Engineering Commons^™

Evolution Of A Computational Domain For Numerical Analysis Of Fluid Mechanical Disturbance Induced By Coronary Stent Deployment, Jonathan Murphy, Fergal Boyle

Conference Papers

No abstract provided.

Sedimentological And Biological Analyses On Hobble Creek Prior To Restoration, Jaron Michael Brown

Theses and Dissertations

Hobble Creek is one of several inflowing streams and rivers into Utah Lake, Utah, USA. Historically, June sucker (Chasmistes liorus), a federally listed endemic fish, spawned up all the major inflowing streams and rivers but is now limited to just the Provo River. The State of Utah has recently proposed restoring the lower reaches of Hobble Creek for additional spawning and rearing needs. This restoration effort will likely involve removal of migration barriers, re-aligning the stream, and removing existing levees that prevent floodplain access. These changes have raised several questions that this study aims to answer. First, what are the …

The Average Mutual Information Profile As A Genomic Signature, Mark Bauer, Sheldon Schuster, Khalid Sayood

Department of Electrical and Computer Engineering: Faculty Publications

Background: Occult organizational structures in DNA sequences may hold the key to understanding functional and evolutionary aspects of the DNA molecule. Such structures can also provide the means for identifying and discriminating organisms using genomic data. Species specific genomic signatures are useful in a variety of contexts such as evolutionary analysis, assembly and classification of genomic sequences from large uncultivated microbial communities and a rapid identification system in health hazard situations.
Results: We have analyzed genomic sequences of eukaryotic and prokaryotic chromosomes as well as various subtypes of viruses using an information theoretic framework. We confirm the existence of a …

Ceas E-News 01.24.2008, College Of Engineering And Applied Sciences

College of Engineering and Applied Sciences News

Engineering students told to get internships, advanced degrees, mentors

Polyelectrolyte Mediated Scalable Synthesis Of Highly Stable Silver Nanocubes In Less Than A Minute Using Microwave Irradiation, Subrata Kundu, Vivek C. Maheshwari, Sanjun Niu, Ravi F. Saraf

Ravi Saraf Publications

Silver nanocubes were synthesized for the first time in large quantities on gold seed in the presence of a polyelectrolyte using microwave heating for 60–120 s. Our experiment indicates that the polyelectrolyte directs the growth of the particle in a specified crystallographic direction resulting in the faceted particle, i.e. a nanocube. The nanocubes are stable for at least 2 months in ambient conditions.

Review Of Design Guidelines For Frp Confinement Of Reinforced Concrete Columns Of Noncircular Cross Sections, Silvia Rocca, Nestore Galati, Antonio Nanni

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Current international design guidelines provide predictive design equations for the strengthening of reinforced concrete (RC) columns of both circular and prismatic cross sections by means of fiber-reinforced polymer (FRP) confinement and subjected to pure axial loading. Extensive studies (experimental and analytical) have been conducted on columns with circular cross sections, and limited studies have been conducted on members with noncircular cross sections. in fact, the majority of available research work has been on small-scale, plain concrete specimens. in this review paper, four design guidelines are introduced, and a comparative study is presented. This study is based on the increment of …

Ceas E-News 01.17.2008, College Of Engineering And Applied Sciences

College of Engineering and Applied Sciences News

STEP first-year experience connects freshmen / raises retention rates

The Military Career Of Ernest A. Love, Alan Roesler

ERAU Prescott Aviation History Program

The Prescott aviator’s 22 WW I combat missions in seven short weeks in France in 1918

In Situ Measurement Of Three-Dimensional Ion Densities In Focused Femtosecond Pulses, James Strohaber, Cornelis J. Uiterwaal

Department of Physics and Astronomy: Dissertations, Theses, and Student Research

We image spatial distribution of xenon ions in the focus of a laser beam of ultrashort, intense pulses in all three dimensions, with a resolution of three by twelve microns in the two transverse directions. This allows for studying ionization processes without spatially averaging ion yields. Our in situ ion imaging is also useful to analyze focal intensity profiles and to investigate the transverse modal purity of tightly focused beams of complex light. As an example, the intensity profile of a Hermite-Gaussian beam mode HG recorded with ions is found to be in good agreement with optical images.

Mechanical Behavior And Failure Analysis Of Prosthetic Retaining Screws After Long‐Term Use In Vivo. Part 4: Failure Analysis Of 10 Fractured Retaining Screws Retrieved From Three Patients, Youssef S. Al Jabbari, Raymond Fournelle, Gerald J. Ziebert, Jeffrey M. Toth, Anthony Iacopino

Biomedical Engineering Faculty Research and Publications

Purpose: The aim of this study was to perform a failure analysis on fractured prosthetic retaining screws after long‐term use in vivo. Additionally, the study addresses the commonly asked question regarding whether complex repeated functional occlusal forces initiate fatigue‐type cracks in prosthetic retaining screws.

