| Durability of Composite Materials and Structures |
02-Nov-2009 |
15 pages |
| Authors:
Hassan Mahfuz; Richard D Granata; William Hartt; Leif Carlsson; Lawrence Drzal; Dayakar Penumadu; Clive Clayton; William Scott; FLORIDA ATLANTIC UNIV BOCA RATON
|
 | This project focused on marine composites and sandwich structures with specific interests on the effects of moisture, seawater, hydrostatic pressure, and temperature on their durability and life prediction. One task revealed fiber changes that occur with nitric acid treatment promoting better engineering design of composite fiber matrix interface and interphase region. Comparative environmental exposures show that moisture absorption was along the F/M interface (wicking). A fracture mechanical model of single ... |
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| Production of Dense Compact Billet From Ti-Alloy Powder Using Equal Channel Angular Extrusion |
06 APR 2007 |
50 pages |
| Authors:
Rimma Lapovok; Dacian Tomus; MONASH UNIV CLAYTON (AUSTRALIA) SCHOOL OF PHYSICS AND MATERIALS ENGINEERING
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| The project was aimed at an investigation of the potential for cost-effective, efficient consolidation of pre-alloyed "PA" Ti-6Al-4V (HDH) powder at temperatures of 400?C and below using Equal Channel Angular Extrusion (ECAE), with applied back pressure. The limit on processing temperature was imposed to minimize the contamination of powder and compact with gaseous constituents known to be harmful to resultant properties. An analysis of existing published investigations of current processing ... |
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| Electromechanics of Dielectric and Piezoelectric Crystals With Point, Line, and Surface Defects |
APR 2007 |
18 pages |
| Authors:
John D. Clayton; Peter W. Chung; Michael A. Grinfeld; WIlliam D. Nothwang; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
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| A mathematical continuum theory is developed to describe the electromechanical behavior of dielectric and piezoelectric solids containing imperfections. The macroscopic distortion field consists of recoverable elasticity, deviatoric plasticity arising from dislocation glide, and volumetric deformation from vacancies. A connection on the spatial manifold of deformed lattice vectors describes gradients of stretch and rotation at the microscale caused by various lattice defects. It is shown that parallel transport of a lattice ... |
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| Exploring the High-Pressure Behavior of PETN: A Combined Quantum Mechanical and Experimental Study |
NOV 2006 |
20 pages |
| Authors:
Jennifer A. Ciezak; Edward F. Byrd; Betsy M. Rice; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
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| In an effort to increase the efficiency of the developmental cycle for future munitions and propellants, integration of standard atomistic simulation methods into the research and development process is being aggressively pursued. In many cases, this approach is not feasible due to the neglect of important crystalline forces in the formulations of the simulation methods. However, within high-pressure regimes it has been shown the predictions are in much closer agreement ... |
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| Naval Applications of Spar Technology in a Seabasing Environment |
Oct-2006 |
33 pages |
| Authors:
Robin Oldfield; NAVAL SURFACE WARFARE CENTER CARDEROCK DIV BETHESDA MD SHIP SYSTEMS INTEGRATION AND DESIGN DEPARTMENT
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| Spar technology was initially explored in a 2003 CISD study for the application of a Deep Water Stable Craneship. This vessel used the enhanced seakeeping properties of a spar to dramatically increase operability in a seaway. Whilst the spar concepts developed to date have offered a range of particularly strong, and sometimes unique, capabilities the design has required an undesirably long spar, restricting use to deeper waters. The first part ... |
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| Eruptive Flow Response in a Multi-Component Driven System by an Interacting Lattice Gas Simulation |
2006 |
8 pages |
| Authors:
R. B. Pandey; J. F. Gettrust; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS SEAFLOOR SCIENCES DIRECTORATE
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| An interacting lattice gas model is used to study flow of immiscible components A and B by Monte Carlo simulations. Concentration gradients and hydrostatic pressure bias drive these constituents from their source at the bottom against gravitational sedimentation in an effective medium. Response of their flux densities to the hydrostatic bias H are examined. If both constituents are released with equal probabilities (a non-interacting source), their flux densities respond linearly ... |
