| A Study of Topic and Topic Change in Conversational Threads |
Sep-2009 |
95 pages |
| Authors:
Jessy Cowan-Sharp; NAVAL POSTGRADUATE SCHOOL MONTEREY CA DEPT OF COMPUTER SCIENCE
|
 | This thesis applies Latent Dirichlet Allocation (LDA) to the problem of topic and topic change in conversational threads using e-mail. We demonstrate that LDA can be used to successfully classify raw e-mail messages with threads to which they belong, and compare the results with those for processed threads, where quoted and reply text have been removed. Raw thread classification performs better, but processed threads show promise. We then present two ... |
|
| Numerical Simulation of Wear in a C/C Composite Multidisk Clutch (Preprint) |
Apr-2009 |
26 pages |
| Authors:
Gregory E Hilmas; Shuangmei Zhao; Lokeswarappa R Dharani; MISSOURI UNIV-ROLLA
|
| Friction and wear of engineering components are critical factors influencing the product life. In this study a wear simulation method is presented to investigate the wear behavior of a C/C composite multidisk clutch under simulated operation conditions. A modified Archard's wear model is implemented into a user subroutine which works in association with an axisymmetric finite element model to predict the progress of wear on friction surfaces. An element removal ... |
|
| Rotational Response of Toe-Restrained Retaining Walls to Earthquake Ground Motions |
DEC 2006 |
343 pages |
| Authors:
Robert M. Ebeling; Barry C. White; ENGINEER RESEARCH AND DEVELOPMENT CENTER VICKSBURG MS INFORMATION TECHNOLOGY LAB
|
| This research report describes the engineering formulation and corresponding software developed for the rotational response of rock-founded, toe-restrained Corps retaining walls to earthquake ground motions. The PC software CorpsWallRotate (sometimes referred to as CWRotate) was developed to perform an analysis of permanent wall rotation for each proposed retaining wall section to a user-specified earthquake acceleration time-history. A particular formulation of the permanent sliding (i.e., translational) displacement response of retaining walls ... |
|
| Structural Design of Wing Twist for Pitch Control of Joined Wing Sensor Craft |
MAR 2006 |
117 pages |
| Authors:
III Kimler Fred A.; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
|
| This research investigated two aspects of the aft wing structure of a joined wing SensorCraft. First, the efficacy of a novel approach for incorporating wing twist for pitch control was analyzed. This design involved adding a spanwise sliding joint into the wing structure at the lower aft spar of the vehicle's aft wing. Second, the joint section where the forward and aft wings connect and form the outboard wing was ... |
|
| Simplex Sliding Mode Control for Nonlinear Uncertain Systems Via Chaos Optimization |
01 DEC 2004 |
10 pages |
| Authors:
Zhao Lu; Leang-SAN Shieh; Guanrong Chen; Norman P. Coleman; HOUSTON UNIV TX DEPT OF ELECTRICAL ANDCOMPUTER ENGINEERING
|
| As an emerging effective approach to nonlinear robust control simplex sliding mode control demonstrates some attractive features not possessed by the conventional sliding mode control method from both theoretical and practical points of view. However no systematic approach is currently available for computing the simplex control vectors in nonlinear sliding mode control. In this paper, chaos-based optimization is exploited so as to develop a systematic approach to seeking the simplex ... |
|
| Friction & Wear Under Very High Electromagnetic Stress |
OCT 2004 |
18 pages |
| Authors:
Richard S. Cowan; Steven Danyluk; Francis Moon; J. C. Ford; Donald W. Brenner; GEORGIA INST OF TECH ATLANTA
|
| This document summarizes initial progress toward advancing the fundamental understanding of the friction, wear and mechanics of interfaces subjected to extreme electromagnetic stress, high relative velocities and elevated temperatures. During this reporting period, faculty and staff from Georgia Tech, Cornell, N.C. State and Rensselaer Polytechnic performed tasks in two thrust areas of basic research: Modeling and Experiment. With respect to the former, investigators are looking at mixed lubrication and its ... |
