Engineering Commons^™

Frequency Response Of Solid-State Impact Ionization Multipliers, Joshua Beutler, Carlton S. Clauss, Michael S. Johnson, Aaron R. Hawkins, Mike D. Jack, George R. Chapman, Ken Kosai

Faculty Publications

A study of the frequency response of solid-state impact ionization multipliers (SIMs) is presented that emphasizes the role of resistive and capacitive elements of the device to establish response limitations. SIMs are designed to amplify input currents from an external source through the impact ionization mechanism. An equivalent circuit model for the SIM is developed based on its current versus voltage characteristics, which is used to derive a frequency response model. Theoretical frequency response matches very closely to measured responses for first generation SIM devices constructed on p-type silicon epitaxial layers with nickel silicide Schottky contact injection points. Devices were …

Soldier/Hardware-In-The-Loop Simulation-Based Combat Vehicle Duty Cycle Measurement: Duty Cycle Experiment 2, Mark Brudnak, Mike Pozolo, Victor Paul, Syed Mohammad, Marc Compere, Et Al.

Publications

This paper describes a human-in-the-loop motion-based simulator interfaced to hybrid-electric power system hardware both of which were used to measure the duty cycle of a combat vehicle in a virtual simulation environment. The project discussed is a greatly expanded follow-on to the experiment published in [1]. This paper is written in the context of [1] and therefore highlights the enhancements. The most prominent of these enhancements is the integration (in real-time) of the Power & Electric System Integration Lab (P&E SIL) with a motion base simulator by means of a “long haul” connection over the Internet (a geographical distance of …

Do Loading Path And Specimen Thickness Affect The Brittle Compressive Failure Of Ice?, A. L. Fortt, E. M. Schulson

Dartmouth Scholarship

Compressive experiments were performed on square (160 mm × 160 mm) prismatic specimens of columnar-grained, S2 freshwater ice, biaxially loaded across the columns at −10°C. The work focused on brittle behavior, achieved by deforming the specimens at an applied strain rate of 4.5 ± 1.2 × 10 3s 1 in the direction of shortening. The results show that the specimen thickness (25–150 mm) has no detectable effect on the terminal failure strength of the ice. Likewise, the strength of the ice when loaded under proportional loading, where the minor stress varies during the test, was similar to that when loaded …

An Investigation Of Methods To Homogeneously Entrain And Suspend Abrasive Particles In A Low Pressure Dental Water Jet, Michael Sean Grygla

Theses and Dissertations

During the past several decades, the water jet cutting concept has developed from a novel concept into a well-accepted machine cutting tool. With the addition of abrasive particles and the improvement of high pressure pumps, the water jet stream is currently capable of cutting through metal, concrete, and composite materials. Water jet systems have been utilized at a wide range of different pressures. Research performed at Brigham Young University has revealed that low pressure water jets have the ability to cut human teeth. Experiments have shown that when abrasive particles are added to the water jet stream, an greater amount …

Detecting Anomalies By Learning Weighted Rules, Guarav Tandon, Philip K. Chan

Electrical Engineering and Computer Science Faculty Publications

Anomaly detection focuses on modeling the normal behavior and identifying significant deviations, which could be novel attacks. The previously proposed LERAD algorithm can efficiently learn a succinct set of comprehensible rules for detecting anomalies. We conjecture that LERAD eliminates rules with possibly high coverage, which can lead to missed detections. This study proposes weights that approximate rule confidence and are learned incrementally. We evaluate our algorithm on various network and host datasets. Compared to LERAD, our technique detects more attacks at low false alarm rates with minimal computational overhead.

