Mechanical Engineering Commons^™

A Three-Dimensional, Time-Dependent Circulation Model Of Utah Lake, Eric V. Callister

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Spatial and temporal variations of Utah Lake’s flow field were modeled using the Estuary Lake and Computer Model from the Centre for Water Research (CWR-ELCOM) at the University of Western Australia as part of an effort to increase understanding of the lake’s natural processes in order to restore the lake to its pristine, clear-water state and preserve the habitat of the June sucker, an endangered species. The model was validated using temperature measurements taken by sensors in 2007. The water temperature was a strong function of air temperature and incident short wave radiation, and was influenced to a lesser degree …

Localised Galvanic Corrosion Processes In Thermal Spray Coated/Cast Aluminium Alloy Systems, David Culliton, Tony Betts, David Kennedy

Conference Papers

Cast Aluminium Alloys, because of the propensity of aluminium to react with impurities and alloying elements, are prone to developing IM impurities during the solidification process. These IM phases can act, in some fluids, as initiation sites for localised corrosion processes, resulting in degradation phenomena, such as pitting. Whilst Thermal Spray coatings can improve the wear resistance of Cast Aluminium Alloys, their corrosion performance may be hampered by the presence of through porosity within the coating.

The present work details some preliminary studies of the localised corrosion processes occurring at the interface area between a Thermal Spray coating and a …

Three-Dimensional Modeling Of The Plasma Arc In Arc Welding, Gu Xu, J. Hu, Hai-Lung Tsai

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Most previous three-dimensional modeling on gas tungsten arc welding (GTAW) and gas metal arc welding (GMAW) focuses on the weld pool dynamics and assumes the two-dimensional axisymmetric Gaussian distributions for plasma arc pressure and heat flux. In this article, a three-dimensional plasma arc model is developed, and the distributions of velocity, pressure, temperature, current density, and magnetic field of the plasma arc are calculated by solving the conservation equations of mass, momentum, and energy, as well as part of the Maxwell's equations. This three-dimensional model can be used to study the nonaxisymmetric plasma arc caused by external perturbations such as …

Progress Toward Meeting The Challenges Of Our Coastal Urban Future, Juile Pullen, Jason Ching, David J. Sailor, William Thompson, Bob Bornstein, Darko Koracin

Mechanical and Materials Engineering Faculty Publications and Presentations

The article provides information on the Seventh Conference on Coastal Atmospheric and Oceanic Prediction and Processes, and the Seventh Symposium on the Urban Environment in San Diego, California on September 9-13, 2008. Topics include the heterogeneity of urban areas, coastal vulnerabilities, urban planning, and emergency response modeling. The conference featured several speakers including Walter Dabberdt and James Voogt.

Homogeneous Dbd In N2: 1) Lif, Talif And Electrical Measurements, N. Gherardi, Et. Es-Sebbar, C. Sarra-Bourret, N. Naudé, F. Massines

Dr. Et-touhami Es-sebbar

In this paper we compare two different discharges that can be obtained in a DBD configuration, that is to say the filamentary discharge (usual regime in atmospheric DBD) with the Atmospheric Pressure Townsend Discharge (APTD), which is a homogeneous regime obtained in nitrogen atmosphere. The aim is to help in the understanding of the processes which control the transition from one regime to the other. To do so, the discharge is characterized through electrical measurements, coupled with optical diagnostics among which Laser Induced Fluorescence (LIF) for radical density measurements. The influence of the addition of small quantities of additives on …

Numerical Simulation Of Thermo-Elasticity, Inelasticity And Rupture Inmembrane Theory, Michael Taylor

Mechanical Engineering

Two distinct two-dimensional theories for the modeling of thin elastic bodies are developed. These are demonstrated through numerical simulation of various types of membrane deformation. The work includes a continuum thermomechanics-based theory for wrinkled thin films. The theory takes into account single-layer sheets as well as composite membranes made of multiple lamina. The resulting model is applied to the study of entropic elastic elastomers as well as Mylar/aluminum composite films. The latter has direct application in the area of solar sails. Several equilibrium deformations are illustrated numerically by applying the theory of dynamic relaxation to a finite difference discretization based …

European Climate Policy And The Position Of Cyprus, Theodoros Zachariadis

Theodoros Zachariadis

No abstract provided.

