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159
Jun 9, 2011
06/11
by
Voas, Jeffre
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This paper introduces a dynamic metric that is based on the estimated ability of a program to withstand the effects of injected ''semantic mutants'' during execution by computing the same function as if the semantic mutants had not been injected. Semantic mutants include: (1) syntactic mutants injected into an executing program and (2) randomly selected values injected into an executing program's internal states. The metric is a function of a program, the method used for injecting these two...
Topics: WAVEGUIDES, COUPLED MODES, PLANAR STRUCTURES, FREQUENCY RANGES, FINITE DIFFERENCE THEORY, TIME...
430
430
May 31, 2011
05/11
by
Telban, Robert J.; Cardullo, Frank M.; Houck, Jacob A
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eye 430
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This paper discusses the continuation of research into the development of new motion cueing algorithms first reported in 1999. In this earlier work, two viable approaches to motion cueing were identified: the coordinated adaptive washout algorithm or 'adaptive algorithm', and the 'optimal algorithm'. In this study, a novel approach to motion cueing is discussed that would combine features of both algorithms. The new algorithm is formulated as a linear optimal control problem, incorporating...
Topics: MICROPHONES, NOISE REDUCTION, PHASED ARRAYS, CYLINDRICAL BODIES, NOISE MEASUREMENT, AIRCRAFT NOISE,...
615
615
Jun 9, 2011
06/11
by
Bradley, Kevin R
texts
eye 615
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This paper describes the development of a methodology for sizing Blended-Wing-Body (BWB) transports and how the capabilities of the Flight Optimization System (FLOPS) have been expanded using that methodology. In this approach, BWB transports are sized based on the number of passengers in each class that must fit inside the centerbody or pressurized vessel. Weight estimation equations for this centerbody structure were developed using Finite Element Analysis (FEA). This paper shows how the...
Topics: PRESSURE SENSORS, LOOP ANTENNAS, FREQUENCY RANGES, RADIO FREQUENCIES, SIGNAL PROCESSING,...
506
506
May 23, 2011
05/11
by
Farassat, F.; Myers, M. K
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eye 506
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In this paper we discuss two problems of classical duct acoustics: (1) wave propagation in infinite ducts with uniform flow based on a graphical approach, and (2) detection of mode radiation from a duct by an external circular microphone array. In (1) we show that the wave number vectors for a given flow Mach number form an ellipse whose center and shape depend on the Mach number only. We construct graphically the upstream and downstream wave number vectors of modes that propagate in the duct....
Topics: PHASE VELOCITY, BOUNDARY CONDITIONS, ULTRASONIC WAVE TRANSDUCERS, PIEZOELECTRIC TRANSDUCERS,...
455
455
May 6, 2010
05/10
by
Korvin, W.; Steckel, J
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eye 455
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Vertical radio frequency test range for antenna radiation measurement
Topics: ANTENNAS, FREQUENCY RANGES, RADIATION MEASUREMENT, RADIO FREQUENCIES, RANGEFINDING, TEST RANGES,...
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198
Jun 13, 2011
06/11
by
Haw, Robert J
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eye 198
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A proposed Neptune Orbiter Aerocapture mission will use solar electric propulsion to send an orbiter to Neptune. Navigation feasibility of direct-entry aerocapture for orbit insertion at Neptune is shown. The navigation strategy baselines optical imaging and VLBI measurements in order to satisfy the flight system s atmosphere entry flight path angle, which is targeted to enter Neptune with an entry flight path angle of 11.6 degrees. Error bars on the entry flight path angle of plus or minus...
Topics: CARBON NANOTUBES, PURIFICATION, FREQUENCY RANGES, DISSOCIATION, WATER, HYDROGEN PEROXIDE
329
329
Jun 9, 2011
06/11
by
Mitcheltree, R. A.; Moss, J. N.; Cheatwood, F. M.; Greene, F. A.; Braun, R. D
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eye 329
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The selection of the unique aeroshell shape for the Mars Microprobes is discussed. A description of its aerodynamics in hypersonic rarefied, hypersonic continuum, supersonic and transonic flow regimes is then presented. This description is based on Direct Simulation Monte Carlo analyses in the rarefied-flow regime, thermochemical nonequilibrium Computational Fluid Dynamics in the hypersonic regime, existing wind tunnel data in the supersonic and transonic regime, additional computational work...