Environmental Effects On Corrosion Properties Of Alloy 22, Mano Misra, L. G. Mcmillion

Publications (YM)

Subtask 1: Experimental Determination of Parameters for the General Corrosion Model Subtask 2: Corrosion Under Dust Deposits Containing Hygroscopic Salts Subtask 3: Heated Electrode Approach for the Study of Corrosion Under Aggressive Conditions Subtask 4: Effect of Hydrogen Permeation on the Stability of the Passive Film of Alloy 22

Sub-Surface Corrosion Research On Rock Bolt System, Perforated Ss Sheets And Steel Sets For Yucca Mountain Repository, Dhanesh Chandra, Jaak J.K. Daemen

Publications (YM)

Outline

Metallurgical Issues in Underground Repository Reinforcement Support for Nuclear Materials Storage in simulated Yucca Mountain Environment used for Corrosion Issues
Issues related to I-beams (Low Carbon) and Rock Bolts (Med. Carbon)

Experimental

Results

1. Corrosion Tests- Effect of Ionic Concentration (1x,10x,100x), Temperature, concentration and aeration/deaeration effects in YM waters (RB and I-Beam)
2. Hydrogen Permeation Tests
3. Environmentally Assisted Corrosion Tests - Stress Corrosion Cracking/Hydrogen Embrittlement in 100x YM water concentration at Room Temperature and 85oC (I-Beams)

Phase Stability And Segregation In Alloy 22 Base Metal And Weldments, Jeffrey Lacombe, G. L. Mcmillon

Publications (YM)

Subtask 1: Microstructural Characterization of Phase Stability and Variability in Alloy 22. Develop an improved understanding of Alloy 22 and the extent to which compositional and microstructural variations are present in otherwise “nominal” as-procured material. Subtask 2: Electrochemical Methods to Detect Susceptibility of Alloy 22 to Localized Corrosion. Study the influence that compositional and microstructural variations have on the corrosion performance of Alloy 22.

A Microfabricated Segmented-Involute-Foil Regenerator For Enhancing Reliability And Performance Of Stirling Engines: Phase Ii Final Report For The Radioisotope Power Conversion Technology Nra Contract Nas3-03124, Mounir B. Ibrahim, Daniel Danila, Terrence Simon, Susan Mantell, Liyong Sun, David Gedeon, Songgang Qiu, Gary Wood, Kevin Kelly, Jeffrey Mclean

Mechanical Engineering Faculty Publications

An actual-size microfabricated regenerator comprised of a stack of 42 disks, 19 mm diameter and 0.25 mm thick, with layers of microscopic, segmented, involute-shaped flow channels was fabricated and tested. The geometry resembles layers of uniformly-spaced segmented-parallel-plates, except the plates are curved. Each disk was made from electro-plated nickel using the LiGA process. This regenerator had feature sizes close to those required for an actual Stirling engine but the overall regenerator dimensions were sized for the NASA/Sunpower oscillating-flow regenerator test rig. Testing in the oscillating-flow test rig showed the regenerator performed extremely well, significantly better than currently used random-fiber material, …

Study Of Structure Development During Melt Spinning Of Isotactic Polypropylene Fibers Using Raman Spectroscopy And Wide Angle X-Ray Diffraction Simultaneously , Dushyanth Pandana

All Theses

ABSTRACT
Isotactic polypropylene (iPP) fibers have a wide variety of applications. Specific end-use applications require specific properties, which are dependent on the polymer morphology produced during processing. Therefore, the final properties of a material are dependent on the processing parameters. iPP fibers are produced mainly by melt spinning. The important processing parameters in the melt spinning process include, the extrusion temperatures, the throughput and shear rates, the rate of cooling, and the feed and draw roll take-up velocities. An understanding of how the morphology develops along the spinline, and the effect of processing parameters on the morphology is crucial in …

Influence Of Lithophysae Geometry On Mechanical Properties Of Hydro-Stone®, Moses Karakouzian, Doug Rigby

Publications (YM)

85 percent of YM drift tunnels will be constructed in lithophysal volcanic tuff. Rock behavior depends on porosity. Limited experimental data exists to characterize rock porosity and dependencies on properties such as σc , E, and n.

