| High-Velocity Impact of Low-Density Projectiles on Structural Aluminum Armor |
Sep-2009 |
14 pages |
| Authors:
B R Sorensen; K D Kimsey; B M Love; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
|
 | The US Army Research Laboratory has been studying the impact physics of low-density projectiles on urban and light-armor structures for use in electro-magnetic cannons. In this report, results of low-aspect ratio projectiles of nylon, aluminum and steel impacting aluminum armor at velocities above 2000 m/s will be presented. Both computational solid mechanics and analytic modeling techniques were used to supplement experiments to derive a toolkit for assessing target response and ... |
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| Microchannel Heat Sink with Micro Encapsulated Phase Change Material (MEPCM) Slurry |
31-May-2009 |
83 pages |
| Authors:
Louis Chow; Jian-hua Du; Amit Gupta; Krishna Kota; Ranganathan Kumar; Sarada Kuravi; UNIVERSITY OF CENTRAL FLORIDA ORLANDO OFFICE OF RESEARCH AND COMMERCIALIZATION
|
| High heat flux removal from devices such as Insulated-Gate Bipolar Transistor (IGBT) and Monolithic Microwave Integrated Circuit (MMIC) will be important for future Navy ships. Micro encapsulated phase change material (MEPCM) slurry was used as a heat transfer fluid inside a microchannel instead single phase fluid. Presence of phase change material increases the effective heat capacity of the fluid. The performance of encapsulated phase change material (EPCM) slurry flow in ... |
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| Multi-Scale Characterization of Inhomogeneous Morphologically Textured Microstructures (Preprint) |
Apr-2009 |
9 pages |
| Authors:
J E Spowart; G B Wilks; M A Tschopp; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING DIRECTORATE
|
| A computationally efficient microstructure characterization technique is presented that separately identifies morphological texture and any orientation dependence of second-phase clustering via a concise visual representation. This technique, the Vector Multi-Scale Analysis of Area Fractions (VMSAAF), is then applied to computer-generated microstructures to understand the effects of second-phase area fraction, aspect ratio, alignment propensity, variant orientation, and degree of microstructure banding on the homogenous length scale- a metric used to quantify ... |
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| Tools for the Conceptual Design and Engineering Analysis of Micro Air Vehicles |
Mar-2009 |
156 pages |
| Authors:
Mustafa Turan; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH GRADUATE SCHOOL OF ENGINEERING AND MANAGEMENT
|
| Micro Air Vehicles (MAV) are a subset of Unmanned Aircraft (UAS) that are up to two orders of magnitude smaller than manned systems. Near-Earth environments, such as forests, caves, tunnels and urban structures make reconnaissance, surveillance and search-and-rescue missions difficult and dangerous to accomplish. Therefore, MAVs are considered ideal for these types of missions. However, the data using full size aircraft is inadequate to characterize miniature aircraft parameters due to ... |
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| Equivalence of Convex Problem Geometry and Computational Complexity in the Separation Oracle Model |
Jan-2009 |
22 pages |
| Authors:
Robert M Freund; Jorge Veraz; MASSACHUSETTS INST OF TECH CAMBRIDGE OPERATIONS RESEARCH CENTER
|
| Consider the following supposedly-simple problem: compute x satisfying x in S, where S is a convex set conveyed by a separation oracle, with no further information (e.g., no bounding ball containing or intersecting S, etc.). Our interest in this problem stems from fundamental issues involving the interplay of (i) the computational complexity of computing a point x in S, (ii) the geometry of S, and (iii) the stability or conditioning ... |
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| The Modal Decomposition of the Quality Factor of an Antenna in Prolate Spheroidal Coordinates |
01-Sep-2008 |
61 pages |
| Authors:
R C Adams; P M Hansen; SPACE AND NAVAL WARFARE SYSTEMS CENTER SAN DIEGO CA
|
| This report discusses extending the results for prolate spheroids by including higher order modes and finding the sum of modes giving the minimum radiation Q. There is no coupling between odd and even modes, but there is coupling between the lowest order even modes. The report also presents a simple result for the values of the degree of mixing of modes 2, 4, and 6 that minimizes Q(sub r). |
