| Characterization of Ceramic Composite Materials Using Terahertz Non-Destructive Evaluation Techniques (Preprint) |
Aug 2012 |
5 pages |
| Authors:
Adam Cooney; Lindsay Owens; Jason A Diebel; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING DIRECTORATE
|
 | THz time-domain reflection imaging is utilized as non-destructive evaluation technique for ceramic composite materials in order to characterize changes in material properties due to mechanical and thermal strain effects. |
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| Air Vehicle Integration and Technology Research (AVIATR). Delivery Order 0023: Predictive Capability for Hypersonic Structural Response and Life Prediction: Phase 2 - Detailed Design of Hypersonic Cruise Vehicle Hot-Structure |
May 2012 |
203 pages |
| Authors:
Brian Zuchowski; LOCKHEED MARTIN AERONAUTICS CO PALMDALE CA
|
| Structural design of hypersonic vehicles requires additional considerations and effort, relative to conventional subsonic and low-supersonic aircraft, because of the wide Mach number range and the associated heating effects at high Mach numbers. At high temperatures, conventional structural materials, such as metals, suffer from reduced strength, reduced stiffness, increased creep, increased oxidation, increased thermal stresses, and other detrimental effects that impact structural design; many of these effects are of limited ... |
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| An FPGA Noise Resistant Digital Temperature Sensor with Auto Calibration |
Mar 2012 |
71 pages |
| Authors:
Brandon A Brown; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH GRADUATE SCHOOL OF ENGINEERING AND MANAGEMENT
|
| In recent years, thermal sensing in digital devices has become increasingly important. From a security perspective, new thermal-based attacks have revealed vulnerabilities in digital devices. Traditional temperature sensors using analog-to-digital converters consume significant power and are not conducive to rapid development. As a result, there has been an escalating demand for low cost, low power digital temperature sensors that can be seamlessly integrated onto digital devices. This research seeks to ... |
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| Air Vehicle Integration and Technology Research (AVIATR). Delivery Order 0013: Nonlinear, Low-Order/Reduced-Order Modeling Applications and Demonstration |
Dec 2011 |
269 pages |
| Authors:
Salvatore L Liguore; Dale M Pitt; Michael J Thomas; Nicholas Gurtowski; BOEING CO ST LOUIS MO
|
| Dynamic response analysis tools used by the aerospace industry rely heavily on linear modal frequency response finite element methods. These linear methods are straight forward to use even in the analysis of a complex structural component that require a large number of degrees-of-freedom to model. However, this approach is not suitable for predicting the response of highly loaded thermal/acoustic aircraft structures that may respond in a nonlinear geometric manner. This ... |
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| Energy Expenditure and Metabolic Heat Production Storage Estimates of Tactical Law Enforcement Personnel during Chemical, Biological, Radiological, and Nuclear (CBRN) Training |
Sep 2011 |
37 pages |
| Authors:
Victoria Goetz; Miyo Yokota; Anthony J Karis; William J Tharion; ARMY RESEARCH INST OF ENVIRONMENTAL MEDICINE NATICK MA BIOPHYSICS AND BIOMEDICAL MODELING DIV
|
| The tactical law enforcement community is involved in a range of missions utilizing various types of personal protective equipment (PPE). They are also exposed to a wide range of environmental conditions. The use of chemical, biological, radiological, and nuclear (CBRN) protective ensembles, either with or without body armor, can add significant thermal stress due to the increased weight and insulating properties of these garments and head gear. High ambient heat ... |
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| Methods of Evaluating Protective Clothing Relative to Heat and Cold Stress: Thermal Manikin, Biomedical Modeling, and Human Testing |
Jan 2011 |
13 pages |
| Authors:
Catherine O'Brien; Laurie A Blanchard; Bruce S Cadarette; Thomas L Endrusick; Xiaojiang Xu; Larry G Berglund; Michael N Sawka; Reed W Hoyt; ARMY RESEARCH INST OF ENVIRONMENTAL MEDICINE NATICK MA THERMAL AND MOUNTAIN MEDICINE DIVISION
|