Comparative Study Of Haptic And Visual Feedback For Kinesthetic Training Tasks, Ravikiran Singapogu

All Theses

Haptics is the sense of simulating and applying the sense of human touch. Application of touch sensations is done with haptic interface devices. The past few years has seen the development of several haptic interface devices with a wide variety of technologies used in their design. This thesis introduces haptic technologies and includes a survey of haptic interface devices and technologies. An improvement in simulating and applying touch sensation when using the Quanser Haptic Wand with proSense is suggested in this work using a novel five degree-of-freedom algorithm. This approach uses two additional torques to enhance the three degree-of-freedom of …

Synthesis And Photocatalysis Study Of Brookite Phase Titanium Dioxide Nanoparticles, Radhika Bhave

All Theses

Titanium dioxide is used in variety of applications like photocatalysis, self-cleaning coatings, fog proof glass and water purifier. A lot of research is being done in synthesis and applications of TiO2. Titanium dioxide or TiO2 mainly exists in three phases namely anatase, brookite and rutile. Current studies relate to synthesis of brookite phase TiO2 nanoparticles by ambient condition sol (ACS) process and characterization of these particles for phase purity, morphology and surface area analysis. The photoactivity of these particles was investigated and absorption in the visible light region was detected. This implies brookite to have good potential to be used …

A Microfabricated Involute-Foil Regenerator For Stirling Engines, Roy C. Tew, Mounir B. Ibrahim, Daniel Danila, Terrence W. Simon, Susan Mantell, Liyong Sun, David Gedeon, Kevin Kelly, Jeffrey Mclean, Gary Wood, Songgang Qiu

Mechanical Engineering Faculty Publications

A segmented involute-foil regenerator has been designed, microfabricated and tested in an oscillating-flow rig with excellent results. During the Phase I effort, several approximations of parallel-plate regenerator geometry were chosen as potential candidates for a new microfabrication concept. Potential manufacturers and processes were surveyed. The selected concept consisted of stacked segmentedinvolute- foil disks (or annular portions of disks), originally to be microfabricated from stainless-steel via the LiGA (lithography, electroplating, and molding) process and EDM. During Phase II, re-planning of the effort led to test plans based on nickel disks, microfabricated via the LiGA process, only. A stack of nickel segmented-involute-foil …

Sub-Surface Corrosion Research On Rock Bolt System, Perforated Ss Sheets And Steel Sets For The Yucca Mountain Repository — Quarterly Technical Report No. 10, 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 tests to determine the corrosion rates of rock bolts, other support materials including bench mark materials. In this quarter: Potentiodynamic tests were performed to determine corrosion …

Process For The Continuous Production Of Aligned Carbon Nanotubes, David N. Jacques, Rodney Andrews

Center for Applied Energy Research Faculty Patents

Novel methods and apparati for continuous production of aligned carbon nanotubes are disclosed. In one aspect, the method comprises dispersion of a metal catalyst in a liquid hydrocarbon to form a feed solution, and volatilizing the feed solution in a reactor through which a substrate is continuously passed to allow growth of nanotubes thereon. In another aspect, the apparatus comprises a reactor, a tube-within-a-tube injector, and a conveyor belt for passing a substrate through the reactor. The present invention further discloses a method for restricting the external diameter of carbon nanotubes produced thereby comprising passing the feed solution through injector …

F- 16xl Unsteady Simulations For The Cawapi Facet Of Rto Task Group Avt- 113, Scott A. Morton, David R. Mcdaniel, Russell M. Cummings

Aerospace Engineering

This work represents the USAF Academy portion of a culmination of three years of cooperative research in the Cranked Arrow Wing Aerodynamics International (CAWAPI) RTO Task Group, AVT-113. The objective of the group was to compute high resolution CFD simulations of a subset of the conditions created in the CAWAP flight test program managed by NASA Langley researchers and others. Seven flight conditions were chosen with four of them at symmetric conditions of medium to high angle of attack and subsonic Mach numbers, one symmetric condition at a transonic low angle of attack condition, and two conditions at medium angle …

Circulation Control And Its Application To Extreme Short Take-Off And Landing Vehicles, Julianna B. De La Montanya, David D. Marshall