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| Novel Carbon Nitride Nanowire (CNW) Conjugates for Breast Cancer Treatment |
Sep-2008 |
11 pages |
| Authors:
David Carroll; WAKE FOREST UNIV WINSTON-SALEM NC
|
| In this program we have tested the concept that carbon nitride nanowires (CNWs)-conjugated to Herceptin can selectively target and photo-thermally ablate HER2-positive breast cancer tissues using penetrating near infra-red radiation (1.06 microns). Our initial results in cell culture suggest that CNWs are far superior transducers of radiation to the SWNTs or Ag nanoshells due to their metallic nature and aspect ratio. Initial animal studies have begun. |
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| Study of the Issues of Computational Aerothermodynamics Using a Riemann Solver |
01-Jul-2008 |
|
| Authors:
James A Menart; Sean J Henderson; WRIGHT STATE UNIV DAYTON OH
|
 | This work is part of a project to more accurately model hypersonic flow. A number of issues in hypersonic flow are addressed. The first issue addressed is that of air properties at increased temperatures. Thermodynamic and transport properties of chemical equilibrium air are found for temperatures up to 30,000 K for a pressure range from 1x10-4 to 100 atm. This work also covers adding equilibrium air chemistry to the computational ... |
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| Advanced Cathodes for Next Generation Electric Propulsion Technology |
01-Mar-2008 |
174 pages |
| Authors:
Dustin J Warner; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
|
| The research presented here investigated the feasibility of a 6.4 mm Lanthanum Hexaboride (LaB6) and Cerium Hexaboride (CeB6) hollow cathode for low power electric propulsion applications (100-300W). Two orifice geometries, one anode configuration, several anode and keeper currents, and a range of flow rates were tested for the LaB6 cathode. The CeB6 cathode underwent the same tests, with the exception of the second orifice geometry due to time constraints. The ... |
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| Seismic Energy Generation and Partitioning into Various Regional Phases from Different Seismic Sources in the Middle East Region |
20 SEP 2007 |
85 pages |
| Authors:
Yefim Gitterman; Vladimir Pinsky; Rami Hofstetter; GEOPHYSICAL INST OF ISRAEL HOLON (ISRAEL)
|
| The project was focused on studying, experimentally, features of seismic energy generation and partitioning of P and S waves from different explosive seismic sources, at near-source and regional distances, in the time and spectral domain. An extensive database of Ground Truth single-fired explosions was created. The explosions selected contain a broad variety of design features (buried and surface sources, tamped and decoupled shots, large diameter 0.5-0.8m borehole and near-spherical cavity ... |
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| Localized Surface Plasmon Resonance of Metal Nanodot Nanowire Arrays Studied by Far-Field and Near-Field Optical |
05 SEP 2007 |
8 pages |
| Authors:
Heh-Nan Lin; NATIONAL TSING HUA UNIV HSINCHU (TAIWAN) DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| A combination of AFM nanomachining and lift-off process based on the one-layer approach is a convenient method for the fabrication of metal nanostructures. For an obtained Au nanodot array with an average diameter of 72 nm, the resonance peak in the LSPR scattering spectrum is located at 548 nm and consistent with simulated spectrum from Mie theory. For the Au nanowire arrays, the LSPR scattering spectra are composed of two ... |
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| Advanced Materials Deposition for Semiconductor Nanostructures Using Supercritical Fluids |
APR 2007 |
78 pages |
| Authors:
Chien M. Wai; IDAHO UNIV MOSCOW
|
| Supercritical fluid carbon dioxide provides an attractive medium for depositing materials in small structures with high aspect ratios and poorly wettable substrates due to the fact that it is able to dissolve solutes like a liquid and transport dissolved materials like a gas. Metal and metal sulfide nanoparticles of controllable size can be synthesized in supercritical fluid carbon dioxide using water-in-CO2 microemulsion as template. Continuous tuning the size of metallic ... |
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| Tip Clearance Control Using Plasma Actuators |
MAR 2007 |
73 pages |
| Authors:
Scott C. Morris; Thomas C. Corke; NOTRE DAME UNIV IN DEPT OF AEROSPACE AND MECHANICAL ENGINEERING
|