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| Design and Analysis of a Hybrid Composite/Metal Structural System for Underwater Lifting Bodies |
30 JUN 2005 |
107 pages |
| Authors:
Larry Thompson; Josh Walls; Vincent Caccese; MAINE UNIV AT ORONO
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| This report summarizes the analysis and design of a hybrid underwater lifting body structure. It is part of an effort to investigate the response of hybrid composite/metal construction techniques and hybrid connection connections in U.S. Navy vessels. This effort includes structural analysis of a lifting body structure designed by Navatek, Ltd of Honolulu HI that was constructed of aluminum for the SES 200. Analysis of this structural system as an ... |
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| High Resolution Results and Scalability of Numerical Modeling of Wind Flow at White Sands Missile Range |
DEC 2004 |
9 pages |
| Authors:
Patrick A. Haines; David J. Grove; Wen-Yih Sun; Wu- Ron Hsu; ARMY RESEARCH LAB WHITE SANDS MISSILE RANGE NM
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| The NTU/ Purdue nonhydrostatic numerical model has been developed over the last 6 years to predict atmospheric motions and conditions for both the mesoscale (200 m to 200 km) and large scale turbulence scale (20 m to 200 m). It is a fully explicit, compressible three-dimensional code and has compared quite to a wide variety of known analytical solution or observed situations including the Boulder Wind Storm, nonhydrostatic and hydrostatic ... |
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| Extension and Validation of UNDEX Analysis Methods |
DEC 2004 |
100 pages |
| Authors:
L. Donahue; MARTEC LIMITED HALIFAX (NOVA SCOTIA)
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| Numerous features have been added to both the IFSAS and Trident codes. Both codes were integrated into a single solver for 3D fluid-structure interaction simulations. A multiple material model using a mixed-cell approach was implemented in the IFSAS code, and validated against experimental data. Adaptive grid schemes for underwater shock and bubble analysis, hydrostatic pressure and airwater/seafloor boundaries, underwater explosion profiles, and fluid-backed shapes were also implemented. The improvements made ... |
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| The Strengthening of Energetic Materials Under Pressure |
DEC 2004 |
8 pages |
| Authors:
Donald A. Wiegand; Brett Reddingius; ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER PICATINNY ARSENAL NJ
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| The mechanical properties of composite plastic bonded explosives are being studied as a function of hydrostatic confining pressure. The flow stress and the modulus obtained in simple compression are both found to increase with increasing confining pressure. Thus, these materials become stronger and stiffer with increasing pressure. The sensitivity to pressure, however, decreases with increasing pressure. The failure process also changes with pressure. At atmospheric pressure failure is primarily due ... |
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| Multidimensional Numerical Modeling of Surges Over Initially Dry Land |
SEP 2004 |
26 pages |
| Authors:
R. C. Berger; L. M. Lee; ENGINEER RESEARCH AND DEVELOPMENT CENTER VICKSBURG MS COASTAL AND HYDRAULICSLAB
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| For modelers evaluating the impact of dam, levee and structure failures the need is to be able to determine the flood height and timing. A two- dimensional (2-D) model needs to be able to reproduce this flood wave along the channel and over dry ground. This report details the testing of the 2-D shallow- water module of the ADaptive Hydraulics (ADH) model for surges over initially dry ground. ADH utilizes ... |
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| Acoustic Cymbal Transducers - Design, Hydrostatic Pressure Compensation, and Acoustic Performance |
MAR 2004 |
99 pages |
| Authors:
Kirk E. Jenne; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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| Continuing U.S. Navy interest in the development of light-weight, low-volume, broadband, underwater acoustic projectors and receivers is the principal motivation for this research topic. Acoustic cymbal transducers, so named for their geometric similarity to the percussion instruments, are miniature "class V" flextensional transducers that consist of a piezoelectric ceramic drive element bonded to two opposing cymbal-shaped metal shells. Operating as mechanical transformers, the two metal shells convert the naturally large ... |