| Personal protective equipment (PPE) refers to clothing and equipment designed to protect individuals from chemical, biological, radiological, nuclear, and explosive hazards. The materials used to provide this protection may exacerbate thermal strain by limiting heat and water vapor transfer. Any new PPE must therefore be evaluated to ensure that it poses no greater thermal strain than the current standard for the same level of hazard protection. This review describes how ... |
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| Fluid and Electrolyte Needs for Training, Competition, and Recovery |
Jan 2011 |
10 pages |
| Authors:
Susan M Shirreffs; Michael N Sawka; ARMY RESEARCH INST OF ENVIRONMENTAL MEDICINE NATICK MA THERMAL AND MOUNTAIN MEDICINE DIVISION
|
| Fluids and electrolytes (sodium) are consumed by athletes, or recommended to athletes, for a number of reasons, before, during, and after exercise. These reasons are generally to sustain total body water, as deficits (hypohydration) will increase cardiovascular and thermal strain and degrade aerobic performance. Vigorous exercise and warm/hot weather induce sweat production, which contains both water and electrolytes. Daily water (4-10 L) and sodium (3500-7000 mg) losses in active athletes ... |
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| Thermal Stress |
2011 |
7 pages |
| Authors:
L. R. Leon; C. J. Gordon; ARMY RESEARCH INST OF ENVIRONMENTAL MEDICINE NATICK MA THERMAL AND MOUNTAIN MEDICINE DIVISION
|
| Thermal stress can have a significant impact on normal physiological functioning if precipitous increases in core temperature are not adequately controlled with behavioral and autonomic mechanisms of body cooling. The United States experiences approximately 200 heat stroke deaths per year with the incidence of heat illness expected to rise as the average life span increases, the rate of obesity is accelerated, and global warming is realized. Heat illness affects all ... |
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| Discrete Film Cooling in a Rocket with Curved Walls |
Dec-2009 |
178 pages |
| Authors:
Jonathan F McCall; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
|
| This study quantified the effects of discrete wall-based film cooling in a rocket with curved walls. Simulations and experiments showed decreasing with wall radius of curvature, holding jet diameter constant, improves net heat flux reduction (NHFR) and adiabatic effectiveness (eta) for 90 compound injected cylindrical jets, though is reduced at the highest curvature. NHFR and eta improved further with a high favorable stream-wise pressure gradient (K=2.1x10-5) at all tested blowing ... |
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| A Three-Dimensional Foil Bearing Performance Map Applied to Oil-Free Turbomachinery |
Apr-2009 |
22 pages |
| Authors:
Christopher Dellacorte; Kevin C Radil; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH GLENN RESEARCH CENTER
|
| To effectively apply compliant foil gas bearings to increasingly larger and more challenging turbomachinery, a comprehensive method that compares a foil bearing's capabilities with the application's operating requirements is needed. Extensive laboratory and field experience suggests foil bearing failure is generally due to thermal stress brought on by excessive viscous power loss; therefore a map that graphically relates component and system-level parameters (bearing size, applied loads, and shaft rotational speeds) ... |
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| Understanding/Modelling of Thermal and Radiation Benefits of Quantum Dot Solar Cells |
11-Jul-2008 |
21 pages |
| Authors:
Ryne P Raffaelle; ROCHESTER INST OF TECH NY
|
| The radiation and thermal dependence of strain compensated InAs QD/ GaAs solar cells have been investigated. Strain compensation is a key step in realizing high efficiency quantum dots solar cells (QDSC). InAs quantum dots (QDs) are grown using the Stranski-Krastenov growth mode which relies on strain, resulting from the mismatch between the InAs and the GaAs lattice parameters, to initiate three-dimensional growth. The generation of QDs does reduce the local ... |
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| Thick Film Metastable Materials via Laser Processing |
18 APR 2008 |
7 pages |
| Authors:
Craig B. Arnold; PRINCETON UNIV NJ
|
| Over course of this project, the objective has evolved based on the results obtained. In the original proposal, our objective was basically to study the interaction between the incident laser and the multiphase materials that are used in laser direct write deposition in order to produce metastable phases of materials for improved performance in a variety of applications such as energy storage and corrosion resistant systems. Based on our results ... |
