Engineering Commons^™

Avoiding Aircraft Icing Accidents, Nihad E. Daidzic

Aviation Department Publications

No abstract provided.

Radiation Detectors And Sources Enhanced With Micro/Nanotechnology, Chad Michael Whitney

Doctoral Dissertations

The ongoing threat of nuclear terrorism presents major challenges to maintaining national security. Currently, only a small percentage of the cargo containers that enter America are searched for fissionable bomb making materials. This work reports on a multi-channel radiation detection platform enabled with nanoparticles that is capable of detecting and discriminating all types of radiation emitted from fissionable bomb making materials. Typical Geiger counters are limited to detecting only beta and gamma radiation. The micro-Geiger counter reported here detects all species of radiation including beta particles, gamma/X-rays, alpha particles, and neutrons. The multi-species detecting micro-Geiger counter contains a hermetically sealed …

Evolution Of Chemical Structure During Silver Photodiffusion Into Chalcogenide Glass Thin Films, A. Kovalskiy, H. Jain, Maria Mitkova

Electrical and Computer Engineering Faculty Publications and Presentations

The change of chemical structure resulting after X–ray and photo-induced silver diffusion into chalcogenide glass (ChG) thin films is monitored by high resolution X-ray photoelectron spectroscopy (XPS). As₄₀S₆₀ and Ge₃₀Se₇₀ thin films, which are based on pyramids and tetrahedral structural units, are investigated as model materials. Survey, core level (As 3d, S 2p, Ge 3d, Ge 2p, Se 3d, Ag 3d_5/2, O 1s, C 1s) and valence band spectra have been recorded and analyzed. Reference point for the …

Performance Limits For 6-In. High Curbs Placed In Advance Of The Mgs Using Mash Vehicles Part:Ii Full-Scale Crash Testing, Karla A. Lechtenberg, Ronald K. Faller, Dean L. Sicking, Robert W. Bielenberg M.S.C.E., E.I.T., Jeffery C. Thiele, John D. Reid

Nebraska Department of Transportation: Research Reports

No abstract provided.

Behavior And Design Of Buried Concrete Pipes Phase Ii, Ece Erdogmus, Maher K. Tadros

Nebraska Department of Transportation: Research Reports

No abstract provided.

Change Blindness In The Synthetic Vision Primary Flight Display: Comparing Eye Tracking Patterns With Pilot Attention, Stephen A. Mayo

Master's Theses - Daytona Beach

There have been a number of important advances in aviation technology that have made the safety rating of flying the best that it has ever been. One of the most important advances made has been in the interface that the pilot relies on for their most critical information during flight. New aviation displays have empirically shown a wide range of improvements across pilot performance. Despite these improvements, there is still a high possibility that pilots may miss pertinent information that changes may occur simultaneously with some sort of distraction - a concept known as change blindness. This study analyzed how …

The Effect Of Pilot And Air Traffic Control Experiences & Automation Management Strategies On Uas Mission Task Performance, Christopher J. Reynolds

Master's Theses - Daytona Beach

Unmanned aircraft are relied on now more than ever to save lives and support the troops in the recent Operation Enduring Freedom and Operation Iraqi Freedom. The demands for UAS capabilities are rapidly increasing in the civilian sector. However, UAS operations will not be carried out in the NAS until safety concerns are alleviated. Among these concerns is determining the appropriate level of automation in conjunction with a suitable pilot who exhibits the necessary knowledge, skills, and abilities to safely operate these systems.

This research examined two levels of automation: Management by Consent (MBC) and Management by Exception (MBE). User …

Flight Regime And Maneuver Recognition For Complex Maneuvers, Jerome H. Travert

Master's Theses - Daytona Beach

The purpose of this study is to demonstrate capability of flight regime recognition during complex maneuvers flown in a fixed wing airplane using measured data from an Inertial Measurement Unit (IMU). Flight Regime Recognition (FRR) is required for numerous applications in the aerospace and aviation industry, including the determination of loads for stress and strain analysis. It can also be used in recreational aviation for maneuver recognition, for example in aerobatics.

This study uses a flight simulator to generate representative flight data that is parsed by a specifically developed algorithm into appropriate flight regimes. This algorithm is a filter technique …

Termination And Anchorage Of Temporary Concrete Barriers, Scott Rosenbaugh, Robert W. Bielenberg, Ronald K. Faller, John R. Rohde, Dean L. Sicking, Karla A. Lechtenberg, James C. Holloway M.S.C.E., E.I.T., John D. Reid

Nebraska Department of Transportation: Research Reports

No abstract provided.

Bs News

Building Services Engineering

No abstract provided.