| This report documents experimental results from a series of experiments using active flow control to improve the performance and efficiency of turbine tip clearance flows. The flow control was based on plasma actuators. Two experimental facilities were used as part of this research project. The first was a low-speed, large-scale turbine cascade using Pak-B turbine blades. The second was a smaller scale, high-speed cascade with low aspect ratio. The active ... |
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| Quantifying the Effect Of Fuselage Cross-Sectional Shape on Structural Weight (PREPRINT) |
MAR 2007 |
22 pages |
| Authors:
Michael A. Falugi; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH ADVANCED STRUCTURAL CONCEPTS BRANCH
|
| Analytical trade studies were set up and are being performed to quantify the effect of fuselage cross-sectional shape on structural weight for a cargo transport aircraft. The target vehicle design reflects various geometry, aerodynamic and inertia loads, internal pressurization, and other requirements associated with a medium-sized military transport configuration. Several elliptical cross-sections and at least one cross section containing one or more flat (LO-friendly) outer mold line segments are being ... |
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| Laser Plasma Instability Experiments with KrF Lasers |
2007 |
40 pages |
| Authors:
J. L. Weaver; J. Oh; B. Afeyan; L. Phillips; J. Seely; U. Feldman; C. Brown; Karasik M.; V. Serlin; Y. Aglitskiy; A. N. Mostovych; NAVAL RESEARCH LAB WASHINGTON DC PLASMA PHYSICS DIV
|
| Deleterious effects of laser-plasma instability (LPI) may limit the maximum laser irradiation that can be used for inertial confinement fusion. The short wavelength (248 nm), large bandwidth, and very uniform illumination available with krypton-fluoride (KrF) lasers should increase the maximum usable intensity by suppressing LPI. The concomitant increase in ablation pressure would allow implosion of low aspect ratio pellets to ignition with substantial gain (>20) at much reduced laser energy. ... |
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| Experimental Investigation of the Aerodynamic Ground Effect of a Tailless Lambda-Shaped UCAV with Wing Flaps |
JUN 2006 |
209 pages |
| Authors:
Jason T. Mostaccio; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
|
| This experimental study adequately identified the ground effect region of a lambda-shaped unmanned combat air vehicle (UCAV). The lambda planform used in this study was originally tested in a previous experiment to determine the stability and control characteristics generated out-of-ground-effect. The following study extends the existing database by analyzing the inherent aerodynamic behavior that is produced by employing trailing edge flap deflections while flying in-ground-effect (IGE). To accomplish this objective, ... |
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| Composites Reinforced with Short Wavy Fibers |
01 MAR 2006 |
30 pages |
| Authors:
C. T. Sun; J. Cho; A. Deo; PURDUE UNIV LAFAYETTE IN
|
| In short fiber composites including nanocomposites, the load transfer efficiency among fibers is crucial in effecting superior composite properties. It is conceivable that this load transfer efficiency depends on the shape, aspect ratio, and surface area of the fiber. The effect of surface area of the reinforcing element is of particular importance because of the increasing use of nanoparticles in nanocomposites. It is well known that for the some volume, ... |
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| Experimental Investigation Into the Aerodynamic Ground Effect of a Tailless Chevron and Lambda-shaped UCAVs |
MAR 2006 |
147 pages |
| Authors:
Won In; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH DEPT OF AERONAUTICS AND ASTRONAUTICS
|
| As future aircraft migrate toward tailless, blended wing body configurations, aircraft designers are faced with a lack of experimental data that represent these types of configurations. A wind tunnel investigation was conducted to identify the ground effect region of two unmanned combat air vehicle (UCAV) models. The AFIT low-speed wind tunnel (LSWT) and ground plane were used to study the forces and moments on the UCAV models in ground effect. ... |
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| Quantifying Consolidation and Reordering in Natural Granular Media from Computed Tomography Images |
2006 |
10 pages |
| Authors:
Allen H. Reed; Karsten E. Thompson; Wenli Zhang; Clinton S. Willson; Kevin B. Briggs; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS SEAFLOOR SCIENCES DIRECTORATE
|
