| Effect of a Compressive Uniaxial Strain on the Critical Current Density of Grain Boundaries in Superconducting YBa2Cu3O7-delta Films |
09-Jul-2009 |
6 pages |
| Authors:
T J Haugan; P N van der Barnes; D C Laan; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
|
 | The mechanism by which grain boundaries impede current flow in high-temperature superconductors has resisted explanation for over two decades. We provide evidence that the strain fields around grain boundary dislocations in YBa2Cu3O7-delta thin films substantially suppress the local critical current density Jc. The removal of strain from the superconducting grain boundary channels by the application of compressive strain causes a remarkable increase in Jc. Contrary to previous understanding, the strain-free ... |
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| Aerodynamic Predictions, Comparisons, and Validations Using MissileLab and Missile Datcom (97) |
Dec-2008 |
51 pages |
| Authors:
Hoon H Teo; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| Aerodynamic prediction software is often used in the early stages of missile systems designed to quickly and accurately estimate the aerodynamics of a wide variety of missile configuration designs operating over many different flight regimes. It is also possible to use these empirical packages to validate flight data collected from wind tunnel tests and other open sources. Analysis of such data provides users with insights to the performance of a ... |
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| Mechanical Response of an Al-PTFE Composite to Uniaxial Compression Over a Range of Strain Rates and Temperatures |
01-Sep-2008 |
28 pages |
| Authors:
Daniel T Casem; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
|
| Compressive stress-strain curves were generated for a pressed and sintered mixture of polytetrafluoroethylene and aluminum powders. Experiments were performed at strain rates ranging from 0.001 to 8000/s using a servo-hydraulic load frame and a split Hopkinson pressure bar. High-rate experiments were also performed over a temperature range of 22-78 C. The data is fit to the Johnson-Cook and Modified Johnson-Cook constitutive equations and also to a Zerilli-Armstrong equation adapted for ... |
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| Aerial Multi-Axis Platform (AMP) |
01-Jul-2008 |
5 pages |
| Authors:
Ed Wasson; SVERDRUP TECHNOLOGY INC FORT WALTON BEACH FL TACTICAL SYSTEMS GROUP
|
| Air Force ManTech accepted the challenge to provide a technology solution to the most labor-intensive tasks performed on large aircraft during depot maintenance. In collaboration with the Air Logistics Centers, they adapted a technology developed by NIST to access the aircraft safely with accurate positioning while reducing costs and flow times. Enhanced sophistication of aircraft outer mold line materials and maintenance techniques provided the basis for providing an advanced technology ... |
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| Background Pressure Effects on Internal and Near-field Ion Velocity Distribution of the BHT-600 Hall Thruster (Preprint) |
24-Jun-2008 |
10 pages |
| Authors:
Michael R Nakles; Hargus; William A Jr; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE
|
| Presented is a study of the effects of chamber background pressure on the ion axial velocity distribution within the discharge chamber and in the near-field of the Busek BHT-HD-600 xenon Hall effect thruster. Ion velocity distributions were measured along the acceleration channel centerline using laser-induced fluorescence of the 5d[4](sub 7/2)-6p[3](sub 5/2) xenon ion excited state transition. Measurements were taken at the lowest possible chamber background pressure and a pressure that ... |
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| Characterization of Graphite Lithium-Ion Cells |
SEP 2007 |
119 pages |
| Authors:
Steven D. Moseley; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| This thesis explores the characterization of graphite lithium-ion cells. A control procedure was performed to ensure any capacity loss or gain seen in tests was not the result of cell cycling. Vibration testing of the cells on all three axes to simulate the spacecraft launch environment showed a slight increase in capacity after vibration. Cell capacity was measured at two current rates at a variety of temperatures to obtain a ... |
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| Microcompression of Bulk Metallic Glass and Tungsten - Bulk Metallic Glass Composites |
