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159
Jun 11, 2011
06/11
by
Abdalati, W.; Koerner, R; Krabill, W.; Frederick, E.; Manizade, S.; Martin, C.; Sonntag, J.; Swift, R.; Thomas, R.; Yungel, J.
texts
eye 159
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Precise repeat airborne laser surveys were conducted over the major ice caps in the Canadian Arctic Archipelago in the spring of 1995 and 2000 in order to measure elevation changes in the region. Our measurements reveal thinning at lower elevations (below 1600 m) on most of the ice caps and glaciers, but either very little change or thickening at higher elevations in the ice cap accumulation zones. Recent increases in precipitation in the area can account for the slight thickening where it was...
Topics: ALGORITHMS, LOW COST, FAST FOURIER TRANSFORMATIONS, ARCHITECTURE (COMPUTERS), GREENHOUSE EFFECT,...
618
618
May 31, 2011
05/11
by
Allan, Brian G.; Yao, Chung-Sheng; Lin, John C
texts
eye 618
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Numerical simulations of a single low-profile vortex generator vane, which is only a small fraction of the boundary-layer thickness, and a vortex generating jet have been performed for flows over a flat plate. The numerical simulations were computed by solving the steady-state solution to the Reynolds-averaged Navier-Stokes equations. The vortex generating vane results were evaluated by comparing the strength and trajectory of the streamwise vortex to experimental particle image velocimetry...
Topics: MULTIDISCIPLINARY DESIGN OPTIMIZATION, CONTROL SYSTEMS DESIGN, MANEUVERABILITY, ENGINE AIRFRAME...
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224
Jul 26, 2010
07/10
by
Anderson, Charles E
texts
eye 224
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The number of tornado outbreak cases studied in detail was increased from the original 8. Detailed ground and aerial studies were carried out of two outbreak cases of considerable importance. It was demonstrated that multiple regression was able to predict the tornadic potential of a given thunderstorm cell by its cirrus anvil plume characteristics. It was also shown that the plume outflow intensity and the deviation of the plume alignment from storm relative winds at anvil altitude could...
Topics: CONTROL SYSTEMS DESIGN, SPACECRAFT STRUCTURES, DESIGN ANALYSIS, FAILURE ANALYSIS, FAULT TOLERANCE,...
210
210
May 22, 2011
05/11
by
Athavale, M. M.; Przekwas, A. J.; Hendricks, R. C.; Steinetz, B. M
texts
eye 210
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A numerical analysis methodology and solutions of the interaction between the power stream and multiply-connected multi-cavity sealed secondary flow fields are presented. Flow solutions for a multi-cavity experimental rig were computed and compared with experimental data of Daniels and Johnson. The flow solutions illustrate the complex coupling between the main-path and the cavity flows as well as outline the flow thread that exists throughout the subplatform multiple cavities and seals. The...
Topics: AIRCRAFT CONTROL, HUMAN FACTORS ENGINEERING, NAVIGATION AIDS, SURVEYS, SYSTEMS MANAGEMENT, AIRCRAFT...
358
358
May 23, 2011
05/11
by
Babcock, Dale A.; Bruce, Robert A
texts
eye 358
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The advantages of high-molecular-weight gas (heavy gas) as a wind-tunnel medium have been recognized for some time. The current heavy gas of choice chlorofluorocarbon-12(CFC-12) (refrigerant R12) for the Transonic Dynamics Tunnel(TDT) must be replaced because manufacture of this gas ceased in 1995. An attractive replacement is 1,1,1,2-tetrafluoroethane (refrigerant R134a). Acceptable properties of this gas include molecular weight and speed of sound. Its vapor pressure allows simplified...
Topics: ALGORITHMS, ROBOT ARMS, DEGREES OF FREEDOM, WEIGHTING FUNCTIONS, MATRICES (MATHEMATICS), LEAST...
192
192
Jul 21, 2010
07/10
by
Backman, D. E
texts
eye 192
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The infrared photometry of epsilon Aur performed prior to and during the ingress phase of the recent eclipse allowed the first solid determination of the temperature of the secondary object. The eclipse depth was significantly less at lambda 5 micrometers than in the near-infrared. This is explained by a model of the secondary as an opaque and very cool object with a temperature of approx. 500 K. During eclipse, the secondary blocks approximately 45% of the near infrared radiation from the...
