Engineering Commons^™

Characterization And Biomechanical Analysis Of The Human Lumbar Spine With In Vitro Testing Conditions, Dean K. Stolworthy

Theses and Dissertations

Biomechanical testing of cadaveric spinal segments forms the basis for our current understanding of healthy, pathological, and surgically treated spinal function. Over the past 40 years there has been a substantial amount of data published based on a spinal biomechanical testing regimen known as the flexibility method. This data has provided valuable clinical insights that have shaped our understanding of low back pain and its treatments. Virtually all previous lumbar spinal flexibility testing has been performed at room temperature, under very low motion rates, without the presence of a compressive follower-load to simulate upper body weight and the action of …

Slides: Natural Gas: Game Changer Or Runner Left On Base? Working To Get It Right In Co!, Gary Graham

Drawing the Blueprint for a Sustainable Natural Gas Future (January 18)

Presenter: Dr. Gary Graham, Director, Lands Program, Western Resource Advocates

21 slides

Slides: Drawing The Blueprint For A Sustainable Natural Gas Future, Mark K. Boling

Drawing the Blueprint for a Sustainable Natural Gas Future (January 18)

Presenter: Mark. K. Boling, Executive Vice-President and General Counsel, Southwestern Energy

23 slides

Slides: Current And Proposed Research Activities Addressing Health, Environmental, Economic, And Political Issues Related To Natural Gas Development, University Of Colorado. School Of Public Health. Department Of Environmental And Occupational Health

Drawing the Blueprint for a Sustainable Natural Gas Future (January 18)

Presenter: Department of Environmental and Occupational Health, University of Colorado School of Public Health

20 slides

Agenda: Drawing The Blueprint For A Sustainable Natural Gas Future, University Of Colorado At Denver. Wirth Chair In Environmental And Community Development Policy, University Of Colorado Boulder. Natural Resources Law Center. Intermountain Oil And Gas Bmp Project

Drawing the Blueprint for a Sustainable Natural Gas Future (January 18)

A stakeholder-led forum discussing the key topics affecting natural gas as a safe and sustainable energy resource. Participants learned about the current research and related resources at Colorado’s three research universities and participated in designing future research needs.

Slides: Jisea Natural Gas Study: Potential U.S. Electric Power Futures, Jeffrey Logan

Drawing the Blueprint for a Sustainable Natural Gas Future (January 18)

Presenter: Jeffrey Logan, Denver Museum of Nature and Science

4 slides

Compact Electronic Mode Stirred Chamber, Q. Dai, W. C. Chew, Lijun Jiang, B. Zhu

Electrical and Computer Engineering Faculty Research & Creative Works

A method and apparatus provide an improved EM reverberation chamber which facilitates the dynamic three-dimensional (3D) manipulation of EM field polarization within the chamber and produces a uniform field distribution inside the chamber. The chamber includes one or more walls with tunable lumped elements. A controller is provided to generate one or more control signals that are applied to the lumped elements and tunes their impedance in response to the one or more control signals. The result is to generate, within the chamber an electromagnetic field that appears to be random or pseudo-random in polarization, but which is sufficiently uniform …

Zeppelins Over London, Ron Anderson

ERAU Prescott Aviation History Program

Hear the story of the first strategic bombing campaign in history. The target was the civilian populated areas of London in World War I. Come on board a giant Zeppelin of the Imperial German Navy Air Service and learn what these raids did, or did not accomplish, from Ron Anderson, local zeppelin historian.

Energy-Based Yield Criterion For Pmma From Large-Scale Molecular Dynamics Simulations, Eugenio Jaramillo, Nathaniel Wilson, Stephen Christensen, Jonathan Gosse, Alejandro Strachan

Birck and NCN Publications

We use molecular dynamics (MD) with the DREIDING force field to characterize the ultimate mechanical response of amorphous poly(methyl methacrylate). We characterize how volumetric and deviatoric strains contribute to yield for a wide range of loading conditions from pure deviatoric, volume-conserving cases to isotropic volume expansion. We propose and apply an energy-based yield criterion to define yield consistently for all cases. Our results show that permanent deformation occurs when either the deviatoric or volumetric strains reach critical values, except in a narrow region around the transformation between deviatoric- and volumetric-dominated yield where the two strain invariants interact. In contrast, the …

High-Density Pressurelessly Sintered Zirconium Diboride/Silicon Carbide Composite Bodies And A Method For Producing The Same, Shi C. Zhang, Greg Hilmas, William Fahrenholtz

