| Novel Metal-Matrix Composites With Integrally-Bound Nanoscale Carbon |
Jun 2012 |
5 pages |
| Authors:
David R Forrest; Iwona Jasiuk; Lloyd Brown; Peter Joyce; Azzam Mansour; Lourdes Salamanca-Riba; NAVAL SURFACE WARFARE CENTER CARDEROCK DIV BETHESDA MD
|
 | We characterized the chemical, thermophysical, and mechanical properties of nanomaterials with up to 5 wt% nanocarbon (aka covetics) in aluminum and copper metals. The nanocarbon is detectable by EDS and XPS but not by analytical methods such as LECO and GDMS. Nanocarbon raises the melting point and significantly alters surface tension, and thus porosity, during solidification. Open questions remain about the observation of higher density than would be predicted by ... |
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| EMIIM Wetting Properties of & Their Effect on Electrospray Thruster Design |
21 Mar 2012 |
75 pages |
| Authors:
Garrett D Reed; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIR
|
| Recent advances in the development of highly conductive ionic liquids have made them of interest for use as propellant in spacecraft propulsion systems. Electrospray thrusters apply strong electrostatic fields to an ionic liquid in order to extract and accelerate charged particles/droplets, producing thrust. The behavior of these ionic liquids as they pass through the components of an electrospray system can have a significant effect on thruster operation. The wetting and ... |
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| Wetting Properties of EMIIm & its Relevance to Electrospray Design |
12 Mar 2012 |
13 pages |
| Authors:
Garrett D Reed; Timothy W Fox; AIR FORCE RESEARCH LAB EDWARDS AFB CA
|
| Recent advances in the development of highly conductive ionic liquids have made them of interest for use as propellant in spacecraft propulsion systems. Electrospray thrusters apply strong electrostatic fields to an ionic liquid in order to extract and accelerate charged particles/droplets, producing thrust. The behavior of these ionic liquids as they pass through the components of an electrospray system can have a significant effect on thruster operation. The wetting and ... |
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| EMIIM Wetting Properties & Their Effect on Electrospray Thruster Design |
Mar 2012 |
75 pages |
| Authors:
Garrett D Reed; AIR FORCE RESEARCH LAB EDWARDS AFB CA
|
| Recent advances in the development of highly conductive ionic liquids have made them of interest for use as propellant in spacecraft propulsion systems. Electrospray thrusters apply strong electrostatic fields to an ionic liquid in order to extract and accelerate charged particles/droplets, producing thrust. The behavior of these ionic liquids as they pass through the components of an electrospray system can have a significant effect on thruster operation. The wetting and ... |
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| Superoleophobic yet Superhydrophilic surfaces for Continuous Liquid-Liquid Separation |
08 Dec 2011 |
21 pages |
| Authors:
Anish Tuteja; MICHIGAN UNIV ANN ARBOR DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| There is a critical need to develop new energy-efficient solutions for the separation of oil-water mixtures, including those stabilized by surfactants. Traditional membrane-based separation technologies for oil-water mixtures are energy-intensive and further limited, either by fouling or the inability of a single membrane to separate all types of oil-water mixtures. The ideal membrane to effect gravity-driven separation of oil-water mixtures is expected to be both hydrophilic and oleophobic, in air ... |
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| The Design of Non-Wetting Surfaces with FluoroPOSS |
19 Aug 2011 |
22 pages |
| Authors:
Anush Tuteja; Joseph M Mabry; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIR/SPACE AND MISSILE PROPULSION DIV
|
| Functional non-wetting materials are of interest for a diverse array of applications. It has long been understood that factors contributing to the wettability of a surface include surface free energy and surface roughness. More recently, surface texture has been found to be of equal or greater importance, especially if the desire is for the surface to repel low surface tension liquids, such as short-chain hydrocarbons and alcohols. This chapter will ... |
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| Exploration of the Fundamental Properties and Consequences of Fluorinated Polyhedral Oligomeric Silsequioxanes (FluoroPOSS) |