Active Species Generation Of Homogeneous Dbd In N2: Experiment And Modelling, N. Gherardi, Et. Es-Sebbar, C. Sarra-Bourret, N. Naudé, F. Massines, D. Tzyganov, P. Ségur, S. Pancheshnyi

Dr. Et-touhami Es-sebbar

No abstract provided.

Deep Sea Underwater Robotic Exploration In The Ice-Covered Arctic Ocean With Auvs, Clayton Kunz, Chris Murphy, Richard Camilli, Hanumant Singh, John Bailey, Ryan M. Eustice, Chris Roman, Michael Jakuba, Claire Willis, Taichi Sato, Ko-Ichi Nakamura, Robert A. Sohn

Graduate School of Oceanography Faculty Publications

The Arctic seafloor remains one of the last unexplored areas on Earth. Exploration of this unique environment using standard remotely operated oceanographic tools has been obstructed by the dense Arctic ice cover. In the summer of 2007 the Arctic Gakkel Vents Expedition (AGAVE) was conducted with the express intention of understanding aspects of the marine biology, chemistry and geology associated with hydrothermal venting on the section of the mid-ocean ridge known as the Gakkel Ridge. Unlike previous research expeditions to the Arctic the focus was on high resolution imaging and sampling of the deep seafloor. To accomplish our goals we …

A Heuristic Scheduling Scheme In Multiuser Ofdma Networks, Zheng Sun, Zhiqiang He, Ruochen Wang, Kai Niu

Zheng Sun

Conventional heterogeneous-traffic scheduling schemes utilize zero-delay constraint for real-time services, which aims to minimize the average packet delay among real-time users. However, in light or moderate load networks this strategy is unnecessary and leads to low data throughput for non-real-time users. In this paper, we propose a heuristic scheduling scheme to solve this problem. The scheme measures and assigns scheduling priorities to both real-time and non-real-time users, and schedules the radio resources for the two user classes simultaneously. Simulation results show that the proposed scheme efficiently handles the heterogeneous-traffic scheduling with diverse QoS requirements and alleviates the unfairness between real-time …

The Dependence Of Measured Modulation Error Ratio On Phase Noise, Ron D. Katznelson

Ron D. Katznelson

This paper reviews the algorithms used by Vector Signal Analyzers to measure Modulation Error Ratio (MER) and derives the explicit functional dependence of measured MER on phase noise of digital transmitters. The modulation error model is introduced and the analytical expression for key estimated parameters required to obtain MER measure are derived. The essential elements of algorithms employed by MER measurement instruments to estimate amplitude scale, frequency offset, and initial phase intercept and the resulting MER are identified. The frequency response of the effective phase-noise rejection filtering action associated with a given measurement epoch is derived. It is shown that …

Sum Frequency Generation Vibrational Spectroscopy Of Pyridine Hydrogenation On Platinum Nanoparticles, Kaitlin M. Bratlie, Kyriakos Komvopoulos, Gabor A. Somorjai

Kaitlin M. Bratlie

Pyridine hydrogenation in the presence of a surface monolayer consisting of cubic Pt nanoparticles stabilized by tetradecyltrimethylammonium bromide (TTAB) was investigated by sum frequency generation (SFG) vibrational spectroscopy using total internal reflection (TIR) geometry. TIR-SFG spectra analysis revealed that a pyridinium cation (C5H5NH+) forms during pyridine hydrogenation on the Pt nanoparticle surface, and the NH group in the C5H5NH+ cation becomes more hydrogen bound with the increase of the temperature. In addition, the surface coverage of the cation decreases with the increase of the temperature. An important contribution of this study is the in situ identification of reaction intermediates adsorbed …

Surface Ion-Electron Recombination As The Main Source Of Atoms In Flowing N2 Dbd, D. Tsyganov, Et. Es-Sebbar, S. Pancheshnyi, N. Gherardi, P. Ségur, F. Massines

Dr. Et-touhami Es-sebbar

No abstract provided.