Topics: COMPUTATION, ELECTRIC FIELDS, DIFFERENTIAL EQUATIONS, APERTURES, CAVITIES, FINITE ELEMENT METHOD,...
247
247
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
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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...
261
261
May 30, 2011
05/11
by
Albertson, Cindy W.; Emami, Saie
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eye 261
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Results of a series of shakedown tests to eliminate facility/engine interactions in an open-jet scramjet test facility are presented. The tests were conducted with the NASA DFX (Dual-Fuel eXperimental scramjet) engine in the NASA Langley Combustion Heated Scramjet Test Facility (CHSTF) in support of the Hyper-X program, The majority of the tests were conducted at a total enthalpy and pressure corresponding to Mach 5 flight at a dynamic pressure of 734 psf. The DFX is the largest engine ever...
Topics: ACOUSTIC MEASUREMENT, AEROACOUSTICS, SHEAR LAYERS, UNSTEADY FLOW, COMPUTERIZED SIMULATION,...
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328
May 29, 2011
05/11
by
Juhasz, Albert J
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eye 328
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The purpose of this report was to analyze the heat-transfer problem posed by the determination of spacecraft temperatures and to incorporate the theoretically derived relationships in the computational code TSCALC. The basis for the code was a theoretical analysis of the thermal radiative equilibrium in space, particularly in the Solar System. Beginning with the solar luminosity, the code takes into account these key variables: (1) the spacecraft-to-Sun distance expressed in astronomical units...
Topics: BODY FLUIDS, WATER, DATA ACQUISITION, IMPEDANCE, FREQUENCY RANGES, RESISTORS, ELECTRIC CURRENT,...
169
169
May 29, 2011
05/11
by
Lindstrom, Marily
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eye 169
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This newsletter contains something for everyone It lists classifications of about 440 meteorites mostly from the 1997 and 1998 ANSMET (Antarctic Search for Meteorites) seasons. It also gives descriptions of about 45 meteorites of special petrologic type. These include 1 iron, 17 chondrites (7 CC, 1 EC, 9 OC) and 27 achondrites (25 HED, UR). Most notable are an acapoloite (GRA98028) and an olivine diogenite (GRA98108).
Topics: TUNABLE LASERS, NITROGEN, STOKES LAW OF RADIATION, ENERGY CONVERSION, ARGON, FLUORIDES, FORCED...
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327
Jun 13, 2011
06/11
by
Matloff, Gregory L.; Johnson, Le
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eye 327
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After considering relevant properties of the local interstellar medium and defining a sample interstellar mission, this paper considers possible interstellar applications of the electrodynamic tether, or EDT. These include use of the EDT to provide on-board power and affect trajectory modifications and direct application of the EDT to starship acceleration. It is demonstrated that comparatively modest EDTs can provide substantial quantities of on-board power, if combined with a large-area...
Topics: AURORAS, LONG WAVE RADIATION, EXTRATERRESTRIAL RADIO WAVES, RADIO WAVES, FREQUENCY RANGES, LOW...
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241
Jun 9, 2011
06/11
by
Hultgren, Lennart; Ashpis, David E
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eye 241
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Modern low-pressure turbines, in general, utilize highly loaded airfoils in an effort to improve efficiency and to lower the number of airfoils needed. Typically, the airfoil boundary layers are turbulent and fully attached at takeoff conditions, whereas a substantial fraction of the boundary layers on the airfoils may be transitional at cruise conditions due to the change of density with altitude. The strong adverse pressure gradients on the suction side of these airfoils can lead to...
Topics: BOUNDARY LAYER STABILITY, SURFACE TEMPERATURE, TEMPERATURE MEASUREMENT, TRANSITION FLOW, HYPERSONIC...
Bell System Technical Journal, 10: 4. October 1931 pp 616-627. Audible Frequency Ranges of Music, Speech and Noise. (Snow, W.B.)
Topics: frequency, audible, frequencies, cycles, observers, bass, range, ranges, tests, noises, audible...
Bell System Technical Journal, 14: 1. January 1935 pp 1-7. Wide Band Transmission Over Balanced Circuits. (Clark, A.B.)
