tension, SST $\kappa - \omega$ 2-equation turbulent model is used to solve the RANS model in ANSYS Fluent 18. The …

Comprehensive Study Of Spray-Painting And 3d Printing Fabrication Methods For Nafion® And Nafion® Equivalents In Ionic Polymer-Metal Composite Actuators And Sensors, Sarah Trabia

UNLV Theses, Dissertations, Professional Papers, and Capstones

Ionic Polymer-Metal Composites (IPMC) are smart materials that are useful in different applications because of their low voltage requirements and light weight. IPMC are made of ion- conducting polymer (ionomer) plated with a noble metal, such as platinum. When a voltage potential is applied to the surface of the IPMC, it creates an electro-mechanical effect, causing it to actuate. This is due to the motion of the cations towards the negatively charged side of the IPMC, causing it to swell, and in turn, bend. Conversely, deforming an IPMC moves cations within it, which produces a small voltage that can be …

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 …

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 …

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 …

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 …

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 …

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 …

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 …

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 …