Engineering Commons^™

Synthesis Of Zinc Oxide Nanorods And Use In Biosensor Applications, Anishkumar Manoharan

Graduate Theses and Dissertations

The main aim of this research was to develop a nanorod based biosensor for biomedical applications. In this project I use zinc oxide nanorods as the bio-material for biosensor. I fabricated these nanorods using a solution-based technique. Initially I coated a zinc oxide seed layer as the base. This seed layer was then annealed at 350 degrees for almost 1 hour. As a next step, interdigitated electrodes were fabricated on the top of the seed layer using a lift off process. The zinc oxide nanorods were then grown at 90 degrees for almost 4 hours along the electrodes. In this …

Studies On Power Hop Using A Nonlinear Model Of An Agricultural Tractor, Adam B. Flaugh

Department of Agricultural and Biological Systems Engineering: Dissertations, Theses, and Student Research

Power hop is an unstable dynamic phenomenon that is observed on agricultural tractors operating at field working speeds under typical draft loads. This dynamic instability can be identified as a bounce motion preceded by an increasing oscillation in either the pitch or bounce modes. A definite and comprehensive correction or prevention strategy for the control of power hop does not exist. In this work a linear and a nonlinear model of an agricultural tractor were developed. The method of multiple time scales has been employed in the analysis of the nonlinear model. Numerical results have been obtained using Mathematica to …

The Economics And Logistics Of The Dual Harvest Of Grain And Biomass In A Single-Pass, Matthew T. Wold

Department of Agricultural and Biological Systems Engineering: Dissertations, Theses, and Student Research

Significant interest has developed in using cellulosic resources, especially crop residues, to create biofuels. Collecting these residues in a single-pass of the harvester across the field has the potential to be a low cost option. Two models have been developed; the first characterizes the in-field logistics of single-pass crop residue collection, the second the economics. These models allow the user to easily examine a wide variety of both grain-only and single-pass residue collection harvest cases. A variety of possible residue collection cases have been examined, and their effects both on harvester field capacity and harvest cost compared to grain-only harvest …

Using A Micro-Integrator To Eliminate The Numerical Butterfly Effect In Non-Linear Chaotic Partial Differential Equations, Joshua Jemegbe

Electrical Engineering Theses

Chaos theory is a relatively new scientific paradigm for the analysis, simulation and prediction of non-linear phenomena whose initial conditions determine the behavior of their entire time series representation. It finds many applications in mathematics, science, and engineering. These include, but are not limited, to data encryption and decryption, designing secure communication systems, predicting weather patterns, noise fluctuations on data lines, understanding turbulence in fluid flow, and analyzing quantum wells. Systems that exhibit chaos are called chaotic systems. In computing solutions to nonlinear chaotic partial differential equation sets, slight deviations in step size could lead to completely diverging trajectories as …

Compressive Sensing For Speech Signals In Mobile Systems, Sabir Ahmed

Electrical Engineering Theses

Compressive sensing is an emerging and revolutionary technology that strongly relies on the sparsity of the signal. In compressive sensing the signal is sparsely compressively sampled by taking a small number of random projections of the signal, which contain most of the salient information. Compressive sensing has been previously applied in areas like: image processing, radar systems and sonar systems. This research work will discuss the potential implementation of compressive sensing in mobile communication systems and how it will influence their data rates. In a typical mobile communication system, the signal of interest is sampled at least at the Nyquist …

Effects Of High-Impedance-Contrast Boundary Upon Multi-Modal Seismic Surface Wave Data, Prajwol Tamrakar

UNLV Theses, Dissertations, Professional Papers, and Capstones

Synthetic studies and analyses of an experimental dataset were conducted to address the use of Rayleigh-type surface waves for estimation of shear wave velocity (VS) profiles of shallow bedrock sites. The shallow bedrock presents a high impedance contrast boundary which causes surface wave energy to be partitioned to higher modes. Idealized studies of hypothetical datasets and root-mean-squared calculations of error surfaces showed that if reliable dispersion data are available over a broad frequency spectrum, the VS profile can be recovered using the fundamental mode alone. However, when dispersion data are limited to a relatively narrow frequency band representing what might …

Sensing And Transmission Strategies In Wireless Cognitive Radio Systems, Babak Abbasi Bastami

UNLV Theses, Dissertations, Professional Papers, and Capstones

The main challenge in any cognitive radio system is to maximize secondary users throughput while limiting interference imposed on licensed users. In this regard, finding the optimal sensing and transmission timing strategies and accurate sensing techniques are of great importance in a cognitive radio network.