MAY 2007 |
13 pages |
| Authors:
Brian E. Schuster; Lee S. Magness; Laszlo J. Kecskes; Qiuming Wei; Michael K. Miller; Matthew F. Ervin; Stephan Hruszkewycz; Todd C. Minagel; Kaliat T. Ramesh; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
|
| Recently, there has been tremendous interest in the size-dependent mechanical properties of materials, in particular, using various applications of the micrometer-scale uniaxial compression technique. In this technique, site-specific focused ion beam (FIB) milling is employed to fabricate micrometer sized compression specimens (micro-posts) from otherwise bulk material. These micro-posts are then tested in uniaxial compression using a flat punch indenter in a conventional nanoindenter. We apply this technique to examine the ... |
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| Characterization of Stable Kinetic Equilibria of Rigid, Dipolar Rod Ensembles for Coupled Dipole-Dipole and Maier-Saupe Potentials |
18-Jan-2007 |
22 pages |
| Authors:
Qi Wang; Hong Zhou; Hongyun Wang; M G Forest; NAVAL POSTGRADUATE SCHOOL MONTEREY CA DEPT OF MATHEMATICS
|
| We study equilibria of the Smoluchowski equation for rigid, dipolar rod ensembles where the intermolecular potential couples the dipole-dipole interaction and the Maier-Saupe interaction. We thereby extend previous analytical results for the decoupled case of the dipolar potential only (Fatkullin and Slastikov 2005 Nonlinearity 18 2565-80; Ji et al Phys. Fluids at press; Wang et al 2005 Commun. Math. Sci. 3 605-20) or the Maier-Saupe potential only (Constantin et al ... |
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| Compressed Elastomer Method for Internal Pressure Testing |
SEP 2006 |
22 pages |
| Authors:
Robert Carter; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
|
| The compressed elastomer likethod is a safe and easy technique for generating high internal pressure for tubular samples. The approach compresses a cylinder of an elastomeric numerial and uses the Poisson's expansion to generate internal pressure. The equations needed to convert the axial force to the internal pressure are derived and the procedure is verified using a steel control sample. To date. pressures have been generated in excess of 340 ... |
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| Experimental Characterization of Nonlinear Viscoelastic and Adhesive Properties of Elastomers |
27 JUL 2006 |
78 pages |
| Authors:
K. Ravi-Chander; R. S. Barsoum; TEXAS UNIV AT AUSTIN CENTER FOR MECHANICS OF SOLIDS STRUCTURES AND MATERIALS
|
| This report describes the characterization of the viscoelastic properties of polyurea and the failure of ductile materials at high strain rates. The mechanical properties of polyurea were determined under monotonic loading conditions, both in the unconfined and confined compression configurations. Direct measurements of the volumetric and shear response has been used to show that the shear resistance is nearly negligible, while the bulk modulus increases significantly with pressure. Expanding ring ... |
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| Effects of Machining on the Uniaxial and Equibiaxial Flexure Strength of CAP3 AD-995 Al2O3 |
SEP 2005 |
70 pages |
| Authors:
Andrew A. Wereszczak; Jeffrey J. Swab; Reuben H. Kraft; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| The effect of surface condition on the uniaxial and equibiaxial flexure strength of CoorsTek's CAP3 AD-995 alumina was examined. (Note that this material was found not to be the same as CoorsTek's AD-955 alumina-a comparison and discussion of the differences are provided in this report.) The following four surface conditions were considered: as-fired (i.e., unmachined) surfaces; the condition produced by CoorsTek's standard surface-grinding procedures (i.e., the condition they will provide ... |
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| Apparatus and Method for Generating Electric Energy in a Fluid Environment |
08 JUN 2005 |
20 pages |
| Authors:
Donald H. Steinbrecher; DEPARTMENT OF THE NAVY WASHINGTON DC
|
| Apparatus for generating electrical energy in a fluid environment, the apparatus including a wing member for disposition in the fluid and pivotally movable about an axis in response to flow of the fluid thereabout, connector rods each pivotally mounted at a first end thereof on the wing on opposite sides of the axis, a crank member attached to a second end of each of the connector rods and rotatable about ... |