Topics: CONTROL SYSTEMS DESIGN, LARGE SPACE STRUCTURES, SPACECRAFT DESIGN, SYSTEMS ENGINEERING, AERODYNAMIC...
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163
Jun 13, 2011
06/11
by
Balakumar, Ponnampala
texts
eye 163
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Receptivity and stability of supersonic boundary layers over blunt flat plates and wedges are numerically investigated at a free stream Mach number of 3.5 and at a high Reynolds number of 10(exp 6)/inch. Both the steady and unsteady solutions are obtained by solving the full Navier-Stokes equations using the 5th-order accurate weighted essentially non-oscillatory (WENO) scheme for space discretization and using third-order total-variation-diminishing (TVD) Runge-Kutta scheme for time...
Topics: CONTROLLERS, F-16 AIRCRAFT, FLIGHT CONTROL, LIAPUNOV FUNCTIONS, LINEAR PARAMETER-VARYING CONTROL,...
304
304
May 28, 2011
05/11
by
Banish, R. Michael; Rosenberger, Fran
texts
eye 304
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This research was to advance the understanding of diffusion mechanisms in liquid metals and alloys through accurate diffusivity measurements over a wide range of temperatures, including the proximity of the materials melting points. Specifically, it was driven towards developing a methodology (and subsequent flight hardware) to enable several diffusion coefficient measurements (i.e., at several different temperatures) to be performed using a single sample. The Liquid Metal Diffusion (LMD) was...
Topics: AEROSPIKE ENGINES, CENTRAL PROCESSING UNITS, FAIL-SAFE SYSTEMS, COSTS, CONTROLLERS, CONTROL SYSTEMS...
506
506
Jul 23, 2010
07/10
by
Bansal, Narottam P
texts
eye 506
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MgO-SiO2 glasses containing up to 15 mol % MgO, which could not have been prepared by the conventional glass melting method due to the presence of stable liquid-liquid immiscibility, were synthesized by the sol-gel technique. Clear and transparent gels were obtained from the hydrolysis and polycondensation of silicon tetraethoxide (TEOS) and magnesium nitrate hexahydrate when the water/TEOS mole ratio was four or more. The gelling time decreased with increase in magnesium content, water/TEOS...
Topics: CONTROL SYSTEMS DESIGN, POINTING CONTROL SYSTEMS, SPACE ERECTABLE STRUCTURES, SYSTEM...
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237
Jun 13, 2011
06/11
by
Barrett, Michael J.; Johnson, Paul K
texts
eye 237
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Contents include the following: 1. Closed-Brayton-cycle (CBC) thermal energy conversion is one available option for future spacecraft and surface systems. 2. Brayton system conceptual designs for milliwatt to megawatt power converters have been developed 3. Numerous features affect overall optimized power conversion system performance: Turbomachinery efficiency. Heat exchanger effectiveness. Working-fluid composition. Cycle temperatures and pressures.
Topics: BRAYTON CYCLE, CLOSED CYCLES, CONTROL SYSTEMS DESIGN, DYNAMIC MODELS, VIBRATION TESTS, SPACECRAFT...
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178
Jun 9, 2011
06/11
by
Barrett, Michael J.; Reid, Bryan M
texts
eye 178
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State-of-the-art closed-Brayton-cycle (CBC) space power systems were modeled to study performance trends in a trade space characteristic of interplanetary orbiters. For working-fluid molar masses of 48.6, 39.9, and 11.9 kg/kmol, peak system pressures of 1.38 and 3.0 MPa and compressor pressure ratios ranging from 1.6 to 2.4, total system masses were estimated. System mass increased as peak operating pressure increased for all compressor pressure ratios and molar mass values examined. Minimum...
Topics: RESEARCH AND DEVELOPMENT, ACTUATORS, X-37 VEHICLE, FLIGHT CONTROL, NEURAL NETS, AIR TO AIR...
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286
Jul 23, 2010
07/10
by
Baumeister, Kenneth J
texts
eye 286
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A finite-element Galerkin formulation has been developed to study transverse magnetic (TM) wave propagation in 2-D S-curved ducts with both perfectly conducting and absorbing walls. The reflection and transmission at the entrances and the exits of the curved ducts are determined by coupling the finite-element solutions in the curved ducts to the eigenfunctions of an infinite, uniform, perfectly conducting duct. Example solutions are presented for a double mitred and S-ducts of various lengths....