02 Jul 2011 |
12 pages |
| Authors:
Gareth H McKinley; Anish Tuteja; Robert E Cohen; MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF MECHANICAL ENGINEERING
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| Designing and producing highly oil-resistant or 'superoleophobic' surfaces that robustly resist wetting by oily liquids is a challenge that has eluded both nature and material scientists to date. The focus of the research performed under this award was to develop a systematic understanding of the design constraints and engineering/materials solutions required to develop truly oleophobic surfaces. Theoretical calculations suggest that creating such superoleophobic surfaces would require a surface energy lower ... |
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| Propulsion and Power Rapid Response Research and Development (R&D) Support. Delivery Order 0011: Analysis of Synthetic Aviation Fuels |
APR 2011 |
251 pages |
| Authors:
Gary B. Bessee; Scott A. Hutzler; George R. Wilson; SOUTHWEST RESEARCH INST SAN ANTONIO TX
|
| The overall aim of this effort was to provide fit-for-purpose testing and subject matter expertise to UTC and AFRL to support the evaluation of emerging synthetic aviation fuels. The report contains information on the evaluations of various synthetic aviation fuels including: Sasol IPK, R-8 HRJ SPK, R-8x HRJ SPK, Boeing Flight Fuels, Camelina HRJ SPK, Camelina/JP-8 (HRJ8), R-8/Jet A, Tallow HRJ SPK and Tallow/JP-8 (HRJ8). In addition, miscellaneous analyses including ... |
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| Temperature Effects on Electrospray Performance |
Mar 2011 |
103 pages |
| Authors:
Nicholas A Kreitinger; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIR/SPACE AND MISSILE PROPULSION DIV
|
| Electrospray thrusters have been considered for the past 50 years. However, the low conductivity and high volatility of liquids that were available in the past resulted in thrusters that required too much power for them to be a viable propulsion option. The lack of micro-fabrication techniques also resulted in electrospray thrusters with a large inert mass fraction. These constraints have changed in recent times with the formulation and development of ... |
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| Two Dynamical System Models Based on Real-World Scenarios: A Swarming Control Model and a Surface Tension Model |
Jan 2011 |
108 pages |
| Authors:
Wangyi Liu; CALIFORNIA UNIV LOS ANGELES
|
| Dynamical systems are quite often used to describe complex real-life phenomena. In this dissertation we consider two different scenarios where we propose such models. In the first part we consider the problem of collaborative searching where agents try to search for unknown targets while keeping group formation. This scenario is observed in many animal groups, and can be applied to man-made problems like searching for mines. We use a basic ... |
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| Particle-laden Thin Film Flow: An Alternating Direction Implicit Scheme and Comparison between Theory, Numerical Simulations, and Experiments |
Jan 2011 |
122 pages |
| Authors:
Matthew R Mata; CALIFORNIA UNIV LOS ANGELES DEPT OF MATHEMATICS
|
| Gravity-driven thin film flows have been analyzed in terms of fourth-order lubrication models, similarity solutions, traveling wave solutions, numerical simulations and experiments. However, in the case where particle are suspended within the fluid, studies have been largely limited to lubrication models, one-dimensional numerical simulations, and experiments. We present a numerical scheme for a lubrication model derived for particle-laden thin film flow in two dimensions with surface tension. The scheme relies ... |
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| Solution Spraying of Poly(methyl methacrylate) Blends to Fabricate Micro-textured, Superoleophobic Surfaces (PREPRINT) |
2011 |
28 pages |
| Authors:
Siddarth Srinivasan; Shreerang S. Chhatre; Joseph M. Mabry; Robert E. Cohen; Gareth H. McKinley; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIR/SPACE AND MISSILE PROPULSION DIV
|
| We describe a simple technique to prepare superhydrophobic and superoleophobic micro-textured surfaces by spray coating a blend of poly(methyl methacrylate) (PMMA) and the low surface energy molecule 1H,1H,2H,2H-heptadecafluorodecyl polyhedral oligomeric silsesquioxane (fluorodecyl POSS, gamma(sv) approximately equal to 10 mN/m) using an air brush with a pressurized nitrogen stream. Scanning electron micrographs show the formation of micro-textured surfaces possessing re-entrant curvature; a critical feature for obtaining liquid repellency with low surface ... |