Topics: coaxial, transmission, circuits, balanced, crosstalk, cable, pairs, frequency, cables, attenuation,...
Bell System Technical Journal, 9: 3. July 1930 pp 550-566. Effects of Phase Distortion on Telephone Quality. (Steinberg, John C.)
Topics: distortion, phase, frequency, attenuation, delay, wave, filters, articulation, band, speech, system...
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260
May 23, 2011
05/11
by
Jolliff, B. L.; Haskin, L. A
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eye 260
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The impact that produced North Ray Crater, Apollo 16 landing site, exhumed rocks that include relatively mafic members of the lunar ferroan anorthositic suite. Bulk and mineral compositions indicate that a majority of 2-4 mm lithic fragments from sample 67513, including impact breccias and monomict igneous rocks, are related to a common noritic-anorthosite precursor. Compositions and geochemical trends of these lithic fragments and of related samples collected along the rim of North Ray Crater...
Topics: AIRCRAFT CONTROL, FLIGHT TESTS, FLIGHT CHARACTERISTICS, AIRCRAFT PILOTS, PILOT INDUCED OSCILLATION,...
393
393
Jun 1, 2011
06/11
by
Sutkus, Donald J., Jr.; Baughcum, Steven L.; DuBois, Douglas P
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eye 393
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This report describes the development of a three-dimensional database of aircraft fuel use and emissions (NO(x), CO, and hydrocarbons) for the commercial aircraft fleet projected to 2020. Global totals of emissions and fuel burn for 2020 are compared to global totals from previous aircraft emission scenario calculations.
Topics: AIRCRAFT NOISE, IMPEDANCE MEASUREMENT, SCALE MODELS, ACOUSTIC PROPERTIES, MINIATURIZATION,...
182
182
Jun 9, 2011
06/11
by
Duquesne, N.; Carlson, J. R.; Rumsey, C. L.; Gatski, T. B
texts
eye 182
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Transport aircraft performance is strongly influenced by the effectiveness of high-lift systems. Developing wakes generated by the airfoil elements are subjected to strong pressure gradients and can thicken very rapidly, limiting maximum lift. This paper focuses on the effects of various pressure gradients on developing symmetric wakes and on the ability of a linear eddy viscosity model and a non-linear explicit algebraic stress model to accurately predict their downstream evolution. In order...
Topics: BOUNDARY LAYER SEPARATION, INCOMPRESSIBLE FLOW, PRESSURE OSCILLATIONS, UPSTREAM, VORTICES, WAKES,...
372
372
May 6, 2010
05/10
by
Socki, Richard A.; Niles, Paul B.; Fu, Qi; Gibson, Everett K., Jr
texts
eye 372
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Discoveries of large deposits of sedimentary materials on the planet Mars by landers and orbiters have confirmed the widely held hypothesis that water has played a crucial role in the development of the martian surface. Recent studies have indicated that both water ice and liquid water may have been present and in the case of water ice perhaps is still present on or near the surface of Mars. However, there remains much controversy about the prevailing atmospheric conditions and climate of Mars...
Topics: REVERBERATION CHAMBERS, LOADS (FORCES), STANDARD DEVIATION, ANTENNA DESIGN, SYSTEMS INTEGRATION,...
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292
Jun 12, 2011
06/11
by
Jones, Thomas W.; Lunsford, Charles B
texts
eye 292
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A series of wind tunnel tests have been conducted to evaluate a multi-camera videogrammetric system designed to measure model attitude in hypersonic facilities. The technique utilizes processed video data and applies photogrammetric principles for point tracking to compute model position including pitch, roll and yaw variables. A discussion of the constraints encountered during the design, development, and testing process, including lighting, vibration, operational range and optical access is...
Topics: VELOCITY DISTRIBUTION, ACOUSTIC EMISSION, ACOUSTIC EXCITATION, ALUMINUM, DISTANCE, EXCITATION,...