Topics: ANTENNAS, OPTOELECTRONIC DEVICES, WAVEGUIDES, CONTROL SYSTEMS DESIGN, OPTICAL FIBERS, PHASED...
457
457
Jul 26, 2010
07/10
by
Belcastro, Celeste M
texts
eye 457
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Control systems for advanced aircraft, especially those with relaxed static stability, will be critical to flight and will, therefore, have very high reliability specifications which must be met for adverse as well as nominal operating conditions. Adverse conditions can result from electromagnetic disturbances caused by lightning, high energy radio frequency transmitters, and nuclear electromagnetic pulses. Tools and techniques must be developed to verify the integrity of the control system in...
Topics: ADAPTIVE CONTROL, BOUNDARY VALUE PROBLEMS, CONTROL SYSTEMS DESIGN, MATHEMATICAL MODELS, ON-LINE...
466
466
May 22, 2011
05/11
by
Bell, J. Brett; Nelms, R. M.; Shepherd, Michael T
texts
eye 466
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The Component Development Division of the Propulsion Laboratory at Marshall Space Flight Center (MSFC) is currently investigating the use of electromechanical actuators for use in space transportation applications such as Thrust Vector Control (TVC). These high power servomechanisms will require rugged, reliable, and compact power electronic modules capable of modulating several hundred amperes of current at up to 270 Vdc. This paper will discuss the design and implementation of a...
Topics: CONTROL SYSTEMS DESIGN, ROBOTICS, DYNAMIC CONTROL, FEEDBACK CONTROL, REAL TIME OPERATION, ROBOT...
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193
Jun 2, 2011
06/11
by
Boccio, Don
texts
eye 193
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Terrorist suitcase nuclear devices typically using converted Soviet tactical nuclear warheads contain several kilograms of plutonium. This quantity of plutonium emits a significant number of gamma rays and neutrons as it undergoes radioactive decay. These gamma rays and neutrons normally penetrate ordinary matter to a significant distance. Unfortunately this penetrating quality of the radiation makes imaging with classical optics impractical. However, this radiation signature emitted by the...
Topics: AUTONOMY, RECONNAISSANCE, SURVEILLANCE, CONTROL SYSTEMS DESIGN, DIAGNOSIS, ROTARY WING AIRCRAFT,...
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224
Jul 21, 2010
07/10
by
Boehm, B
texts
eye 224
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The unique and challenging nature of the Space Station Program requires that software standards be effectively used to control costs, facilitate enhancements and ensure safety. The Software Standards Panel identified and developed recommendations in four areas to help the Space Station Program achieve these objectives. The areas in which recommendations are offered are policy, organization, process and candidate software standards for the Space Station Program. The concensus process employed by...
Topics: COOLING SYSTEMS, CRYOGENIC COOLING, LOSS OF COOLANT, PISTONS, REFRIGERATING, STIRLING CYCLE, CLOSED...
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243
May 31, 2011
05/11
by
Booth, Earl R., Jr.; Wilbur, Matthew L
texts
eye 243
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The use of an Active Twist Rotor system to provide both vibration reduction and performance enhancement has been explored in recent analytical and experimental studies. Effects of active-twist control on rotor noise, however, had not been determined. During a recent wind tunnel test of an active-twist rotor system, a set of acoustic measurements were obtained to assess the effects of active-twist control on noise produced by the rotor, especially blade-vortex interaction (BVI) noise. It was...
Topics: REUSABLE LAUNCH VEHICLES, X-33 REUSABLE LAUNCH VEHICLE, AEROSPACE SAFETY, MONTE CARLO METHOD,...
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25
Jan 13, 2020
01/20
by
Boudarel, R. (Rene)
texts
eye 25
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xiv, 252 pages ; 24 cm
Topics: Programmation dynamique, Commande, Théorie de la, Control systems Design Optimisation methods...
1
1.0
Oct 5, 2020
10/20
by
Boudarel, R. (René)
texts
eye 1
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xiv, 252 pages ; 24 cm
Topics: Control theory, Dynamic programming, Dynamische Optimierung, Kontrolltheorie, Optimale Kontrolle,...