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| A Numerical Study of Breaking Waves |
27 AUG 2003 |
6 pages |
| Authors:
R. Muscari; A. Di Mascio; FLORENCE UNIV (ITALY) DEPT OF ENERGETICA
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| The focus of the present work is on the numerical simulation of steady flows with spilling breaking waves. In particular, the breaker is modeled through a hydrostatic pressure and a shear stress exerted on the free-surface. Many elements of the exposed model are derived by Cointe and Tulin's theory of steady breaker. The model has been implemented in a RANSE code in a simple but effective way through a modification ... |
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| Sensitivity of Spores to Hydrostatic Pressure Mechanisms of Inactivation, Injury and Repair Phase II |
MAR 2003 |
41 pages |
| Authors:
Dallas G. Hoover; Adrienne E. H. Shearer; Anthony Sikes; C. P. Dunne; DELAWARE UNIV NEWARK DEPT OF ANIMAL AND FOOD SERVICE
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| Over the past fifteen years, it has been established that high- hydrostatic pressure processing (HPP) has significant potential to function as an effective nonthermal method in the destruction of microorganisms in foods with little effect on the sensory qualities of the food product. However, bacterial endospores are very pressure-resistant and have been shown to require a hurdle approach for inactivation when HPP is employed. This study investigated the inhibitory effect ... |
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| Intensity Probe 02-20 Using Miniature Hollow Spheres |
JAN 2003 |
17 pages |
| Authors:
David J. Van Tol; Gerald C. Lauchle; Thomas B. Gabrielson; PENNSYLVANIA STATE UNIV UNIVERSITY PARK APPLIED RESEARCH LAB
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| A probe is designed to measure the acoustic intensity at the primary frequencies (20-30 kHz) of a parametric array. It is designed to operate at depths up to 61 m with a pressure sensitivity of less than -235dB re 1V/mPa while not disturbing the acoustic field of interest. Higher sensitivity would result in saturation when exposed to the expected sound pressure levels. The sensitivity and depth requirements were met, while ... |
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| Vacuum Infusion of Low-Cost Aerospce Composites |
2002 |
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| Authors:
Maarten Labordus; R. C. Verhoef; INSTITUTE OF INDUSTRIAL TECHNOLOGY TNODELFT (NETHERLANDS)
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 | This report results from a contract tasking TNO Industrie as follows: A mold system will be designed in which the hydrostatic pressure can be measured in the resin during the vacuum infusion process. Pressure transducers will be mounted in the surface of a flat aluminum plate and data will be digitally recorded. Simple compression tests on dry and impregnated laminate will provide data to relate the pressure gradient (out of ... |
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| International Conference on Solid State Crystals 2000: Growth, Characterization, and Applications of Single Crystals Held in Zakopane, Poland on 9-12 October 2000 |
24 OCT 2001 |
426 pages |
| Authors:
Antoni Rogalski; Pawet Madejczyk; Krzysztof Adamiec; MILITARY UNIV OF TECHNOLOGY KALISKIEGO(POLAND) INST OF APPLIED PHYSICS
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| Partial Contents: Scope of ZnO growth; Influence of mechanical stress on the growth of crystals; Crystal growth of new functional materials for electro-optical applications; Possibilities and limitations of multioxide crystals growth; Single-domain HTC superconducting materials synthesis: BaZrO3 substrates as a tool for optimized systems; Very high quality crystals of wide- gap II-V semiconductors: What for?; Annealing of GaSb single crystals in ionized hydrogen atmosphere; Growth and structure of strontium-doped LaGaO3; ... |
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| Resaerch Investigation Directed Toward Extending the Useful Range of the Electromagnetic Spectrum |
30 JUN 2001 |
43 pages |
| Authors:
George W. Flynn; Richard M. Osgood Jr.; Louis E. Brus; Tony F. Heinz; Irving P. Herman; TRUSTEES OF COLUMBIA UNIV NEW YORK
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| Experiments are described that have the goal of understanding the basic physics of quantum confined electronics. In the first experiment new fabrication processes for making GaSb-based quantum dots have been examined. The scientific goal of this work is to develop methods to realize damage free etching of the dots. In the second experiment stepped metal surfaces have been used to measure the scattering cross-sections of electrons at simple features, such ... |