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| Inverse Coarse-Graining: A New Tool for Molecular Design |
16 Dec 2010 |
4 pages |
| Authors:
Gregory A Voth; UTAH UNIV SALT LAKE CITY
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| In this AFOSR project a very important set of atomistic and coarse-grained (CG) molecular dynamics (MD) simulations were designed and performed to study the structure and dynamical properties of room temperature ionic liquids (ILs). Eight papers in total were published during the grant period.1-8 Overall, a number of particularly high impact and ground-breaking publications have come out of this body of research, including a reviews in a Special Issue of ... |
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| Understanding Nanoscale Thermal Conduction and Mechanical Strength Correlation in High Temperature Ceramics With Improved Thermal Shock Resistance for Aerospace Applications |
21 Oct 2010 |
16 pages |
| Authors:
Vikas Tomar; John E Renaud; NOTRE DAME UNIV IN
|
| Ceramics and semiconductors are an integral part of today s energy devices. This research addresses conductive heat transfer issues in such materials using a combination of classical and quantum mechanical atomistic simulations. For any kind of thermal system, thermal stress and thermal conduction cannot be decoupled. Such analyses have to be performed together. This research also focuses on understanding how mechanical strength gets affected by thermal conduction and vice-versa. We ... |
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| Design of Superhydrophobic Ultraoleophobic NyCo (POSTPRINT) |
Mar 2010 |
9 pages |
| Authors:
Hoon Joo Lee; Jeffery R Owens; NORTH CAROLINA STATE UNIV AT RALEIGH
|
| The apparent contact angles of dodecane droplets deposited on a 50:50 nylon:cotton blended woven fabric (NyCo) were measured, and the characteristics required for an ultraoleophobic surface were described. The metastable Cassie -Baxter model, a transition status from the original Cassie-Baxter model to the Wenzel model, was investigated to design ultraoleophobic surfaces and to understand the wetting behavior of such surfaces. Using chemical and geometrical modifications of NyCo, a surface having ... |
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| Hydrophobic Silsesquioxane Nanoparticles and Nanocomposite Surfaces |
23-Sep-2008 |
13 pages |
| Authors:
Darrell Marchant; Ashwani Vij; Isha Vij; Scott Iacono; Joseph M Mabry; Brent D Viers; Wade W Grabow; Patrick N Ruth; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE
|
| Fluorinated Polyhedral Oligomeric Silsesquioxanes are hydrophobic nanoparticles. One compound, FD8T8, is ultrahydrophobic, possessing a water contact angle of 154-deg. This is believed to be the most hydrophobic and lowest surface tension crystalline substance known. Analysis of the x-ray crystal structure indicates a large number of Si-deg F contacts may lead to ultrahydrophobicity. |
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| The Key Role of Surface Tension in the Theory of Bubble-Assisted Explosion/Combustion Triggering |
01-Sep-2008 |
20 pages |
| Authors:
Michael Grinfeld; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
|
| We have revised the classical and widely accepted theory of (Bowden, F. P.; Yoffe, A. D. The Initiation and Growth of Explosion in Liquids and Solids; Cambridge University Press: New York, NY, 1952) explaining the initiation of explosion/combustion by means of adiabatic compression of the dissolved gaseous bubbles within condensed liquid substances. The main thrust of our study is to explore the role of surface tension at the interface liquid ... |
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| Modeling Liquid Rocket Engine Atomization and Swirl/Coaxial Injectors |
27-Feb-2008 |
95 pages |
| Authors:
Stephen Heister; PURDUE UNIV LAFAYETTE IN SCHOOL OF AERONAUTICS AND ASTRONAUTICS
|
| This report summarizes efforts to enhance our knowledge of the dynamic processes associated with injectors in liquid rocket engines. Progress has been made on a number of fronts. Linear stability analysis has been performed to assess the wavelengths of instabilities in oxygen rich staged combustion (ORSC) injector elements. Most unstable wavelengths have been characterized over a wide parameter space to provide researchers with an understanding of drop sizes shed from ... |