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| Evaluation of Catalytic and Thermal Cracking in a JP-8 Fueled Pulsed Detonation Engine (Postprint) |
SEP 2007 |
15 pages |
| Authors:
Timothy M. Helfrich; Frederick R. Schauer; Royce P. Bradley; John L. Hoke; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
|
| Pulsed detonation engines (PDEs) depend on rapid ignition and transition from deflagration to detonation. The prospect of converting the PDE from experimental to operational use necessitates a considerable reduction in the time required to ignite and detonate a liquid hydrocarbon fuel in air, such as JP-8. This research effort is focused on PDE operation enhancements using dual detonation tube, concentric-counter-flow heat exchangers to elevate the fuel temperature levels sufficiently to ... |
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| Temperature Stabilization for Negative Bias Temperature Instability |
SEP 2007 |
79 pages |
| Authors:
Brian K. Harbison; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| Previous research was conducted on a Complementary Metal Oxide Semiconductor (CMOS) to determine the impact of a phenomenon known as Negative Bias Temperature Instability (NBTI). NBTI affects the operational characteristics of these devices, with a stronger effect on p-channel devices. This instability is apparent when the semiconductor is on biased, and exacerbated under thermal stress. This data is useful in determining the projected failure rate of certain submicron technologies. The ... |
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| The Efficacy of an Air-Cooling Vest to Reduce Thermal Strain for Light Armour Vehicle Personnel |
JAN 2007 |
|
| Authors:
Tom M. McLellan; DEFENCE RESEARCH AND DEVELOPMENT TORONTO (CANADA)
|
 | Light armour vehicle (LAV) personnel are being subjected to high ambient temperatures and radiant heat loads for hours during recent deployments to Afghanistan. One option to reduce the heat strain of crew members is to use the existing air-conditioning discharge outlets as a source of cool air to provide microclimate cooling through an individual air-vest. In this study, seven males were exposed to either hot, dry (HD, 49 C, 10% ... |
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| Thermo-mechanical Analysis of Ground-based Directed Energy Weapons on Satellites and Intercontinental Ballistic Missiles |
SEP 2006 |
122 pages |
| Authors:
Georgios Mantzouris; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| Thermo mechanical modeling and simulation of a satellite and intercontinental ballistic missile assumes importance due to the increased interest in assessing the potential of such attacks. Effective and innovative methods are sought in assessing the structural integrity of such structural components. In this study, we present modeling and simulation aspects of two generic models loaded by high energy laser beam. We present an application of MSC software in modeling thermo-mechanical ... |
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| Mathematical Modeling of Rail Gun |
SEP 2006 |
99 pages |
| Authors:
Nikolaos Pratikakis; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| The exit velocity of the launch object along with the values of electric and thermal conductivity at the interfaces between the rails and the armature of a rail gun are critical issues. This thesis, using finite element method, estimates the former by solving the proper multiphysics governing equations along with exploiting the contact theory between flat surfaces. A parametric analysis in the vicinity of the standard deviation of the normalized ... |
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| A 37-mm Ceramic Gun Nozzle Stress Analysis |
MAY 2006 |
28 pages |
| Authors:
Xiaogang Huang; James Garner; Paul Conroy; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| A series of shooting tests was conducted on a 37-mm gun fixture with ceramic nozzles. The primary concern for the design and test of the ceramic nozzle is the combination of the thermal stress and dynamic ballistic stress during the launch. On the basis of previous thermal analysis, a transient sequentially coupled finite-element model is performed to investigate the thermal stresses due to the large temperature gradient and coefficient mismatch ... |
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| Stress Intensity Solutions of Thermally Induced Cracks in Combustor Liner Hot Spots Using Finite Element Analysis (FEA) |
DEC 2005 |
158 pages |
| Authors:
Donald W. Rhymer; GEORGIA TECH RESEARCH CORP ATLANTA