Steel Sheet Sheathing Options For Cold-Formed Steel Framed Shear Wall Assemblies Providing Shear Resistance - Phase 2, Cheng Yu, Yujie Chen

CCFSS Library (1939 - present)

Monotonic and cyclic tests on cold-formed steel shear walls sheathed with steel sheets on one side were conducted to (1) verify the published nominal shear strength for 18-mil and 27-mil steel sheets; and (2) investigate the behavior of 6-ft. wide shear walls with multiple steel sheets. This project is the continuation of a completed project titled “Steel Sheet Sheathing Options for Cold-Formed Steel Framed Shear Wall Assemblies Providing Shear Resistance” by Yu (2007). This Phase 2 project confirms the discrepancy in the published nominal strength of 27-mil sheets discovered by the Phase 1 project, and proposes new values. The project …

Strengthening Of Rural Bridges Using Rapid-Installation Frp Technology: Route 63 Bridge No. H356, Phelps County, Dongming Yan, Jianbo Li, Chenglin Wu, Genda Chen

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

This report presents the use of externally bonded fiber reinforced polymers (FRP) laminates for the flexural strengthening of a concrete bridge. The bridge selected for this project is a two-span simply supported reinforced concrete slab with no transverse steel reinforcement located in Phelps County, MO. The original construction combined with the presence of very rigid parapets caused the formation of a 1-inch wide longitudinal crack, which resulted in the slab to behave as two separate elements. The structural behavior was verified using a finite element model (FEM) of the bridge. The bridge analysis was performed for maximum loads determined in …

Molecular Dynamics Simulations Of Lattice Thermal Conductivity Of Bismuth Telluride Using Two-Body Interatomic Potentials, Bo Qiu, X Ruan

Birck and NCN Publications

Two-body interatomic potentials in the Morse potential form have been developed for bismuth telluride, and the potentials are used in molecular dynamics simulations to predict the thermal conductivity. The density-functional theory with local-density approximations is first used to calculate the total energies for many artificially distorted Bi2Te3 configurations to produce the energy surface. Then by fitting to this energy surface and other experimental data, the Morse potential form is parameterized. The fitted empirical interatomic potentials are shown to reproduce the elastic and phonon data well. Molecular dynamics simulations are then performed to predict the thermal conductivity of bulk Bi2Te3 at …

Molecular Dynamics Simulations Of Lattice Thermal Conductivity Of Bismuth Telluride Using Two-Body Interatomic Potentials, Bo Qiu, X Ruan

Birck and NCN Publications

Two-body interatomic potentials in the Morse potential form have been developed for bismuth telluride, and the potentials are used in molecular dynamics simulations to predict the thermal conductivity. The density-functional theory with local-density approximations is first used to calculate the total energies for many artificially distorted Bi2Te3 configurations to produce the energy surface. Then by fitting to this energy surface and other experimental data, the Morse potential form is parameterized. The fitted empirical interatomic potentials are shown to reproduce the elastic and phonon data well. Molecular dynamics simulations are then performed to predict the thermal conductivity of bulk Bi2Te3 at …

Numerical Simulation Of Gas-Phonon Coupling In Thermal Transpiration Flows, Xiaohui Guo, Dhruv Singh, Jayathi Murthy, Alina A. Alexeenko

PRISM: NNSA Center for Prediction of Reliability, Integrity and Survivability of Microsystems

Thermal transpiration is a rarefied gas flow driven by a wall temperature gradient and is a promising mechanism for gas pumping without moving parts, known as the Knudsen pump. Obtaining temperature measurements along capillary walls in a Knudsen pump is difficult due to extremely small length scales. Meanwhile, simplified analytical models are not applicable under the practical operating conditions of a thermal transpiration device, where the gas flow is in the transitional rarefied regime. Here, we present a coupled gas-phonon heat transfer and flow model to study a closed thermal transpiration system. Discretized Boltzmann equations are solved for molecular transport …

Gate-Induced G-Factor Control And Dimensional Transition For Donors In Multivalley Semiconductors, Rajib Rahman, Seung H. Park, Timothy B. Boykin, Gerhard Klimeck, Sven Rogge, Lloyd Cl Hollenberg

Birck and NCN Publications

The dependence of the g factors of semiconductor donors on applied electric and magnetic fields is of immense importance in spin-based quantum computation and in semiconductor spintronics. The donor g-factor Stark shift is sensitive to the orientation of the electric and magnetic fields and is strongly influenced by the band-structure and spin-orbit interactions of the host. Using a multimillion atom tight-binding framework, the spin-orbit Stark parameters are computed for donors in multivalley semiconductors, silicon, and germanium. Comparison with limited experimental data shows good agreement for a donor in silicon. Results for gate-induced transition from three-dimensional to two-dimensional wave-function confinement show …

Atomistic Full-Band Simulations Of Silicon Nanowire Transistors: Effects Of Electron-Phonon Scattering, Mathieu Luisier, Gerhard Klimeck