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181
May 28, 2011
05/11
by
Bowen, Brent D.; Headley, Dean E
texts
eye 181
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The Airline Quality Rating (AQR) was developed and first announced in early 1991 as an objective method of comparing airline performance on combined multiple factors important to consumers. Development history and calculation details for the AQR rating system are detailed in The Airline Quality Rating 1991 issued in April, 1991, by the National Institute for Aviation Research at Wichita State University. This current report, Airline Rating 1997, contains monthly Airline Quality Rating scores...
Topics: VIBRATION DAMPING, EXTRACTION, ACTIVE CONTROL, SPACEBORNE EXPERIMENTS, CONTROL SYSTEMS DESIGN,...
250
250
Jun 12, 2011
06/11
by
Bowen, Brent; Johnson, Paul, et al; Vlasek, Karisa; Russell, Valerie; Teasdale, Jean; Downing, David R.; deSilva, Shan; Higginbotham, Jack; Duke, Edward; Westenkow, Dwayne
texts
eye 250
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This report contains two sections, each of which describes a proposal for a program at the University of Nebraska. The sections are entitled: 1) Aerospace Workforce Development Augmentation Competition; 2) Native Connections: A Multi-Consortium Workforce Development Proposal.
Topics: REAL TIME OPERATION, RUDDERS, TRAJECTORIES, MONTE CARLO METHOD, EXCITATION, FAST FOURIER...
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328
May 23, 2011
05/11
by
Brentner, Kenneth S
texts
eye 328
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A new formulation for the Ffowcs Williams-Hawkings quadrupole source, which is valid for a far-field in-plane observer, is presented. The far-field approximation is new and unique in that no further approximation of the quadrupole source strength is made and integrands with r(exp -2) and r(exp -3) dependence are retained. This paper focuses on the development of a retarded-time formulation in which time derivatives are analytically taken inside the integrals to avoid unnecessary computational...
Topics: AIR TRAFFIC CONTROL, AUTOMATIC LANDING CONTROL, CONTROLLERS, COMPUTERIZED SIMULATION, RADAR DATA,...
192
192
Jun 12, 2011
06/11
by
Buczkowski, D. L.; Frey, H. V.; McGill, G. E
texts
eye 192
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It has been suggested that quasicircular depressions (QCDs) without a structural representation in Viking and MOC visible imagery represent buried impact craters [1,2,3,4]. Topographic depressions will form over impact craters buried by a differentially compacting cover material because total cover thickness, and thus total compaction, is greater over the center of completely buried impact craters than their rims [5]. If this is the process by which QCDs form, then only areas of differentially...
Topics: LIQUID HYDROGEN, GROUND TESTS, RESEARCH FACILITIES, TEST FACILITIES, COMPUTERIZED SIMULATION,...
1,111
1.1K
Aug 1, 2010
08/10
by
Byrdsong, Thomas A.; Adams, Richard R.; Sandford, Maynard C
texts
eye 1,111
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No Abstract Available
Topics: AIRCRAFT CONTROL, HUMAN FACTORS ENGINEERING, INFORMATION MANAGEMENT, SAFETY FACTORS, TRANSPORT...
168
168
May 31, 2011
05/11
by
Cabell, Randolph H.; Kegerise, Michael A.; Cox, David E.; Gibbs, Gary P
texts
eye 168
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An experimental study of the application of discrete-time, linear quadratic control design methods to the cavity tone problem is described. State space models of the dynamics from a synthetic jet actuator at the leading edge of the cavity to two pressure sensors in the cavity were computed from experimental data. Variations in model order, control order, control bandwidth, and properties of a Kalman state estimator were studied. Feedback control reduced the levels of multiple cavity tones at...
Topics: AEROELASTICITY, AERODYNAMIC BALANCE, AUTOMATIC CONTROL, SIMULATION, FLIGHT CONTROL, PILOTLESS...
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239
May 31, 2011
05/11
by
Cabra, R.; Chen, J. Y.; Dibble, R. W.; Hamano, Y.; Karpetis, A. N.; Barlow, R. S
texts
eye 239
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An experimental and numerical investigation is presented of a H2/N2 turbulent jet flame burner that has a novel vitiated coflow. The vitiated coflow emulates the recirculation region of most combustors, such as gas turbines or furnaces. Additionally, since the vitiated gases are coflowing, the burner allows for exploration of recirculation chemistry without the corresponding fluid mechanics of recirculation. Thus the vitiated coflow burner design facilitates the development of chemical kinetic...