|
| Developing stress intensity solutions for thermal strain inducing cracking in hot spots is the chief goal of this research. Using finite element analysis (FEA) to model the stress state and crack stress intensities resulting from thermal gradients, a model is needed to represent and predict this cracking and eventual crack arrest in combustor liners in turbine engines. In determining the number of cycles until the crack arrests, the model estimates ... |
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| Thermal Analysis for a 37-MM Gun Chamber With Ceramic Nozzles |
SEP 2005 |
24 pages |
| Authors:
Xiaogang Huang; James Garner; Paul Conroy; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| The 37-mm interior ballistics chamber is primarily a test bed to evaluate new propellant properties and their effects on gun systems. Experiments were conducted examining the properties of various ceramics under realistic interior ballistic loadings. The thermal response during the launch will cause stresses due to the large temperature gradient and coefficient of thermal expansion mismatch between the ceramic nozzle and steel gun chamber. In the first step of the ... |
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| Manned Evaluation of a Diver Heater for SDV Applications Using Hydrogen Catalytic Reactions |
JUN 2005 |
61 pages |
| Authors:
M. L. Nuckols; J. C. Chao; M. J. Swiergoaz; NAVY EXPERIMENTAL DIVING UNIT PANAMA CITY FL
|
| Naval Sea Systems Command (NAVSEA) 000 tasked Navy Experimental Diving Unit (NEDU) to assess the effectiveness of an experimental diver heater being developed in partnership by Duke University and NSWC Panama City under sponsorship of the Office of Naval Research.1 This proof of concept study was designed to investigate whether a prototype hydrogen catalytic heater, when used in conjunction with a recently developed integrated closed-circuit tube suit-dry suit thermal protection ... |
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| Fundamental Structure-Property Relationships for High-Temperature Ceramic Composites |
MAY 2005 |
13 pages |
| Authors:
Elizabeth C. Dickey; PENNSYLVANIA STATE UNIV UNIVERSITY PARK DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| This research program focused on studying interface structure and thermal compatibility stresses in several directionally solidified eutectic ceramic materials, which are candidates for high-temperature and ultra-high temperature structural materials in aerospace applications. Under this award we specifically investigated the alumina-zirconia and lanthanum hexaboride-zirconium diboride eutectic systems. High-resolution transmission electron microscopy was utilized to understand interfacial structures in these materials and x-ray diffraction was utilized to measure thermal residual stresses. A ... |
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| Analytical Model for Sensor Placement on Microprocessors |
2005 |
5 pages |
| Authors:
Kyeong-Jae Lee; Kevin Skadron; Wei Huang; VIRGINIA UNIV CHARLOTTESVILLE
|
| Thermal management in microprocessors has become a major design challenge in recent years. Thermal monitoring through hardware sensors is important, and these sensors must be carefully placed on the chip to account for thermal gradients. In this paper, we present an analytical model that describes the maximum temperature differential between a hot spot and a region of interest based on their distance and processor packaging information. We also use a ... |
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| Advanced Oxide Material Systems for 1650 Deg. C Thermal/Environmental Barrier Coating Applications |
DEC 2004 |
13 pages |
| Authors:
Dongming Zhu; Dennis S. Fox; Narottam P. Bansal; Robert A. Miller; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH GLENN RESEARCH CENTER
|
| Advanced thermal and environmental barrier coatings (TEBCs) are being developed for low- emission SiC/SiC ceramic matrix composite (CMC) combustor and vane applications to extend the CMC liner and vane temperature capability to 1650 degrees C (3000 degrees F) in oxidizing and water-vapor-containing combustion environments. The advanced 1650 degrees C TEBC system is required to have a better high temperature stability, lower thermal conductivity, and more resistance to sintering and thermal ... |
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| Aeroelasticity, Aerothermoelasticity and Aeroelastic Scaling of Hypersonic Vehicles |
DEC 2004 |
21 pages |
| Authors:
Peretz P. Freidmann; Kenneth G. Powell; MICHIGAN UNIV ANN ARBOR DEPT OF AEROSPACE ENGINEERING