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| Low-Cost Production of Photonic Bandgap Materials Through Bubbling |
SEP 2007 |
38 pages |
| Authors:
Daniel J. O'Brien; Eric D. Wetzel; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| Photonic bandgap materials (PBGMs) prevent the propagation of electromagnetic waves across certain wavelengths the so-called bandgap. This behavior is the result of periodic variations in the material's dielectric constant, with the location of the bandgap as a function of the spacing between dielectric features. PBGMs show great promise in optoelectronics as waveguides and in sensors. Unfortunately, the large-scale production of PBGMs is difficult. This report proposes a simple low-cost method ... |
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| Conduction and Convection of Heat Produced by the Attenuation of Laser Beams in Liquids |
SEP 2007 |
44 pages |
| Authors:
Irwin S. Goldberg; Misty Garcia; Saher Maswadi; Robert J. Thomas; Clifton D. Clark; SAINT MARY'S UNIV OF SAN ANTONIO TX
|
| Mathematical models are used to simulate temperature changes that are induced by the absorption of energy from propagating laser beams in water. Both convective and conductive heat transfer are considered. Thermally insulated surfaces as well as surfaces involving heat transfer with the surroundings are considered. The simulated results demonstrate the importance of thermal convection. In the first part of this report containers with closed surfaces are considered. In the second ... |
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| Firefighting Agent Research, Phase I |
APR 2007 |
73 pages |
| Authors:
Douglas S. Dierdorf; Mark A. Enlow; Seymour Stern; Virgil J. Carr; APPLIED RESEARCH ASSOCIATES INC TYNDALL AFB FL
|
| This project's objective is to replace current firefighting aqueous film forming foams, AFFF, with an agent that is twice as effective as fire extinguishment. By reducing the required foam/water solution, the deployed firefighting footprint will thereby be reduced. In order to do this, the mechanism of firefighting foams and surfactants must be determined. Such physical characteristics as equilibrium surface tension, dynamic interfacial tension, and surface pressure have been examined in ... |
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| A Method to Predict Atomization Performance in Gas-Centered Swirl-Coaxial Injectors |
27 MAR 2007 |
11 pages |
| Authors:
M. D. Lightfoot; S. A. Danczyk; D. G. Talley; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE
|
| The ability to predict atomizer performance can reduce the cost of system development in many areas. This paper investigates the atomization efficiency and droplet distribution from films with strong gas-phase influences. A prediction of atomization efficiency based on a general theory of the droplet creation process is given. In this process a disturbance is created on the film surface then broken down into droplets via stripping. The theory relates the ... |
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| Ultrahydrophobic Fluorinated Polyhedral Oligomeric Silsesquioxanes (F-POSS) (Preprint) |
25 JAN 2007 |
11 pages |
| Authors:
Joseph M. Mabry; Scott T. Iacono; Brent D. Viers; Ashwani Vij; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE
|
| Recently, significant attention has been drawn to preparing low surface energy materials inspired by naturally evolved biological systems possessing a high degree of ultrahydrophobicity. Specifically, the lotus leaf exhibits an inherent self-cleaning mechanism resulting from micron-sized waxy nodes protruding from its surface so that water is naturally repelled removing any foreign debris. This remarkable cleansing mechanism, coined the "lotus effect," has been artificially mimicked to produce materials with pronounced ultrahydrophobicity. ... |
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| Carbon Materials Research |
AUG 2006 |
49 pages |
| Authors:
Wesley P. Hoffman; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE
|
| A basic research study in carbon materials for propulsion applications led to research in seemingly diverse areas, which include carbon-carbon composite fabrication, oxidation protection of carbon, microelectromechanical (MEMs) devices, and surface tension phenomena. Carbon-carbon composites are the material of choice in many high temperature thermostructural applications, such as rocket nozzles and exit cones, missile nosetips, and leading edges of hypersonic vehicles. Although these materials are stronger than steel, stiffer than ... |