Topics: CONVEXITY, INEQUALITIES, FAULT TOLERANCE, CONTROL THEORY, CONTROL SYSTEMS DESIGN, ACTUATORS,...
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306
Jun 12, 2011
06/11
by
Calhoun Philip C.; Harris, Steven B.; Raiszadeh, Behzad; Zaleski, Kristina D
texts
eye 306
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The NASA Langley Research Center has been developing a novel concept for a Mars planetary rover called the Mars Tumbleweed. This concept utilizes the wind to propel the rover along the Mars surface, bringing it the potential to cover vast distances not possible with current Mars rover technology. This vehicle, in its deployed configuration, must be large and lightweight to provide the ratio of drag force to rolling resistance necessary to initiate motion from rest on the Mars surface. One...
Topics: CONTROL SYSTEMS DESIGN, MALFUNCTIONS, AIRBORNE/SPACEBORNE COMPUTERS, ELECTROMAGNETIC INTERFERENCE,...
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297
Jul 26, 2010
07/10
by
Calogeras, James E.; Dustin, Miles O.; Secunde, Richard R
texts
eye 297
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Development of solar dynamic (SD) technologies for space over the past 25 years by NASA Lewis Research Center brought SD power to the point where it was selected in the design phase of Space Station Freedom Program as the power source for evolutionary growth. More recent studies showed that large cost savings are possible in establishing manufacturing processes at a Lunar Base if SD is considered as a power source. Technology efforts over the past 5 years have made possible lighter, more...
Topics: APPLICATIONS PROGRAMS (COMPUTERS), COMPUTER NETWORKS, CONTROL SYSTEMS DESIGN, LIBRARIES, PRINTERS,...
264
264
Jun 12, 2011
06/11
by
Campbell, B. A.; Maxwell, T. A.; Freeman, A
texts
eye 264
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Many regions of the martian surface are covered by fine-grained materials emplaced by volcanic, fluvial, or aeolian processes. These mantling deposits likely hide ancient channel systems (particularly at smaller scale lengths) and volcanic, impact, glacial, or shoreline features. Synthetic aperture radar (SAR) offers the capability to probe meters below the surface, with imaging resolution in the 10 s of m range, to reveal the buried terrain and enhance our understanding of Mars geologic and...
Topics: INFORMATION SYSTEMS, CONTROL SYSTEMS DESIGN, LIFE SUPPORT SYSTEMS, ON-LINE SYSTEMS, NASA PROGRAMS,...
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184
Jun 3, 2011
06/11
by
Carsey, F. D.; Hecht, M. H
texts
eye 184
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Icy sites on Mars continue to be of high scientific importance. These sites include the polar caps, the southern mid-latitude subsurface permafrost, and the seasonal frost. These sites have interest due to their roles in climate processes, past climates, surface and near-surface water, astrobiology, geomorphology, and other topics. As is the case for many planetary features, remote sensing, while of great value, cannot answer all questions; in-situ examination is essential, and the motivation...
Topics: FAULT TOLERANCE, ACTUATORS, SENSORS, STABILITY TESTS, FEEDBACK CONTROL, FUNCTIONS (MATHEMATICS),...
A library for use by the computer aided design system, known as the Control System Design Environment, made up of hardware and software primitives of the Intel 80 86 microprocessor family, was written to extend the capabilities of the design system to more than two microprocessor families. Compatibility between this library and the Intel 8080 library was desired and achieved by use of designs originally realized with the 8080 library.
Topics: Computer Aided Design, Microprocessor, Control Systems Design, Assembly Language Library
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1.1K
May 29, 2011
05/11
by
Chambers, Joseph R
texts
eye 1,117
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Established in 1917 as the nation#s first civil aeronautics research laboratory under the National Advisory Commit-tee for Aeronautics (NACA), Langley was a small laboratory that solved the problems of flight for military and civil aviation. Throughout history, Langley has maintained a working partnership with the Department of Defense, U.S. industry, universities, and other government agencies to support the defense of the nation with research. During World War II, Langley directed virtually...