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| Surface Layer Thermodynamics of Steel Penetrators at High and Very High Sliding Velocities |
JUN 2001 |
78 pages |
| Authors:
Janusz R. Klepaczko; FLORIDA UNIV SHALIMAR GRADUATE ENGINEERING AND RESEARCH CENTER
|
| One of the most difficult problems in the mechanics of kinetic energy projectiles penetrating geological or cementitious target materials is a proper understanding of the frictional properties between the projectile surface and the target. The model developed in this study is limited to a simple definition of the state of the projectile surface as a set of uniformly distributed micro- asperities with the same active height, h = 20 microns, ... |
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| Variation of CdS sub 1-x Se sub x Nanocrystal Parameters Under Hydrostatic Pressure |
JUN 2001 |
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| Authors:
V. S. Shusta; A. V. Gomonnai; A. G. Slivka; O. I. Gerzanich; Y. M. Azhniuk; UZHGOROD NATIONAL UNIV (UKRAINE)
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| The effect of hydrostatic pressure on the optical absorption spectra of CdS(1-x)Se(x) nanocrystals embedded in borosilicate glass matrix is studied. The energy gap pressure coefficients and compressibility values for CdS(0.4)Se(0.6) (average size 2.76 nm) and CdS(0.22)Se(0.78) (3.08 nm) samples are obtained. The effect of the glass matrix pressure upon the nanocrystals is discussed. |
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| International Workshop on Amorphous and Nanostructured Chalcogenides. Fundamentals and Applications (1st) held in Bucharest, Romania on 25-28 June 2001. Proceedings, Part 1 |
JUN 2001 |
|
| Authors:
Mihai A. Popescu; NATIONAL INST OF MATERIALS PHYSICS BUCHAREST (ROMANIA)
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| Includes papers presented at the First International Workshop on Amorphous and Nanostructured Chalcogenides Fundamentals and Applications held in Bucharest, Romania June 25-28, 2001. |
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| The Effects of Body Size and Environmental Temperatures on Swimming Efficiency in Marine Mammals: Guidelines for Novel Underwater Propulsive Systems |
31 MAY 2001 |
45 pages |
| Authors:
Terrie M. Williams; CALIFORNIA UNIV SANTA CRUZ DEPT OF BIOLOGY
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| The effects of body size and environmental temperature on locomotor efficiency were examined for the bottlenose dolphin (Tursiops Truncatus). Because dolphins rely on limited on board energy supplies during submergence, they represent ideal models for assessing mechanisms of fuel efficiency for autonomous underwater vehicles. This study found that submergence could be prolonged by: (1) packaging of energy stores based on body size, (2) opportunistic use of hydrostatic pressure to reduce ... |
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| Theoretical Studies of the Hydrostatic Compression of RDX, HMX, HNIW, and PETN Crystals |
APR 2001 |
46 pages |
| Authors:
Dan C. Sorescu; Betsy M. Rice; Donald L. Thompson; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| A previously developed intermolecular potential for nitramines and several other classes of nitrocompound crystals has been used to investigate the behavior of the energetic materials hexhydro-1,3,5-trinitro-1,3,5-s-trazine (RDX) 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclo-octane (HMX), 2,4,6,8,10,12- hexanitrohexaazaisowurtzitane (HNIW), and pentaerythritol tetranitrate (PETN) under hydrostatic compression. Isothermal-isobaric molecular simulations (assuming the rigid-molecule approximation) molecular-packing calculations were used to perform the analyses. In the case of the RDX, HMX, and HNIW crystals, the results indicate that the proposed ... |
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| Effect of Silicon Microstructure on Stress - Stimulated Creation of Thermal Donors |
2001 |
|
| Authors:
Andrzej Misiuk; INSTITUTE OF ELECTRON TECHNOLOGY WARSAW(POLAND)
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| Effect of intentionally created oxygen - related structural defects on generation of thermal donors, TD's, in Cz-Si treated at (670 K) 720 K under enhanced hydrostatic pressure of gas ambient, HP, up to 1.5 GPa (HT - HP treatment) was investigated. The as - grown Cz-Si samples with initial interstitial oxygen content up to 1.2 x 10(exp 18)/cu cm, as well as that pre - annealed at 720 - 1020 ... |
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| Effect of Hydrostatic Pressure on the Induction and Inactivation of Bacterial Spores Phase 1 |