Aerospace Engineering

Circulation Control is a high-lift method discovered in 1935 when Henry Coanda accidentally stumbled upon the technology. Research was conducted in the 1970‘s and 1980‘s to develop this technique, but the idea fell out of vogue until recently. Energy is introduced into the flow field by means of a jet ejected tangentially from a slot located near the trailing edge of the airfoil; thus changing the effective chamber of the airfoil and increasing lift. Extreme Short Take-Off and Landing (ESTOL) vehicles can use this technology to alleviate today‘s congested airports by reutilizing the small runways that are currently unexploited due …

The Role Of Error In The Conceptual Design Of A Transport Aircraft, Robert A. Mcdonald

Aerospace Engineering

A fidelity trade environment was demonstrated by using it to simulate a decision making process for a transport aircraft. This scenario was not possible without the fidelity trade environment. The role of system feedback and coupling in error stability was also investigated.
A sensitivity approach which relies on the system sensitivity matrix was used to rapidly approximate the propagation of error through the complex system. In verification tests, the sensitivity approach provided approximate results substantially similar to a Monte Carlo approach that was many orders of magnitude more expensive. The rapid sensitivity approach to modeling error propagation enabled the responsive …

The Happy Accidents Of Teaching Aircraft Design, David W. Hall, Russell M. Cummings

Aerospace Engineering

The aircraft design curriculum at Cal Poly has grown and evolved over the past decades to include a full year of senior aircraft design and an introductory aircraft design course in the sophomore year. The combination of sophomore and senior aircraft design courses has created the circumstance where a “cult” of aircraft design has developed. The curriculum is producing students who are enthusiastic and motivated education, as well as being competent designers after they graduate. A number of “happy accidents” has led to this fortunate situation, including: allowing the sophomores to perform a full aircraft design, having the sophomores work …

Wing-Nacelle Assembly Multidisciplinary Performance Optimization, Yevgeniy M. Gisin, David D. Marshall

Aerospace Engineering

The paper analyzes the aerodynamics benefits of above-wing mounting of turbofan engines and performs a trade-off study of the structural limitations with this mounting method. This research is based on the US Patent #6,308,913, aiming to quantify the actual benefit derived from the drag reduction measure described in the patent. The paper focuses on the analysis of a turbofan engine, which when installed above an aircraft’s wing creates a flow field optimized to reduce the overall drag experienced by the wing nacelle assembly. This installation is designed to reduce wave drag during transonic cruise and therefore the wing-nacelle geometry was …

Application Of Classical Versus Bayesian Statistical Methods To On-Line Radiological Monitoring, Amy Attardo

All Theses

The on-line monitoring for illicit radioactive material with a minimum number of false detections is a critical need for homeland security. The primary objectives of this work were to apply both Bayesian and classical statistical process control chart techniques to the on-line monitoring of radiological data and to then compare the Type I and Type II error incidence rates. Two versions of the cumulative sum (CUSUM) and Shiryayev-Roberts (S-R) procedures known as total reset and alarm reset methods were developed. The best method in terms of Type I errors was the S-R total reset method. In terms of Type II …

Comparison Of Des And Urans For Unsteady Vortical Flows Over Delta Wings, L. A. Shiavetta, K. J. Badcock, Russell M. Cummings

Aerospace Engineering

The unsteady behaviour of delta wing vortical flows is still a subject which is a challenge for numerical methods, such as computational fluid dynamics. New approaches to turbulence modelling, such as detached eddy simulation (DES) have been proposed which allow for greater accuracy of the numerical predictions. However, this increase in accuracy comes with a considerable increase in computational expense compared to traditional turbulence modelling. This investigation considers the use of both DES and unsteady Reynolds averaged Navier-Stokes (URANS) turbulence methods in the prediction of unsteady vortical flows. Calculations using DES are initially considered for two test cases and the …

An Improved Model For Calculating Heats Of Dilution And Equilibrium Constants For High Temperature Aqueous Electrolyte Solutions, Xiaoyun Lin