|
| An Experimental Approach for Studying the Creep Behavior of Thin Film/ Substrate Interfaces |
SEP 2004 |
59 pages |
| Authors:
Carl L. Parks; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| Large shear stresses often develop at the interface between dissimilar materials in microelectronic devices, when they are subjected to thermo-mechanical excursions. These stresses, which typically occur due to thermal expansion mismatch between the adjoining materials, are usually confined near the edges of films. However, for narrow thin film lines, these stresses may exist over a large fraction of the film-substrate interface. When the substrate is subjected to relatively high homologous ... |
|
| Elevated Temperature Fretting Facility |
JUL 2004 |
5 pages |
| Authors:
Richard W. Neu; GEORGIA INST OF TECH ATLANTA SCHOOL OFMECHANICAL ENGINEERING
|
| The primary equipment purchased is a Phoenix Tribology Ltd. DN55 High Temperature Sliding and Fretting Machine. The machine was designed from the ground up specifically for high temperature (up to 8OOoC) fretting experiments. The system has lower mass actuator system which is ideal for fretting and reciprocal sliding experiments to enable cycling at higher frequencies (up to 500 Hz) while minimizing dynamic effects. The system can also perform reciprocating sliding ... |
|
| Identification of Deformation Mechanisms During Bi-Axial Straining of Superplastic AA5083 Material |
JUN 2004 |
69 pages |
| Authors:
Rebecca M. Fowler; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| This study evaluated dome test samples of a superplastic AA5083 aluminum alloy deformed at nominally constant strain rates under biaxial strain conditions. Dome test samples resulted from gas-pressure forming of sheet material; for this study, samples were deformed at strain rates corresponding either to grain boundary sliding or dislocation creep control of deformation. Orientation Imaging Microscopy was utilized to determine texture development, grain size and grain-to-grain misorientation angle distributions for ... |
|
| Bearing Friction Torque in Bolted Joints |
12 FEB 2004 |
|
| Authors:
Sayed A. Nassar; G. C. Barber; Dajun Zuo; OAKLAND UNIV ROCHESTER MI DEPT OF MECHANICAL ENGINEERING
|
 | In this paper, formulas are developed for the calculation of the effective radius of the bearing friction forces on the rotating contact surface in threaded fasteners. These formulas provide a more accurate estimation of the underhead bearing friction torque component in threaded fastener applications. This enhances the reliability, safety, and the quality of bolted assemblies, especially in critical applications. It is well known that the torque-tension correlation in threaded fasteners, ... |
|
| Dynamic Cracking and Energy Absorption in Laminates Containing Through- Thickness Reinforcement |
FEB 2004 |
177 pages |
| Authors:
Brian N. Cox; Sridhar Narayanaswamy; ROCKWELL SCIENTIFIC CO THOUSAND OAKS CA
|
| Inertial effects in the mechanism of fiber pullout were examined, with emphasis on how the rate of propagation of stress waves along the fiber, and thence the pullout dynamics, are governed by friction and the propagation of companion waves excited in the matrix. The frictional sliding between the fiber and the matrix is described by a constant interfacial friction stress, the sign of which depends on the relative particle velocity ... |
|
| Study of Cavitation and Failure Mechanisms of a Superplastic 5083 Aluminum Alloy |
SEP 2003 |
87 pages |
| Authors:
Juanito F. Boydon Jr; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| Superplastic forming of AA5083 is an economical way to create components of complex shape while retaining the high strength and stiffness-to- weight ratios associated with aluminum alloys. However, failure of the material due to formation and linkage of cavities during superplastic deformation poses a major obstacle in effective industrial employment of this technology. Deformed samples of AA5083 were analyzed by various techniques after superplastic deformation under uniaxial tension, biaxial tension, ... |
|