186
186
Jun 12, 2011
06/11
by
Blair, M. W.; Kalchgruber, R.; Deo, S.; McKeever, S. W. S
texts
eye 186
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The surface of Mars has been subject to aeolian, fluvial, and periglacial activity in the (relatively) recent past. Unfortunately, chronological dating of recent events on Mars is difficult as the errors associated with crater counting are comparable to younger ages (approx. 1 Ma). Consequently, techniques to quantify the ages of geological processes on Mars have become an important area of research. Optically stimulated luminescence (OSL) dating is one candidate technique for in-situ dating of...
Topics: MINERALS, MARS SURFACE, HEMATITE, CURIE TEMPERATURE, FERROMAGNETIC MATERIALS, TITANIUM, CRYSTALS,...
457
457
May 23, 2011
05/11
by
Suder, Kenneth L
texts
eye 457
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A detailed experimental investigation to understand and quantify the development of loss and blockage in the flow field of a transonic, axial flow compressor rotor has been undertaken. Detailed laser anemometer measurements were acquired upstream, within, and downstream of a transonic, axial compressor rotor operating at design and off-design conditions. The rotor was operated at 100, 85, 80, and 60 of design speed which provided inlet relative Mach numbers at the blade tip of 1.48, 1.26, 1.18,...
Topics: FLIGHT CONDITIONS, ROBUSTNESS (MATHEMATICS), YAW, DEGREES OF FREEDOM, FLY BY WIRE CONTROL,...
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215
May 31, 2011
05/11
by
Gill, E.; Naasz, Bo; Ebinuma, T
texts
eye 215
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A closed-loop system for the demonstration of autonomous satellite formation flying technologies using hardware-in-the-loop has been developed. Making use of a GPS signal simulator with a dual radio frequency outlet, the system includes two GPS space receivers as well as a powerful onboard navigation processor dedicated to the GPS-based guidance, navigation, and control of a satellite formation in real-time. The closed-loop system allows realistic simulations of autonomous formation flying...
Topics: AIRCRAFT NOISE, FLIGHT CREWS, SOUND PRESSURE, SHAFTS (MACHINE ELEMENTS), NOISE INTENSITY, FREQUENCY...
654
654
Jul 11, 2010
07/10
by
NON
texts
eye 654
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THIS COLLECTION PRESENTS EXPERIMENTAL STUDIES OF THE COMBINED EFFECT OF DYNAMIC FACTORS (ACCELERATION AND VIBRATION) AND IONIZING RADIATION ON THE FUNCTIONAL STATE OF THE VESTIBULAR ANALYSOR, HIGHER NERVOUS ACTIVITY AND ANIMAL BEHAVIOR. THE ARTICLE SUMMARIZING THE RESULTS OF THESE AND PREVIOUSLY PUBLISHED WORKS SUBSTANTIATES THE THEORY OF THE IMPORTANCE OF INTRACENTRAL PROCESSES IN THE REACTIONS OF THE CENTRAL NERVOUS SYSTEM TO APPLIED COMBINED FORCES. THE COLLECTION ALSO INCLUDES STUDIES OF...
Topics: GROUND STATIONS, SYNCHRONOUS METEOROLOGICAL SATELLITE, AUTOMATIC PICTURE TRANSMISSION, BLOCK...
334
334
May 23, 2011
05/11
by
Coppenbarger, Richard A
texts
eye 334
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Helmet-mounted display (HMD) symbology for an automated Nap-of-the-Earth (NOE) guidance and control system is described. In the automated system, referred to as Pilot-Directed Guidance (PDG), pilot control inputs are interpreted as high-level velocity commands to an inner-loop guidance and control system that is responsible for obstacle detection and avoidance maneuvering. The success of the PDG concept has been shown to be highly dependent upon the intelligent use of inertially stabilized...
Topics: RADOME MATERIALS, TRANSMISSION LOSS, MILLIMETER WAVES, PERMITTIVITY, FREQUENCY RANGES, INCIDENCE,...
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155
texts
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Hewlett-Packard Journal Vol. 3 No. 3 (1951-11)(Hewlett-Packard)
Topics: model, probe, vswr, kmc, waveguide, slotted, coaxial, center, frequency, type, coaxial slotted,...