Materials Science and Engineering Faculty Research & Creative Works

A method of sintering a ZrB₂-SiC composite body at ambient pressures, including blending a first predetermined amount of ZrB₂ powder with a second predetermined amount of SiC powder, wherein both powders are characterized by the presence of surface oxide impurities. Next the blended powders are mixed to yield a substantially homogeneous powder mixture and a portion of the substantially homogeneous powder mixture is formed into a green body. The body is fired to a first temperature, wherein substantially all surface oxide impurities are reduced and/or volatilized to substantially eliminate oxides from the green body, and the body …

The Effect Of Elevated Temperature On The Inelastic Deformation Behavior Of Pmr-15 Solid Polymer, Chad E. C. Ryther

Theses and Dissertations

The inelastic deformation behavior of PMR-15 neat resin, a high-temperature thermoset polymer, was investigated at temperatures in the 274-316°C range. The experimental program was developed to explore the influence of temperature on tensile loading, relaxation and creep behaviors of PMR-15. The results demonstrate that the mechanical behavior of PMR-15 exhibits a strong dependence on temperature. During strain-controlled tensile loading, the slope of the stress-strain curve in the quasi-elastic region decreases and the flow stress level decreases with increasing temperature. During relaxation, the amount of the stress drop decreases with increasing temperature. Based on experimental results the Viscoplasticity Based on Overstress …

Optimally Enhanced Optical Emission In Laser-Induced Breakdown Spectroscopy By Combining Spatial Confinement And Dual-Pulse Irradiation, L. B. Guo, B. Y. Zhang, X. N. He, C. M. Li, Y. S. Zhou, T. Wu, J. B. Park, X. Y. Zeng, Yongfeng Lu

Department of Electrical and Computer Engineering: Faculty Publications

In laser-induced breakdown spectroscopy (LIBS), a pair of aluminum-plate walls were used to spatially confine the plasmas produced in air by a first laser pulse (KrF excimer laser) from chromium (Cr) targets with a second laser pulse (Nd:YAG laser at 532 nm, 360 mJ/pulse) introduced parallel to the sample surface to re-excite the plasmas. Optical emission enhancement was achieved by combing the spatial confinement and dual-pulse LIBS (DP-LIBS), and then optimized by adjusting the distance between the two walls and the interpulse delay time between both laser pulses. A significant enhancement factor of 168.6 for the emission intensity of the …

Sheathless Size-Based Acoustic Particle Separation, Rasim Guldiken, Myeong Chan Jo, Nathan D. Gallant, Utkan Demirci, Jiang Zhe

Mechanical Engineering Faculty Research

Particle separation is of great interest in many biological and biomedical applications. Flow-based methods have been used to sort particles and cells. However, the main challenge with flow based particle separation systems is the need for a sheath flow for successful operation. Existence of the sheath liquid dilutes the analyte, necessitates precise flow control between sample and sheath flow, requires a complicated design to create sheath flow and separation efficiency depends on the sheath liquid composition. In this paper, we present a microfluidic platform for sheathless particle separation using standing surface acoustic waves. In this platform, particles are first lined …

Temperature Dependence Of Current Conduction In Semi-Insulating 4h-Sic Epitaxial Layer, P. G. Muzykov, Ramesh Madhu Krishna, K. C. Mandal

Faculty Publications

No abstract provided.

The Nucleus 2011-2012, Rosalie A. Richards

Science Education Center

No abstract provided.

Optimization Of Power And Efficiency Of Thermoelectric Devices With Asymmetric Thermal Contacts, Kazuaki Yazawa, Ali Shakouri

Birck and NCN Publications

We report the theoretical efficiency of thermoelectric power generation with asymmetric thermal contacts to reservoirs. A key ingredient is the electrical and thermal co-optimization. Generic formula of the maximum power output and the optimum leg length are obtained. The Curzon-Ahlborn limit at maximum power can be rigorously derived when the dimensionless figure-of-merit is very large for any asymmetric thermal contact resistances. The results differ from cyclic thermodynamic engines, and some of the reasons are discussed. We also point out the similarity and differences with single-level quantum dot heat engines, which assume no explicit thermal contact resistance with reservoirs. (C) 2012 …

Computational Study Of Energy Filtering Effects In One-Dimensional Composite Nano-Structures, Raseong Kim, Mark S. Lundstrom