In this thesis, we study a sensing-transmission scheme for secondary user in a cognitive radio system where the secondary user senses every primary channel independently and transmits a signal for a fixed duration if it finds the channel empty and stays idle for another fixed duration if it senses the channel busy. We obtain optimal …

Energy-Based Analysis Of Utility Scale Hybrid Power Systems, Kwame Agyenim-Boateng

UNLV Theses, Dissertations, Professional Papers, and Capstones

The promise of large-scale use of renewables such as wind and solar for supplying electrical power is tempered by the sources' transient behavior and the impact this would have on the operation of the grid. Among the methods cited for addressing some of those concerns are exploring the complementary nature of solar and wind power generation, and through the use of supplemental energy storage. While the technology for the latter has not been proven to be economical on a large scale at the present time, some assessments of what magnitude is required can be made. An energy-based analysis of utility …

Towards Failure Free Design: An Analysis Of Risk Mitigation Communication, Daniel Krus, Katie Grantham

Engineering Management and Systems Engineering Faculty Research & Creative Works

In order to ensure that risk mitigation strategies are properly communicated to and understood by those who would use them in future designs, a common language of risk mitigation should exist. This paper focuses on a set of elements for describing risk mitigation strategies based on a linguistic analysis of the information such strategies must communicate to the design team. Sample strategies are then decomposed into these attributes and evaluated using the Gricean cooperation principle, relevance theory, and functional analysis theories from the pragmatics sub-field of linguistics. using the deficiencies found from this analysis, a format for risk mitigation strategies …

Influence Of Grain Size And Texture On Hall-Petch Relationship For A Magnesium Alloy, W. Yuan, S. K. Panigrahi, J. Q. Su, R. S. Mishra

Materials Science and Engineering Faculty Research & Creative Works

Friction stir processing was applied to a magnesium alloy to generate various grain sizes with the same intense basal texture. Subsequent tensile deformation along two orthogonal directions by easy activation or inhibition of basal slip follows the Hall-Petch relationship between yield stress and grain size in both directions. the Hall-Petch parameters are texture dependent. Easy activation of basal slip introduces lower values, while inhibition of basal slip leads to higher values. the Hall-Petch parameters are interpreted by texture and microstructural factors. © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Grain Boundary Behavior In An Ultrafine-Grained Aluminum Alloy, P. S. De, R. S. Mishra

Materials Science and Engineering Faculty Research & Creative Works

The low-angle grain boundary (LAGB) stability in an ultrafine-grained (UFG) Al alloy during monotonic loading was investigated by orientation imaging microscopy (OIM). the experiments show that boundaries with misorientation below ∼2.5 deg are stable, while boundaries with misorientation between 2.5 and 15 deg are unstable. Similar results were observed during cyclic loading of UFG Al alloy. This behavior was rationalized using the nonequilibrium thermodynamics concept. on the other hand, it is postulated that the grain boundary behavior in microcrystalline alloy is different because of the larger dislocation mean free path. © 2011 the Minerals, Metals & Materials Society and ASM …

Fluid Flow-Related Transport Phenomena In Steel Slab Continuous Casting Strands Under Electromagnetic Brake, Yufeng Wang, Lifeng Zhang

Materials Science and Engineering Faculty Research & Creative Works

In the current study, a three-dimensional (3D) numerical model is built to investigate the effect of a local-type electromagnetic brake (EMBr) on the fluid flow, heat transfer, and inclusion motion in slab continuous casting strands. the results indicate that the magnetic force affects the jet characteristics, including jet angle, turbulent kinetic energy, and its dissipation rate. to reduce the top surface velocity and stabilize the top surface, the magnetic flux intensity should be larger than a critical value. with a 0.39 T magnetic flux intensity, the top surface velocity and its fluctuation can be well controlled, and less slag is …