Materials and Methods: Ten fractured prosthetic retaining screws retrieved from three patients treated with fixed detachable hybrid prostheses were subjected to a failure analysis. In patients 1 and 2, the middle three retaining screws of the prostheses were found fractured at retrieval time after they had been in service for 20 and 19 months, respectively. In …

Abrasion Resistance Of Concrete Made With Various Types Of Aggregates, Mohamed Hamada Rashwan

Archived Theses and Dissertations

No abstract provided.

Effects Of Ferroelectricity And Magnetism On Electron And Spin Transport In Fe/Batio3 /Fe Multiferroic Tunnel Junctions, Julian P. Velev, Chun-Gang Duan, Kirill D. Belashchenko, Sitaram Jaswal, Evgeny Y. Tsymbal

Nebraska Center for Materials and Nanoscience: Faculty Publications

First principles electronic structure and transport calculations are used to demonstrate the impact of the electric polarization on electron and spin transport in Fe/BaTiO₃/Fe multiferroic tunnel junctions (MFTJs). We find that the polarization of BaTiO₃ reduces the tunneling conductance, as compared to a nonpolarized barrier, due to the change in the electronic structure driven by ferroelectric displacements, similar to that found previously for Pt/BaTiO₃/Pt. For the MFTJ, however, this effect has different magnitudes for majority- and minority-spin channels and for parallel and antiparallel orientations of the magnetization of the electrodes. As a result, we find …

Mechanical Behavior And Failure Analysis Of Prosthetic Retaining Screws After Long‐Term Use In Vivo. Part 3: Preload And Tensile Fracture Load Testing, Youssef S. Al Jabbari, Raymond Fournelle, Gerald J. Ziebert, Jeffrey M. Toth, Anthony Iacopino

Biomedical Engineering Faculty Research and Publications

Purpose: The aim of this study was to determine the preload and tensile fracture load values of prosthetic retaining screws after long‐term use in vivo compared to unused screws (controls). Additionally, the investigation addressed whether the preload and fracture load values of prosthetic retaining screws reported by the manufacturer become altered after long‐term use in vivo.

Materials and Methods: For preload testing, 10 new screws (controls) from Nobel Biocare (NB) and 73 used retaining screws [58 from NB and 15 from Sterngold (SG)] were subjected to preload testing. For tensile testing, eight controls from NB and 58 used retaining screws …

Preparation And Characterization Of Tapioca Starch–Poly(Lactic Acid) Nanocomposite Foams By Melt Intercalation Based On Clay Type, Siew-Yoong Lee, Han Chen, Milford Hanna

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

Abstract Tapioca starch (TS), poly(lactic acid) (PLA), and four different organoclays (Cloisite 10A, Cloisite 25A, Cloisite 93A and Cloisite 15A) were used to produce nanocomposite foams by melt-intercalation. Structural, thermal, physical and mechanical properties were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and an Instron universal testing machine, respectively. The first XRD peaks for all four nanocomposite foams, were observed to shift to lower angles, indicating that intercalation occurred. The extent of intercalation depended on the type of organoclay and was exhibited in the sequence of Cloisite 10A > 25A > 93A > 15A. Glass transition temperatures …

Polarization Properties Of Retroreflecting Right-Angle Prisms, R. M.A. Azzam, H. K. Khanfar

Electrical Engineering Faculty Publications

The cumulative retardance Δ_t introduced between the p and the s orthogonal linear polarizations after two successive total internal reflections (TIRs) inside a right-angle prism at complementary angles Φ and 90°−Φ is calculated as a function of Φ and prism refractive index n. Quarter-wave retardation (QWR) is obtained on retroreflection with minimum angular sensitivity when n=(√2+1)^1/2=1.55377 and Φ=45°. A QWR prism made of N-BAK4 Schott glass (n=1.55377 at λ=1303.5 nm) has good spectral response (<5° retardance error) over the 0.5-2 μm visible and near-IR spectral range. A ZnS-coated right-angle Si prism achieves QWR with an error of <±2.5° in the 9-11 μm (CO₂ laser) IR spectral range. This device functions as a linear-to-circular polarization transformer and can be tuned to exact QWR at any …

Sub-Surface Corrosion Research On Rock Bolt System, Perforated Ss Sheets And Steel Sets For The Yucca Mountain Repository — Quarterly Technical Report No. 14, Dhanesh Chandra, Jaak J.K. Daemen

Publications (YM)

