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 …

Design, Layout, And Testing Of Sige Apds Fabricated In A Bicmos Process, Dane Laurence Gentry

UNLV Theses, Dissertations, Professional Papers, and Capstones

This Thesis is concerned with the design, layout, and testing of avalanche photodiodes (APDs). APDs are a type of photodetector and, thus, convert light signals into electrical signals (current or voltage). APDs can be fabricated using silicon (Si). In this Thesis, however, three integrated circuit (IC) chips containing various silicon-germanium (SiGe) APDs with different sizes, structures, and geometries were designed, laid out, and fabricated using the Austriamicrosystems (AMS) 0.35μm SiGe BiCMOS (S35) process. This was done in order to compare SiGe APDs to Si only APDs and investigate the hypothesis that SiGe APDs are capable of detecting longer wavelengths than …

Optimization Of Useful Hard X-Ray Photochemistry, David Lewis Goldberger

UNLV Theses, Dissertations, Professional Papers, and Capstones

X-ray induced damage is generally considered a nuisance, but in the field of Useful Hard X-ray Photochemistry we harness the highly ionizing and penetrating properties of hard X-rays (> 7 keV) to initiate novel photochemical decomposition and synthesis at ambient and extreme conditions. Preliminary experiments suggest that the energy of irradiating photons and the sample pressure play roles in determining the nature of X-ray induced damage. Here, we present the X-ray energy dependence of damage induced in strontium oxalate, strontium nitrate, and barium nitrate, as well as the pressure dependence of X-ray induced damage of strontium oxalate. Our results indicate …

First Observation Of P-Odd Gamma Asymmetry In Polarized Neutron Capture On Hydrogen, D. Blyth, J. Fry, N. Fomin, R. Alarcon, L. Alonzi, E. Askanazi, S. Baeßler, S. Balascuta, L. Barrón-Palos, Alex Barzilov, J. D. Bowman, N. Birge, J. R. Calarco, T. E. Chupp, V. Cianciolo, C. E. Coppola, C. B. Crawford, K. Craycraft, D. Evans, C. Fieseler, E. Frlež, I. Garishvili, M. T. W. Gericke, R. C. Gillis, K. B. Grammer, G. L. Greene, J. Hall, J. Hamblen, C. Hayes, E. B. Iverson, M. L. Kabir

Mechanical Engineering Faculty Research

We report the first observation of the parity-violating gamma-ray asymmetry A(gamma)(np) in neutron-proton capture using polarized cold neutrons incident on a liquid parahydrogen target at the Spallation Neutron Source at Oak Ridge National Laboratory. A(gamma)(np) isolates the Delta I = 1, S-3(1)-> P-3(1) component of the weak nucleon-nucleon interaction, which is dominated by pion exchange and can be directly related to a single coupling constant in either the DDH meson exchange model or pionless effective field theory… See full text for full abstract.

College Of Engineering Senior Design Competition Fall 2018, University Of Nevada, Las Vegas

Fred and Harriet Cox Senior Design Competition Projects

Part of every UNLV engineering student’s academic experience, the senior design project stimulates engineering innovation and entrepreneurship. Each student in their senior year chooses, plans, designs, and prototypes a product in this required element of the curriculum. A capstone to the student’s educational career, the senior design project encourages the student to use everything learned in the engineering program to create a practical, real world solution to an engineering challenge. The senior design competition helps focus the senior students in increasing the quality and potential for commercial application for their design projects. Judges from local industry evaluate the projects on …

Mitigating Accumulation Of Aeolian Dust Particles On Solar Power Generator Panels Without Water, Sanjana Das

UNLV Theses, Dissertations, Professional Papers, and Capstones

Accumulation of dust on solar panels poses a serious problem as it can significantly reduce light absorption and electrical energy output. Several factors affect the dust accumulation such as location, dust properties, wind velocity, system orientation, ambient temperature, humidity, and panel surface properties. Experimental and theoretical studies show that short circuit current and maximum power output of photovoltaic panels reduce approximately linearly with dust concentration. Incidentally, the locations with higher solar energy concentrations are also arid or semi-arid regions with higher dust concentrations. In order to avoid loss in power output, most PV installations perform periodic panel cleaning with water. …

Conformal Mapping Improvement Of The Boundary Element Method Solution For Underground Water Flow In A Domain With A Very Singular Boundary, Megan Romero

UNLV Theses, Dissertations, Professional Papers, and Capstones

Numerical solutions using a Boundary Element Method (BEM) for a confined flow in a very singular finite domain are developed. Typically, in scientific journal publications, authors avoid domains with many and more malignant singularities due to the extremely big and difficult to estimate errors in the numerical calculations. Using exact Conformal Mapping solutions for simplified domains with the same singularity as in the original domain, this problem can be solved numerically with improvements introduced by Conformal Mapping solutions. Firstly, to experiment with improving the BEM solution by Conformal Mapping, a domain inside a rectangle is considered. The exact solution inside …

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 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 …

Static And Dynamic Quantitative Microbial Risk Assessment Of Potable Reuse Paradigms, Erfaneh Amoueyan

UNLV Theses, Dissertations, Professional Papers, and Capstones

In recent years, potable reuse applications have become more common due to population growth and increased water demand, especially in communities with limited or variable water resources. However, there are concerns about potential exposure to pathogens and chemical compounds in treated wastewater. Therefore, advanced wastewater treatment processes are of paramount importance in any potable reuse system. The overall aim of this study was to develop and implement static and dynamic QMRAs to compare public health risk in various potable reuse scenarios. Cryptosporidium, norovirus, adenovirus, and Salmonella were chosen as the target pathogens. The research evaluated the performance of full advanced …

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 …

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 & 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 …

Management Of An Urban Stormwater System Using Projected Future Scenarios Of Climate Models: A Watershed-Based Modeling Approach, Ranjeet Thakali, Ajay Kalra, Sajjad Ahmad, Kamal Qaiser

Civil and Environmental Engineering and Construction Faculty Research

Anticipating a proper management needs for urban stormwater due to climate change is becoming a critical concern to water resources managers. In an effort to identify best management practices and understand the probable future climate scenarios, this study used high-resolution climate model data in conjunction with advanced statistical methods and computer simulation. Climate model data from the North American Regional Climate Change Assessment Program (NARCCAP) were used to calculate the design storm depths for the Gowan Watershed of Las Vegas Valley, Nevada. The Storm Water Management Model (SWMM), developed by the Environmental Protection Agency (EPA), was used for hydrological modeling. …

Climate Change And Eutrophication: A Short Review, Mohammad Nazari-Sharabian, Sajjad Ahmad, Moses Karakouzian

Civil and Environmental Engineering and Construction Faculty Research

Water resources are vital not only for human beings but essentially all ecosystems. Human health is at risk if clean drinking water becomes contaminated. Water is also essential for agriculture, manufacturing, energy production and other diverse uses. Therefore, a changing climate and its potential effects put more pressure on water resources. Climate change may cause increased water demand as a result of rising temperatures and evaporation while decreasing water availability. On the other hand, extreme events as a result of climate change can increase surface runoff and flooding, deteriorating water quality as well. One effect is water eutrophication, which occurs …