Mechanical Characterization Of Fourth Generation Composite Humerus, Prateek Grover, Carolyne Albert, Mei Wang, Gerald F. Harris

Biomedical Engineering Faculty Research and Publications

Mechanical data on upper extremity surrogate bones, supporting use as biomechanical tools, is limited. The objective of this study was to characterize the structural behaviour of the fourth-generation composite humerus under simulated physiologic bending, specifically, stiffness, rigidity, and mid-diaphysial surface strains. Three humeri were tested in four-point bending, in anatomically defined anteroposterior (AP) and mediolateral (ML) planes. Stiffness and rigidity were derived using load–displacement data. Principal strains were determined at the anterior, posterior, medial, and lateral surfaces in the humeral mid-diaphysial transverse plane of one specimen using stacked rosettes. Linear structural behaviour was observed within the test range. Average stiffness …

Mixed Integral-Differential Skin-Effect Models For Peec Electromagnetic Solver, Giulio Antonini, Albert E. Ruehli, Lijun Jiang

Electrical and Computer Engineering Faculty Research & Creative Works

Efficient modeling of the broadband skin-effect for conducting 3D shapes is a challenging issue for the solution of large electromagnetic problems. The inclusion of such models in an EM solver can be very costly in compute time and memory requirements. Several properties of a model are desirable for the solution of practical problems such as the broadband frequency domain or the time domain applicability. In this paper, we present a model which meets some of these challenges and which is suitable for the PEEC solution method. © 2011 IEEE.

Validation Of The Triply Selective Fading Channel Model Through A Mimo Test Bed And Experimental Results, Saurav Subedi, Huang Lou, Fei Ren, Mingxi Wang, Y. Rosa Zheng

Electrical and Computer Engineering Faculty Research & Creative Works

Multiple-input multiple-output (MIMO) channel is often triply selective, meaning that it has spatial, temporal and inter-tap correlation. the temporal correlation is well characterized by its Doppler spectrum, but spatial and inter-tap correlation and their impact on MIMO channels are less studied in the literature. a MIMO testbed has been established to measure the impulse response of MIMO channels and an estimation method is developed to quantitatively measure the correlation matrices from experimental data. © 2011 IEEE.

Evaluating The Cost-Effectiveness Of Roadside Culvert Treatments, Francisco Daniel B. De Albuquerque, Dean L. Sicking, Ronald K. Faller, Karla A. Lechtenberg

Department of Civil and Environmental Engineering: Faculty Publications

Roadside cross-drainage culverts have been found to affect vehicle accident injury levels. As a result, highway designers have commonly used three safety treatments to protect errant motorists from striking culvert openings. These safety treatments have included: culvert extension, guardrail installation, and the application of safety grating. However, the identification of the most appropriate safety treatment for roadside culverts may be challenging; accident costs may dramatically change under different road and traffic characteristics. The purpose of this study was to estimate accident costs for a wide range of road and traffic scenarios and then define the safest treatment (i.e., treatment with …

Evaluation And Seismically Isolated Substructure Redesign Of A Typical Multi-Span Pre-Stressed Concrete Girder Highway Bridge, Brian D. Richins

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Seismic considerations greatly influence the lateral and vertical design of a structure, often necessitating larger elements than would otherwise be required. Seismic isolation greatly reduces the demands on a structure due to earthquake loading, allowing the use of smaller, more efficient members and foundations. This case study illustrates the theory and procedure of evaluating the response of a recently built multi-span highway bridge using the most recent (2009) AASHTO code. Based on this response, an equivalent structure was designed to incorporate a seismic isolation system, and the substructure of the isolated bridge redesigned to meet the reduced demands more economically. …

Subthreshold 3 Phase Mixers, Jesus Angel Torres

Theses and Dissertations - UTB/UTPA

This thesis will discuss subthreshold FET mixers with a focus on conversion loss derivations. To begin understanding the mixers, a look into the FET model is first taken in Chapter II. Then in Chapter III, a single FET device mixer is studied and its conversion loss is found from its small-signal model. The chapter will then include a two FET device mixer and a four device FET mixer. Finally a new type of mixer will be discussed in Chapter IV. The new type of mixer is a 3 phase mixer with the phase angles being 0°, 120°, and 240°. The …

