Engineering Commons^™

Discrete Film Cooling In A Rocket With Curved Walls, Jonathan F. Mccall

Theses and Dissertations

This study quantified the effects of discrete wall-based film cooling in a rocket with curved walls. Simulations and experiments showed decreasing with wall radius of curvature, holding jet diameter constant, improves net heat flux reduction (NHFR) and adiabatic effectiveness (η) for 90˚ compound injected cylindrical jets, though η is reduced at the highest curvature. NHFR and η improved further with a high favorable stream-wise pressure gradient (K=2.1x10^-5) at all tested blowing ratios, but were affected little by a high density ratio (DR=1.76) using carbon dioxide as the coolant. Experiments were run at a Reynolds number of 31K and …

Laser-Induced Fluorescence And Synthetic Jet Fuel Analysis In The Ultra Compact Combustor, Aaron C. Drenth

Theses and Dissertations

The Ultra-Compact Combustor (UCC) is currently under investigation at the Air Force Institute of Technology (AFIT) and Air Force Research Laboratory’s Propulsion Directorate. The combustor is a small-scale, axi-symmetric, atmospheric pressure, laboratory combustor with an outer circumferential cavity in which the flame is stabilized by a highly accelerated swirled flow. UCCs will enable aero gas turbine reheat cycle engines and significantly shorten conventional aero gas turbine engines. The experiments of this work utilized the AFIT small-scale combustion diagnostics facility, investigating a sector model of the UCC. The research objectives were to perform an addition to the COAL lab laser diagnostic …

Fatigue Behavior Of An Advanced Sic/Sic Composite At Elevated Temperature In Air And In Steam, Devon T. Christensen

Theses and Dissertations

The fatigue behavior of an advanced Silicon Carbide/Silicon Carbide (SiC/SiC) ceramic matrix composite (CMC) was investigated at 1200 ˚C in laboratory air and in steam environments. The composite consisted of a SiC matrix reinforced with Boron Nitride (BN) coated Hi-Nicalon fibers woven into eight-harness-satin (8HS) weave plies. Tensile stress-strain behavior and tensile properties were also evaluated at 1200 ˚C. Tension-tension fatigue tests were conducted in both laboratory air and in steam at 1200 ˚C at frequencies of 0.1 Hz, 1.0 Hz, and 10 Hz. The tension-tension fatigue tests had a ratio of minimum stress to maximum stress of R = …

Flow Measurements Using Particle Image Velocimetry In The Ultra Compact Combustor, Levi M. Thomas

Theses and Dissertations

Velocity measurements were performed using the Particle Image Velocimetry (PIV) technique on the Ultra Compact Combustor (UCC) test rig at the Air Force Institute of Technology (AFIT). Velocity patterns and time-averaged turbulence statistics were calculated for data taken with the UCC burning hydrogen fuel in the straight cavity vane and curved cavity vane configurations. The equivalence ratio was varied from 0.7 to 1.5, while the ratio of cavity air to main air was varied from 5% to 20% in testing performed on the straight vane configuration. Spanwise velocity was observed to decrease linearly with distance from the cavity vane over …

Flow Visualization Study Of Passive Flow Control Features On A Film-Cooled Turbine Blade Leading Edge, Daniel R. Carroll

Theses and Dissertations

A flow visualization study was conducted on a model of a film-cooled turbine blade leading edge in a closed-loop water channel at Re_D = 30k. The model consisted of an 8.89 cm diameter half-cylinder with flat afterbody joined at the ninety degree point. A single radial coolant hole (d_c / D = 0.054) drilled 21.5° from the stagnation line, angled 20° to the surface and 90° to the flow direction generated a coolant jet transverse to the freestream. Water channel testing assessed the hydrodynamic effects of 16 passive flow control features, to include a variety of …

Tailored Systems Architecture For Design Of Space Science And Technology Missions Using Dodaf V2.0, Nicholas J. Merski