DEC 2000 |
28 pages |
| Authors:
Norasak Kalchyanand; Bibek Ray; Anthony Sikes; C. P. Dunne; WYOMING UNIV LARAMIE DEPT OF ANIMAL SCIENCE
|
| Destruction of microbial cells and bacterial spores by hydrostatic pressure is being envisioned as a nonthermal novel technique in food preservation. A combination of 50000 psi (345 MPa) at 50C could kill over 6 log cycles of foodborne pathogenic and spoilage bacteria within 5 min. In contrast, even 200,000psi at 80C for 60min will not be able to inactivate important bacterial spores to the same level. However, bacterial spores can ... |
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| Electric Field Induced Strain in Electrostrictive Polymers Under High Hydrostatic Pressure - System Development and Material Characterization |
15 JUL 2000 |
16 pages |
| Authors:
Q. M. Zhang; PENNSYLVANIA STATE UNIV UNIVERSITY PARK MATERIALS RESEARCH LAB
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| This program has been used to support the training of a graduate student, Steve Gross, in the area of (i) developing a high performance piezo- bimorph based dilatometer which can be used to characterize the electric field induced strain response in polymer films under high hydrostatic pressure, (ii) using the set-up developed to evaluate the field induced strain performance of high energy electron irradiated P(VDF-TrFE) ... |
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| Photoluminescence of InAs/GaAs Quantum Dots Under Hydrostatic Pressure |
23 JUN 2000 |
3 pages |
| Authors:
V. A. Gaisin; Dinh Son Thach; B. S. Kulinkin; B. V. Novikov; V. N. Petrov; SAINT PETERSBURG STATE UNIV (RUSSIA) INST OF PHYSICS
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| The baric dependencies (0-20 kbar) of luminescence spectra (77 K) of InAs quantum dots have been investigated. InAs quantum dots on vicinal substrates GaAs at misorientation angle 3OO1, 7OO1 and 7O11 were grown. At P = 0 in the luminescence spectra a set of lines 1.235, 1,290, 1.343 eV of quantum dots of different sizes with base lengths 8-9 nm was observed. The dependence of baric coefficients on size of ... |
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| Ultrahigh Density Charge Transfer Device |
07 DEC 1999 |
|
| Authors:
Carmen I. Huber; Tito E. Huber; Nicholas Caviris; DEPARTMENT OF THE NAVY WASHINGTON DC
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| Metal heated to a molten state is injected under a high hydrostatic penetration pressure into extremely small and closely spaced channels of an insulating matrix to form an array of electrically conductive pins or wires. The materials for the pins and matrix are selected for compatibility with respect to melting, matrix sintering and surface tension penetration conditions associated with the fabrication of a high density charge transfer device. |
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| Novel Tungsten-Based Composites: Designer Materials for Ultra-High-Rate Deformation and Failure |
DEC 1999 |
6 pages |
| Authors:
K. T. Ramesh; JOHNS HOPKINS UNIV BALTIMORE MD DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| Broadly, the results under this grant are: The thermoviscoplastic behavior of pure polycrystalline tungsten at high rates of deformation was measured. This is the basis for some models of tungsten-based composites. The mechanical behaviors of two modified tungsten phases (made at Penn State and ARDEC) were measured at high rates and high temperatures. A model was developed for this behavior. The mechanical behavior of an alternate matrix material (hafnium) was ... |
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| Dual-Section Push-Pull Underwater Projector |
07 SEP 1999 |
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| Authors:
Jean C. Piquette; DEPARTMENT OF THE NAVY WASHINGTON DC
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| The present invention relates to an underwater acoustic projector comprising a housing formed from a rigid material, a fixed plate secured to the housing, a first annular electrostrictive ring and a second annular electrostrictive ring positioned on one side of the fixed plate, and a third annular electrostrictive ring and a fourth annular electrostrictive ring positioned on a second side of the fixed plate. The first and second annular rings ... |
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| Calibration of te Normal Pressure Transfer Function of a Compliant Fluid-Filled Cylinder |
07 SEP 1999 |
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| Authors:
Mark S. Peloquin; DEPARTMENT OF THE NAVY WASHINGTON DC