| Acquisition of a Nanoindenter for Research on Small-Scale Materials and Structures |
AUG 2003 |
6 pages |
| Authors:
Frank W. Zok; D. R. Clarke; N. C. MacDonald; Kimberly L. Turner; CALIFORNIA UNIV SANTA BARBARA DEPT OF MECHANICAL AND ENVIRONMENTAL ENGINEERING
|
| The first project is "Matrix Enabled Damage Tolerance in Oxide Continuous Fiber Reinforced Ceramic Composites", PIs: Frank Zok, Carlos Levi and Robert McMeeking, funded by AFOSR. Here, the nanoindenter is being used for measuring the mechanical properties of fiber-matrix interfaces, through the so- called "fiber push-in" test. In essence, the test involves pushing an individual fiber past the surrounding matrix while simultaneously measuring the sliding displacement at the fiber/matrix interface. ... |
|
| Sliding Mode Control of a Shape Memory Alloy Actuated Manipulator |
JUN 2003 |
8 pages |
| Authors:
Mohammad H. Elahinia; T. M. Siegler; Donald J. Leo; Mehdi Ahmadian; VIRGINIA POLYTECHNIC INST AND STATE UNIV BLACKSBURG DEPT OF MECHANICAL ENGINEERING
|
| This paper presents a two-pan controller that uses a state variable estimator for control of a single degree of freedom rotary manipulator acutated by Shape Memory Alloy (SMA) wire. A model for the SMA actuated manipulator is presented. The model includes nonlinear dynamics of the manipulation a constitutive model of the Shape Memory Alloy. and the electrical and heat transfer behavior of SMA wire. The estimator predicts the state vector ... |
|
| Simulation of Carbon Nanotube Pull-out When Bonded to a Polymer Matrix |
2003 |
6 pages |
| Authors:
S. J. Frankland; V. M. Harik; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CENTER
|
| A carbon nanotube pulling through a polyethylene matrix was simulated using molecular dynamics. The interfacial sliding was characterized in terms of a nanoscale friction model, which is parametrized from the molecular dynamics simulation, and involves determining the critical pull-out force on the nanotube and the effective viscosity at the nanotube/polymer interface. Comparison was made of the pull-out behavior of non-bonded and functionalized nanotube composites. Chemical bonds between the polymer and ... |
|
| Nash Solution by Extremum Seeking Control Approach |
DEC 2002 |
|
| Authors:
Yaodong Pan; Tankut Acarman; Umit Ozguner; OHIO STATE UNIV COLUMBUS DEPT OF ELECTRICAL ENGINEERING
|
| In this paper, we propose an algorithm to solve the Nash equilibrium solution for an n-person noncooperative dynamic game by the extremum seeking control approach with sliding mode. For each player, a switching function is defined as the difference between the player's cost function and a reference signal. The extremum seeking controller for each player is designed so that the system converges to a sliding boundary layer defined in the ... |
|
| Effects of Counterface Roughness and Conformity on the Tribological Performance of Crosslinked and Non-crosslinked Medical-Grade Ultra-High Molecular Weight Polyethylene |
APR 2002 |
|
| Authors:
A. D. Chawan; A. M. Chakravartula; J. Zhou; L. A. Pruitt; M. Reis; CALIFORNIA UNIV BERKELEY DEPT OF MECHANICAL ENGINEERING
|
| The tribological behavior of crosslinked ultra-high molecular weight polyethylene (UHMWPE) was compared to that of non-crosslinked UHMWPE used as control sample. A reciprocating pin-on-disk tribometer was used to determine the effects of countersurface roughness and conformity on wear mechanisms occurring during the initial stage of sliding. Pin samples of two different radii of curvature were slid against medical-grade Co-Cr alloy disks with surface roughness ranging from 0.005 to 0.04 micrometers ... |
|
| Stable Neural Control of Uncertain Multivariable Systems |
DEC 2001 |
26 pages |
| Authors:
Mark J. Mears; Marios M. Polycarpou; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH AIR VEHICLES DIRECTORATE
|
| Tracking control of a class of nonlinear, uncertain, multi-input, multiple-output systems is addressed in this paper. The control system architecture uses neural networks for function approximation, certainty equivalent control inputs to cancel plant dynamics and smoothed sliding mode control to insure that the trajectories remain bonded. Lyapunov analysis is used to derive equations for the sliding mode control, neural network training, and to show uniform ultimate boundedness of the closed ... |