82
82
Aug 2, 2010
08/10
by
Kanavarioti, A.; Bernasconi, C. F.; Alberas, D. J
texts
eye 82
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Non-enzymatic, template-directed reactions have been proposed as models for prebiological polynucleotide synthesis. Chemically activated mononucleotides react in the presence of a polynucleotide, acting as the template in a Watson-Crick base-pairing fashing, and form the complementary daughter polynucleotide. Phosphoimidazolide-activated nucleotides have been used successfully as substrates in these reactions. The kinetics of the guanosine 5'-monophosphate-2-methylimidazolide (2-MelmpG)...
Topics: EXTRATERRESTRIAL INTELLIGENCE, PARABOLIC REFLECTORS, RADIO FREQUENCY INTERFERENCE, SIGNAL...
989
989
Jul 11, 2010
07/10
by
Gluzek, F.; Mokadam, R. G.; To, I. H.; Stanitz, J. D.; Wollschlager, J
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eye 989
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A rotating, positive displacement vane pump with an integral boost stage was designed to pump saturated liquid oxygen and liquid hydrogen for auxiliary propulsion system of orbit transfer vehicle. This unit is designed to ingest 10% vapor by volume, contamination free liquid oxygen and liquid hydrogen. The final pump configuration and the predicted performance are included.
Topics: AEROELASTICITY, TRANSFER FUNCTIONS, WIND TUNNEL MODELS, CONTROL THEORY, FLUTTER, OPTIMAL CONTROL,...
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250
May 27, 2011
05/11
by
Thompson, Wilbur E.; Horne, Walter B
texts
eye 250
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The low-speed (up to 4 miles per hour) yawed-rolling characteristics of two 56 x 16 32-ply-rating, type 7 aircraft tires under straight-yawed rolling were determined over a range of inflation pressures and yaw angles for a vertical load approximately equal to 75 percent of the rated vertical load. The quantities measured or determined included cornering force, drag force self-alining torque, pneumatic caster vertical tire deflection, yaw angle, and relaxation length. During straight-yawed...
Topics: CONTROL THEORY, EQUATIONS OF MOTION, AIRCRAFT STABILITY, BLOCK DIAGRAMS, TRANSFER FUNCTIONS,...
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240
May 22, 2011
05/11
by
NON
texts
eye 240
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A device for measuring turbulence in high-speed flows is provided which includes a micro-sensor thin-film probe. The probe is formed from a single crystal of aluminum oxide having a 14 deg half-wedge shaped portion. The tip of the half-wedge is rounded and has a thin-film sensor attached along the stagnation line. The bottom surface of the half-wedge is tilted upward to relieve shock induced disturbances created by the curved tip of the half-wedge. The sensor is applied using a...
Topics: DENSITY (MASS/VOLUME), FEEDBACK, FIBERS, SIGNAL GENERATORS, TRANSDUCERS, VIBRATION, FREQUENCY...
Technique reduces task of filter design by using cut off frequency, termination frequency and weight number to determine filter effect on frequency domain of digital filter input data function.
Topics: NASA Technical Reports Server (NTRS), AMPLITUDES, BANDWIDTH, COMPUTER PROGRAMS, DIGITAL FILTERS,...
Analytical techniques were developed to evaluate braided hoses and bellows for possibility of flow induced resonance. These techniques determine likelihood of high cycle fatigue failure when such resonance exists.
Topics: NASA Technical Reports Server (NTRS), ANALYSIS (MATHEMATICS), BELLOWS, FAILURE ANALYSIS, FATIGUE...
An effort was made to determine the effects of electromagnetic radiation on the terminal properties of electrochemical cells. Various constituents of the battery were measured to determine basic electromagnetic properties. These properties were used to predict how much radiation would be absorbed by a battery in a particular field configuration. The frequency range covered from 0 to 40 GHz with the greatest emphasis on the microwave range from 2.6 to 40 GHz. The measurements were made on NiCd,...
Topics: NASA Technical Reports Server (NTRS), ELECTROCHEMICAL CELLS, ELECTROMAGNETIC RADIATION, RADIATION...
An iterative computer method is described for identifying boiler transfer functions using frequency response data. An objective penalized performance measure and a nonlinear minimization technique are used to cause the locus of points generated by a transfer function to resemble the locus of points obtained from frequency response measurements. Different transfer functions can be tried until a satisfactory empirical transfer function to the system is found. To illustrate the method, some...