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| A method is presented to calibrate the transfer function for a fluid-filled compliant cylinder as a function of wave number and frequency. An air-filled compliant cylinder has a first linear array of force sensors coupled to the cylinder's exterior surface. A turbulent flow field is generated in a fluid environment about the first linear array which generates an output indicative of pressure incident thereupon. A fluid- filled compliant cylinder identical ... |
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| Development of a Constitutive Model for Numerical Simulation of Projectile Penetration into Brittle Geomaterials |
SEP 1999 |
227 pages |
| Authors:
J. D. Cargile; ARMY ENGINEER WATERWAYS EXPERIMENT STATION VICKSBURG MS ENGINEER RESEARCH AND DEVELOPMENT CENTER
|
| A nonlinear, inelastic fracture model for brittle geomaterials has been developed for simulating the response of these materials to high-velocity projectile penetration. Laboratory mechanical property experiments show a transition in the shearing response for these materials from brittle at low pressures to ductile at high pressures. The model has the underlying assumption that the shearing response can be resolved into a brittle cohesive component and ... |
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| Fiber Optic Accelerometer Sensor and a Method of Constructing Same |
11 MAY 1999 |
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| Authors:
Sandeep T. Vohra; Bruce Danver; Alan Tveten; Anthony Dandridge; DEPARTMENT OF THE NAVY WASHINGTON DC
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| The interferometric fiber optic accelerometer is viewed as a mass spring transducer housed in a sensor case. The sensor case is attached to a moving part whose motion is inferred from the relative motion between the mass and the sensor case. A flexural disk is housed in a sensor case which is accelerated in a direction normal to the plate surface. The plate undergoes displacement resulting in strains on the ... |
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| Impulsive Snap-Through Acoustic Pulse Generator |
13 APR 1999 |
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| Authors:
Jerome F. DeJaco; Willard F. Rask; DEPARTMENT OF THE NAVY WASHINGTON DC
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| An impulsive snap through acoustic pulse generator may be used to generate an acoustic pulse in an aqueous environment without gas bubbles. The impulsive snap through acoustic pulse generator includes a support structure having an open end: a resilient shell mounted to the support structure to define a chamber, and a gas vent in fluid communication with the chamber through which a gas passes for changing the pressure in the ... |
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| Engineering and Design: Inspection, Monitoring and Maintenance of Relief Wells |
25 SEP 1998 |
8 pages |
| Authors:
CORPS OF ENGINEERS WASHINGTON DC
|
| This regulation provides policy guidance for scheduled monitoring, inspection, evaluation, maintenance and rehabilitation of relief wells at civil works projects. |
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| Shelf-Life and Safety Enhancement of Processed Meat by Hydrostatic Pressure in Combination with Moderate Temperature and Biopreservatives, Phase IV |
SEP 1998 |
37 pages |
| Authors:
Norasak Kalchayanand; Bibek Ray; Anthony Sikes; C. P. Dunne; WYOMING UNIV LARAMIE
|
| The effectiveness of a moderate hydrostatic pressure in combination with moderate temperature and biopreservatives to reduce high populations of pathogenic and spoilage bacteria in processed meat products was determined. Roast beef and fermented summer sausage were inoculated with 10(3) to 10(4) cells/g of four pathogens and four spoilage bacteria along with pediocin AcH or one of two bacteriocin-based biopreservatives. After vacuum-packaging, the bags were pretempered in a water bath to ... |
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| Optimizing the Compressional Wave Energy Response of an Elastic Fluid-Filled Cylinder |
14 JUL 1998 |
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| Authors:
Mark S. Peloquin; DEPARTMENT OF THE NAVY WASHINGTON DC
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| A method and system are provided to optimize filtering of compressional wave energy in the wavenumber domain for a given frequency range using a fluid-filled elastic cylinder. The fluid is selected based on its fluid density pi, and dilatational wave phase velocity C sub i |
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| High Pressure Spectroscopic Studies of AlGaAs, GaAs, and II-VI and Other Semiconductors and Heterostructures |
12 JUL 1998 |
28 pages |
| Authors:
M. Chandrasekhar; MISSOURI UNIV-COLUMBIA DEPT OF PHYSICS
|