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| Plain-Woven, 600-Denier Kevlar KM2 Fabric Under Quasistatic, Uniaxial Tension |
MAR 2005 |
32 pages |
| Authors:
Martin N. Raftenberg; Mike Scheidler; Thomas J. Moynihan; Charles A. Smith; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| We analyzed data from quasistatic, uniaxial tension tests on single- ply specimens of plain-woven, 600-denier KM2. Failure strains were found to range from 0.120 to 0.144 for warp-loaded and from 0.143 to 0.160 for fill- loaded tests. Failure stresses (strengths) ranged from 0.424 to 0.543 GPa for warp-loaded and from 0.593 to 0.642 GPa for fill-loaded tests. A least-squares fit, in the form of a rational function, was obtained to ... |
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| Omni-Azimuthal Pattern Generator for VLF and LF Communication |
18 FEB 2005 |
18 pages |
| Authors:
David A. Tonn; DEPARTMENT OF THE NAVY WASHINGTON DC
|
| It is a general purpose and object of the present invention to generate an antenna pattern that does not change as a function of azimuth angle, but has equally good reception from all azimuth angles. It is an additional purpose to generate such an omni-azimuthal antenna pattern over a broad range of frequencies in a manner that does not require manual retuning or adjustment. These objects are accomplished through the ... |
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| Head and Helmet Biodynamics and Tracking Performance During Exposure to Whole-Body Vibration |
FEB 2005 |
18 pages |
| Authors:
Suzanne D. Smith; Jeanne A. Smith; Raymond J. Newman; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH HUMAN EFFECTIVENESS DIRECTORATE
|
| Helmet-mounted equipment is being designed to optimize military aircrew effectiveness. The objective of this study was to quantify the effects of head orientation and helmet weight distribution on head, helmet, and helmet slippage rotations, and tracking performance during exposures to fighter aircrew buffeting and multi-axis quasi-random vibration. For both exposures, significant increases in the roll displacements were observed with the SIDE orientation (40 deg elevation, 70 deg azimuth). Significant increases ... |
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| Predicting the Crack Growth Behavior in a Filled Elastomer |
14 JAN 2005 |
7 pages |
| Authors:
C. T. Liu; Max Yen; H. K. Ching; SOUTHERN ILLINOIS UNIV AT CARBONDALE MATERIALS TECHNOLOGY CENTER
|
| In this study, single-edge cracked uniaxial specimens with an initial crack length of 0.1 in or 0.3 in and wedge-shaped sheet specimens with an initial crack length of 0.3 in were tested at a constant displacement rate of 50 in/min under 1000 psi confining pressure. The specimens were made of a highly filled polymeric material, containing 86% by weight of hard particles embedded in a rubbery matrix. The uniaxial crack ... |
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| Polymer Waveguides for Quantum Information |
JAN 2005 |
10 pages |
| Authors:
Kamala Mahanta; STATE UNIV OF NEW YORK COLL AT ONEONTA
|
| Electro-optic materials have shown great potential for improving the performance of waveguided communication systems for use in quantum information processing (cryptography, communication, computing, etc.) where the transmission of a single photon or a very small amount of light plays a critical role in establishing the quantum nature of the process. These materials offer significant advantages over inorganic materials such as LiNbO3 or compound semiconductors due to their large EO-coefficients, low ... |
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| Development Of A Control Moment Gyroscope Controlled, Three Axis Satellite Simulator, With Active Balancing For The Bifocal Relay Mirror Initiative |
DEC 2004 |
125 pages |
| Authors:
Wayne J. Kulick; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| This thesis develops and implements a Control Moment Gyroscope (CMG) steering law, controller and active balancing system for a three-axis satellite simulator (TASS). The CMGs are configured in a typical pyramid configuration (the fourth CMG position being null). The development was done primarily with simulation and experiments utilizing Real Time Workshop and XPC Target of MATLAB and SIMULINK. The TASS is a double circular platform mounted on a spherical air ... |
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| Design of Two-Axis Capacitive Accelerater Using MEMS |
DEC 2004 |