This report shows the work done for this period in accordance to cooperative agreement of University of Nevada system for the Task 019 “Subsurface Corrosion Research on Rock Bolt System, Perforated SS Sheets and Steel Sets for the Yucca Mountain Repository”, the overall objective of which is to conduct corrosion research and predict the durability of rock-bolts and other underground metallic roof supports. We are performing oxidation tests using Thermogravimetric Analyzer (TGA), and Potentiodynamic and immersion tests to determine the corrosion rates of rock bolts. In this quarter specifically we have accomplished the following: Potentiodynamic tests were performed to determine …

Mechanical Properties Of A Reinforced Composite Polymer Electrolyte Membrane And Its Simulated Performance In Pem Fuel Cells, Yaliang Tang, Ahmet Kusoglu, Anette M. Karlsson, Michael H. Santare, Simon Cleghorn, William B. Johnson

Mechanical Engineering Faculty Publications

The hygro-thermo-mechanical properties and response of a class of reinforced perfluorosulfonic acid membranes (PFSA), that has potential application as an electrolyte in polymer fuel cells, are investigated through both experimental and numerical modeling means. A critical set of material properties, including Young’s modulus, proportional limit stress, break stress and break strain, is determined for a range of temperature and humidity levels in a custom-built environmental test apparatus. The swelling strains are also determined as functions of temperature and humidity level. To elucidate the mechanical response and the potential effect these properties have on the mechanical durability, mechanics-based simulations are performed …

Ceas E-News 01.08.2008, College Of Engineering And Applied Sciences

College of Engineering and Applied Sciences News

CEAS showcases student organizations at the first Engineering Bronco Bash

Aerodynamic Performance Enhancement Of A Naca 66-206 Airfoil Using Supersonic Channel Airfoil Design, David Giles, David D. Marshall

Aerospace Engineering

Supersonic channel airfoil design techniques have been shown to significantly reduce drag in high-speed flows over diamond shaped airfoils by Ruffin and colleagues. The effect of applying these techniques to a NACA 66-206 airfoil is presented. The design domain entails channel heights of 8-16.6% thickness-to-chord and speeds from Mach 1.5-3.0. Numerical simulations show an increase in the lift-to-drag ratio for airfoils at Mach 2.5 at a 35,000-ft altitude with a 12% channel height geometry showing a benefit of 17.2% at 6-deg angle of attack and a sharp channel leading edge. Wave drag is significantly reduced while viscous forces are slightly …

Detached-Eddy Simulation Of The Vortical Flowfield About The Vfe-2 Deltawing, Russell M. Cummings, Andreas Schϋtte

Aerospace Engineering

The numerical simulation of the flow around a 65° delta wing configuration with rounded leading edges is presented. For the numerical simulation the Cobalt Code uses a cell-centered unstructured hybrid mesh approach. Several numerical results are presented for the steady RANS equations as well as for DES and DDES hybrid approaches. The simulations are done as part of the NATO RTO/AVT 113 working group focusing on experimental and numerical research on delta wing configurations with rounded leading edges. Within this paper the focus is related to the dual primary vortex flow topology, especially the sensitivity of the flow to angle …

Short Takeoff Performance Using Circulation Control, Tyler Ball, Scott Turner, David D. Marshall

Aerospace Engineering

Historically, powered lift takeoff analysis has been prohibitively expensive for use in preliminary design. For powered lift, the coupling of aircraft systems invalidates traditional simplistic methods often used in early aircraft sizing. This research creates a tool that will automate the process of takeoff and balanced field length calculations for a circulation control wing aircraft. The process will use high fidelity techniques, such as computational fluid dynamics in order to capture the coupled effects present in circulation control along with Gaussian processes to create a metamodel of that same data to be implemented in a modular takeoff/BFL model. The model …

Introduction Of Software Development Practices Into Aerospace Engineering Curriculum, David D. Marshall, Eric A. Mehiel

Aerospace Engineering

This paper will discuss the attempts to incorporate software development practices into the aerospace engineering curriculum in order to improve the computer programming capabilities of the students. The main focus is on techniques to integrate functional decomposition, unit level testing, system integration and testing, and verification and validation processes without significantly increasing the workload on the students. The approach taken is an integrated approach where the required information needed for testing and validation are integrated into the course content via in-class examples and homework problems. This same approach was taken for the other software development skills. This has been integrated …

Hardware/Software Codesign In A Compact Ion Mobility Spectrometer Sensor Systemfor Subsurface Contaminant Detection, Sin Ming Loo, Jonathan P. Cole, Molly M. Gribb

Electrical and Computer Engineering Faculty Publications and Presentations

A field-programmable-gate-array-(FPGA-) based data acquisition and control system was designed in a hardware/software codesign environment using an embedded Xilinx Microblaze soft-core processor for use with a subsurface ion mobility spectrometer (IMS) system, designed for detection of gaseous volatile organic compounds (VOCs). An FPGA is used to accelerate the digital signal processing algorithms and provide accurate timing and control. An embedded soft-core processor is used to ease development by implementing nontime critical portions of the design in software. The design was successfully implemented using a low-cost, off-the-shelf Xilinx Spartan-III FPGA and supporting digital and analog electronics.