Topics: NASA Technical Reports Server (NTRS), BOILERS, COMPUTER TECHNIQUES, TRANSFER FUNCTIONS, DYNAMIC...
A technique for extending the frequency range of a presettable digital divider is described. The conventional digital divider consists of several counter stages with the count of each stage compared to a preselected number. When the counts for all stages are equal to the preselected numbers, an output pulse is generated and all stages are reset. For high input frequencies, the least significant stage of the divider has to be reset in a very short time. This limits the frequency that can be...
Topics: NASA Technical Reports Server (NTRS), FREQUENCY DIVIDERS, FREQUENCY RANGES, COMPARATORS, COUNTING...
The mean and turbulent u, v, and w components of a gaseous fully developed turbulent pipe flow were measured with a laser Doppler velocimeter system. Measurements of important system parameters are presented and discussed in relation to the measurement accuracy. Simultaneous comparisons of the laser Doppler and hot wire anemometer measurements in the turbulent flow provided evidence that the two systems were responding to the same flow phenomena.
Topics: NASA Technical Reports Server (NTRS), LASER DOPPLER VELOCIMETERS, PIPE FLOW, TURBULENCE, ELECTRONIC...
The command and data acquisition (CDA) station for the Synchronous Meteorological Satellite (SMS) program, located on the Eastern shore of Virginia, is described in terms of facility layout, ground support instrumentation, and capabilities. Data systems and equipment are described in detailed block diagrams. The major subsystems are identified and information on equipment specifications, frequency ranges, and data processing format is given. Automatic picture transmission, data utilization...
Topics: NASA Technical Reports Server (NTRS), GROUND STATIONS, SYNCHRONOUS METEOROLOGICAL SATELLITE,...
The solar radio spectra were recorded in real time, both on film and magnetic tape, during the period from November 1972 to February 1974. A catalogue of the observations is given for the frequency range 565-1000 MHz and includes descriptions of the bursts, intensity scales, and pertinent remarks. Some theoretical considerations resulting from the research are given. Equipment modified for the experiment is described and the text of the final report which summarizes the research on type IV...
Topics: NASA Technical Reports Server (NTRS), RADIO BURSTS, SKYLAB 1, SOLAR RADIO EMISSION, FREQUENCY...
The functions of the Tracking and Data Relay Satellite System (TDRSS) are discussed. The primary purpose of the system is to transmit signals to and receive signals from earth orbiting user spacecraft, and provide data from which user spacecraft ephemerides can be calculated. The system configuration is described and illustrated. The frequency plan is analyzed to show the frequency coverage and the signal handling capability of the system. The characteristics of the components of the system are...
Topics: NASA Technical Reports Server (NTRS), DATA TRANSMISSION, SPACE COMMUNICATION, TDR SATELLITES,...
Simplified methods are described to estimate the test criteria of primary structures at component attachment points subjected to broadband random acoustic excitations. The current method utilizes a constant smeared component mass attenuation factor across the frequency range of interest. The developed method indicates that the attenuation factor is based on a frequency dependent ratio of the mechanical impedances of both the component and primary structures. The procedures used to predict the...
Topics: NASA Technical Reports Server (NTRS), ACOUSTIC EXCITATION, BROADBAND, RANDOM VIBRATION, SPACECRAFT...
An electronic sensor was built to measure the position of the terminal shock in a supersonic inlet. The sensor uses several static-pressure taps in the inlet wall. The sensor output is continuously proportional to shock position. When the sensor was installed in a YF-12 aircraft flight inlet during wind tunnel tests, it indicated shock position within + or - 5 percent of the total distance covered by the static-pressure-tap region. The maximum error caused by an angle of attack change of 4 deg...
Topics: NASA Technical Reports Server (NTRS), PRESSURE SENSORS, SUPERSONIC INLETS, WIND TUNNEL TESTS, YF-12...
A statistical evaluation of some of the recent satellite determined gravity models, including some with distinct data base, indicates that the geopotential coefficients of these models are individually meaningful for frequencies with wave numbers n = 2 through 7 certainly and wave numbers n = 8 through 10 probably. Geopotential coefficients in higher frequency ranges while apparently important for computing accurate satellite orbits seem to have little geophysical significance in an individual...