|
| Authors:
Chun M. Lee; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
 | MEMS technology is rapidly taking an important role in today's and future military systems. MEMS are able to lower the device size from millimeter to micrometer and maintain and sometimes surpass the performance of conventional devices. This thesis encompasses the knowledge acquired throughout the MEMS courses to design a two-axis capacitive accelerometer. The required acceleration and operating temperature range were 50g in each axis and -40 C to +80 C, ... |
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| Magnetogasdynamic Flow Acceleration in a Scramjet Nozzle |
JUN 2004 |
83 pages |
| Authors:
Brian H. Harrington; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
|
| The effect of magnetogasdynamic (MGD) interactions on flow acceleration and thrust in a scramjet accelerator/nozzle are examined numerically at a free-stream flight condition of Mach 8. The parameters of conductivity pattern and load factor are varied in both inviscid and viscous flow regimes with the intent of increasing axial force exerted on the flow through a scramjet accelerator. The numerical code solves the Navier-Stokes equations with additional source terms for ... |
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| Experimental Investigation into the Aerodynamic Performance of Both Rigid and Flexible Wing Structured Micro-Air-Vehicles |
MAR 2004 |
174 pages |
| Authors:
Anthony M. DeLuca; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
|
| The Air Force Research Lab, Munitions Directorate, Eglin Air Force Base, Florida has designed a man-portable carbon-fiber Micro-Air-Vehicle (MA V) used for on-the-spot surveillance by Special Operations Forces (SOF) for enemy reconnaissance as well as post-strike Battle Damage Assessment (BDA).The main goals of this experiment are: 1) characterize the flow quality of the new AFIT 3' x 3' wind tunnel and 2) determine the aerodynamic performance characteristics of the 24" ... |
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| Design and Cold-Flow Evaluation of a Miniature Mach 4 Ramjet |
JUN 2003 |
85 pages |
| Authors:
Kevin M. Ferguson; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| Methods used for designing the ramjet included conic shock tables; isentropic flow tables and the GASTURB code was used for aerothermodynamic performance prediction. The flow field through the proposed geometry was computed using the OVERFLOW code, and small modifications were made. Geometry and solid models were created and built using SolidWorks 3D solid modeling software. A prototype ramjet was manufactured with wind tunnel mounting struts capable of measuring axial force ... |
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| Propulsion Technologies for Microsatellite Missions |
11 APR 2003 |
3 pages |
| Authors:
Daron Bromaghim; James Singleton; Stewart Bushman; Ron Spores; Lee Johnson; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE
|
| Many near, to mid-term satellite missions have been identified for 200 kg class spacecraft. For many of these applications, significant delta-v capability is desired in order to perform orbit transfer, on-orbit repositioning and formation flying. Several of these systems are in advanced engineering development and could be ready to support flight opportunities as early as summer 2004. A 200 W Hall Effect Thruster (RET) system is being developed to satisfy ... |
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| Study on Unsteady Vortex Behaviour of a Rolling Sixty Five Degree (65) Delta Wing at M=0.8 Using Pressure Sensitive Paint (PSP) |
MAR 2003 |
|
| Authors:
Rolf H. Engler; Christian Klein; Sergey Fonov; Karl-Aloys Butefisch; Kari-Wilhelm Bock; NATO RESEARCH AND TECHNOLOGY ORGANIZATION NEUILLY-SUR-SEINE (FRANCE)
|
| Since the need for improvements in high angle-of-attack maneuverability of aircraft's in transonic flight was of concern, a model was rotated around its longitudinal body axis with a dimensionless rolling rate of pi = 0.0762 (10 Hz), resulting in flow conditions with extensive vortical behavior and strongly non-linear, wing/vortex interference effects. This paper deals with validation experiments performed at the DLR Goettingen. The objective of this activity was to provide ... |
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| Hybrid Control Strategies for Rapid, Large Angle Satellite Slew Maneuvers |
MAR 2003 |
135 pages |
| Authors:
David B. French; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