|
| Sliding Mode Observers Versus Kalman Filter in the Homing Loop |
23 JUL 2001 |
8 pages |
| Authors:
I. A. Schkolnikov; Y. B. Shtessel; P. Zarchan; D. P. Lianos; ALABAMA UNIV IN HUNTSVILLE DEPT OF ELECTRICAL AND COMPUTER ENGINEERING
|
| A comparison via Monte-Carlo simulations is made of Sliding Mode Observers versus Kalman Filter in the homing missile guidance system using different guidance laws. It's shown that the sliding mode observer contributes to less miss distance due to noise than Kalman filter. Application of sliding mode estimators in the homing loop with Proportional Navigation guidance and with a phase-lead compensation based on sliding mode estimators for the flight control system ... |
|
| A Hot-Stage Atomic Force Microscope for the Measurement of Plastic Deformation in Metallic Thin Films During Thermal Cycling |
JUN 2001 |
86 pages |
| Authors:
Thomas E. Shultz; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| An Atomic Force Microscope is equipped with a hot-stage and a vacuum system in order to enable in-situ studies of plastic deformation and interfacial sliding of thin metallic films on Si substrates during thermal cycling. The apparatus can reach sample temperatures of lOO deg C while maintaining optimum resolution. The system will allow future in-situ thermal cycling experiments on microelectronic devices in a protected environment to provide insight into the ... |
|
| 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, ... |
|
| Mechanical and Microstructural Analysis on the High Temperature Deformation of Gamma TiAl Alloy |
04 JAN 2001 |
77 pages |
| Authors:
Jeonung H. Kim; Chong S. Lee; POHANG UNIV OF SCIENCE AND TECHNOLOGY (KOREA) CENTER FOR ADVANCED AEROSPACE MATERIALS
|
| It is aimed in this study to investigate the high temperature deformation mechanisms of two-phase gamma titanium-aluminum alloy in view of the inelastic deformation theory and to quantify the relative contribution of each mechanism to the overall deformation. The influence of y/a2 volume fraction on high temperature deformation behavior and the preferable cavity initiation sites have also been studied. For this purpose, a series of load relaxation tests and tensile ... |
|
| Enhancing TCP Performance Over Satellite Channels |
NOV 2000 |
|
| Authors:
Maik Kammermann; Hugues Latour; DEFENCE RESEARCH ESTABLISHMENT OTTAWA (ONTARIO)
|
| In general the Transmission Control Protocol (TCP) works well while establishing end-to-end connections for common Internet services. However, there are two problem areas associated with performance over satellite channels: propagation delay and channel noise effects. Noise is a common problem in wireless technologies and consequently the bit-error-rate (BER) is significantly higher than in wired networks. TCP is particularly vulnerable to BER because it is a reliable protocol. TCP will retransmit ... |
|
| Frictional Characteristics of Cracks and Failure of Brittle Materials under Dynamic Compression |
17 JUL 2000 |
10 pages |
| Authors:
Guruswami Ravichandran; CALIFORNIA INST OF TECH PASADENA
|
| A newly developed specimen has been used to investigate the compressive failure due to the presence of flaws in brittle materials. Experiments were conducted under both static and dynamic loading conditions to delineate the role of friction on sliding induced crack initiation. Specimens with different coefficients of friction and crack inclination were prepared and a systematic understanding of crack initiation under compressive loading has ... |
|
| Reliability and Stability Assessment of Concrete Gravity Structures (RCSLIDE): User's Guide |
JUL 2000 |
350 pages |
| Authors:
Mary Ann Leggett; Michael E. Pace; Fredrick Lyles; Kevin Abraham; ENGINEER RESEARCH AND DEVELOPMENT CENTER VICKSBURG MS INFORMATION TECHNOLOGY LAB
|