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| Collaborative Research and Development Delivery. Order 0041: Models for the Prediction of Interfacial Properties |
AUG 2006 |
24 pages |
| Authors:
Bence Bartha; UNIVERSAL TECHNOLOGY CORP DAYTON OH
|
| The research in support of the Air Force Research Laboratory, Materials and Manufacturing Directorate was conducted at Wright-Patterson AFB, Ohio from 25 July 2005 through 4 August 2006. The task developed various experimental and computational tools to determine the material behavior of weld interfaces and local grain behavior of materials. Stereo imaging, optical microscopy and scanning electron microscopy were used to determine the local interfacial characteristics of welds as well ... |
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| Mixing Dynamics of Supercritical Droplets and Jets (Revised To Include Appendices) |
AUG 2006 |
375 pages |
| Authors:
D. G. Talley; R. K. Cohn; E. B. Coy; B. Chehroudi; D. W. Davis; AIR FORCE RESEARCH LAB EDWARDS AFB CA SPACE AND MISSILE PROPULSION DIV
|
| This report summarizes a research program to understand the mixing dynamics of supercritical droplets and jets. The research was motivated by the recognition that pressures in modern liquid rocket engine combustion chambers tend to be higher than the critical pressure of one or more of the propellants. Prior to the beginning of this research, combustion processes were largely modeled using low pressure, subcritical spray combustion concepts. At supercritical pressures, however, ... |
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| Hydrophobic Silsesquioxane Nanoparticles and Nanocomposite Surfaces (POSTPRINT) |
04 MAY 2006 |
13 pages |
| Authors:
Joseph M. Mabry; Darrell Marchant; Brent D. Viers; Ashwani Vij; Wade Grabow; Patrick N. Ruth; Isha Vij; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE
|
| Fluorinated Polyhedral Oligomeric Silsesquioxanes are hydrophobic nanoparticles. One compound, FD8T8, is ultrahydrophobic, possessing a water contact angle of 154 deg. This is believed to be the most hydrophobic and lowest surface tension crystalline substance known. Analysis of the x-ray crystal structure indicates a large number of Si...F contacts may lead to ultrahydrophobicity. |
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| Supercritical Hydrocarbon Impinging Injector Simulation Facility |
APR 2006 |
7 pages |
| Authors:
Michael M. Micci; PENNSYLVANIA STATE UNIV UNIVERSITY PARK DEPT OF AEROSPACE ENGINEERING
|
| A supercritical hydrocarbon impinging injector simulation facility was procured and installed to increase the available computational capability to conduct molecular dynamics simulations of supercritical impinging injectors using hydrocarbon propellants. Supercritical impinging injectors using hydrocarbon propellants are of interest to the next generation of liquid propellant rocket engines. The procured high performance computing cluster allows simulations to be conducted in a sufficiently short time period to allow investigation of the effects ... |
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| Control Issues for Microelectromechanical Systems |
APR 2006 |
6 pages |
| Authors:
B. Borovic; F. L. Lewis; W. McCulley; Ai Q. Liu; E. S. Kolesar; D. O. Popa; TEXAS UNIV AT ARLINGTON
|
| MEMS is a disruptive technology that requires unparalleled synergy between previously unrelated fields such as biology and microelectronics. With successful integration of electrical, mechanical, material, computer science, control, and bioengineering, new MEMS applications are emerging. Progress is facilitated by the fact that silicon, which is among the world's best-characterized materials, surpasses stainless steel in yield strength and aluminum in strengthtoweight ratio. Despite their small size on the order of that ... |
|
| On Boundary Condition Capturing for Multiphase Interfaces |
31 MAR 2006 |
26 pages |
| Authors:
Jeong-Mo Hong; Tamar Shinar; Myungjoo Kang; Ronald Fedkiw; STANFORD UNIV CA DEPT OF COMPUTER SCIENCE
|
| This paper begins with an overview of the boundary condition capturing approach to solving problems with interfaces. Although, the authors' original motivation was to extend the ghost fluid method from compressible to incompressible flow, the elliptic nature of incompressible flow quickly quenched the idea that ghost cells could be defined and used in the usual manner. Instead the boundary conditions had to be implicitly captured by the matrix formulation itself, ... |