Theses and Dissertations

The use of systems architecture, following a set of integrated descriptions from an architecture framework, has been well codified in Department of Defense acquisition and systems engineering. However, in the Space Science and Technology (S&T) community, this guidance and practice is not commonly adopted. This paper outlines an approach to leverage the changes made in DoD Architecture Framework 2.0 (DoDAF2.0), and the renewed emphasis on data and support to acquisition decision analysis. After decomposing the Space S&T design lifecycle into phases, design milestones and activities using process models, a set of DoDAF prescribed and Fit-for-Purpose views are constructed into a …

Heat And Current Propagation In Buffered Superconducting And Hyper-Conducting Wire, Jesse L. Lynn

Theses and Dissertations

This research models and analyzes the distribution of heat and current in a buffered superconducting or hyper-conducting wire that shows potential for use in different capacities in multiple Air Force systems including the Active Denial System. The thesis includes a brief background of the reaction-diffusion system of partial differential equations provided by AFRL/RZPG and development of the numerical scheme. It then explores solutions to the model. These solutions indicate some of the various heat-related failures that may be observed in such a wire. The nature of the solutions observed depends on the characteristics of the wire, operating temperature and efficiency …

Cellular Multilayer Perceptron For Prediction Of Voltages In A Power System, Lisa L. Grant, Ganesh K. Venayagamoorthy

Electrical and Computer Engineering Faculty Research & Creative Works

With the increase in renewable energy sources connected to the power grid, better identification tools are needed for power system voltage profile prediction. Current deregulation trends have led to voltages operating close to stability limits which increases the need for quick estimation tools for system security and contingency analysis. This paper presents a Cellular Multilayer Perceptron (CMLP) architecture for fast identification and prediction of bus voltages. the CMLP method is compared with a standard MLP neural network for bus voltage prediction on the 12-bus three-area test power system. CMLPs can represent a direct mapping of any power system simplifying the …

Oculomotor Control In Patients With Parkinson's Disease, George Gitchel

Theses and Dissertations

There have been few studies investigating the eye movement behavior of Parkinson’s disease patients during fixation. This study objectively measured the eye movements of 36 patients with Parkinson’s disease, and 20 age matched controls. Stimuli consisted of ten standardized text passages first organized by Miller and Coleman. In addition, subjects followed a randomly displaced step jump target motion. Pendular nystagmus was found in all Parkinson’s subjects, with an average frequency of 7.44 Hz. Saccadic peak velocity and duration along the main sequence were not statistically different from controls. A slower rate of reading was also noted in the Parkinson’s group …

An Introduction To The Echo State Network And Its Applications In Power System, Jing Dai, Ganesh K. Venayagamoorthy, Ronald G. Harley

Electrical and Computer Engineering Faculty Research & Creative Works

Echo State Network (ESN) is a new type of Recurrent Neural Network (RNN) proposed in recent years. the training process of ESN is easier and requires less computational effort than regular RNN which has the same size. Due to its high modeling capability of complex dynamic system, ESN has been used in various power system applications such as power system nonlinear load modeling and true harmonic current detection, wide area monitoring, intelligent control of an Active Power Filter (APF), overhead conductor thermal dynamics identification, wind speed or water inflow forecasting, etc. This paper introduces the basic concept and the offline …

Atomic Force Microscopy Of Dna Self-Assembled Nanostructures For Device Applications, Hieu Bui, Craig Onodera, Bernard Yurke, Elton Graugnard, Wan Kuang, Jeunghoon Lee, William B. Knowlton, William L. Hughes

Electrical and Computer Engineering Faculty Publications and Presentations

DNA nanotechnology, which relies on Watson-Crick hybridization, is a versatile selfassembly process whereby a variety of complex nanostructures can be fabricated with sublithographic features.[1] Adopting this technology, 1012 identical devices can be synthesized to have hundreds of components with 1nm resolution. Example nanostructures include: 1) DNA motifs [2], 2) two-dimensional DNA crystals [3], and DNA origami [4]. Currently, this technology is being adopted towards electronic, optical, and opto-electronic devices.[5]

Investigation Into Contact Resistance And Damage Of Metal Contacts Used In Rf-Mems Switches, Kevin W. Gilbert