Theses and Dissertations

At high temperatures, the properties of aqueous electrolyte systems differ markedly from those at 25°C. For mixed-electrolyte dilute solutions at high temperatures, the degree of ion-association is sufficiently large that the association equilibrium must be incorporated in any model describing the solutions. These association reactions usually do not occur to a measurable extent at room temperature. Oscarson and co-workers have designed a correlation model based on the excess Gibbs energy which can correlate log K and ∆H values as well as the heats of dilution for aqueous electrolyte systems as a function of temperature (T) and ionic strength (I) from …

Dynamic Networking Of Exemplars: Towards A Mechanical Design Visual Programming Language, Shashidhar Putti

All Theses

Developing mechanical engineering design automation applications using current day textual programming languages like C, C++ requires extensive programming skills. However, learning to program in these environments can be time consuming and often frustrating to mechanical engineers due to the use of complex textual constructs and syntax to represent an algorithm in a linear fashion. Further, these programming languages offer a poor visualization of the data and the data flow due to their textual nature. The use of graphical objects for programming makes visualization easier and also eliminates the need for linear representation of algorithms. This thesis initiates the development of …

A Numerical Blade Element Approach To Estimating Propeller Flowfields, Doug F. Hunsaker

Mechanical and Aerospace Engineering Faculty Publications

A numerical method is presented as a low computational cost approach to modeling an induced propeller flowfield. This method uses blade element theory coupled with momentum equations to predict the axial and tangential velocities within the slipstream of the propeller, without the small angle approximation assumption common to most propeller models. The approach is of significant importance in the design of tail-sitter vertical takeoff and landing (VTOL) aircraft, where the propeller slipstream is the primary source of air flow past the wings in some flight conditions. The algorithm is presented, the model is characterized, and the results (including the results …

Application Of H-, P- And Hp-Adaptation For Convective Heat Transfer Problems, Xiuling Wang, Darrell W. Pepper

Mechanical Engineering Faculty Research

The purpose of this paper is to describe the development and employment of an hp-adaptive finite element method (FEM) algorithm for solving heat transfer problems in partitioned enclosures, which has attracted the attention of both experimental and theoretical researchers in recent years.

Design/methodology/approach – In the hp-adaptive FEM algorithm presented here, both the element
size and the shape function order are dynamically controlled by an a posteriori error estimator based on the L2 norm; a three-step adaptation strategy is used with a projection algorithm for the flow solver.

Findings – Simulation results are obtained for 2D and 3D natural convection …

Polarizing Properties Of Embedded Symmetric Trilayer Stacks Under Conditions Of Frustrated Total Internal Reflection, Rasheed M.A. Azzam, Siva R. Perla

Electrical Engineering Faculty Publications

An error in the application of the design procedure described in a previous paper [Appl. Opt. 45, 1650 (2006)] has been corrected, and new revised figures are included in this erratum.

Parallel-Slab Polarizing Beam Splitter And Photopolarimeter, R. M.A. Azzam

Electrical Engineering Faculty Publications

A dielectric-slab polarizing beam splitter (PBS) is described that generates two parallel beams of orthogonal p and s linear polarizations in reflection and functions as a diattenuator in transmission. The plane-parallel slab, which is set at Brewster's angle, is uncoated on one side and has an s-polarization antireflection coating (s-ARC) on the other side. Analytical results are presented for a PBS that uses a high-index slab coated with a low-index single-layer s-ARC, which is particularly suited for the IR. A novel multistage photopolarimeter that uses two such PBSs in series is described as being capable of sequential and simultaneous measurement …

Experimental Evaluation Of Nightcool Nocturnal Radiation Cooling Concept: Performance Assessment In Scale Test Buildings, Florida Solar Energy Center, Danny Parker

FSEC Energy Research Center®

An experimental test evaluation has been conducted of a night sky cooling system designed to substantially reduce space cooling needs in homes in North American climates. The system uses a sealed attic covered by a highly conductive metal roof (a roof integrated radiator) which is selectively linked by air flow to the main zone with the attic zone to provide cooling- largely during nighttime hours. Available house mass is used to store sensible cooling. Additional dehumidification is done during the evening hours as warranted by interior conditions.

A previous report describes a detailed simulation model of the relevant night cooling …