| Packing of granular media is an extremely important determinant in reservoir rock evolution, sound speed propagation, fluid flow and sediment compressibility. X-ray microfocus computed tomography (XMCT) images with high-resolution were evaluated using a grain-based algorithm that quantifies discrete components and bulk properties of sedimentary systems at different states of compaction or at approximately minimum and maximum packing densities. Angularity of these sands ranges from rounded to subrounded to subangular. Network ... |
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| Mid-Infrared Quantum Dot Cascade Lasers |
18 NOV 2005 |
10 pages |
| Authors:
Dennis G. Deppe; TEXAS UNIV AT AUSTIN OFFICE OF SPONSORED PROJECTS
|
| This project conducts research necessary to design, growth, and demonstrate laser action in semiconductor quantum dots based on unipolar injection. The designs use new injection techniques that account for the electron wavefunction symmetries based on the height-to-base aspect ratios of self-organized quantum dots. The material systems being explored are InAs quantum dots grown within either GaAs-based or InP-based heterostructures. While GaAs-based quantum dots are better developed, InP-based quantum dots benefit ... |
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| Application of a New Grain-Based Reconstruction Algorithm to Microtomography Images, for Quantitative Characterization and Flow Modeling |
OCT 2005 |
12 pages |
| Authors:
Karsten E. Thompson; Clinton S. Willson; Christopher D. White; Stephanie Nyman; Janok Bhattacharya; Allen H. Reed; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS SEAFLOOR SCIENCES DIRECTORATE
|
| X-ray computed microtomography (XMT) is used for high-resolution, non-destructive imaging and has been applied successfully to geologic media. Despite the potential of XMT to aid in formation evaluation, currently it is used mostly as a research tool. One factor preventing more widespread application of XMT technology is limited accessibility to microtomography beamlines. Another factor is that computational tools for quantitative image analysis have not kept pace with the imaging technology ... |
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| Multilayer and Functional Coatings on Carbon Nanotubes using Atomic Layer Deposition |
29-Jul-2005 |
4 pages |
| Authors:
C F Herrman; F H Fabreguette; D S Finch; R Geiss; S M George; COLORADO UNIV AT BOULDER DEPT OF CHEMISTRY AND BIOCHEMISTRY
|
| Atomic layer deposition ALD can be used to deposit ultra-thin and conformal films on flat substrates, high aspect ratios structures and particles. In this paper, we demonstrate that insulating, multilayered and functionalized ALD coatings can also be deposited conformally on carbon nanotubes. Multilayered coatings consisting of alternating layers of dielectric and conductive materials, such as Al2O3 and W, respectively, are deposited on conductive multi-walled carbon nanotubes. This coated carbon nanotube ... |
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| Three-Dimensional Rayleigh-Benard Convection of a Rarefied Gas: DSMC and Navier-Stokes Calculations |
13 JUL 2005 |
7 pages |
| Authors:
S. K. Stefanov; V. M. Roussinov; C. Cercignani; BULGARIAN ACADEMY OF SCIENCES SOFIA INST OF MECHANICS
|
| The three-dimensional Rayleigh-Benard convection of a rarefied gas is studied numerically by using DSMC and Navier-Stokes finite difference methods. We present the results obtained in a three-dimensional box with an aspect ratio A=Lx:Ly:Lz at a fixed wall temperature ratio r=Tc/Th=0.1. In general, the three-dimensional results confirm the validity of the zone of convection obtained in the previous author's two-dimensional considerations. A detailed analysis has been performed for Knudsen number Kn=0.02 ... |
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| Experimental Investigation Into the Aerodynamic Ground Effect of a Tailless Chevron-Shaped UCAV |
JUN 2005 |
128 pages |
| Authors:
Brett L. Jones; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
|
| This experimental study adequately identified the ground effect region of an unmanned combat air vehicle (UCAV). The AFIT 3' x 3' low-speed wind tunnel and a ground plane were used to simulate the forces and moments on a UCAV model in ground effect. The chevron planform used in this study was originally tested for stability and control and the following extends the already existing database to incude ground effects. The ... |
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| Two-Dimensional Photonic Crystals for Near IR and Visible Optoelectronics Applications |
2005 |
|
| Authors:
David McIlroy; IDAHO UNIV MOSCOW