|
| This research investigated hybrid control strategies for rapid satellite pointing. First, a detailed computer simulation model of AFIT's SIMSAT satellite simulator was constructed. Control strategies were developed to enable the system to perform large-angle, 3-axis slewing maneuvers using a combination of both thrusters and reaction wheels. To handle the non-linear model, a State Dependent Riccati Equation controller was programmed and successfully controlled the computer-modeled satellite for any given slewing maneuver. ... |
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| Optical Frequency Domain Reflectometry for High Density Multiplexing of Multi-Axis Fiber Bragg Gratings |
2003 |
5 pages |
| Authors:
Stephen Kreger; Sean Calvert; Eric Udd; BLUE ROAD RESEARCH GRESHAM OR
|
| An interferometric fiber grating interrogation system utilizing a depolarized Erbium ring laser was used to interrogate transversely strained gratings written through the polyimide coating with 1 mm spatial resolution, and the interferometric results were compared to waveforms taken using a broadband source and OSA. |
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| Quasi-Static Uniaxial Tension Characteristics of Plain-Woven Kevlar KM2 Fabric |
DEC 2002 |
42 pages |
| Authors:
Martin N. Raftenberg; Thomas J. Mulkern; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| Quasi-static uniaxial tension tests were conducted on 30.8-mm-wide single-ply specimens of plain-woven DuPont Keviar KM2 aramid fabric (style 706). Six specimens were pulled along the warp direction, and six were pulled along the fill direction. The strength was found to range from 2.07 to 2.33 GPa, with a mean of 2.23 GPa in the warp direction and from 2.47 to 2.77 GPa, with a mean of 2.67 GPa in the ... |
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| Kevlar KM2 Yarn and Fabric Strength Under Quasi-Static Tension |
OCT 2002 |
34 pages |
| Authors:
Thomas J. Mulkern; Martin N. Raftenberg; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| Kevlar KM2, 600 denier, was Instron tested in quasi-static, uniaxial tension to determine its strength. Specimens included both single yarns and 68- yarn-wide, single-ply strips of plain-woven fabric (Style 706). Never-woven single-yarn speciens were tested with varying degrees of initial twist. Strength of the untwisted, never-woven yarn was 2.66 +/= 0.04 GPa. The twist multiplier was 1.2. Single warp-oriented and fill-oriented yarns were extracted from Style 706 fabric, tested, and ... |
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| Textures in Aluminum and Titanium: Their On-Line Evaluation and Quantitative Effects on Formability |
10 AUG 2002 |
12 pages |
| Authors:
Chi-Sing Man; KENTUCKY UNIV RESEARCH FOUNDATION LEXINGTON
|
| The main findings of this project were as follows: (1) For samples of an AA5xxx aluminum alloy sheet at temperatures up to 750 deg F, the degree of recrystallization could be monitored by using either resonance-EMAT spectroscopy or laser-ultrasound resonance spectroscopy. (2) Formulae showing explicitly the effects of crystallographic texture on the planar plastic anisotropy of sheets of cubic (e.g., aluminum) and of hexagonal (e.g., titanium) metals in uniaxial tension ... |
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| Locating an Appropriate Saddlepoint for M-Dimensional Probability Integrals |
15 JUL 2002 |
74 pages |
| Authors:
Albert H. Nuttall; NAVAL UNDERSEA WARFARE CENTER NEWPORT DIV RI
|
| The evaluation of the joint probability density function from the joint moment generating function involves an M-dimensional inverse laplace transform. The analytic and numerical difficulty of performing this task for large values of M prompts consideration of an approximate technique such as the saddlepoint method. Advantage can be taken of the fact that the joint probability density function is real and positive, to show that the dominant saddlepoint in the ... |
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| Summary of Rollover Crash Tests |
JUN 2002 |
41 pages |
| Authors:
Louise A. Carter; Joseph A. Pellettiere; Arnold K. Johnson; Annette Rizer; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH HUMAN EFFECTIVENESS DIRECTORATE
|
| Over a period of several years, the National Highway Traffic Safety Administration (NHTSA) has sponsored a total of twenty-four full-scale rollover crash tests (contract # DTNH22-87-X-07477) to investigate vehicle and occupant dynamics during rollover crashes. A variety of pickup trucks, vans and automobiles were tested with a fully instrumented dummy seated in either the driver's or passenger's front seat. For some tests, the dummy was unrestrained and for others the ... |