| This report is a documentation of RCSLIDE, the reliability version of CSLIDE, a computer program for assessing the sliding stability of concrete gravity structures using the limit equilibrium method described in EC 110-2-291, "Stability Analysis of Concrete Structures." CSLIDE can compute the factor of safety against sliding considering the effects of numerous and varied conditions. The report is organized to present an overview of the sliding ... |
|
| Reliability and Stability Assessment of Concrete Gravity Structures (RCSLIDE): User's Guide |
JUL 2000 |
350 pages |
| Authors:
Mary Ann Leggett; Michael E. Pace; Fredrick Lyles; Kevin Abraham; ENGINEER RESEARCH AND DEVELOPMENT CENTER VICKSBURG MS INFORMATION TECHNOLOGY LAB
|
| This report is a documentation of RCSLIDE, the reliability version of CSLIDE, a computer program for assessing the sliding stability of concrete gravity structures using the limit equilibrium method described in EC 1110-2- 291, "Stability Analysis of Concrete Structures." CSLIDE can compute the factor of safety against sliding considering the effects of numerous and varied conditions. The report is organized to present an overview of the ... |
|
| A Large Deformation Finite Element Analysis of Soil-Tire Interaction Based on the Contact Mechanics Theory of Rolling and/or Sliding Bodies |
30 JUN 2000 |
10 pages |
| Authors:
Antoinette Tordesillas; MELBOURNE UNIV PARKVILLE (AUSTRALIA)
|
| This research program is aimed at the development of a soil-tire interaction model based on Contact Mechanics Theory. The model developed obviates the need for a priori knowledge of soil-tire contact properties and instead relies on directly and accurately measurable quantities. Other major research outcomes of this program include: 1) the first complete solution to the frictional contact problem between a granular material and a deformable ... |
|
| Ruhedruck und Entspannungsbewegungen Ueberkonsolidierter Boeden. Zum Einfluss Negativer Porenwasserspannungen auf die Standsicherheit von Einschnittsboeschungen in Ueberkonsolidierten Boeden (Pressure and Tension- Reducing Movements of Over-Consolidated S |
2000 |
134 pages |
| Authors:
Hartmut Schulz; Peter Schick; UNIVERSITAET DER BUNDESWEHR MUENCHEN NEUBIBERG (GERMANY) INST FUER BODENMECHANIK UND GRUNDBAU
|
| In the first section one finds the results of tests to measure horizontal stresses in over-consolidated soils. The measurements have shown that the theorem for in situ effective horizontal stress based on the friction angle may not always be valid for plastic soils. The second section deals with calculating the factor of safety of cutting slopes in over-consolidated, fine- grained soils: earth pressure at rest, the swelling and reduction of ... |
|
| New Statistical Textural Transforms for Non-Stationary Signals; Application to Generalized Multifractal Analysis |
2000 |
12 pages |
| Authors:
Antoine Saucier; Jiri Muller; CENTRE DE RECHERCHE EN CALCUL APPLIQUE MONTREAL (QUEBEC)
|
| We introduce a method to generate statistical textural transforms that improves the treatment of non-stationarity and leads to a sharper detection of the boundaries between distinct textures (texture segmentation). This method is based on a sliding window processing with fixed size. The basic idea proposed by the authors is to readjust the measuring window around each pixel so as to maximize homogeneity. We use this method with the dimensions D ... |
|
| An Approach for Studying the Creep/Sliding Behavior of Planar Metal- Silicon Interface |
DEC 1999 |
65 pages |
| Authors:
Ioannis Farsaris; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| There has been considerable recent interest in interfacial sliding during creep of multi-phase materials. The effect of interfacial creep is crucial for the deformation of metal-matrix composites and thin film systems, where the isostrain condition between the constituent components is often violated. An experimental approach has been developed to investigate the deformation kinetics of planar interfaces, using a double-shear specimen geometry where the interfaces ... |
|
| Micromechanical Modeling of Superplastic Materials |
21 SEP 1999 |
127 pages |
| Authors:
Namas Chandra; FLORIDA AGRICULTURAL AND MECHANICAL UNIV TALLAHASSEE
|