|
| This final report describes the work during the period of the grant. Three separate hypersonic aeroelastic stability problems were considered: (a) a typical cross section having a double wedge airfoil, (b) the stability of a low aspect ratio wing, also with a double wedge airfoil, and (c) the behavior of a complete generic hypersonic vehicle. For problems (a) the unsteady airloads were computed using third order piston theory, as well ... |
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| Evaluation of a Jet Fuel Thermal Stability Rig |
NOV 2004 |
|
| Authors:
Paul Rawson; DEFENCE SCIENCE AND TECHNOLOGY ORGANISATION VICTORIA (AUSTRALIA) PLATFORM SCIENCES LAB
|
| Current and planned gas turbine engines use fuel as their primary heat sink. When jet fuel is thermally stressed it will form gums and deposits. These deposits can block engine fuel nozzles, causing damage to the engine hot sections, especially the combustor region. The fuel's thermal stability is a critical fuel property with respect to optimum performance of modern military gas turbine engines. The current standard method to rate fuel ... |
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| Fundamental Issues Regarding the High Temperature Failure Properties of Graphite/Polyimide Fabric Composites |
OCT 2004 |
172 pages |
| Authors:
M. S. Kumosa; DENVER UNIV CO DEPT OF ENGINEERING
|
| In this work, a method based on X-ray diffraction (XRD) measurements of internal stresses in embedded metallic ellipsoidal inclusions is briefly described. The method has been recently developed for the determination of residual thermal stresses in high temperature graphite/polyimide composites. The effects of external bending loads and aging on the measurements of the internal stress in unidirectional and woven graphite fiber (T650-3 5)/polyimide (PMR-15) composites were examined in addition to ... |
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| Secondary Electron Emission Measurements on Materials Under Stress |
OCT 2004 |
99 pages |
| Authors:
Shinichi Kobayashi; Yoshio Saito; SAITAMA UNIV URAWA (JAPAN)
|
| The breakdown of rf windows used in high-power klystron is one of the most serious problems in the development of klystrons. The dielectric breakdown strength of an alumina ceramic surface depends on the secondary electron emission which is influenced by the electronics states of the oxygen vacancy existing adjacent to the ceramic surface. In this report, the durability of several dielectric materials used for rf windows is discussed in terms ... |
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| Development of Nickel-Titanium Graded Composition Components |
AUG 2004 |
14 pages |
| Authors:
M. S. Domack; J. M. Baughman; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CENTER
|
| The potential of various manufacturing methods was evaluated for producing nickel-titanium graded composition material. The selected test case examined attachment brackets that join nickel-based metallic thermal protection systems to titanium-based launch vehicle structure. The proposed application would replace nickel-based components with graded composition components in an effort to alleviate service induced thermal stresses. Demonstration samples were produced by laser direct metal deposition, flat wire welding, and ultrasonic consolidation. Microstructure, general ... |
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| Relaxation of Kevlar Braided Cords |
28 JUN 2004 |
87 pages |
| Authors:
Russell B. Fete; GEORGE WASHINGTON UNIV WASHINGTON DC
|
| NASA uses Kevlar Aramid Fiber in constant strain applications in the form of braided cord. Questions about its behavior in load relaxation with variables including time, temperature, humidity, initial and re-tensioning loads are probed by this report, beginning with a literature review. Testing was performed at NASA Goddard SFC to attempt to resolve unanswered questions. The results are demonstrative of three important findings: 1) The first is that the initial ... |
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| Risk Mitigaion for HTS Motors: Intermediate Temperature (27 K) Strain Effects in Reinforced Bi-Sr-Ca-Cu-O Superconductors |
07 JUN 2004 |
13 pages |
| Authors:
Justin Schwartz; FLORIDA STATE UNIV TALLAHASSEE
|
| High temperature superconductors , known for their high critical temperatures, also have very high upper critical fields and thus have received significant attention for superconducting magnets (SCMs). To operate in a SCM, however, the superconductor must have high J(sub c) in the presence of high magnetic field and under the action of mechanical strain (Epsilon) that results from the manufacturing processes, differential thermal contraction, and Lorentz forces. For some FITS ... |