| We summarize our work over the last five years on high pressure studies using optical techniques such as photoluminescence, photoreflectance and Raman scattering of GaAs/AlAs superlattices, polycrystalline and amorphous powder samples of phenylene-type polymers and oligomers, ordered and disordered GaInP2, and ZnCdSe heterostructures. In order to modulate interatomic electronic interactions in the conventional semiconductors and to study both intrachain and interchain interactions in the conjugated polymers,these investigations were performed at ... |
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| Investigation of the Constitutive Model Used in Nonlinear, Incremental Structural Analyses |
JUN 1998 |
58 pages |
| Authors:
Barry D. Fehl; Sharon B. Garner; ARMY ENGINEER WATERWAYS EXPERIMENT STATION VICKSBURG MS INFORMATION TECHNOLOGY LAB
|
| Nonlinear, incremental structural analysis (NISA) has been used on Corps of Engineer projects for the last decade. An integral part of the NISA methodology is the constitutive model used when performing a NISA study. This constitutive model contains age-dependent characteristics for the modulus of elasticity, autogenous shrinkage, and creep as well as a stress-strain smeared cracking relationship. Before performing a NISA study on a project, the constitutive model is typically ... |
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| Mechanisms of Resistance in Microbial Spores |
02 MAR 1998 |
5 pages |
| Authors:
Phillipp Gerhartdt; Robert E. Marquis; MICHIGAN STATE UNIV EAST LANSING DEPT OF MICROBIOLOGY AND PUBLIC HEALTH
|
| Pursuant to the goals and objectives of the project, the following principal results were obtained: (1) the native peptidoglycan in the cortex around the dormant spore protoplast has low electrical conductivity and is highly cross-linked, contrary to results usually reported; (2) the water within the entire spore is in a free state and exchangeable by diffusion with external water; (3) hydrostatic pressure enhances the heat killing of spores; (4) the ... |
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| High Pressure Spectroscopic Studies of AlGaAs, GaAs, and II-VI semiconductors and Heterostructures |
14 OCT 1997 |
7 pages |
| Authors:
Meera Chandrasekhar; MISSOURI UNIV-COLUMBIA DEPT OF PHYSICS
|
| We have conducted four studies on three different but related materials. The first is a temperature study of a pseudomorphic epilayer of ZnSe on GaAs, where we measured the temperature dependence of the interlayer biaxial strain. The measurement was performed via photomodulation spectroscopy, tracking the splitting of the heavy - light hole transition energies. This method provides an accurate and direct measure of the strain. In the second study we ... |
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| Axisymmetric Compression of a Mohr-Coulomb Medium with Arbitrary Dilatancy, Including Free-Field Yielding |
01 OCT 97 |
132 pages |
| Authors:
David M. Kendall; Gary L. Wintergerst; Danny N. Burgess; BDM INTERNATIONAL INC MCLEAN VA
|
| A dosed-form analytical solution is developed for hole closure and stresses and strains in a Mohr-Coulomb medium surrounding a circular hole and loaded axisymmetrically in plane strain. This solution extends multiple-plastic- zone solutions developed by others to allow arbitrary dilatancy. It also extends the solution to include cases where particular combinations of friction angle, elastic properties, and free-field pressure cause the free field to yield before significant deformation of the ... |
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| Underwater Mateable Electrical Connector with Anti-Hydrolock Feature |
24 JUN 1997 |
21 pages |
| Authors:
Victor J. Marolda; Roy Manstan; DEPARTMENT OF THE NAVY WASHINGTON DC
|
| An electrical connector includes a plug section having a body, and a receptacle section which is connected to the plug section. A collapsible seal is disposed within a circumferential groove formed in the plug section. The receptacle section has a cylindrical housing with a clamping ring for securely engaging and connecting the receptacle section to the plug section. Upon connecting the receptacle section to the plug section any hydrostatic forces ... |
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| Experimental Determination of Transfer Functions for a Coated, Ring Stiffened Cylinder as a Function of Hydrostatic Pressure |
JUN 97 |
|
| Authors:
Robert H. Meyer; MASSACHUSETTS INST OF TECH CAMBRIDGE
|
| Coating effectiveness, as measured by the change in a ring stiffened cylinder's transfer function, is experimentally determined in the acoustic far field for increasing hydrostatic pressure. Polymer coating response characteristics are a function of temperature, frequency, molecular structure, chemical crosslinking systems and fillers. A sample coating, of unknown composition, is provided for analysis to gage performance as a function of frequency and filler (indirectly through hydrostatic pressure). Limited instrumentation assets ... |