Estimating The Subsonic Aerodynamic Center And Moment Components For Swept Wings, W. F. Phillips, Doug F. Hunsaker, R. J. Niewoehner

Mechanical and Aerospace Engineering Faculty Publications

An improved method is presented for estimating the subsonic location of the semispan aerodynamic center of a swept wing and the aerodynamic moment components about that aerodynamic center. The method applies to wings with constant linear taper and constant quarter-chord sweep. The results of a computational fluid dynamics study for 236 wings show that the position of the semispan aerodynamic center of a wing depends primarily on aspect ratio, taper ratio, and quarter-chord sweep angle. Wing aspect ratio was varied from 4.0 to 20, taper ratios from 0.25 to 1.0 were investigated, quarter-chord sweep angles were varied from 0 to …

Air-Trench Splitters For Ultra-Compact Ring Resonators In Low Refractive Index Contrast Waveguides, Seunghyun Kim, Gregory P. Nordin, Yongbin Lin, Nazli Rahmanian

Faculty Publications

We demonstrate air-trench splitters in low index contrast perfluorocyclobutyl (PFCB) waveguides. Splitters are fabricated by etching 800 nm wide high aspect ratio (18:1) trenches. The measured optical loss is 0.4 dB/splitter. The reflection/transmission splitting ratio is 0.859/0.141, which closely matches two-dimensional finite difference time domain (2DFDTD) simulation results. Air-trench splitters and bends are used to demonstrate an ultra-compact ring resonator (RR) with a size reduction of 1,700 compared to a RR based on traditional curved waveguides in the same material system. A comparison between the RR’s measured and analytically calculated performance shows close agreement when splitter and bend losses are …

Composition Dependence Of The In-Plane Cu-O Bond-Stretching Lo Phonon Mode In Yba2cu3o6+X, F. Stercel, T. Egami, Herbert A. Mook, M. Yethiraj, J.-H. Chung, M. Arai, C. Frost, Fatih Dogan

Materials Science and Engineering Faculty Research & Creative Works

An inelastic pulsed neutron scattering study was performed on the dependence of the dispersion and spectral intensity of the in-plane Cu-O bond-stretching LO phonon mode on doped charge density. The measurements were made in the time-of-flight mode with the multiangle position sensitive spectrometer of the ISIS facility on single crystals of YBa2Cu3O6+x x=0.15, 0.35, 0.6, 0.7, and 0.95. The focus of the study is the in-plane Cu-O bond-stretching LO phonon mode, which is known for strong electron-phonon coupling and unusual dependence on composition and temperature. It is shown that the dispersions for the samples with x=0.35, 0.6, and 0.7 are …

Threat-Driven Security Architecture Modeling And Analysis Of Web Services-Based Systems, Yomna Mostafa El-Sayed Aly

Archived Theses and Dissertations

No abstract provided.

Estimation Of Sound Transmission Class And Impact Insulation Class Rating For Steel Framed Assemblies, American Iron And Steel Institute

American Iron and Steel Institute (AISI) Specifications, Standards, Manuals and Research Reports (1946 - present)

No abstract provided.

Use Of Variable Incidence Angle For Glide Slope Control Of Autonomous Parafoils, Nathan Slegers, Eric Beyer, Mark Costello

Faculty Publications - Biomedical, Mechanical, and Civil Engineering

Strictly speaking, most autonomous parafoil and payload systems possess only lateral control, achieved by right and left parafoil brake deflection. An innovative technique to achieve direct longitudinal control through incidence angle changes is reported. Addition of this extra control channel requires simple rigging changes and an additional servoactuator. The ability of incidence angle to alter the glide slope of a parafoil and payload aircraft is demonstrated through a flight-test program with a microparafoil system. Results from the flight-test program are synthesized and integrated into a six degree-of-freedom simulation. The simulation model is subsequently used to assess the utility of glide …

Correlation Of Tellurium Inclusions And Carrier Lifetime In Detector Grade Cadmium Zinc Telluride, Ezzat S. Elshazly, Gary C. Tepper

Mechanical and Nuclear Engineering Publications

Carrier lifetimes and telluriuminclusion densities in detector grade cadmiumzinc telluride crystals grown by the high pressure Bridgman method were optically measured using pulsed laser microwavecavity perturbation and infrared microscopy. Excess carriers were produced in the material using a pulsed laser with a wavelength of 1064 nm and pulse width of 7 ns, and the electronic decay was measured at room temperature. Spatial mapping of lifetimes and defect densities in cadmiumzinc telluride was performed to determine the relationship between telluriumdefect density and trapping. A strong correlation was found between the volume fraction of telluriuminclusions and the carrier trapping time.