The Role Of Thermally-Induced Geometrical Changes In Temperature Trending Of Railroad Tapered Roller Bearings, Andrei G. Vaipan

Theses and Dissertations - UTB/UTPA

The understanding of the phenomenon of temperature trending of railroad tapered roller bearings is of paramount importance to the railroad industry. The problem that this poses to the industry is that it leads to false alarms triggered by wayside detectors, which forces the premature removal of defect-free bearings. This thesis provides more insight into this phenomenon and answers questions regarding the importance of key tapered roller bearing components geometry and geometrical changes during temperature trending events. In this study, dynamic experiments conducted in the laboratory have represented the primary method of testing bearing temperature trending. The experimental results are brought …

Analysis And Design Of An Anisotropic, Compliant Suspension Component, Samantha Jean Salinas

Theses and Dissertations - UTB/UTPA

A steering pad on a train is meant to reduce the force on the wheel while moving along a curve in the rail. A new steering pad was desired with properties tuned for a new suspension system design. An anisotropic, compliant pad was designed for a specific stiffness anisotropy, 20:1. Finite element analysis was performed on various models as a guide to designing a pin with the desired stiffness ratio. A design was chosen for a prototype made of thermoset polyurethane, a similar material to that currently used. Experiments were performed on the prototype pad model to determine vertical and …

Auto-Tuning Antenna, John Chen, Jennifer Tighe

Electrical Engineering

Radio transmitters and antennas have differing impedances at the output and feedpoint, depending on frequency. Modern antenna tuning methods involve manual or automatic resistance and reactance network adjustment to match transmitter and antenna impedance. This reduces power reflections to the transmitter, but introduces losses and prevents full transmitter power from being radiated at the antenna. This project utilizes a variable length antenna element to tune and match transmitter and antenna impedances, allowing efficient power transfer to the antenna. The antenna length varies from 0 to 30.5 inches. The method involves an RF signal with a maximum power of 2 watts …

A Model For Rapid Charging Events On International Space Station, Debrup Hui

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

Surface charging by plasma can be a serious issue for any spacecraft. Though significant charging is not observed in all spacecrafts at all times, it only requires a single episode of extreme charging to result in serious damage. The International Space Station (ISS) is an interesting platform to study these charging effects because of its size and relatively high voltage systems. Of the many kinds of charging observed on ISS, the rapid charging events during solar eclipse exit in a low-density ionosphere is not yet understood. This report is an investigation to understand this phenomenon. This report proposes a simple …

Engineering Model To Calculate Mass Flow Rate Of A Two-Phase Saturated Fluid Through An Injector Orifice, Brian J. Solomon

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

An engineering model is developed to calculate mass flow rate of nitrous oxide, a self-pressurizing saturated oxidizer commonly used in hybrid rocket motors. While use of N_{2}0 cannot be accurately modeled using traditional ideal gas, compressible, or incompressible flow assumptions. To obtain accurate mass flow rate this one-dimensional analysis includes both incompressible fluid and homogeneous equilibrium mass flow rate models. Mass flow calculations from the two models are independently weighted and summed to obtain representative two-phase mass flow rate. Fluid properties are iterated in time by keeping track of fluid enthalpy and are propagated across the injector using either isentropic …

Bottom Topography Mapping Via Nonlinear Data Assimilation, Edward D. Zaron, Marie-Aude Pradal, Patrick D. Miller, Alan F. Blumberg, Nickitas Georgas, Wei Li, Julia Muccino Cornuelle

Civil and Environmental Engineering Faculty Publications and Presentations

A variational data assimilation method is described for bottom topography mapping in rivers and estuaries using remotely sensed observations of water surface currents. The velocity field and bottom topography are related by the vertically integrated momentum and continuity equations, leading to a nonlinear inverse problem for bottom topography, which is solved using a Picard iteration strategy combined with a nonlinear line search. An illustration of the method is shown for Haverstraw Bay, in the Hudson River, where the known bottom topography is well reconstructed. Once the topography has been estimated, currents and water levels may be forecast. The method makes …