Predicting The Longevity Of Dvdr Media By Periodic Analysis Of Parity, Jitter, And Ecc Performance Parameters, Daniel Patrick Wells

Theses and Dissertations

For the last ten years, DVD-R media have played an important role in the storage of large amounts of digital data throughout the world. During this time it was assumed that the DVD-R was as long-lasting and stable as its predecessor, the CD-R. Several reports have surfaced over the last few years questioning the DVD-R's ability to maintain many of its claims regarding archival quality life spans. These reports have shown a wide range of longevity between the different brands. While some DVD-Rs may last a while, others may result in an early and unexpected failure. Compounding this problem is …

Talif Quantification Of Nitrogen Atoms Applied To Experimental Simulation Of Titan’S Atmosphere, Et. Es-Sebbar, Y. Benilan, E. Arzoumanian, M.-C. Gazeau

Dr. Et-touhami Es-sebbar

No abstract provided.

S.E.T.U.P., A New Program Of Representative Simulations Of Titan’S Atmosphere: Current Status, M-C. Gazeau, E. Arzoumanian, Y. Benilan, Et. Es-Sebbar, A. Jolly, S. Perrier, C. Romanzin

Dr. Et-touhami Es-sebbar

No abstract provided.

A Finite Difference Method For Studying Thermal Deformation In Three-Dimensional Thin Films Exposed To Ultrashort Pulsed Lasers, Suyang Zhang

Doctoral Dissertations

Thermal analysis related to ultrashort-pulsed lasers has been intensely studied in science and engineering communities in recent years, because the pulse duration of ultrashort-pulsed lasers is only the order of sub-picoseconds to femtoseconds, and the lasers have exclusive capabilities in limiting the undesirable spread of the thermal process zone in the heated sample. Studying the thermal deformation induced by ultrashort-pulsed lasers is essential for preventing thermal damage. For the ultrashort-pulsed laser, the thermal damage is different from that caused by the long pulsed lasers and cracks occur after heating.

This dissertation presents a new finite difference method for studying thermal …

High-Resolution Optical Imaging For Deep-Water Archaeology, Hanumant Singh, Christopher Roman, Oscar Pizarro, Brendan Foley, Ryan Eustice, Ali Can

Christopher N. Roman

No abstract provided.

Predicting The Hydrogen Pressure To Achieve Ultralow Friction And Diamondlike Carbon Surfaces From First Principles, Haibo Guo, Yue Qi, Xiaodong Li

Faculty Publications

Hydrogen atmosphere can significantly change the tribological behavior at diamond and diamondlike carbon (DLC) surfaces and the friction-reducing effect depends on the partial pressure of hydrogen. We combined density functional theory modeling and thermodynamic quantities to predict the equilibrium partial pressures of hydrogen at temperature T, P_H2 (T), for a fully atomic hydrogen passivated diamondsurface. Above the equilibrium P_H2 (T), ultralow friction can be achieved at diamond and DLC surfaces. The calculation agrees well with friction tests at various testing conditions. We also show that P_H2 (T) …

Comparison Of Townsend Dielectric Barrier Discharge In N2, N2/O2 And N2/N2o: Behavior And Density Of Radicals, F. Massines, Et. Es-Sebbar, N. Gherardi, N. Naudé, D. Tsyganov, P. Ségur, S. Pancheshnyi

Dr. Et-touhami Es-sebbar

No abstract provided.

Fuel Taxation And Social Policy, Theodoros Zachariadis

Theodoros Zachariadis

No abstract provided.

Writing Research Proposal: Literature Review And Database Search, Mamoudou H. Dicko Prof.