|
| Services to Operate and Maintain a Microwave Research Laboratory |
MAY 2004 |
453 pages |
| Authors:
Shin-Tsu Lu; MCKESSON BIOSERVICES ROCKVILLE MD
|
| Due to growing concerns for the health and safety of military and civilian personnel exposed to radiofrequency radiation (RFR), a series of research have been performed at the U.S. Army Medical Research Detachment, Microwave Bioeffects Branch at Brooks City-Base, Texas. The research has been concentrated on neurotoxic effects of high peak power but low average power RFR, Interact ion between neurotoxin and RFR on manifestation of neurotoxic effects, effects of ... |
|
| Numerical and Experimental Investigation of the Turbulent Flow in a Ribbed Serpentine Passage |
24 MAR 2004 |
9 pages |
| Authors:
Gianluca Iaccarino; Georgi Kalitzin; Christopher J. Elkins; STANFORD UNIV CA DEPT OF MECHANICAL ENGINEERING
|
| Modern gas turbine engines operate at high combustor outlet temperatures to achieve higher thermal efficiency and thrust. Turbine blades are exposed to these high-temperature gases and undergo severe thermal stress and fatigue. The design of highly efficient cooling systems for turbine blades has an enormous potential impact on engine development. Cooling devices are based on a secondary flow system built into each blade, as illustrated in Fig. 1. The secondary ... |
|
| Evaluation of the Integrity of the MK 21 Contaminated Water Diving System and of the Efficacy of Decontamination Procedures |
MAR 2004 |
24 pages |
| Authors:
F. F. Leyva; NAVY EXPERIMENTAL DIVING UNIT PANAMA CITY FL
|
| Current Navy recommendations for diving in contaminated water include wearing a vulcanized rubber dry Suit mated to a MK 21 helmet with double exhaust valve to isolate the diver from the contaminated environment. No full-scale testing of this configuration or of the efficacy of recommended decontamination procedures has been performed. The purpose of this immersion testing therefore is to evaluate the integrity of the MK 21 contaminated water diving system ... |
|
| Memowire: Polycrystalline Silicon Memory Effects |
13 FEB 2004 |
32 pages |
| Authors:
Serge Ecoffey; D. Bouvet; A. M. Ionescu; SWISS FEDERAL INST OF TECHNOLOGY LAUSANNE (SWITZERLAND)
|
| This report results from a contract tasking Swiss Federal Inst. of Tech. Lausanne as follows: The contractor will study and report on materials and device information for the polysilicon memory project. Contractor to provide materials information on how polysilicon. silicon dioxide and the polysilicon/ silicon dioxide interfaces behave under temperature and electric field stresses. Specific device information to be applicable to e-beam fabricated memory devices, the specific effect under study ... |
|
| Operator Functional State Assessment (L'evaluation de l'aptitude operationnelle de l'operateur humain) |
FEB 2004 |
|
| Authors:
NATO RESEARCH AND TECHNOLOGY ORGANIZATION NEUILLY-SUR-SEINE (FRANCE)
|
| The human operator is a crucial component of complex modern systems. The complexity of these systems, the rapid tempo of contemporary military operations and reduced staffing all contribute to the high cognitive demands experienced by military personnel. The rate of intonation flow, the number of decisions, and actions that must be carried out can exceed the cognitive capacity of the operator. This can result in disastrous consequences. Other system components ... |
|
| Erbium: YAG Laser Incision of Urethral Strictures for Treatment of Urinary Incontinence after Prostate Cancer Surgery |
FEB 2004 |
50 pages |
| Authors:
Nathaniel Fried; JOHNS HOPKINS UNIV BALTIMORE MD SCHOOLOF MEDICINE
|
| Urethral and bladder neck strictures occur in 5 to 20 percent of all prostate cancer surgery patients, resulting in urinary incontinence. Conventional treatments for stricture (including balloon dilation, cold knife incision, electrocautery, and Holmium laser incision) have widely variable success rates with suboptimal long-term results. The failure of these conventional stricture treatments is presumably due to mechanical and/or thermal damage to the urethral wall during the procedure. The purpose of ... |
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| Evaluation of a Diver Cooling System for Use With Personal Protective Equipment in Contaminated Water Diving |
JAN 2004 |
15 pages |
| Authors:
Fernando F. Leyva; George S. Goehring; NAVY EXPERIMENTAL DIVING UNIT PANAMA CITY FL