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| Semiconductor Ultraviolet Detectors |
25 APR 97 |
33 pages |
| Authors:
P. I. Cohen; M. I. Nathan; MINNESOTA UNIV MINNEAPOLIS DEPT OF ELECTRICAL ENGINEERING
|
| Materials and structures crucial to the development of semiconducting ultraviolet detectors were examined. The chemical beam epitaxy of GaN was compared to the growth of GaN using supersonic jet sources. The main characterization techniques employed were reflection high energy electron diffraction (RHEED) and desorption mass spectroscopy (DMS). It was found that a supersonic jet of molecular nitrogen seeded in molecular hydrogen would react at the surface to form GaN at ... |
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| Nonlinear Rheology of Rock at Moderate Strains and Its Importance to Discrimination, Detection, and Yield Estimation of Underground Explosions |
03 APR 97 |
50 pages |
| Authors:
Greg N. Boitnott; NEW ENGLAND RESEARCH INC WHITE RIVER JUNCTION VT
|
| A laboratory experimental program has been performed to characterize the rheology of rock subject to moderate perturbations in stress. The objectives were to provide laboratory data to aid in the development and constraint of realistic rock rheologies suitable for modeling wave propagation in the moderate-strain and brittle-damage regimes. This information was needed to better understand the extent to which nonlinear material properties are important to regional discriminants and event detection. ... |
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| Destruction of Spoilage and Pathogenic Bacteria by Hydrostatic Pressure and Electroporation in Combination with Biopreservatives. Phase 2 |
APR 97 |
32 pages |
| Authors:
Norasak Kalchayanand; Bibek Ray; Anthony Sikes; C. P. Dunne; WYOMING UNIV LARAMIE
|
| Escherichia coli O157:H7, Salmonella typhimurium ATCC 14028, Listeria monocytogenes Scott A, Leuconostoc mesenteroides Ly and Lactobacillus sake FMl were evaluated for their sensitivity to either hydrostatic pressure (HP) or electroporation (EP) in combination with temperature, biopreservative and lysozyme. Both HP and EP caused viability loss and sublethal injury to bacterial cells. A combination of HP and mild temperature induced greater sublethal injury to cells. Sublethally injured cells became sensitive to ... |
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| Set-Up Under a Natural Wave |
MAR 97 |
51 pages |
| Authors:
Bruce J. Morris; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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| Field measurements from a cross shore array of two pressure sensors to measure waves and eight manometer tubes to measure mean water elevation are used to examine set-down/up across the surf zone. The manometer tubes are connected to differential pressure transducers onshore allowing continuous set- down/up measurements. Flume measurements of set-down/up are also examined. Measured values are compared with numeric set-up values incorporating roller theory describing wave breaking. The model ... |
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| Application of Mismatch Induced Superplasticity to the Consolidation of Composite Compacts |
31 DEC 96 |
8 pages |
| Authors:
Glenn S. Daehn; OHIO STATE UNIV COLUMBUS DEPT OF MATERIALS SCIENCE AND ENGINEERING
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| It has been postulated that mismatch induced superplastic effects can be attained in the pressure cycling of materials that have a mismatch in compressibility. This project sought to: (1) experimentally verify that superplastic effects can be attained this way, and (2) apply this effect to the practical forming of metal matrix composites and the consolidation of composite powder compacts. This project was fully successful in demonstrating that the effect exists ... |
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| High Pressure, high Frequency Reciprocal Transducer. |
05 NOV 1996 |
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| Authors:
James A. Tims; DEPARTMENT OF THE NAVY WASHINGTON DC
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| A high frequency transducer capable of transmitting and receiving having an operational range from 100 kHz to 2 MHz, a free field voltage sensitivity (FFVS) greater than -218 dB re 1 V/(mu)Pa (300 kHz), and a maximum hydrostatic pressure rating of 20.68 Mpa (3000 psi). The sensor element is made of lead titanate with a radial mode of 150 kHz being suppressed by the use of a rubber grommet surrounding ... |
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Reports by Keyword(s)
HYDROSTATIC PRESSURE