|
| The focus of this project is to develop a process for constructing two-dimensional (2D) photonic crystals, which will be amenable to commercialization. Our approach has been to utilize nanochannel glass (NCG), which consists of a 2D hexagonal arrays of cylindrical voids that traverse the entire thickness of the glass. A 2D photonic can be realized with NCG if high index materials with good transmission properties can be introduced into the ... |
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| Multifrequency Retrieval of Cloud Ice Particle Size Distributions |
2005 |
87 pages |
| Authors:
Brian D. Griffith; COLORADO STATE UNIV FORT COLLINS DEPT OF ATMOSPHERIC SCIENCE
|
| There are many sources of uncertainty in remote sensing retrievals. This is particularly true where complex parameters such as liquid or ice hydrometeors must be retrieved. Many of the uncertainties are the direct result of assumptions made in the retrieval process to address the ill-posed nature of the inverse problem namely that there are more variables than measurements. In this paper, an optimal estimation retrieval technique is applied to a ... |
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| Polymer Nanocomposites by Melt Processing |
DEC 2004 |
21 pages |
| Authors:
D. R. Paul; TEXAS UNIV AT AUSTIN
|
| The objective of this project was to establish the basic principles of formation of polymer-organoclay nanocomposites by melt processing techniques and their performance. The key issue is to exfoliate, or disperse, the clay platelets in the polymer so that the highest possible aspect ratio is achieved. It was shown that this depends critically on the extruder type, screw configuration, the structure of the surfactant on the organoclay, and the melt ... |
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| Fundamental Issues Regarding the High Temperature Failure Properties of Graphite/Polyimide Fabric Composites |
OCT 2004 |
172 pages |
| Authors:
M. S. Kumosa; DENVER UNIV CO DEPT OF ENGINEERING
|
| In this work, a method based on X-ray diffraction (XRD) measurements of internal stresses in embedded metallic ellipsoidal inclusions is briefly described. The method has been recently developed for the determination of residual thermal stresses in high temperature graphite/polyimide composites. The effects of external bending loads and aging on the measurements of the internal stress in unidirectional and woven graphite fiber (T650-3 5)/polyimide (PMR-15) composites were examined in addition to ... |
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| Evaluation of "Q" in an Electrically Small Antenna in Prolate Spheroidal Coordinates |
SEP 2004 |
30 pages |
| Authors:
R. C. Adams; P. M. Hansen; SPACE AND NAVAL WARFARE SYSTEMS COMMANDSAN DIEGO CA
|
| This document describes the energy distribution within an electrically small antenna. Chu (1948) derived expressions for the "Q" of an omnidirectional antenna whose entire structure is enclosed within a sphere. Many authors have extended this technique. Because the sphere is not conformal to the structure of most linear polarized antennas, much energy is not accounted for. If the structure is surrounded by an ellipsoid of revolution, the fit is much ... |
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| Wide-Angle X-Ray Scattering Characterization of the Morphology of Nylon 6 6 Obturator Materials |
AUG 2004 |
26 pages |
| Authors:
Frederick L. Beyer; Christopher Ziegler; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| Two polyamides. both nylon 6 6. were characterized by wide angle X- ray scattering (WAXS) for variations in morphology that would account for observed differences in mechanical properties. Both materials were found to be macroscopically isotropic. consisting almost entirely of lamellae composed of alpha(sub p) sheets. No evidence of beta(sub p) phase material was found. but both materials showed some evidence of the presence of the nonequilibnum gamma (pseudo-hexagonal) phase. ... |
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| Flow Control Enabled Aircraft Design |
JUL 2004 |
236 pages |
| Authors:
Rajendar K. Nangia; NANGIA AERO RESEARCH ASSOCIATES BRISTOL(UNITED KINGDOM)
|
| This report results from a contract tasking Nangia Aero Research Associates as follows: Many future advanced aircraft concepts being considered by the Air Force fall outside the current aerodynamic design practice and will rely heavily on the use of flow control technology to optimize flight performance. Examples include SensorCraft, long range strike aircraft, ultra STOL transports, and hypersonic aircraft. To properly design and optimize the aerodynamic performance of these vehicle ... |