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| Effect of Porous Media and Fluid Properties on Dense Non-Aqueous Phase Liquid Migration and Dilution Mass Flux |
AUG 2005 |
|
| Authors:
Christian T. Totten; FLORIDA UNIV GAINESVILLE DEPT OF ENVIRONMENTAL ENGINEERING SCIENCES
|
 | The influence of porous media and fluid properties on Non Aqueous Phase Liquid (NAPL) residual geometry and associated contaminant mass flux characteristics was investigated. Contaminant mass flux is a function of the source zone cross sectional area exposed to groundwater flow. Porous media and fluid properties affect source zone morphology leading to cross sectional area development. Media grain size and NAPL wettability were varied for relative comparisons. Fluid properties including ... |
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| Investigating the Effect of Displacement Rate on Deformation and Failure Mechanism in Bonded Elastomers |
JUL 2005 |
7 pages |
| Authors:
Fu-Pen Chiang; STATE UNIV OF NEW YORK AT STONY BROOK DEPT OF MECHANICAL ENGINEERING
|
| Bonded sandwich laminates are being used widely in various industries. They have been successfully used in aircraft and space structures, pipes, chemical tanks, ship hulls, and in other structural applications in which a high strength-to-weight ratio is a desirable feature. Joining structural components with adhesives provides a number of advantages. Bonding does not require rivet holes, which are stress raisers and may cause premature failure either under static or fatigue ... |
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| Light Actuation of Liquid by Optoelectrowetting |
01 JUN 2005 |
8 pages |
| Authors:
Pei Y. Chiou; Hyejin Moon; Hiroshi Toshiyoshi; Chang-Jin Kim; Ming C. Wu; CALIFORNIA UNIV LOS ANGELES DEPT OF ELECTRICAL ENGINEERING
|
| Optical actuation of liquid droplets has been experimentally demonstrated for the first time using a novel optoelectrowetting (OEW) principle. The optoelectrowetting surface is realized by integrating a photoconductive material underneath a two-dimensional array of electrowetting electrodes. Contact angle change as large as 30 degrees has been achieved when illuminated by a light beam with an intensity of 65 mW/sq cm. A micro-liter droplet of deionized water has been successfully transported ... |
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| The Molecular Design of Smart Polymer Surfaces |
25 OCT 2004 |
7 pages |
| Authors:
Jeffrey T. Koberstein; COLUMBIA UNIV NEW YORK
|
| Our long-term objective is to develop two new concepts for molecular design of smart polymer surfaces: end functional surface active block copolymers to create smart surfaces with selective adhesion properties, and surfaces with properties that can be switched with light. In the former case, chain interpenetration, if present, does not contribute significantly to the interfacial energy release rate; adhesion enhancement is only observed when the copolymer terminus reacts with the ... |
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| Interfacial Synthesis of Electrically Conducting Polyaniline Nanofiber Composites |
10 AUG 2004 |
14 pages |
| Authors:
A. R. Hopkins; D. D. Sawall; R. M. Villahermosa; R. A. Lipeles; AEROSPACE CORP EL SEGUNDO CA LAB OPERATIONS
|
| In this work, polyaniline/poly(sulfonated styrene) nanofiber composites were prepared by an interfacial method. The in-situ polymerization technique of these PANI nanofibers in the presence of sulfonated polystyrene allowed for the growth of PANI 2-D nanostructures embedded in the polymerized sulfonated host. This facile approach enables a self-assembly of these nanofibers into a workable, robust, conductive composite that can be processed and cast from water. A low accelerating voltage SEM was ... |
|
| A Cartesian Adaptive Level Set Method for Two-Phase Flows |
24 MAR 2004 |
11 pages |
| Authors:
F. Ham; Y. N. Young; STANFORD UNIV CA
|
| Simulations of flows involving free surfaces have become ubiquitous in the literature. The evolution of both simulation methods and computer speed have allowed the investigation of many problems of increasing complexity and engineering relevance. For 2D simulations, it is reasonably common to use grid resolutions of 512 x 512 or larger. See for example the 2D planar breaking wave simulations of Chen et al. (1999), or the axisymmetric drop breakup ... |