Birck and NCN Publications

Possibilities to improve the Seebeck coefficient S versus electrical conductance G trade-off of diffusive composite nano-structures are explored using an electro-thermal simulation framework based on the non-equilibrium Green's function method for quantum electron transport and the lattice heat diffusion equation. We examine the role of the grain size d, potential barrier height Phi(B), grain doping, and the lattice thermal conductivity kappa(L) using a one-dimensional model structure. For a uniform kappa(L), simulation results show that the power factor of a composite structure may be improved over bulk with the optimum Phi(B) being about k(B)T, where k(B) and T are the Boltzmann …

Quantum-Hall Plateau-Plateau Transition In Top-Gated Epitaxial Graphene Grown On Sic (0001), T. Shen, A. T. Neal, M. L. Bolen, Jiangjiang Gu, L. W. Engel, Michael A. Capano, Peide D. Ye

Birck and NCN Publications

We investigate the low-temperature magneto-transport properties of monolayer epitaxial graphene films formed on the Si-face of semi-insulating 4H SiC substrates by a high-temperature sublimation process. A high-k top-gate on the epitaxial graphene is realized by inserting a fully oxidized nanometer-thin aluminum film as a seeding layer, followed by an atomic layer deposition process. At low temperatures, the devices demonstrate a strong field effect by the top gate with an on/off ratio of similar to 7 and an electron mobility up to similar to 3250 cm(2)/Vs. After the observation of the half-integer quantum-Hall effect for monolayer epitaxial graphene films, detailed magneto-transport …

Altering Iron Oxide Nanoparticle Surface Properties Induce Cortical Neuron Cytotoxicity, Christopher J. Rivet, Yuan Yuan, Diana Andra Borca-Tasciuc, Ryan J. Gilbert

Chemical and Biochemical Engineering Faculty Research & Creative Works

Superparamagnetic iron oxide nanoparticles, with diameters in the range of a few tens of nanometers, display the ability to cross the blood-brain barrier and are envisioned as diagnostic and therapeutic tools in neuro-medicine. However, despite the numerous applications being explored, insufficient information is available on their potential toxic effect on neurons. While iron oxide has been shown to pose a decreased risk of toxicity, surface functionalization, often employed for targeted delivery, can significantly alter the biological response. This aspect is addressed in the present study, which investigates the response of primary cortical neurons to iron oxide nanoparticles with coatings frequently …

One-Pot Synthesis In Polyamines For Preparation Of Water-Soluble Magnetite Nanoparticles With Amine Surface Reactivity, Haiou Qu, Hui Ma, Aurélien Riviere, Weilie Zhou, Charles J. O'Connor

Chemistry Faculty Publications

Magnetite nanoparticles with hydrophilic surface coating are prepared in polyamine solvents. The resulting products are highly stable in polar solvent. The surface amine groups are available for secondary reactions.

Can Morphology Tailoring Improve The Open Circuit Voltage Of Organic Solar Cells?, Biswajit Ray, M. S. Lundstrom, Muhammad A. Alam

Birck and NCN Publications

While the effect of interfacial morphology on the short circuit current (I_SC) of organic photovoltaic devices (OPVs) is well known, its impact on open circuit voltage (V_OC) and fill-factor (FF) are less clear. Since the output power of a solar cell Pout = I_SCV_OCFF, such understanding is critical for designing high-performance, morphology-engineered OPVs. In this letter, we provide an explicit analytical proof that any effort to radically improve V_OC by tailoring bulk heterojunction morphology is futile, because any increase in ISC due to larger interface area is counterbalanced by corresponding increase …

Lynches Lane Reed & Willow Bed Facility Final Report South Dubin County Council, Liam Mccarton, Sean O'Hogain, Don Mcdonald, Anna Reid

Reports

This final report will present results from a two year study to monitor the performance of a hybrid reed willow bed facility at Lynches Lane, in the administrative area of South Dublin County Council (SDCC). Design specifications for the facility are presented. Monitoring results for a two year period including influent and effluent parameters, rainfall, potential evapotranspiration, and soil classification are also presented and discussed. During the two year monitoring period the system achieved a zero discharge. This report will discuss the potential application of similar systems within South Dublin County Council administrative area. This is in the context of …

Use Of Building Information Modelling In Responding To Low Carbon Construction Innovations: An Irish Perspective, Alan V. Hore