Topics: NASA Technical Reports Server (NTRS), EARTH GRAVITATION, GEOPOTENTIAL, GRAVITATIONAL FIELDS,...
The acoustic emission (AE) characteristics of pure copper, zirconium-copper, and several copper alloys were determined to develop nondestructive evaluation schemes of thrust chambers through AE techniques. The AE counts rms voltages, frequency spectrum, and amplitude distribution analysis evaluated AE behavior under fatigue loading conditions. The results were interpreted with the evaluation of wave forms, crack propagation characteristics, as well as scanning electron fractographs of...
Topics: NASA Technical Reports Server (NTRS), ACOUSTIC MEASUREMENT, COPPER ALLOYS, FATIGUE TESTS, LOAD...
Signal processing equipment specifications, operating and test procedures, and systems design and engineering are described. Five subdivisions of the overall circuitry are treated: (1) the spectrum analyzer; (2) the spectrum integrator; (3) the velocity discriminator; (4) the display interface; and (5) the formatter. They function in series: (1) first in analog form to provide frequency resolution, (2) then in digital form to achieve signal to noise improvement (video integration) and frequency...
Topics: NASA Technical Reports Server (NTRS), DESIGN ANALYSIS, DISPLAY DEVICES, EQUIPMENT SPECIFICATIONS,...
Precipitation backscatter limits the effectiveness of a remote sensing radar in a satellite. Scatterometer operation on SEASAT is considered in one of the following frequency ranges: 12.5 GHz; 13.4-14.0 GHz; and 14.4-15.35 GHz. The effect of backscatter from precipitation in these frequency ranges is compared.
Topics: NASA Technical Reports Server (NTRS), BACKSCATTERING, REMOTE SENSORS, SCATTEROMETERS, SEASAT...
An airborne electromagnetic environment survey is described of five urban areas where terrestrially-generated radio-frequency interference was measured over the frequency range from 0.4 to 18.0 GHz. A chartered Cessna 402 aircraft contained necessary measurement test equipment, including the receiving antennas mounted beneath the fuselage. Urban areas including Washington, D.C.; Baltimore, MD; Philadelphia, PA; New York, NY; Chicago, ILL; and Palestine, TX were surveyed. A flight test plan and...
Topics: NASA Technical Reports Server (NTRS), AIRBORNE EQUIPMENT, CITIES, ELECTROMAGNETIC NOISE, RADIO...
A linear analysis and comparison of the damping properties of six dynamic initialization schemes is presented, indicating that the Okamura-Rivas scheme has the most efficient damping properties over the whole frequency range, and suggesting that it should be faster than the other methods and given more stable results. The results obtained with a nonlinear shallow water equations model agree well with the linear analysis. The Okamura-Rivas scheme attains complete balance in the equivalent of 5...
Topics: NASA Technical Reports Server (NTRS), DAMPING, FREQUENCY RANGES, LINEAR EQUATIONS, MATHEMATICAL...
A design study is described for a mechanically scanned offset fed parabolic torus reflector antenna having a 4m x 2m aperture for simultaneous use at eleven frequency channels from UHF to millimeter wavelengths. A design for the antenna is presented utilizing dipole and horn feeds at the low frequencies and a Gregorian aberration correcting subreflector system for feeding the torus at the high frequencies. The results and details of a theroetical study based on geometrical optics performed to...
Topics: NASA Technical Reports Server (NTRS), ANTENNA DESIGN, MICROWAVE ANTENNAS, PARABOLIC REFLECTORS,...
Magnetospheric radio noise spectra (30 kHz to 10 MHz) taken by IMP-6 and RAE-2 exhibit time varying characteristics which are related to spacecraft position and magnetospheric processes. In the midfrequency range (100-1000 kHz) intense noise peaks rise a factor of 100 or more above background; 80% of the peak frequencies are within the band 125 kHz to 600 kHz, and the peak occurs most often (18% of the time) at 280 kHz. Bandwidths of the peaks range from about 100 kHz to more than 500 kHz; most...
Topics: NASA Technical Reports Server (NTRS), EARTH MAGNETOSPHERE, ELECTROMAGNETIC NOISE, NOISE SPECTRA,...