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| Numerical Prediction of Residual Stress and Deformation of Cannon Tubes |
JAN 2002 |
10 pages |
| Authors:
Anthony P. Parker; EUROPEAN RESEARCH OFFICE LONDON (UNITED KINGDOM)
|
| An experimental program involving uniaxial testing of candidate gun steels was undertaken at Benet Laboratory. One striking feature is a very significant reduction in elastic modulus during load reversal. These data were then fitted numerically using a new variant of the non-linear kinematic hardening model. Numerical fits to the uniaxial behavior were incorporated into a non-linear numerical stress analysis program. Residual stress profiles for each of the candidate gun steels ... |
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| Numerical Computations of Supersonic Flow Over Elliptical Projectiles |
DEC 2001 |
47 pages |
| Authors:
Jubaraj Sahu; Karen R. Heavey; Harris L. Edge; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
|
| Computational fluid dynamics (CFD) approaches were used to compute the supersonic and hypersonic flow fields and aerodynamic forces and moments on elliptical projectiles. Steady state numerical results have been obtained at several supersonic Mach numbers between 2.5 and 4.0 and several angles of attack from 0 to 12 degrees for the 'jet-off' conditions with the use of Euler and Navier-Stokes flow solvers. In addition, numerical computations have been performed for ... |
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| High-Strain Rate Uniaxial Compression of Future Combat Systems (FCS) generation One High-Energy Gun Propellants |
SEP 2001 |
37 pages |
| Authors:
Michael G. Leadore; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
|
| Six lots of Thiokol-manufactured Future Combat Systems (FCS) generation One experimental high-energy gun propellants were tested in uniaxial compression. The materials were taken to ^60% strain at a strain rate of 100 per second, while conditioned at 21 degrees C, 63 degrees C, and -32 degrees C. The stress at yield, strain at yield, Young's modulus, failure modulus, incremental energy density, and fracture assessment values were recorded for each test. ... |
|
| Mechanical Damage and Combustion of TNT and Composition-B |
AUG 2001 |
49 pages |
| Authors:
Robert J. Lieb; John J. Starkenberg; William Lawrence; Patrick J. Baker; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
|
| Fracture damage was introduced into trinitrotoluene (TNT) and Composition-B (Comp-B) through uniaxial compression applied at controlled strain rates from 0.1 to 100 s-1. The mechanical response was measured with parameters that have been used to characterize the fracture response of gun propellant during its development over the last decade. The damaged high explosive was burned in a small closed bomb in an effort to characterize the fracture surface area that ... |
|
| Assessment of the Viscoelastic Properties of Normal and Abnormal Breast Tissue |
JUL 2001 |
24 pages |
| Authors:
Donald B. Plewes; SUNNYBROOK HEALTH SCIENCE CENTER TORONTO (ONTARIO)
|
| It is well known that variations in biomechanical properties of breast tissue are associated with the presence of disease. As a result, it is thought that stiffness represent an attractive property by which to detect disease and aid in differentiation between normal and benign breast tissues. Over the past few years, a number of investigators have attempted to measure breast tissue biomechanical properties based on ex-vivo tissue samples. These studies ... |
|
| Guidance and Control Technology |
JUL 2001 |
16 pages |
| Authors:
Erik Berglund; SWEDISH DEFENCE RESEARCH AGENCY STOCKHOLM
|
| The fundamental ideas and the basic mathematics of the most common missile guidance laws are outlined. Rules of thumb for the required lateral acceleration for the different guidance laws are given. A brief summary of flight mechanics is given. The pitch axis control is treated and the dynamic properties are identified. Design of the autopilot for the inner loop using modem methods of controller design is briefly outlined. |
|
| Yaw Control at High Angles of Attack Through Vortex Manipulation Using Rotating Nose Strakes |
JUN 2001 |
6 pages |
| Authors:
Peter R. Hakenesch; DAIMLER CHRYSLER AEROSPACE AG MUENCHEN (GERMANY) MILITARY AIRCRAFT DIV