Birck and NCN Publications

An atomistic full-band quantum transport simulator has been developed to study three-dimensional Si nanowire field-effect transistors in the presence of electron-phonon scattering. The nonequilibrium Green's function (NEGF) formalism is solved in a nearest-neighbor sp(3)d(5)s* tight-binding basis. The scattering self-energies are derived in the self-consistent Born approximation to inelastically couple the full electron and phonon energy spectra. The band dispersion and the eigenmodes of the confined phonons are calculated using a dynamical matrix that includes the bond and the angle deformations of the nanowires. The optimization of the numerical algorithms and the parallelization of the NEGF scheme enable the investigation of …

Gate-Induced G-Factor Control And Dimensional Transition For Donors In Multivalley Semiconductors, Rajib Rahman, Seung H. Park, Timothy B. Boykin, Gerhard Klimeck, Sven Rogge, Lloyd Cl Hollenberg

Birck and NCN Publications

The dependence of the g factors of semiconductor donors on applied electric and magnetic fields is of immense importance in spin-based quantum computation and in semiconductor spintronics. The donor g-factor Stark shift is sensitive to the orientation of the electric and magnetic fields and is strongly influenced by the band-structure and spin-orbit interactions of the host. Using a multimillion atom tight-binding framework, the spin-orbit Stark parameters are computed for donors in multivalley semiconductors, silicon, and germanium. Comparison with limited experimental data shows good agreement for a donor in silicon. Results for gate-induced transition from three-dimensional to two-dimensional wave-function confinement show …

Determination Of Size Effects During The Phase Transition Of A Nanoscale Au-Si Eutectic, B J. Kim, J Tersoff, C Y. Wen, M C. Reuter, E A. Stach, F M. Ross

Birck and NCN Publications

The phase diagram of a nanoscale system can be substantially different than in the bulk, but quantitative measurements have proven elusive. Here we use in situ microscopy to observe a phase transition in a nanoscale system, together with a simple quantitative model to extract the size effects from these measurements. We expose a Au particle to disilane gas, and observe the transition from a two-phase Au + AuSi system to single-phase AuSi. Size effects are evident in the nonlinear disappearance of the solid Au. Our analysis shows a substantial shift in the liquidus line, and a discontinuous change in the …

Impact Of Sacrificial Layer Type On Thin-Film Metal Residual Stress, Anurag Garg, Joshua A. Small, Xiaoguang Liu, Ajit Mahapatro, Dimitrios Peroulis

Birck and NCN Publications

In this paper we study the impact of two sacrificial layers on the final residual stress of thin gold films. In particular, we comapre a typical photoresist layer (Shipley SC1827) to single-crystalline silicon. We fabricate and measure cantilever beams on both sacrificial layers and study their residual stresses by analyzing the final displacement profile of the released beams. All samples were fabricated at the same time and under identical conditions. The study clearly shows that the induced stress on thin films is dependent on the sacrificial layer. The gold film deposited over the single-crystalline silicon shows nearly zero gradient stress …

Sers In Salt Wells, G. V. Pavan Kumar, Joseph Irudayaraj

Birck and NCN Publications

We report herein a simple, inexpensive fabrication methodology of salt microwells, and define the utility of the latter as nanoparticle containers for highly sensitive surface-enhanced Raman scattering (SERS) studies. AFM characterization of Ag and Au loaded salt microwells reveal the ability to contain favorable nanostructures such as nanoparticle dimers, which can significantly enhance the Raman intensity of molecules. By performing diffraction-limited confocal Raman microscopy on salt microwells, we show high sensitivity and fidelity in the detection of dyes, peptides, and proteins, as a proof of our concept. The SERS limit of detection (accumulation time of 1 s) for rhodamine B …

A Numerical Fatigue Damage Model For Life Scatter Of Mems Devices, Behrooz Jalalahmadi, Farshid Sadeghi, Dimitrios Peroulis

PRISM: NNSA Center for Prediction of Reliability, Integrity and Survivability of Microsystems

This paper presents a fatigue damage model to estimate fatigue lives of microelectromechanical systems (MEMS) devices and account for the effects of topological randomness of material microstructure. For this purpose, the damage mechanics modeling approach is incorporated into a new Voronoi finite-element model (VFEM). The VFEM developed for this investigation is able to consider both intergranular crack initiation (debonding) and propagation stages. The model relates the fatigue life to a damage parameter "D" which is a measure of the gradual material degradation under cyclic loading. The fatigue damage model is then used to investigate the effects of microstructure randomness on …

Observation Of Quantum-Hall Effect In Gated Epitaxial Graphene Grown On Sic (0001), T Shen, J J. Gu, Y Q. Wu, M L. Bolen, Michael A. Capano, L W. Engel, P. D. Ye

Birck and NCN Publications

Epitaxial graphene films examined were formed on the Si-face of semi-insulating 4H-SiC substrates by a high temperature sublimation process. A high-k gate stack on the epitaxial graphene was realized by inserting a fully oxidized nanometer thin aluminum film as a seeding layer, followed by an atomic-layer deposition process. The electrical properties of epitaxial graphene films are retained after gate stack formation without significant degradation. At low temperatures, the quantum-Hall effect in Hall resistance is observed along with pronounced Shubnikov-de Haas oscillations in diagonal magnetoresistance of gated epitaxial graphene on SiC (0001).