Theses and Dissertations

This research examines the physical and electrical processes involved in lifecycle failure of Microelectromechanical (MEMS) Radio-Frequency (RF) cantilever beam ohmic contact switches. Failures of these switches generally occur at the contact, but complete details of performance of microcontacts are difficult to measure and have not been previously reported. This study investigated the mechanics of microcontact behavior by designing and constructing a novel experimental setup. Three representative contact materials of varying microstructure (Au, Au5%Ru, Au4%V₂O₅) were tested and parameters of contact during cycling were measured. The Au4%V₂O₅, a dispersion strengthened material developed at …

Egoviz – A Mobile Based Spatial Interaction System, Keith Gardiner, Junjun Yin, James Carswell

Articles

This paper describes research carried out in the area of mobile spatial interaction and the development of a mobile (i.e. on-device) version of a simulated web-based 2D directional query processor. The TellMe application integrates location (from GPS, GSM, WiFi) and orientation (from digital compass/tilt sensors) sensing technologies into an enhanced spatial query processing module capable of exploiting a mobile device’s position and orientation for querying real-world 3D spatial datasets. This paper outlines the technique used to combine these technologies and the architecture needed to deploy them on a sensor enabled smartphone (i.e. Nokia 6210 Navigator). With all these sensor technologies …

Graphene On Pt(111): Growth And Substrate Interaction, Peter Sutter, Jerzy T. Sadowski, Eli Sutter

Department of Electrical and Computer Engineering: Faculty Publications

In situ low-energy electron microscopy (LEEM) of graphene growth combined with measurements of the graphene structure and electronic band structure has been used to study graphene on Pt (111). Growth by carbon segregation produces macroscopic monolayer graphene domains extending continuously across Pt (111) substrate steps and bounded by strongly faceted edges. LEEM during cooling from the growth temperature shows the propagation of wrinkles in the graphene sheet, driven by thermal stress. The lattice mismatch between graphene and Pt (111) is accommodated by moiré structures with a large number of different rotational variants, without a clear preference for a particular interface …

Studies On The Performance And Impact Of Channel Estimation In Mimo And Ofdm Systems, Michael David Larsen

Theses and Dissertations

The need for reliable, high-throughput, mobile wireless communication technologies has never been greater as increases in the demand for on-the-go access to information, entertainment, and other electronic services continues. Two such technologies, which are at the forefront of current research efforts, are orthogonal frequency division multiplexing (OFDM) and multiple-input multiple-output (MIMO) systems, their union being known simply as MIMO-OFDM. The successful performance of these technologies depends upon the availability of accurate information concerning the wireless communication channel. In this dissertation, several issues related to quality of this channel state information (CSI) are studied. Specifically, the first part of this dissertation …

East Bay Energy Consortium Meeting Minutes, December 7, 2009, East Bay Energy Consortium

East Bay Energy Consortium Meeting Minutes

No abstract provided.

Automatic Exposure Control And Estimation Of Effective System Noise In Diffuse Fluorescence Tomography, Dax L. Kepshire, Hamid Dehghani, Frederic Leblond, Brian W. Pogue

Dartmouth Scholarship

A diffuse fluorescence tomography system, based upon time-correlated single photon counting, is presented with an automated algorithm to allow dynamic range variation through exposure control. This automated exposure control allows the upper and lower detection levels of fluorophore to be extended by an order of magnitude beyond the previously published performance and benefits in a slight decrease in system effective noise. The effective noise level is used as a metric to characterize the system performance, integrating both model-mismatch and calibration bias errors into a single parameter. This effective error is near 7% of the reconstructed fluorescent yield value, when imaging …

Optical Properties Of Semiconducting Boron Carbide For Neutron Detection Applications, Ravi B. Billa

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Solid state neutron detection devices based on semiconducting boron carbide have the potential for nearly ideal neutron detection effciency for thermal neutrons. The present work is focused on characterizing optical properties of this semiconducting boron carbide material as a step in further development of the material for neutron detection and other applications.