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| Advanced Fabrication and Characterization of Quantum and Nanophotonic Devices and Systems |
30 JUN 2004 |
23 pages |
| Authors:
Y. Fainman; CALIFORNIA UNIV REGENTS SAN DIEGO LA JOLLA CA
|
| The program completed its acquisition of equipment for the Micro- Fabrication Facility. The facility is used for fabrication of Quantum and Nanophotonic devices and consists of a CAIBE system capable of sub- micron resolution anisotropic (i.e. high aspect-ratio) etching and a RIE refurbished by INTELVAC Inc. A major capability is a facility for near field complex amplitude characterization with nanoscale spatial and femtosecond scale time resolution for nanophotonics applications. This ... |
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| A Photoelastic Study of Cracking in Motor Grain Models |
21 MAY 2004 |
11 pages |
| Authors:
C. W. Smith; J. D. Hansen; VIRGINIA POLYTECHNIC INST AND STATE UNIV BLACKSBURG DEPT OF ENGINEERING SCIENCE AND MECHANICS
|
| By capitalizing on observed similarities between the cracked finned model and a cracked cylinder when placing the fin top at the inner edge of the cylinder, estimates were made by assuming a plane strain solution for the finned model in finite length models. Based upon the aforementioned limited results, use of a modified plane strain solution appears to yield a slightly conservative prediction for long shallow cracks to significantly conservative ... |
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| Increasing Wet Green Strength of Alumina Body During Microfabrication by Colloidal Isopressing |
06 MAY 2004 |
9 pages |
| Authors:
Zhuo Zhang; Biao Liu; Frederick F. Lange; CALIFORNIA UNIV SANTA BARBARA DEPT OF MATERIALS
|
| Colloidal Isopressing involves formulating a slurry with a weakly attractive particle network that can be pre-consolidated to a high relative density by pressure filtration and still retain fluid-like characteristics. The pre-consolidated slurry is injected into an elastomeric mold and isopressed. Isopressing rapidly convert the slurry into an elastic body that can be removed from the mold without shape distortion. Not only is this process rapid, but since the water saturated ... |
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| Dynamics of Etching at the Gas-Surface Interface |
19 JAN 2004 |
16 pages |
| Authors:
Timothy K. Minton; MONTANA STATE UNIV BOZEMAN
|
| The primary objective of this research project is to elucidate fundamental chemical and physical processes that contribute to the etching of polymers and semiconductors in dry etching environments. This fundamental knowledge should help enable the design of novel etch processes for specialty applications where fine features with high aspect ratios are critical. The new knowledge generated by this project will not only suggest new etch processes, but it will add ... |
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| Development of Composites Reinforced with Short Wavy Fibers |
2004 |
8 pages |
| Authors:
C. T. Sun; PURDUE UNIV LAFAYETTE IN
|
| In short fiber composites including nanocomposites, the load transfer efficiency among fibers is crucial in effecting superior composite properties. It is conceivable that this load transfer efficiency depends on the shape, aspect ratio, and surface area of the fiber. The effect of surface area of the reinforcing element is of particular importance because of the increasing use of nano particles in nanocomposites. It is well known that for the same ... |
|
| Neural Network Control of a Parallel Hybrid-Electric Propulsion System for a Small Unmanned Aerial Vehicle |
2004 |
29 pages |
| Authors:
Frederick G. Harmon; Andrew A. Frank; Jean-Jacques Chattot; Sanjay S. Joshi; CALIFORNIA UNIV DAVIS
|
| Parallel hybrid-electric propulsion systems would be beneficial for small unmanned aerial vehicles (UAVs) used for military, homeland security, and disaster monitoring missions involving intelligence, surveillance, or reconnaissance (ISR). The benefits include increased time-on-station and range than electric-powered UAVs and stealth modes not available with gasoline-powered UAVs. A conceptual design of a small UAV with a parallel hybrid-electric propulsion system, an optimization routine for the energy use, the application of a ... |
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| Configuration Studies Supporting Design/Assessment of Sensor Craft |
21 NOV 2003 |
70 pages |
| Authors:
Rajendar K. Nangia; NANGIA AERO RESEARCH ASSOCIATES BRISTOL(UNITED KINGDOM)
|
| This report results from a contract tasking Nangia Aero Research Associates as follows: The objective of the proposed work is to support on-going research at the Configuration Aerodynamics Branch (AFRL/VA) for design/ assessment of a Sensor Craft configuration. The sensor aircraft is subject to challenging flight envelope (mission profile). The design at present is relatively "fluid". Box wings of different layouts arise. It has to cruise and loiter (very high ... |
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| Micromachined Precision Inertial Instruments |
NOV 2003 |
106 pages |
| Authors:
Khalil Najafi; MICHIGAN UNIV ANN ARBOR
|
| This program focuses on developing inertial-grade micromachined accelerometers and gyroscopes and their associated electronics and packaging for use in a variety of military and commercial applications. During the project timeline in-plane, out-of-plane and monolithic 3-axis accelerometers have been developed with their interface electronics. Analysis, simulation, fabrication, and testing techniques for these accelerometer systems have been developed. |
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| Micro-Fabrication of Spray Cooling Nozzles for High-Power Diode Laser Arrays |
28 AUG 2003 |
10 pages |
| Authors:
Louis C. Chow; UNIVERSITY OF CENTRAL FLORIDA ORLANDO DEPT OF MECHANICAL MATERIALS AND AEROSPACE ENGINEERING
|
| An important growing field in today's engineering is the development of Micro-Electrical and Mechanical Systems (MEMS). Over the years there have been many different fabrication processes that have been developed to meet these new demands. Most of the current micro-fabrication techniques work well for simple two-dimensional components. However, the demand for more complicated three-dimensional parts requiring a high aspect ratio requires that a new approach must be taken to make ... |
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| Numerical and Experimental Analysis of the Performance of Staggered Short Pin-Fin Heat Exchangers |
JUN 2003 |
187 pages |
| Authors:
Leonard J. Hamilton; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| A three dimensional finite element based numerical model was used to analyze the heat transfer characteristics of various staggered short pin-fin array heat exchangers. The simulation was validated against data from an experimental rig as well as historical data and then used to estimate the heat transfer coefficient and pressure drop for a wide range of Reynolds numbers for circular and airfoil-shaped pin fins. Circular pin configuration variations included changes ... |
|
| Development of Artificial Y-Type Hexaferrites |
01 MAY 2003 |
2 pages |
| Authors:
C. Vittoria; NORTHEASTERN UNIV BOSTON MA
|
| We have developed a technique to orient particles of Y-type hexaferrite in which the c-axis of the particles are oriented perpendicular to a plane As such, that plane becomes necessarily the easy plane of magnetization. For microwave device application the easy plane of magnetization is chosen as the plane to deposit a metallic microstrip and related circuit patterns. The technique entails the rotation of an external magnetic field in the ... |
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| Radiolytic Synthesis of Bimetallic Nanoparticles with High Aspect Ratio |
2003 |
6 pages |
| Authors:
C. M. Doudna; M. F. Bertino; S. Pillalamarri; F. D. Blum; A. T. Tokuhiro; MISSOURI UNIV-ROLLA DEPT OF PHYSICS
|
| We present a technique to synthesize high aspect ratio metallic nanostructures based on the radiolysis method. In our experiments, we use gamma rays to irradiate aqueous solutions containing Ag and Pt ions and a water-soluble polymer. The aspect ratio of the nanoparticles is controlled by varying the radiation dose rate, the type of polymer, and the type of counter ions. Transmission electron microscopy shows that wire-like structures composed of grains ... |
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| Computational Analysis of High Aspect Ratio Cooling Channels |
03 DEC 2002 |
3 pages |
| Authors:
Matt Gotchy; Al Ferrenberg; Curtis Johnson; Dan Greisen; SIERRA ENGINEERING INC CARSON CITY NV
|
| Many parameters can have an effect of the cooling ability and pressure drop performance in high aspect ratio cooling channels (HARCC) However few studies have attempted to quantify these effects In the present study Fluent was used to solve the three-dimensional fluid dynamics and conjugate heat transfer within cooling channels of a variety of aspect ratios. The objective of these studies was to explore the potential impact of the asymmetric ... |