| In this work, superplastic deformation were studied at atomistic, mesoscopic and macroscopic levels with a special focus on the former two. At the atomistic level, we studied the energy and structure of symmetric tilt boundaries and examined the energy barriers during grain boundary sliding of Aluminum bicrystal. We also studied the effect of temperature and impurity atoms on the structure, energy and deformation of grain boundary sliding. ... |
|
| Anti Tip-Off Device |
11 MAY 1999 |
|
| Authors:
Thomas A. DelGuidice; Fred W. Watson Jr; DEPARTMENT OF THE NAVY WASHINGTON DC
|
| An anti tip off device for rocket rockets adapted for collapsible tube-in-tube launchers is provided. The dual- diameter launch tube requires stabilization of the rocket within the larger diameter tube. The anti tip-off device has two segments which together form a hollow cylinder which fits over the nose section of a standard high explosive anti-armor rocket. A sliding surface is located around the circumference of the cylinder to provide support ... |
|
| Influence of Loading Frequency on the Elevated Temperature Fatigue Behavior of Fiber-Reinforced Ceramic Composites |
15 JAN 1999 |
33 pages |
| Authors:
John W. Holmes; MICHIGAN UNIV ANN ARBOR CERAMIC COMPOSITES RESEARCH LAB
|
| Cyclic tension-tension experiments were conducted on a ceramic matrix composite of continuous Nicalon SiC-fibers in a calcium-aluminosilicate matrix. Two different stress ratios (R = sigma(min)/sigma(max)) were studied (R = 0.5 and R = 0.05) at a loading frequency of 200 Hz. Specimens tested at R = 0.05 were found to have a shorter fatigue life than specimens tested at R = 0.5. The fatigue limit (defined ... |
|
| Recoilless and Gas-Free Projectile Propulsion |
23 APR 1998 |
12 pages |
| Authors:
Matthew J. Sanford; Larry E. Crabtree; Roger L. Ellis; James F. Cahill; OFFICE OF NAVAL RESEARCH ARLINGTON VA
|
| A recoilless and gas-free projectile propulsion device is provided. A hollow pressure vessel is sealed on a first end to an AFT end of a projectile in a launch tube. The pressure vessel is further open on a second end. A propellant charge filled pressure chamber, defined in a forward portion of the pressure vessel, has holes venting to the pressure vessel AFT thereof. A piston, sealed within the pressure ... |
|
| Construction Productivity Advancement Research (CPAR) Program |
APR 1998 |
198 pages |
| Authors:
Kimberlie Staheli; David Bennett; Hugh W. O'Donnell; Timothy J. Hurley; ARMY ENGINEER WATERWAYS EXPERIMENT STATION VICKSBURG MS GEOTECHNICAL LAB
|
| Early methods of installing pipelines and utilities across rivers and streams involved excavation of trenches. After the placement of the pipeline, the trenches were backfilled to protect the pipeline from hazards. These early dredged crossings were generally sited at the channel crossing of the thalweg between bends of the river. Here the river is generally a wide, shallow rectangle. This location is chosen due to its hydraulic stability and the ... |
|
| Evaluating the State Probabilities of M out of N Sliding Window Detectors |
FEB 1998 |
|
| Authors:
Peter Williams; DEFENCE SCIENCE AND TECHNOLOGY ORGANISATION CANBERRA (AUSTRALIA)
|
| The term M out of N sliding window detectors refers to processes that determine whether there have been M successes in a sequence of N binary trials, where the window (of N trials under examination) slides along a possibly infinite sequence stopping when the criterion (of M successes in N successive trials) is met. They are frequently used to model the operators of naval surveillance systems such as radar and ... |
|
| Human Factors in Tele-Inspection and Tele-Surgery (ARPA) |
JAN 1998 |
|
| Authors:
Thomas B. Sheridan; Juanjuen Hu; James M. Thompson; MASSACHUSETTS INST OF TECH CAMBRIDGE
|
| Closed loop control of a telemanipulator such as is used for telesurgery is intolerant to loop time delay of more than 0.05 second. Such a system goes unstable, especially when force feedback is employed. The time delay inherent in modem high-bandwidth communication channels such as satellite or ISDN telephone systems is mostly attributable to required modulation/ demodulation time, and can easily exceed 0.5 second. (I) ... |