|
| Current Navy recommendations for diving in contaminated water include wearing a vulcanized rubber dry suit mated to a MK 21 diving helmet to isolate the diver from the contaminated environment. However, even in situations (e.g., visible oil spills, noxious fumes, and sewer outflows) where the need for protective gear is uneguivocal, thermal stress from working in a warm environment often precludes the use of such gear. The purpose of this ... |
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| Characterization of Uncertainties in a Thermal Strain Prediction Model for Military Applications |
DEC 2003 |
|
| Authors:
Miyo Yokota; William T. Matthew; Larry G. Berglund; Mark J. Buller; Reed W. Hoyt; ARMY RESEARCH INST OF ENVIRONMENTAL MEDICINE NATICK MA
|
| SCENARIO-J is a Java (R)-based thermoregulatory prediction model developed by Kraning and Gonzalez of USARIEM. The model was previously evaluated under thermally stressful laboratory environments and the model performance in long-term field conditions was still unclear. This study evaluates the reliabilities of SCENARIO-J in long term military field training and showed the comparisons in these results with previous laboratory controlled validation studies. |
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| Characterization of Uncertainties in a Thermal Strain Prediction Model for Military Applications |
DEC 2003 |
38 pages |
| Authors:
Miyo Yokota; William T. Matthew; Larry G. Berglund; Mark J. Buller; Reed W. Hoyt; ARMY RESEARCH INST OF ENVIRONMENTAL MEDICINE NATICK MA
|
| Thermoregulatory prediction models are increasingly needed for accurate physiological status and risk assessment to prevent heat and cold injuries among deployed soldiers. These biophysical prediction models can provide consistent and repeatable simulations over a wide range of working and environmental conditions to assess physiological risks because they are rationally based on thermodynamics and heat transfer coupled with active physiological control systems and biophysical properties. In contrast, a statistical regression prediction ... |
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| Review of Improved Methods for Analysing Load Attraction and Thermal Effects in Bonded Composite Repair Design |
DEC 2003 |
|
| Authors:
A. B. Harman; K. F. Walker; DEFENCE SCIENCE AND TECHNOLOGY ORGANISATION VICTORIA (AUSTRALIA) PLATFORM SCIENCES LAB
|
| Adhesive bonded repairs to aircraft involving metallic and composite structures have proven to be an effective, efficient means of repair and life extension. The simplified closed form equations used by the RAAF in an Engineering Standard (DEF(AUST)90O5) have proven to be effective and conservative. Recent work, however, has identified improved equations to account for load attraction into the stiffened repaired area, and evaluate the thermally induced stresses in the repaired ... |
|
| Residual Stresses in Thermosetting Resins for Polymer Matrix Composites: Modeling and Effects on Long Term Performance |
NOV 2003 |
35 pages |
| Authors:
Gregory B. McKenna; Sindee L. Simon; TEXAS TECH UNIV LUBBOCK
|
| We extended a previous model due to the PIs for the evolution of the properties of curing thermoset resins to the BMI/SOC resins of interest to the Air Force. The model was used to estimate the cure stresses in this system in an ideally and isotropically constrained system. The results were surprising in the large magnitude of the stresses predicted and showed that judicious selection of polymer materials for low ... |
|
| Spray Forming Iron Based Amorphous Metals |
SEP 2003 |
46 pages |
| Authors:
Leslie K. Kohler; Louis F. Aprigliano; A. S. Rao; NAVAL SURFACE WARFARE CENTER CARDEROCK DIV BETHESDA MD METALS PROCESSING AND ANALYSIS BRANCH
|
| Spray metal forming has been used to produce deposits of iron-based alloys DAR1A, DAR27, DAR35, and BMA1. The deposits were made on tubular and flat plate substrates and were up to 1.25 inches in thickness. Most of the deposits were found to be partially amorphous in the as-sprayed condition. Measurements were made of microhardness and porosity, and corrosion and wear tests were conducted. Severe cracking occurred in the thick section ... |
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| A Comparison of the Predictive Accuracy of Human Thermoregulatory Models |
SEP 2003 |
|
| Authors:
Peter Sanders; DEFENCE SCIENCE AND TECHNOLOGY ORGANISATION VICTORIA (AUSTRALIA) PLATFORM SCIENCES LAB
|