Semiconducting boron carbide films were grown on silicon substrates using plasma enhanced chemical vapor deposition and their optical properties were characterized using variable angle spectroscopic ellipsometry over a wide spectral range, from mid-infrared to vacuum-ultraviolet wavelengths. The effects of deposition substrate temperature and of post-deposition heat treatments on …

Automated Methods For Fiber Diameter Measurement Of Fibrous Scaffolds, Anna Bulysheva

Theses and Dissertations

The purpose of this work was to develop an automated method of measuring fiber diameters of electrospun scaffolds from scanning electron microscopy images of these scaffolds. Several automated methods were developed and evaluated by comparison to known values and data obtained via the standard manual method. Simulated images with known diameters were used as test images to evaluate the accuracy of each measurement technique. Eight scanning electron microscopy images were also used for the evaluation of the automated methods compared to the standard manual method. All diameter measurements were made in pixels. Five new automated methods coded in MATLAB were …

Efficient Implementation Of Raid-6 Encoding And Decoding On A Field Programmable Gate Array (Fpga), David Jacob

Theses and Dissertations

RAID-6 is a data encoding scheme used to provide single drive error detection and dual drive error correction for data redundancy on an array of disks. Here we present a thorough study of efficient implementations of RAID-6 on field programmable gate arrays (FPGAs). Since RAID-6 relies heavily on Galois Field Algebra (GFA), an efficient implementation of a GFA FPGA library is also presented. Through rigorous performance analysis, this work shows the most efficient ways to tradeoff FPGA resources and execution time when implementing GFA functions as well as RAID-6 encoding and decoding.

Fabrication Methods For Creating Flexible Polymer Substrate Sensor Tags, Jack L. Skinner, Harvey Ho

Mechanical Engineering

The authors describe the design, fabrication, and testing of a passive wireless sensor platform utilizing low-cost commercial surface acoustic wave filters and sensors. Polyimide and polyethylene terephthalate sheets are used as substrates to create a flexible sensor tag that can be applied to curved surfaces. A microfabricated antenna is integrated on the substrate in order to create a compact form factor. The sensor tags are fabricated using 315 MHz surface acoustic wave filters and photodiodes and tested with the aid of a fiber-coupled tungsten lamp. Microwave energy transmitted from a network analyzer is used to interrogate the sensor tag. Due …

Creating Insanity In Learning Systems: Addressing Ambiguity Effects Of Predicting Non-Linear Continuous Valued Functions With Reconstructabilty Analysis From Large Categorically Valued Input Data Sets, William D. Eisenhauer

Systems Science Friday Noon Seminar Series

Being told to give two different, and potentially counter, responses to the same stimulus can set up a double bind in humans, leading to a type of insanity. So what how do you deal with it when it comes up quite frequently in modeling through simplification and removal of predictive variables?

In his current dissertation research Ike Eisenhauer is using reconstructability analysis to implement K-System, U-System, and B-System approaches to predict a continuously valued function through discrete categorically valued input variables [e.g. textual data]. One of the key issues is how to address the inability of K-Systems and U-Systems to …

Development Of The Mask Scentometer, A Comparison Of Ambient Odor Assessment Methods, And Their Application In Ground Truthing Atmospheric Dispersion Models, Christopher G. Henry

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

This dissertation is organized as four stand-alone papers. Paper No. 1 describes the development of the Mask Scentometer and reports dilution ratios measured during use by twelve different people. Dilution ratios at the Mask Scentometer’s five dilution-to-threshold (D/T) settings were found to be 0.35, 1, 2, 4.5 and 18. In Paper No.’s 2 and 4, ambient odor assessment methods were compared in both controlled laboratory conditions and in the field. Laboratory analysis of ambient air samples using dynamic triangular forced-choice olfactometry (DTFCO) did not correlate well with any of the ambient odor assessment methods. Average intensity-predicted D/T was roughly five …

Wim Based Live Load Model For Bridge Reliability, Marek Kozikowski

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

Development of a valid live load model is essential for assessment of serviceability and safety of highway bridges. The current HL-93 load model is based on the Ontario truck measurements performed in 1975. Since that time truck loads have changed significantly. Therefore, the goal of this study is to analyze 2005-2007 Weigh-In-Motion (WIM) data and develop a new statistical live load model.