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| Surface Over-Melt during Laser Polishing of Indirect-SLS Metal Parts |
19 NOV 2003 |
12 pages |
| Authors:
J. A. Ramos; D. L. Bourell; J. J. Beaman; TEXAS UNIV AT AUSTIN DEPT OF MECHANICALENGINEERING
|
| Laser polishing of indirect-SLS parts made from 420 stainless powder infiltrated with bronze has been achieved using CO2 and Nd:YAG lasers. Two mechanisms have been previously proposed for the reduction in surface roughness, namely: shallow surface melting (SMM) and surface over-melt (SOM). In SMM reflow of the molten surface minimizes the peak-valley height driven by capillary pressure and liquid curvature. On the other hand, during SOM the melting depth is ... |
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| Predicting the Effect of Defect Distributions in the Bulk and on Surfaces of Ceramic Materials |
31 OCT 2003 |
25 pages |
| Authors:
Mark R. Levy; Robin W. Grimes; IMPERIAL COLL LONDON (UNITED KINGDOM)
|
| This report results from a contract tasking Imperial College, London as follows: The contractor will investigate and ultimately develop ways to select optimum compositions for materials using atomic scale computer simulation. The particular material systems to be studied are: pyrochiores and fluorites (important in fuel cell and oxygen generator applications and as thermal barrier coatings on turbine blades in jet engines), and the perovskites, important electronic ceramics that also act ... |
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| What Xe Nanocrystals in Al Can Teach Us in Materials Science |
NOV 2001 |
6 pages |
| Authors:
C. W. Allen; R. C. Birtcher; U. Dahmen; K. Furuya; M. Song; NATIONAL INST FOR MATERIALS SCIENCE TSUKUBA (JAPAN)
|
| Noble gases are generally very insoluble in solids. For example, Xe implanted into Al at 300 K forms a fine dispersion of crystalline precipitates and, at large enough fluence. fluid precipitates, both of which are stabilized, relative to the gas phase, by the Laplace pressure due to precipitate/matrix interface tensions. High resolution electron microscopy has been performed to determine the largest Xe nanocrystalline precipitate in local equilibrium with fluid Xe ... |
|
| Computations of Droplet/Flow Interactions in Sprays |
02 OCT 2001 |
3 pages |
| Authors:
Gretar Tryggvason; MICHIGAN UNIV ANN ARBOR DEPT OF MECHANICAL ENGINEERING AND APPLIED MECHANICS
|
| The behavior of liquid fuel sprays was studied by direct numerical simulations. Two- and three- dimensional simulations were used to determine both the formation of drops and their interaction with the ambient flow. The Navier- Stokes equations were solved by a finite difference/front tracking technique that allowed resolution of inertial and viscous forces as well as the inclusion of surface tension at the deformable boundary between the fuel and the ... |
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| Issues in the Design, Modeling, and Manufacture of Multiple Joint Solder Self-Assembled Micro-Electro-Mechanical Systems (MEMS) |
06 AUG 2001 |
332 pages |
| Authors:
Paul E. Kladitis; AIR FORCE INST OF TECH WRIGHT-PATTERSONAFB OH
|
| Using the surface tension of molten solder to assemble micro-sized structures or micro-electro-mechanical systems (MEMS), otherwise known as "solder self-assembly" is a recent development. Complex three-dimensional assemblies, previously not realizable, can now be realized using surface micromachined MEMS and solder assembly. Not only can complex or non-complex assemblies be realized using solder self-assembly, but realized by adopting means already established commercially for mass production. This work is the first in ... |
|
| The International Conference on Intergranular and Interphase Boundaries (10th) Held in Haifa, Israel on July 23-26, 2001 |
26 JUL 2001 |
107 pages |
| Authors:
OFFICE OF NAVAL RESEARCH EUROPEAN OFFICE FPO AE 09499-0700
|
| This volume contains abstracts of paper presented at the 10th. International Conference on Intergranular and Interphase Boundaries (IIB2001) held in Haifa, Israel on July 23-26, 2001. Session topics include: Interfacial structure & defects; electronic structure at interfaces; interfaces in nano- structures; solid-liquid interfaces & wetting; segregation; grain boundary & interface ensembles; interface energy & morphology; interface diffusion & external fields; interface motion & dynamics. |