|
| The effect of nose strakes on the flow field in the vicinity of the forward fuselage section of an aircraft was investigated. Emphasis was placed on the manipulation of the vortices in order to generate a significant side force and yawing moment with the purpose not only to stabilize the aircraft at high angles of incidence but also to achieve yaw control. Aside from conventional control surfaces an additional control ... |
|
| Landing Approach Flying Qualities Criteria For Active Control Transport Aircraft |
JUN 2001 |
14 pages |
| Authors:
Edmund J. Field; Kenneth F. Rossitto; David G. Mitchell; BOEING CO LONG BEACH CA
|
| Flying qualities databases and criteria have existed for fighter aircraft for several decades. However, there have been a lack of databases and criteria for active control transport aircraft. During the 1990's Boeing undertook a series of in-flight simulation experiments to generate a comprehensive longitudinal axis database for transport aircraft in the landing approach task. This database has subsequently been applied to the more established longitudinal flying qualities criteria flat were ... |
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| Computerized Generation and Simulation of Meshing of Modified Spur and Helical Gears Manufactured by Shaving |
MAY 2001 |
27 pages |
| Authors:
Faydor L. Litvin; Qi Fan; Daniele Vecchiato; Alberto Demengo; ILLINOIS UNIV AT CHICAGO DEPT OF MECHANICAL ENGINEERING
|
| Modification of geometry of spur and helical gears with parallel axes and helical gears with crossed axes is proposed. The finishing process of gear generation is shaving. The purposes of modification of the gear geometry are to localize and stabilize the bearing contact, and to reduce noise and vibration. The goals mentioned above are achieved by using profile crowning and plunging the shaver by a prescribed motion during pinion generation. ... |
|
| Guidance and Control Technology |
SEP 2000 |
11 pages |
| Authors:
Erik Berglund; NATIONAL DEFENCE RESEARCH ESTABLISHMENT STOCKHOLM (SWEDEN) DEPT OF DEFENCE ANALYSIS
|
| The fundamental ideas and the basic mathematics of the most common missile guidance laws are outlined. Rules of thumb for the required lateral acceleration for the different guidance laws are given. A brief summary of flight mechanics is given. The pitch axis control is treated and the dynamic properties are identified. Design of the autopilot for the inner loop using modem methods of controller design is briefly outlined. |
|
| Attitude Determination of a Three-Axis Stabilized Spacecraft Using Star Sensors |
DEC 1999 |
86 pages |
| Authors:
Jay D. Vogt; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| The purpose of this thesis is to investigate the application of a six-state discrete Kalman filter for estimates of angular rates based solely on star sensor data. The satellite is in a Molnyia orbit where orbital angular velocity and orbital angular acceleration are predetermined and stored in the on-board computer; such that they will be available each time a star observation is made. A two-axis star ... |
|
| Investigation of a New Class of Low-Profile Multi-Layer Printed Antennas |
22 OCT 1999 |
29 pages |
| Authors:
Ahmad Hoorfar; VILLANOVA UNIV PA DEPT OF ELECTRICAL AND COMPUTER ENGINEERING
|
| This progress report outlines our research efforts on modeling, analyses and optimization of multi-layered printed antennas for high gain applications. Our research during this interim period has resulted in progress in the following four areas. (1) Performance analysis of a linear array of Yagi- like printed sub-array antennas. Effects of mutual couplings on gain and pattern degradation of previously optimized Yagi-like structures are investigated for various array configurations. (2) Development ... |
|
| A Comparison of Intelligent, Adaptive, and Nonlinear Flight Control Laws |
04 JUN 1999 |
12 pages |
| Authors:
Marc L. Steinberg; NAVAL AIR WARFARE CENTER AIRCRAFT DIV PATUXENT RIVER MD
|
| This paper compares in simulation six different nonlinear control laws for multi-axis control of a high performance aircraft. The control law approaches are fuzzy logic control, backstepping adaptive control, variable structure control, and indirect adaptive versions of Model Predictive Control and Dynamic Inversion. In addition, a more conventional scheduled dynamic inversion control law is used as a baseline. In some of the cases, a stochastic genetic algorithm was used to ... |