Conference papers

At present the Irish construction industry is facing one of its most uncertain and challenging periods and will see major cuts in all areas of the economy in 2012. Despite this, Ireland pushes forward in sustainability initiatives with the Government ruling that environmentally-friendly policies are to get priority in competing for State contracts worth up to €16 billion a year. This and further initiatives are in place, so as to reduce greenhouse gas emissions by up to 20% by the year 2020. By the end of 2018 the public sector must own or rent only buildings with high energy-saving standards …

Method For Converting An Input Color Signal, Ronald S. Cok, Michael E. Miller

AFIT Patents

A white light-emitting microcavity light-emitting diode device, comprising a method for converting a red, green, and blue (RGB) input signal to a converted signal having RGB color signals and an additional saturated color signal, by calculating saturation of the additional saturated color in the RGB input signal to determine the proportion of the additional saturated color signal to the sum of the converted RGB color signals such that the proportion of the additional saturated color signal is constant or decreases as the saturation of the additional color in the RGB input signal increases.

Stereoscopic Display System With Flexible Rendering Of Disparity Map According To The Stereoscopic Fusing Capability Of The Observer, Elaine W. Jin, Michael E. Miller, Serguei Endrikhovski, Cathleen D. Cerosaletti

AFIT Patents

A method is provided for customizing scene content, according to a user or a cluster of users, for a given stereoscopic display, including obtaining customization information about the user; obtaining a scene disparity map for a pair of given stereo images and/or a three-dimensional (3D) computer graphic model; and determining an aim disparity range for the user. The method of the present invention also generates a customized disparity map and/or rendering conditions for a three-dimensional (3D) computer graphic model correlating with the user's fusing capability of the given stereoscopic display; and renders or re-renders the stereo images for subsequent display.

Gpu-Accelerated Large-Eddy Simulation Of Turbulent Channel Flows, Rey Deleon, Inanc Senocak

Mechanical and Biomedical Engineering Faculty Publications and Presentations

High performance computing clusters that are augmented with cost and power efficient graphics processing unit (GPU) provide new opportunities to broaden the use of large-eddy simulation technique to study high Reynolds number turbulent flows in fluids engineering applications. In this paper, we extend our earlier work on multi-GPU acceleration of an incompressible Navier-Stokes solver to include a large-eddy simulation (LES) capability. In particular, we implement the Lagrangian dynamic subgrid scale model and compare our results against existing direct numerical simulation (DNS) data of a turbulent channel flow at Re_τ = 180. Overall, our LES results match fairly well with …

Aircraft Operations Based Mission Requirements, Robert A. Mcdonald

Aerospace Engineering

The mission capabilities of aircraft in the current commercial fleet are a combined result of many factors. The launch customer for each aircraft has a voice in determining the requirements. The manufacturer desires to best position the aircraft in the market considering their own aircraft and their competitors aircraft it will replace and compete with. Consequently, anyone considering the development of an aircraft to compete with or replace an aircraft in-service must do more than simply choose to meet the capabilities of that aircraft. This is especially true when unconventional systems are considered; the fundamental trade-offs for these systems may …

Laser Direct Growth Of Graphene On Silicon Substrate, Dapeng Wei, Xianfan Xu

Birck and NCN Publications

We demonstrate laser direct growth of few layer graphene on a silicon substrate. In our study, a continuous wave laser beam was focused on a poly(methyl methacrylate) (PMMA)-coated silicon wafer to evaporate PMMA and melt the silicon wafer. Carbon atoms, decomposed from PMMA, were absorbed by the molten silicon surface, and then separated from silicon in the cooling process to form few-layer graphene. This Si-catalyzed method will provide a new approach and platform for applications of graphene. (C) 2012 American Institute of Physics. [doi: 10.1063/1.3675636]

Biomechanical Implications Of Lumbar Spinal Ligament Transectiona Finite Element Study, Gregory Allen Von Forell

Theses and Dissertations

The purpose of this work was to determine the possible effects of isolated spinal ligament transection on the biomechanics of the lumbar spine. A finite element model of a lumbar spine was developed and validated against experimental data. The model was tested in the primary modes of spinal motion in the intact condition, followed by comparative analysis of isolated removal of each spinal ligament. Results showed that stress increased in the remaining ligaments once a ligament was removed, potentially leading to ligament damage. Results also showed changes in bone remodeling "stimulus" which could lead to changes in bone density. Isolated …

Six Reasons Why The Property Market Will Be Slow To Recover, Lorcan Sirr

Media

No abstract provided.