Topics: FLIGHT CONTROL, F-18 AIRCRAFT, CONTROL SYSTEMS DESIGN, COMPUTERIZED SIMULATION, ACTUATORS, FAILURE,...
337
337
Jun 1, 2011
06/11
by
Chapman, J. N.; Schmidt, H. J.; Ruoff, R. S.; Chandrasekhar, V.; Dikin, D. A.; Litchford, R. J
texts
eye 337
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Virtually all plasma-based systems for advanced airborne/spaceborne propulsion and power depend upon the future availability of flightweight magnet technology. Unfortunately, current technology for resistive and superconducting magnets yields system weights that tend to counteract the performance advantages normally associated with advanced plasma-based concepts. The ongoing nanotechnology revolution and the continuing development of carbon nanotubes (CNT), however, may ultimately relieve this...
Topics: SPACECRAFT CONTROL, VECTORS (MATHEMATICS), ENERGY STORAGE, KINETIC ENERGY, INTERNATIONAL SPACE...
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326
May 23, 2011
05/11
by
Chattopadhyay, Aditi; Jha, Ratneshwa
texts
eye 326
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Composite wings have become increasingly popular in recent years due to significant potential of weight savings and stiffness tailoring. For aircraft wings made out of composite materials, aeroelastic tailoring presents an opportunity to enhance the aircraft performance by utilizing their unique stiffness and strength properties. Therefore, the goal of the current research are as follows: (1) Development of a new composite beam modeling, technique to represent the principal load-carrying member...
Topics: H-INFINITY CONTROL, TRANSFER FUNCTIONS, ROBUSTNESS (MATHEMATICS), COMPUTERIZED SIMULATION, SELF...
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142
May 29, 2011
05/11
by
Chen, Zhikai; Maly, Kurt; Mehrotra, Piyush; Zubair, Mohamma
texts
eye 142
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Distributed heterogeneous environments are being increasingly used to execute a variety of large size simulations and computational problems. We are developing Arcade, a web-based environment to design, execute, monitor, and control distributed applications. These targeted applications consist of independent heterogeneous modules which can be executed on a distributed heterogeneous environment. In this paper we describe the overall design of the system and discuss the prototype implementation...
Topics: ACCELEROMETERS, ON-LINE SYSTEMS, FLIGHT CONTROL, NONLINEAR SYSTEMS, CONTROL SYSTEMS DESIGN,...
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91
Sep 12, 2018
09/18
by
Chesmond, C. J. (Colin J.)
texts
eye 91
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xiii, 465 pages : 27 cm
Topics: Automatic control, Automatic control, Controle, Control systems Design
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226
May 29, 2011
05/11
by
Choi, Michael K
texts
eye 226
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Landsat-7 was successfully launched into orbit on April 15, 1999. After devoting three months to the t bakeout and cool-down of the radiative cooler, and on- t orbit checkout, the Enhanced Thematic Mapper Plus (ETM) began the normal imaging phase of the mission in mid-July 1999. This paper presents the thermal performance of the ETM from mid-July 1999 to mid-May 2000. The flight temperatures are compared to the yellow temperature limits, and worst cold case and worst hot case flight temperature...
Topics: SPACECRAFT GUIDANCE, FLIGHT SAFETY, RISK, CONTROL SYSTEMS DESIGN, SPACECRAFT CONTROL, X-33 REUSABLE...
399
399
Jun 1, 2011
06/11
by
Choi, Sung R.; Bansal, Narottam P
texts
eye 399
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Various electrolyte materials for solid oxide fuel cells were fabricated by hot pressing 10 mol yttria-stabilized zirconia (10-YSZ) reinforced with two different forms of alumina particulates and platelets each containing 0 to 30 mol alumina. Flexure strength and fracture toughness of platelet composites were determined as a function of alumina content at 1000 C in air and compared with those of particulate composites determined previously. In general, elevated-temperature strength and fracture...
Topics: NANOSATELLITES, GLOBAL POSITIONING SYSTEM, LINEAR QUADRATIC REGULATOR, COMPUTERIZED SIMULATION,...