The analyzed WIM data includes 47,000,000 records obtained from different states. A special program was developed to calculate the maximum live load effect. Comparison of the old and new truck data showed that on average Ontario trucks are …

Experimental And Numerical Investigation On Pyroelectric Energy Scavenging, Jingsi Xie

Theses and Dissertations

Pyroelectric energy scavenging is the process of converting wasted energy from a system to power another one, based on the pyroelectric effect of piezoelectric materials. Pyroelectrically generated power is a function of the surface of material, the pyroelectric coefficient, and the temporal temperature gradient. In the current project, a simple model is developed to predict the power generation based on the temporal change in temperature of material. In addition, a model is validated with experimental measurements from several piezoelectric materials. It is shown that energy generation can be enhanced by using piezoelectric materials with significantly higher pyroelectric coefficients such as …

Ceas E-News 12.03.2009, College Of Engineering And Applied Sciences

College of Engineering and Applied Sciences News

SWE workshop offers Girl Scouts an introduction to engineering

Quality-Driven Cross Layer Design For Multimedia Security Over Resource Constrained Wireless Sensor Networks, Wei Wang

Department of Computer Electronics and Engineering: Dissertations, Theses, and Student Research

The strong need for security guarantee, e.g., integrity and authenticity, as well as privacy and confidentiality in wireless multimedia services has driven the development of an emerging research area in low cost Wireless Multimedia Sensor Networks (WMSNs). Unfortunately, those conventional encryption and authentication techniques cannot be applied directly to WMSNs due to inborn challenges such as extremely limited energy, computing and bandwidth resources. This dissertation provides a quality-driven security design and resource allocation framework for WMSNs. The contribution of this dissertation bridges the inter-disciplinary research gap between high layer multimedia signal processing and low layer computer networking. It formulates the …

Biological Sequence Simulation For Testing Complex Evolutionary Hypotheses: Indel-Seq-Gen Version 2.0, Cory L. Strope

School of Computing: Dissertations, Theses, and Student Research

Reconstructing the evolutionary history of biological sequences will provide a better understanding of mechanisms of sequence divergence and functional evolution. Long-term sequence evolution includes not only substitutions of residues but also more dynamic changes such as insertion, deletion, and long-range rearrangements. Such dynamic changes make reconstructing sequence evolution history difficult and affect the accuracy of molecular evolutionary methods, such as multiple sequence alignments (MSAs) and phylogenetic methods. In order to test the accuracy of these methods, benchmark datasets are required. However, currently available benchmark datasets have limitations in their sizes and evolutionary histories of the included sequences are unknown. These …

Prediction Of Fluid Viscosity Through Transient Molecular Dynamic Simulations, Jason Christopher Thomas

Theses and Dissertations

A novel method of calculating viscosity from molecular dynamics simulations is developed, benchmarked, and tested. The technique is a transient method which has the potential to reduce CPU requirements for many conditions. An initial sinusoidal velocity profile is overlaid upon the peculiar velocities of the individual molecules in an equilibrated simulation. The transient relaxation of this initial velocity profile is then compared to the corresponding analytical solution of the momentum equation by adjusting the viscosity-related parameters in the constitutive equation that relate the shear rate to the stress tensor. The newly developed Transient Molecular Dynamics (TMD) method was tested for …

College Of Engineering Senior Design Competition Fall 2009, University Of Nevada, Las Vegas

Fred and Harriet Cox Senior Design Competition Projects

Each student in his or her senior year chooses, plans, designs, and prototypes a product in this required element of the curriculum. 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.

A highlight of the year-long senior design project is the senior design competition. This competition, which usually takes place the week before finals each semester, helps focus the senior students on increasing the quality and potential for commercial application for their design projects.

Judges from local industry evaluate the projects on innovation, commercial …