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| A Numerical Study of Combined Convective and Radiative Heat Transfer in a Rocket Engine Combustion Chamber |
DEC 2002 |
|
| Authors:
Mehmet K. Savur; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| A numerical study was conducted to predict the combined convective and radiative heat transfer rates on the walls of a small aspect ratio cylinder representative of the scaled model of a rocket engine combustion chamber. A high-temperature, high-pressure environment was simulated in the cylinder, with gas velocities at low subsonic levels typical of the conditions leading to the entrance of the nozzle section of a rocket engine. The composition of ... |
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| Analytical Series Expressions for the Self- and Mutual Inductances of Two-Dimensional Coils in the Form of Partial Sectors |
NOV 2002 |
16 pages |
| Authors:
V. Thiagarajan; TEXAS UNIV AT AUSTIN INST FOR ADVANCED TECHNOLOGY
|
| Pulsed power generators of the drum type utilize radial components of magnetic fields created by field coils located on a rotor to induce voltage on stator coils located at larger radii. Conventionally, two-dimensional field analyses are used, and further, the field is expressed as a harmonic series and the fundamental part of the radial field is used for initial designs. Analytical series expressions for two-dimensional potentials and fields are utilized ... |
|
| Acoustic Scattering from Large Aspect Ratio Elastic Targets |
OCT 2002 |
85 pages |
| Authors:
Gary S. Sammelmann; COASTAL SYSTEMS STATION PANAMA CITY FL
|
| This paper applies the spheroidal T-matrix approach of Dr. Roger H hackman described in his paper 'The Transition Matrix for Acoustic and Elastic Wave Scattering in Prolate Spheroidal Coordinates', Journal of the Acoustic Society of America, 75(1), PP. 35-45 to describe the scattering from large aspect ratio targets. Due to the limits of double precision arithmetic in the computation of the spheroidal wave functions, these methods are limited to frequencies ... |
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| Ordered and Quantum Treemaps: Making Effective Use of 2D Space to Display Hierarchies |
OCT 2002 |
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| Authors:
Benjamin B. Bederson; Ben Shneiderman; Martin Wattenberg; MARYLAND UNIV COLLEGE PARK DEPT OF COMPUTER SCIENCE
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| Treemaps, a space-filling method for visualizing large hierarchical data sets, are receiving increasing attention. Several algorithms have been previously proposed to create more useful displays by controlling the aspect ratios of the rectangles that make up a treemap. While these algorithms do improve the visibility of small items in a single layout, they introduce instability over time in the display of dynamically changing data, fail to preserve order of the ... |
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| Mission and Micronozzle Flow Analysis of a High-Temperature Chemical Micropropulsion System |
14 AUG 2002 |
276 pages |
| Authors:
Jessy R. Jones; AIR FORCE INST OF TECH WRIGHT-PATTERSONAFB OH
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| Recent trends in small-scale satellites motivate the further development of the propulsion subsystem. Micro-electromechanical systems (MEMS) micronozzles provide sufficient geometries to produce impulse bits suitable for this scale of satellite. An area of concern with MEMS micronozzles is the inefficiency associated with viscous losses of the developing boundary layer. The University of Washington recently commenced research on a high- temperature propulsion system. An advantage of increased temperature levels is an ... |
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| Multi-Scale Finite Element Approximation for Transport in Heterogeneous Porous Media |
01 JUL 2002 |
9 pages |
| Authors:
Thomas Y. Hou; CALIFORNIA INST OF TECH PASADENA DEPT OF APPLIED MATHEMATICS
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| The main objective of this study is to develop an efficient multiscale coarse grid method which can be used as a competitive algorithm in studying composite materials and flow transport in strongly heterogeneous porous media. On one hand, we have explored the possibility of using adaptive mesh to reduce the modeling error introduced by the traditional moment average technique. On the other hand, we found that in the case of ... |
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