An Analytical Investigation Of Natural Frequency For A Symmetric Composite Box-Beam With Thermal Effects, Lakshmi Narayana Sanjeev Chitikela

Master's Theses - Daytona Beach

The main purpose of the following analysis is to develop an analytical method for determining the natural frequency of a symmetric composite box-beam subjected to temperature gradient. A set of coupled partial differential equations of motion is obtained by means of small defection theory and D'Alembert's method. The Smith and Chopra stiffness matrix is used in the governing equations of motion and an appropriate MATLAB® code has been written to solve for the stiffness matrix elements of the box-beam. The resulting governing equations of motion are solved to obtain the natural frequencies of the box-beam in flap and lag directions …

Compression After Impact Load Prediction In Graphite/Epoxy Laminates Using Acoustic Emission And Artificial Neural Networks, Anthony Michael Gunasekera

Master's Theses - Daytona Beach

The purpose of this research was to investigate the effectiveness of artificial neural networks (ANNs) in predicting the compression after impact (CAI) load of graphite/epoxy laminates from acoustic emission (AE) nondestructive testing (NDT) data. Thirty-four 24-ply bidirectional woven cloth laminate coupons were constructed and impacted at various energy levels ranging from 8 to 20 Joules, generating barely visible impact damage (BVID). Acoustic emission data were acquired as the coupons were compressed to failure. Not having been analyzed by previous experimenters, several noise tests were also performed to determine the impact of external noise on acoustic emission data during testing. Once …

Thermal Modeling Of Lithium-Ion Energy Storage Systems For Hybrid Electric Vehicles Using Computational Fluid Dynamics With Conjugate Heat Transfer, Craig R. Czlapinski

Master's Theses - Daytona Beach

The success and performance of a Hybrid Electric Vehicle (HEV) relies largely on its Energy Storage System (ESS). High temperatures and thermal variations can significantly affect a battery's performance and lifecycle. An effective thermal management system is vital to the health and safe operation of the ESS's batteries. A well designed thermal management system begins with the accurate prediction of the battery's thermal conditions. In hot climates, HEVs may be required to operate within ten degrees Celsius of the maximum safe operating temperature of their batteries. This study aims to evaluate the thermal management system of a lithium-ion based energy …

Determination Of Stability And Control Derivatives For A Modern Light Composite Twin Engine Airplane, Monica M. Londono

Master's Theses - Daytona Beach

To develop and compare full envelope stability and control derivatives and their associated errors for a modern light composite twin engine airplane from flight test data and digital DATCOM (Data Compendium). This development is to serve three purposes 1) to provide data for validation of newer analytical techniques such as Computational Fluid Dynamics (CFD), 2) to provide public domain static and dynamic stability and control derivatives for a modern twin engine airplane, 3) to analyze the relationship between test design and error for both output error and equation error methods.

A flight test program was conducted on a Diamond Twin …

National Center For Hydrogen Technology, University Of North Dakota. Energy And Environmental Research Center

EERC Brochures and Fact Sheets

Brochure about the Energy & Environmental Research Center's National Center for Hydrogen Technology. Includes its role in developing technologies that produce and utilize hydrogen. [This item is an outdated or superseded version and retained for historical purposes only. It may no longer reflect current information, policies, or practices.]

Nebraska Blueprint- Fall 2009

Nebraska Blueprint (Student Publication)

Table of Contents:

From the Editor

Then and Now

Engineering Block: A History of Home

College of Engineering Timeline

Longtime Professors Leave Lasting Impact

IEEE 125th Anniversary Celebration

Computing Arrival Cost Parameters In Moving Horizon Estimation Using Sampling Based Filters, Sridhar Ungarala

Chemical & Biomedical Engineering Faculty Publications

Moving horizon estimation (MHE) is a numerical optimization based approach to state estimation, where the joint probability density function (pdf) of a finite state trajectory is sought, which is conditioned on a moving horizon of measurements. The joint conditional pdf depends on the a priori state pdf at the start of the horizon, which is a prediction pdf based on historical data outside the horizon. When the joint pdf is maximized, the arrival cost is a penalty term based on the a priori pdf in the MHE objective function. Traditionally, the a priori pdf is assumed as …