|
| Sliding Mode Controller Design for Kinetic Energy Kill Vehicle in a Hostile Environment |
1998 |
10 pages |
| Authors:
Yuri Shtessel; Mark Brown; Kevin Moore; Richard Toomey; Koy Cook; ARMY SPACE AND MISSILE DEFENSE COMMAND HUNTSVILLE AL
|
| Current guidance and control systems for interceptor missiles use algorithins that require knowledge of the target. These systems are not robust to target maneuvers and disturbances. In this paper, we investigate the use of a novel controller named a Sliding Mode Controller (SMC). We consider two types of interceptors or kinetic energy kill vehicles (KEKVs): a ballistic missile and a cruise missile. Sliding mode controllers are robust, ... |
|
| Anti Tip-Off Device |
30 SEP 97 |
20 pages |
| Authors:
DEPARTMENT OF THE NAVY WASHINGTON DC
|
| An anti tip-off device for rocket rockets adapted for collapsible tube-in-tube launchers is provided. The dual-diameter launch tube requires stabilization of the rocket within the larger diameter tube. The anti tip-off device has two segments which together form a hollow cylinder which fits over the nose section of a standard high explosive anti-armor rocket. A sliding surface is located around the circumference of the cylinder to provide support for the ... |
|
| Joint U.S./ROK R&D Program for New Underground Ammunition Storage Technologies. Explosion Effects Modeling of Self-Sealing Underground Explosive Storage Chamber Designs |
FEB 97 |
60 pages |
| Authors:
Ali Amini; Eugene L. Foster; Colin J. Shellum; UTD INC NEWINGTON VA
|
| This study investigates the potential performance of self sealing chambers in rock as a means of containing the blast effects from an accidental explosion in an underground ammunition storage complex. The work was performed as part of the Joint U.S./ROK R&D Program for New Underground Ammunition Storage Technologies. A coherent method for modeling of self sealing systems is presented. This method illustrated that observations made during field investigations can be ... |
|
| Superplasticity at High Strain Rates in Aluminum Alloys |
10 OCT 96 |
16 pages |
| Authors:
Kenji Higashi; OSAKA PREFECTURE UNIV SAKAI (JAPAN)
|
| The detailed experimental data of microstructural developments during the optimum thermomechanical treatments and superplastic properties in the wide deformation range have been investigated on fourteen P/M aluminum alloys with various chemical matrix compositions and different typed precipitate particles. It was revealed that the differences in both size and volume among the second phase particles, which increase with content of Zr, Cr, Mn or Y, affect on the recrystallization behavior, grain ... |
|
| Autonomous Control of Underwater Vehicles and Local Area Maneuvering |
SEP 96 |
359 pages |
| Authors:
David B. Marco; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| The major thrust of this work is the development and demonstration of new capabilities for the use of small autonomous vehicles in mine countermeasure applications. Key to the new capabilities lies in an open architecture tri-level software structure for hybrid control, of which this work is the first validated implementation. The two upper levels run asynchronously in computing logical operations based on numerical decision making, while the lowest, the Execution ... |
|
| Split Gasket Attachment Method. |
23 JUL 1996 |
|
| Authors:
Paul E. Moody; DEPARTMENT OF THE NAVY WASHINGTON DC
|
| The present invention relates to a method and hardware for bonding together ends of a sealing strip. The method of the present invention comprises the steps of cutting a slot in both a first end and a second end of a sealing strip, inserting an attachment strip having a plurality of engaging members into the slot cut into the first end, applying adhesive to the second end of the sealing ... |
|
| Removable One-Piece Truck Bed Divider. |
MAY 1996 |
|
| Authors:
Peter R. Tkachuk; DEPARTMENT OF THE NAVY WASHINGTON DC
|