Pr. Mamoudou H. DICKO, PhD

College Of Engineering Senior Design Competition Spring 2008, 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 to focus the senior students in increasing the quality and potential for commercial application for their design projects. Judges from local industry evaluate the projects …

Incorporation Of Evidences Into An Intelligent Computational Argumentation Network For A Web-Based Collaborative Engineering Design System, Xiaoqing Frank Liu, Ekta Khudkhudia, Ming-Chuan Leu

Computer Science Faculty Research & Creative Works

Conflicts among the stakeholders are unavoidable in the process of collaborative engineering design. Resolution of these conflicts is a challenging task. In our previous research, a web based intelligent collaborative system was developed which provides decision-making support, using computational argumentation techniques. Enhancements were done to this system to incorporate the priorities of the stakeholders and to detect arguments that self conflict. As an effort to make this system more effective and more objective in the process of decision making, we develop a method to assess the effect of evidences in the argumentation network, using Dempster-Shafer theory of evidence and fuzzy …

Benefits Of Leed Designs In Arkansas K-12 Schools, Philip Thrift

Mechanical Engineering Undergraduate Honors Theses

This paper provides and evaluation of an existing LEED certified sustainable green building for energy-efficiency, environmental impact, economic value, and occupant health. The new Bethel Middle School located in Bryant, Arkansas was the first LEED (Leadership in Energy and Environmental Design) certified public school building in the state. Based on actual building specifications and validated with the first year's utility bills, a simulation model was used to evaluate various design aspects of the school building. The building's baseline energy usage was compared with numerous energy and environmental scenarios. Results include both environmental and economic assessments. Overall, the study found that …

Tractor Inventory, Nebraska Tractor Test Lab

Nebraska Tractor Tests

No abstract provided.

Digital Media Agco Challenger, Nebraska Tractor Test Lab

Nebraska Tractor Tests

Images and videos of the 2008 Agco Challenger Tractor Testing.

Criteria On Utility Designing Of Convex Optimization In Fdma Networks, Zheng Sun, Wenjun Xu, Zhiqiang He, Kai Niu

Zheng Sun

In this paper, we investigate the network utility maximization problem in FDMA systems. We summarize with a suite of criteria on designing utility functions so as to achieve the global optimization convex. After proposing the general form of the utility functions, we present examples of commonly used utility function forms that are consistent with the criteria proposed in this paper, which include the well-known proportional fairness function and the sigmoidal-like functions. In the second part of this paper, we use numerical results to demonstrate a case study based on the criteria mentioned above, which deals with the subcarrier scheduling problem …

Parallel Mpi/Fortran Finite Element Symmetrical/Unsymmetrical Domain Decomposition, Siroj Tungkatara

Civil & Environmental Engineering Theses & Dissertations

MPI/FORTRAN finite element analysis software based on Domain Decomposition (DD) formulas has been developed in this work. Efficient input data storage/data communication schemes, domain partitioning, fast symbolical and numerical sparse assembly, symmetrical/unsymmetrical sparse solver and robust symmetrical/unsymmetrical iterative solvers algorithms are all incorporated into the developed code. Parallel Precondition Conjugated Gradient (PCG) and Flexible Generalized Minimum Residual (FGMRES) are developed. Efficient computational techniques used in the developed code are explained. Numerical performance and the accuracy of the developed code are conducted on acoustic examples with medium to large grid sizes. The results obtained from ODU Wilbur cluster (under parallel processing …

Caffeine Model Identification For Vigilance Performance Prediction, Chun-Hui Huang

Mechanical & Aerospace Engineering Theses & Dissertations

The pharmacodynamics and pharmacokinetics of caffeine have been well characterized. In this study, a caffeine dynamic model is developed to describe its pharmacodynamic effects on vigilance performance. Validated biomathematical models developed to address both individual and group fatigue and alertness in a non-laboratory setting represent a tremendous commercial opportunity. First, a test data set with caffeine effects isolated from circadian and homeostatic effects is created. Then a modeling approach for input and output effects is developed and different model structures for the caffeine effects are considered. Observer/Kalman filter Identification (OKID) algorithm is proposed and developed to identify the caffeine model …