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| Numerical Analysis of Cell Deformation of Two-Phase Flow With Discontinuous Viscosity and Non-Linear Surface Tension |
10 SEP 2000 |
16 pages |
| Authors:
Zhilin Li; Sharon Lubkin; NORTH CAROLINA STATE UNIV AT RALEIGH CENTER FOR RESEARCH IN SCIENTIFIC COMPUTATION
|
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| Microsensors that Function on the Basis of Surface and Wettability |
26 JUN 2000 |
3 pages |
| Authors:
P. Wapner; W. Hoffman; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE WEST
|
| The displacement of non-wetting fluid droplets contained within capillaries that have axial profiles and are non-uniform can be used to accurately and reproducibility measure the forces acting upon these droplets. The position of droplets within such micro-sensors is dictated by surface tension, wettability, geometric configuration of the confining walls, and the forces acting upon the droplet. These micro-sensors can measure pressure and acceleration, and can also be made to operate ... |
|
| Micro-Hydraulics Employing Non-Wetting Fluids |
26 JUN 2000 |
4 pages |
| Authors:
P. Wapner; W. Hoffman; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE WEST
|
| Hydraulic actuation is a mature technology that is widely used in a variety of applications in the macroscopic world. Its use in miniaturized devices such as microelectromechanical systems (MEMS), however, is just beginning to be exploited. This lag in development of micro-hydraulics results from the fact that it is not easy to construct miniaturized analogs of macroscopic hydraulic system using traditional MEMS fabrication techniques, such as photolithography. Tight-clearance pistons that ... |
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| An Experimental Approach for Studying Creep Behavior of Model Planar Interfaces |
JUN 2000 |
68 pages |
| Authors:
Keith A. Peterson; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| An apparatus for measuring the steady state creep behavior of interfaces in aluminum-silicon-aluminum multilayered specimens has been assembled. In the experiment scheme, a double-shear specimen geometry was used to load the interfaces in a state of nominally constant shear. The deformation kinetics for interfacial sliding during constant shear stress creep experiments were measured for various applied interfacial shear Stress levels and temperatures. Interfacial ... |
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| Computational Investigation of Atomization |
31 MAR 2000 |
45 pages |
| Authors:
Gretar Tryggvason; MICHIGAN UNIV ANN ARBOR DEPT OF MECHANICAL ENGINEERING AND APPLIED MECHANICS
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| The secondary breakup of liquid fuel drops was studied by numerical simulations. The Navier-Stokes equations were solved by a finite difference/ front tracking technique that included inertia, viscous forces, and surface tension at the deformable boundary between the fuel and the air. The breakup of drops accelerated impulsively was studied by axisymmetric simulations for two different density ratios (1.15 and 10). The low density ratio ... |
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| Injection of Cryogenic Jets into Subcritical and Supercritical Environments: Raman Measurements |
15 MAR 2000 |
16 pages |
| Authors:
Bruce Chehroudi; A. Badakshan; R. Cohn; Doug Talley; ENERGY RESEARCH CONSULTANTS INC LAGUNA HILLS CA
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| Stability of Compressive and Undercompressive Thin Film Traveling Waves |
08 DEC 1999 |
45 pages |
| Authors:
Andrea Bertozzi; Andreas Munch; Michael Shearer; Kevin Zumbrun; NORTH CAROLINA STATE UNIV AT RALEIGH CENTER FOR RESEARCH IN SCIENTIFIC COMPUTATION
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| Recent studies of liquid films driven by competing forces due to surface tension gradients and gravity reveal that undercompressive traveling waves play an important role in the dynamics when the competing forces are comparable. In this paper we provide a theoretical framework for assessing the spectral stability of compressive and undercompressive traveling waves in thin film models. Associated with the linear stability problem is an Evans function which vanishes precisely ... |
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| Basic Research in Supercritical Combustion |
30 NOV 1999 |
14 pages |
| Authors:
Douglas Talley; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE WEST
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Reports by Keyword(s)
SURFACE TENSION