| A truck bed divider having a unitary, one-piece structure which may be easily positioned in and instantly removed from a truck bed includes a dividing portion having a plurality of bars for preventing articles in the truck bed from moving or sliding in the truck bed. The divider further includes top and bottom frame portions which are joined to the divider portion and which support the divider portion in the ... |
|
| Palletized Loading System (PLS) Flatrack Sideboard Kit Evaluation |
APR 96 |
11 pages |
| Authors:
A. C. McIntosh Jr; ARMY DEFENSE AMMUNITION CENTER AND SCHOOL SAVANNA IL
|
| The U.S. Army Defense Ammunition Center and School (USADACS), Validation Engineering Division (SMCAC-DEV), was tasked by USADACS, Supply Engineering Division (SMCAC-DES), to perform a sliding pallet test on the Palletized Loading System (PLS) flatrack sideboard kit (rear panel). One of the requirements of the PLS M1077 flatrack contract was for the fabrication of sideboards. The strength required of the sideboards could not be clearly defined as to the amount of ... |
|
| In Situ Analysis of the Tribochemical Films Formed by SiC Sliding Against Mo in Partial Pressures of SO2, O2, and H2S Gases |
FEB 1996 |
9 pages |
| Authors:
I. L. Singer; T. Le Mogne; C. Donnet; J. M. Martin; NAVAL RESEARCH LAB WASHINGTON DC
|
| X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES) were used to identify gas reaction layers and tribochemical films formed during reciprocating sliding tests in an ultrahigh vacuum (UHV) tribometer. Tests were performed on UHV cleaned SiC pins and Mo flats during or after exposure to SO2, O2, or H2S gas at pressures around 40 Pa. XPS identified the gas reaction layers on Mo to be chemisorbed MoS2 and/or MoO2 ... |
|
| Assessment of Grain Refinement by Microtexture Analysis in Thermomechanically Processed Al 2519 Alloy |
DEC 95 |
67 pages |
| Authors:
Steven L. Stancy; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| The first part of this study involved determining the mechanism by which elevated-temperature deformation occurred for selected tensile specimens from previous research on thermomechanically processed Al2519 alloy. Microtexture information in the form of discrete pole figures indicated that the most highly superplastic material had completely recrystallized and deformed via grain boundary sliding, whereas material that did not display superplastic behavior deformed via slip. The second part of the study was ... |
|
| The Gouging Phenomenon at Low Relative Sliding Velocities |
DEC 95 |
143 pages |
| Authors:
Kenneth R. Tarcza; TEXAS UNIV AT AUSTIN
|
| Surface gouging by metals in high-velocity sliding contact has been observed for more than thirty years in engineering applications involving rocket sleds, two-stage gas guns, and electromagnetic railguns. The onset of gouging is usually observed to occur at sliding velocities in excess of 100%) mIs (3821 ft/s). Previous investigations of the phenomenon have indicated that the gouging onset velocity is proportional to the yield strength and hardness of the materials ... |
|
| Human Factors in Tele-Inspection and Tele-Surgery |
09 OCT 95 |
|
| Authors:
Thomas B. Sheridan; James Thompson; Jianjuen Hu; Mark Ottensmeyer; Jie Ren; MASSACHUSETTS INST OF TECH CAMBRIDGE
|
| In telesurgery a physician operates on a remote patient through a two-way communication and telerobot link. This first-year progress report describes development of a telesurgical simulator with force reflection and time delay, simulating what occurs with satellite communication. Also developed was a remotely controlled endoscopic tool. Using the simulator, preliminary experiments have been conducted with human subjects to evaluate alternative means to stabilize control movements under time delay, including a ... |
|
| Shutter Door Assembly. |
19 SEP 1995 |
|
| Authors:
Paul E. Moody; DEPARTMENT OF THE NAVY WASHINGTON DC
|
| A torpedo tube shutter door assembly includes a series of segmented, abutting panels constituting a shutter door for selectively blocking an elongate opening formed in an outer hull of a submarine. The panels are movable between a closed position in which the panels fair to the outer hull and block the opening, and an open position in which the panels slid ably move away from the opening along a longitudinal ... |
|
Reports by Keyword(s)
SLIDING