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| Test Specimen Design Incorporating Multiple Fracture Sites and Multiple Strain Material Fractures. |
18 MAY 1999 |
|
| Authors:
Virginia G. DeGlorgi; Andrew B. Geltmucher; DEPARTMENT OF THE NAVY WASHINGTON DC
|
| A material test specimen design is taught for the determination of critical strain and stress states for multiaxial fracture. The objective of the specimen is to increase the amount of data obtained per specimen while retaining simplicity in testing procedure by using standard tension testing machines to generate the primary deformation of the specimen. The specimen, in conjunction with analytical or computational simulation, uses nonuniform deformation fields produced by secondary ... |
|
| X-Ray Source for Lithography % |
06 APR 1999 |
|
| Authors:
Phillip Sprangle; Bahman Hafizi; Frederick MAKO; DEPARTMENT OF THE NAVY WASHINGTON DC
|
| An x-ray lithography device in which a beam of electrons interacts with a microwave field of a quasi-optical maser such as a quasi-optical gyrotron. This maser comprises a pair of spaced mirrors defining a quasi-optical cavity there between, with one mirror being provided with an orifice to permit extraction of the x-ray beam produced. A Bragg reflector is connected to the mirror orifice to reduce the microwave power loss from ... |
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| Computational Investigation of Subsonic Torsional Airfoil Flutter |
DEC 1998 |
110 pages |
| Authors:
Constantinos Kakkavas; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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| In this thesis single-degree-of-freedom torsional airfoil flutter is investigated using an incompressible potential flow code, a compressible inviscid Euler code and a compressible viscous Navier-Stokes code. It is found that the classical linearized incompressible and compressible flow theories yield unconservative flutter estimates. The computations based on the non-linear codes show for NACA 0006, NACA 0009, NACA 0012 and NACA 0015 airfoils, that the regions of torsional flutter instability increase as ... |
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| Dynamic Properties of the International Space Station throughout the Assembly Process |
29 JUN 1998 |
112 pages |
| Authors:
John A. Wojtowicz; AIR FORCE INST OF TECH WRIGHT-PATTERSONAFB OH SCHOOL OF ENGINEERING
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| Attitude control and spacecraft dynamics have always demanded serious attention from spaceflight personnel. Proper utilization of the basic tools of dynamics and controls can help alleviate the problems associated with the somewhat unpredictable nature of attitude control in the most basic spacecraft. Soon a new spacecraft will be placed in orbit that will truly test man, machine and the forces that bind them. The International Space Station is the culmination ... |
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| Subcritical Crack Growth in a Composite Solid Propellant |
10 JUN 1998 |
15 pages |
| Authors:
D. T. Baron; C. T. Liu; T. C. Miller; AIR FORCE RESEARCH LAB EDWARDS AFB CA SPACE AND MISSILE PROPULSION DIV
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| Unixial tension tests using a strain rate of 0.04 in./in./min. are performed on rectangular smooth and single edge-notched specimens of varying thicknesses for a composite solid propellant. Stress strain, crack growth, crack growth rate and crack growth resistance data are provided. Thickness effects and the mechanism of crack growth are described. Methods of calculation are explained for the crack growth rate and the Mode 1 stress intensity factor. A model ... |
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| The 1998 Version of the NSWC Aeroprediction Code: Part I-Summary of New Theoretical Methodology |
APR 98 |
129 pages |
| Authors:
Frank G. Moore; Roy M. Mcinville; Tom Hymer; NAVAL SURFACE WARFARE CENTER DAHLGREN DIV VA
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| The NSWC Aero prediction code has been extended to the roll position of 45 deg (fins in 'x' or cross roll orientation) in addition to the roll position of 0 deg (fins in '+' or plus roll orientation). It has also been extended to compute aerodynamics of nonaxisymmetric bodies based on an equivalent axisymmetric body. In addition, the nonlinear aerodynamic loads have been distributed over the body and lifting surfaces ... |
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