357
357
Jun 2, 2011
06/11
by
Choi, Sung R.; Pereira, J. Michael; Janosik, Lesley A.; Bhatt, Ramakrishna T
texts
eye 357
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Foreign object damage (FOD) behavior of two commercial gas-turbine grade silicon nitrides, AS800 and SN282, was determined at ambient temperature through post-impact strength testing for thin disks impacted by steel-ball projectiles with a diameter of 1.59 mm in a velocity range from 115 to 440 m/s. AS800 silicon nitride exhibited a greater FOD resistance than SN282, primarily due to its greater value of fracture toughness (K(sub IC)). The critical impact velocity in which the corresponding...
Topics: FLIGHT CONTROL, AIRCRAFT MODELS, SYSTEMS ENGINEERING, CONTROL THEORY, UH-60A HELICOPTER, ROTARY...
492
492
Jul 26, 2010
07/10
by
Choi, Y. H.; Soh, W. Y
texts
eye 492
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A time-iterative full Navier-Stokes code, PARC, is used to analyze the flowfield of a two-dimensional ejector nozzle system. A parametric study was performed for two controlling parameters, duct to nozzle area ratio and nozzle pressure ratio. Results show that there is an optimum area ratio for the efficient pumping of secondary flow. At high area ratios, a freestream flow passes directly through the mixing duct without giving adequate pumping. At low area ratios, the jet boundary blocks the...
Topics: ARCHITECTURE (COMPUTERS), CHEMICAL PROPULSION, CONTROL SYSTEMS DESIGN, PROPULSION SYSTEM...
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163
Jul 25, 2010
07/10
by
Chou, Chaur-Min
texts
eye 163
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The Space Station Structural Characterization Experiment (SSSCE) 1,2 is an early space flight experiment that uses the space station as a generic structure to study the dynamic characteristics of Large Space Structures (LSS). On-orbit modal testing will be conducted to determine natural frequencies, mode shapes and damping of dominant structural modes of the space structure assembly. This experiment will utimately support the development of system identification and analytical modeling...
Topics: APPLICATIONS PROGRAMS (COMPUTERS), RESEARCH MANAGEMENT, SYSTEMS INTEGRATION, USER MANUALS (COMPUTER...
431
431
Jul 26, 2010
07/10
by
Choudhary, Alok Nidh
texts
eye 431
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Computer vision is regarded as one of the most complex and computationally intensive problems. An integrated vision system (IVS) is a system that uses vision algorithms from all levels of processing to perform for a high level application (e.g., object recognition). An IVS normally involves algorithms from low level, intermediate level, and high level vision. Designing parallel architectures for vision systems is of tremendous interest to researchers. Several issues are addressed in parallel...
Topics: AIRCRAFT MANEUVERS, FLIGHT SIMULATION, PERTURBATION THEORY, AUTOMATIC PILOTS, CONTROL THEORY,...
481
481
Aug 1, 2010
08/10
by
Crannell, Carol; Pick, Monique, et al; Dennis, Brian; Davis, John; Emslie, Gordon; Haerendel, Gerhard; Hudson, High; Hurford, Gordon; Lin, Robert; Ling, James
texts
eye 481
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The High Energy Solar Physics mission offers the opportunity for major breakthroughs in the understanding of the fundamental energy release and particle acceleration processes at the core of the solar flare problem. The following subject areas are covered: the scientific objectives of HESP; what we can expect from the HESP observations; the high energy imaging spectrometer (HEISPEC); the HESP spacecraft; and budget and schedule.
Topics: CONTROL STABILITY, LINEARIZATION, ROBOT CONTROL, SPACE SHUTTLE PAYLOADS, CONTROL SYSTEMS DESIGN,...
186
186
May 22, 2011
05/11
by
Crowley, James L.; Christensen, Henri
texts
eye 186
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The development of an experimental test-bed to investigate the integration and control of perception in a continuously operating vision system is described. The test-bed integrates a 12 axis robotic stereo camera head mounted on a mobile robot, dedicated computer boards for real-time image acquisition and processing, and a distributed system for image description. The architecture was designed to: (1) be continuously operating, (2) integrate software contributions from geographically dispersed...
Topics: AEROSPACE SYSTEMS, COLLISION AVOIDANCE, COMPUTER PROGRAMMING, SPACE EXPLORATION, SYSTEMS...