| The core temperature predictions from four computer models of the human thermoregulatory response were compared with results from laboratory exercise studies published locally and in the open literature. Although none of the models were able to predict deep body temperatures to within an accuracy of 0.1 degrees C to 0.5 degrees C in all instances, the model from the United States Army Research Institute of Environmental Medicine (ARIEM) in the ... |
|
| Potential for Expansion of Coral Reefs into Higher Latitudes due to Climate Change |
Sep-2003 |
4 pages |
| Authors:
Gang Liu; William Skirving; Alan E Strong; NOAA/NESDIS OFFICE OF RESEARCH AND APPLICATIONS CAMP SPRINGS MD
|
| With the occurrence of recent strong climate events (e.g. El Nino 1997-1998 and La Nina 1999-2000) over the last couple of decades, it has become interesting to investigate if there have been any effects on Sea Surface temperature (SST) at geographical margins of coral reefs. It is generally accepted that the sea temperature range for coral reefs is 18-36 deg C, with the optimal range being between 22-deg and 28-deg ... |
|
| Controlled-Stress Large-Area Pulsed Laser Deposition of Yttria Stabilized Zirconia |
01 AUG 2003 |
258 pages |
| Authors:
Paul C. Rounsavall; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
|
| The US Air Force has need of parabolic-shaped membrane mirrors for surveillance satellites. The current polymer membrane technology has been unable to overcome shape deformation problems caused by intrinsic stresses from the membrane casting and mounting processes. One proposed solution was to coat the membrane mirrors with a stressed coating to compensate for shape deformations. Thus, the research presented in this dissertation produced controlled-stress large-area pulsed laser deposition (PLD) grown ... |
|
| Tri-Services Workshop on Process Induced Defects in Wide Bandgap Semiconductors |
AUG 2003 |
87 pages |
| Authors:
Shari J. Allwood; ALLWOOD AND ASSOCIATES INC MENTOR OH
|
| Meeting program, abstracts, and attendee roster for Tri-Services Workshop on Process Inducted Defects in Wide Bandgap Semiconductors held in Grants Pass, OR, on August 17-21, 2003. Sponsored by the Air Force Office of Scientific Research; U.S. Army Research Office; and Office of Naval Research. |
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| Reduction of Thermal Residual Strains in Adhesively Bonded Composite Repairs |
JUN 2003 |
138 pages |
| Authors:
Heather R. Crooks; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
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| Many military and commercial aircraft are being called upon to fly well beyond their original intended service lives. This has forced the United States Air Force (USAF) to increasingly rely on structural repairs to address fatigue induced damage and to extend aircraft useful life. The focus of this research is the use of a high-strength composite patch technique to repair a fatigue crack on an aluminum aircraft structure. This study ... |
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| Laterally Overgrown Structures as Substrates for Lattice Mismatched Epitaxy |
21 MAY 2003 |
12 pages |
| Authors:
Z. R. Zytkiewicz; POLISH ACADEMY OF SCIENCES WARSAW INSTOF PHYSICS
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| This article provides a general review of epitaxial lateral overgrowth (ELO) technology and of the application of ELO layers as substrates with an adjustable value of lattice constant. In particular, the issues of ELO growth mechanism, substrate defect filtration during ELO procedure, and strain in ELO layers will be addressed. Recent data on Metalorganic Vapor Phase Epitaxy (MOVPE) ELO growth of Gallium Nitride (GaN) on sapphire and the author's results ... |
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| Thermal and Residual Stress Modelling of the Selective Laser Sintering Process |
2003 |
7 pages |
| Authors:
Ameer K. Ibraheem; Brian Derby; Phillip J. Withers; MANCHESTER UNIV (UNITED KINGDOM) MATERIALS SCIENCE CENTER
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| The production of functional tool steel components by selective laser sintering requires an understanding of the effects of the laser processing parameters on the microstructure evolution during the fabrication process. This would allow the production of tools that have predictable and reproducible microstructure good mechanical properties and low residual stresses. In this paper, finite element modelling has been carried out to investigate the temperature distribution and residual stresses during laser ... |
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Reports by Keyword(s)
THERMAL STRESSES