Calibration Of Highway Safety Manual: Predictive Models For Oregon State Highways, Fei Xie, Kristie Gladhill, Karen Dixon, Christopher Monsere

Civil and Environmental Engineering Faculty Publications and Presentations

The recently released "Highway Safety Manual" (HSM) published by AASHTO provides a comprehensive set of tools for evaluating and identifying opportunities to improve safety for highway facilities. Included in the HSM is a quantitative method for predicting crashes on the basis of recently developed scientific approaches. These predictive methods currently exist for three facility types: rural two-lane roads; rural multilane highways; and urban and suburban arterial highways. To enhance precision, each HSM predictive method should be calibrated for location conditions. This paper demonstrates the HSM calibration procedure for total crashes in Oregon. The research identified three critical data collection limitations …

Modeling Of A Novel Solar Down Beam Test Facility Utilizing Newtonian Optics, Ryan J. Hoffmann

UNLV Theses, Dissertations, Professional Papers, and Capstones

As advances in concentrated solar energy progress there will inevitably be an increase in the demand of resources for testing new conceptions. Currently, there are limited facilities available for taking concentrated solar energy concepts from the laboratory bench scale to the engineering test scale. A proposed solution is a scientific and developmental facility that provides highly concentrated solar energy at ground level. The design presented is a solar down beam test facility utilizing a Newtonian optics approach with a flat rectangular down beam mirror to reflect and concentrate the sun's rays at ground level.

Literature review suggests a hyperbolic reflector …

Spectroscopic Methods Of Process Monitoring For Safeguards Of Used Nuclear Fuel Separations, Jamie Lee Warburton

UNLV Theses, Dissertations, Professional Papers, and Capstones

To support the demonstration of a more proliferation-resistant nuclear fuel processing plant, techniques and instrumentation to allow the real-time, online determination of special nuclear material concentrations in-process must be developed. An ideal materials accountability technique for proliferation resistance should provide nondestructive, realtime, on-line information of metal and ligand concentrations in separations streams without perturbing the process. UV-Visible spectroscopy can be adapted for this precise purpose in solvent extraction-based separations.

The primary goal of this project is to understand fundamental URanium EXtraction (UREX) and Plutonium-URanium EXtraction (PUREX) reprocessing chemistry and corresponding UV-Visible spectroscopy for application in process monitoring for safeguards. By …

Quantification Of Stochastic Uncertainty Propagation For Monte Carlo Depletion Methods In Reactor Analysis, Quentin Thomas Newell

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Monte Carlo method provides powerful geometric modeling capabilities for large problem domains in 3-D; therefore, the Monte Carlo method is becoming popular for 3-D fuel depletion analyses to compute quantities of interest in spent nuclear fuel including isotopic compositions. The Monte Carlo approach has not been fully embraced due to unresolved issues concerning the effect of Monte Carlo uncertainties on the predicted results.

Use of the Monte Carlo method to solve the neutron transport equation introduces stochastic uncertainty in the computed fluxes. These fluxes are used to collapse cross sections, estimate power distributions, and deplete the fuel within depletion …

Ultrasonic Flow Measurement For Pipe Installations With Non-Ideal Conditions, Devin M. Stoker

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

In the arid west, water is among the most valuable of resources. One of the most critical aspects of water resource management is that of flow measurement. Accurate flow measurement data is needed to effectively manage any water distribution system, whether for culinary or irrigation use. In order to successfully and accurately measure water flow in pipes, it is recommended that a straight section of pipe be installed immediately upstream from the flow meter to avoid distorted flow patterns at the metering location. In many existing piping scenarios, however, such flow conditions are impossible to achieve.

The performance of ultrasonic …

Movement Of Air Through Submerged Air Vents, Clay W. Woods

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The Utah Water Research Lab (UWRL) proposes to study the behavior of air bubbles in submerged vent tubes. This study is coordinated with a study for the Las Vegas wastewater treatment system that discharges into Lake Mead. The UWRL collaborates with government agencies and private companies to research water-related issues around the world. The behavior of air bubbles is of interest in order to more efficiently vent air from pipelines with submerged vent tubes. The Las Vegas wastewater treatment system discharges into Lake Mead and is required to meet an environmental guideline that no air bubbles are discharged into the …