224
224
May 6, 2010
05/10
by
Cutler, Andrew D.; Magnotti, Gaetan
texts
eye 224
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The dual pump CARS technique is often used in the study of turbulent flames. Fast and accurate algorithms are needed for fitting dual-pump CARS spectra for temperature and multiple chemical species. This paper describes the development of such an algorithm. The algorithm employs sparse libraries, whose size grows much more slowly with number of species than a conventional library. The method was demonstrated by fitting synthetic ''experimental'' spectra containing 4 resonant species (N2, O2, H2...
Topics: ACTIVE CONTROL, COMPUTATIONAL FLUID DYNAMICS, CONTROL SYSTEMS DESIGN, HIGH REYNOLDS NUMBER, FLOW...
496
496
May 31, 2011
05/11
by
DAgostino, Mark G.; Lee, Young C.; Wang, Ten-Se
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Wide band plume radiation data were collected during ten sea level tests of a single XRS-2200 engine at the NASA Stennis Space Center in 1999 and 2000. The XRS-2200 is a liquid hydrogen/liquid oxygen fueled, gas generator cycle linear aerospike engine which develops 204,420 lbf thrust at sea level. Instrumentation consisted of six hemispherical radiometers and one narrow view radiometer. Test conditions varied from 100% to 57% power level (PL) and 6.0 to 4.5 oxidizer to fuel (O/F) ratio....
Topics: INTERNETS, NASA PROGRAMS, PROTOCOL (COMPUTERS), ARCHITECTURE (COMPUTERS), SPACECRAFT CONTROL,...
440
440
May 22, 2011
05/11
by
Dattoli, G.; Torre, Amalia; Lorenzutta, S.; Maino, G.; Chiccoli, C
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The phase-space approach to classical and quantum systems demands for advanced analytical tools. Such an approach characterizes the evolution of a physical system through a set of variables, reducing to the canonically conjugate variables in the classical limit. It often happens that phase-space distributions can be written in terms of quadratic forms involving the above quoted variables. A significant analytical tool to treat these problems may come from the generalized many-variables Hermite...
Topics: ACTUATORS, MODULATION, SPACE TRANSPORTATION, THRUST VECTOR CONTROL, WAVEFORMS, CONTROL SYSTEMS...
415
415
Jul 26, 2010
07/10
by
Davidson, Frederic; Sun, X
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This interim report describes the progress in the construction of a 220 Mbps Q=4 PPM optical communication system that uses a semiconductor laser as the optical transmitter and an avalanche photodiode (APD) as the photodetector. The transmitter electronics have been completed and contain both GaAs and ECL III IC's. The circuit was able to operate at a source binary data rate from 75 Mbps to 290 Mbps with pulse rise and fall times of 400 ps. The pulse shapes of the laser diode and the response...
Topics: AIRBORNE/SPACEBORNE COMPUTERS, CONTROL SYSTEMS DESIGN, EXPERT SYSTEMS, GROUND BASED CONTROL,...
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330
May 27, 2011
05/11
by
Decker, R. F.; Rowe, John P.; Freeman, J. W
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The relative hot-workability and creep-rupture properties at 1600 F of a complex 55Ni-20Cr-15Co-4Mo-3Ti-3Al alloy were evaluated for vacuum-induction, vacuum-arc, and air-induction melting. A limited study of the role of oxygen and nitrogen and the structural effects in the alloy associated with the melting process was carried out. The results showed that the level of boron and/or zirconium was far more influential on properties than the melting method. Vacuum melting did reduce corner cracking...
Topics: LATERAL CONTROL, TRAJECTORIES, ROTATION, LONGITUDINAL CONTROL, TRAJECTORY CONTROL, SEQUENTIAL...
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131
May 23, 2011
05/11
by
Deere, Karen A.; Asbury, Scott C
texts
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A translating throat single expansion-ramp nozzle (SERN) concept was designed to improve the off-design performance of a SERN with a large, fixed expansion ratio. The concept of translating the nozzle throat provides the SERN with a variable expansion ratio. An experimental and computational study was conducted to predict and verify the internal performance of this concept. Three nozzles with expansion ratios designed for low, intermediate, and high Mach number operating conditions were tested...
Topics: ROTARY WING AIRCRAFT, CONTROL SYSTEMS DESIGN, FLIGHT CONTROL, MIMO (CONTROL SYSTEMS), DYNAMIC...
