ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Ihre E-Mail wurde erfolgreich gesendet. Bitte prüfen Sie Ihren Maileingang.

Leider ist ein Fehler beim E-Mail-Versand aufgetreten. Bitte versuchen Sie es erneut.

Vorgang fortführen?

Exportieren
Filter
  • Weitere Quellen  (2.030)
  • NASA Technical Reports  (2.030)
  • STRUCTURAL MECHANICS  (1.043)
  • COMMUNICATIONS AND RADAR  (987)
  • 1975-1979  (2.030)
  • 1930-1934
Sammlung
  • Weitere Quellen  (2.030)
Datenquelle
  • NASA Technical Reports  (2.030)
Schlagwörter
Erscheinungszeitraum
Jahr
  • 1
    facet.materialart.
    Unbekannt
    Propagation predictions for the HF-range by the Research Institute of the Deutsche Bundespost (1979)
    In:  CASI
    Details
    Publikationsdatum: 2009-11-16
    Beschreibung: Long term and short term HF propagation prediction service is described. The long term prediction method is computer based. The short term prediction method is still a manual method which relies mainly on a number of continuous field strength recordings and on the forecaster's ability to interpret the recordings and to combine this information with all available solar-geophysical data. Examples of the predictions are given and are compared with actually observed HF propagation conditions.
    Schlagwort(e): COMMUNICATIONS AND RADAR
    Materialart: NOAA Solar-Terrest. Predictions Proc., Vol. 1; p 25-43
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 2
    facet.materialart.
    Unbekannt
    Combined vibration/temperature/sideload environmental testing of UHF blade antennas (1979)
    In:  CASI
    Details
    Publikationsdatum: 2006-07-02
    Beschreibung: Service problems encountered on the F-4 aircraft showed that the environmental qualification requirements for the UHF blade antenna were not adequate. Although the individual environmental levels were stringent enough, only combined environmental testing could duplicate the conditions in which service problems occurred. Techniques for applying static side load simultaneously with vibration and temperature were developed. The combined environment testing was instrumental in the rapid assessment of antenna modifications and resulted in a final configuration which proved satisfactory in service. A need to include combined environmental testing for qualification of blade antennas was established.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: Shock and Vibration Inform. Center The Shock and Vibration Bull., Pt. 3; p 79-84
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 3
    facet.materialart.
    Unbekannt
    A circuit model for electromagnetic properties of waveguide arcs (1979)
    In:  CASI
    Details
    Publikationsdatum: 2006-06-01
    Beschreibung: A dielectric model of waveguide arcs is presented to relate measurable electromagnetic quantities to the physical parameters characterizing the breakdown process.
    Schlagwort(e): COMMUNICATIONS AND RADAR
    Materialart: The Deep Space Network; p 193-195
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 4
    facet.materialart.
    Unbekannt
    Assessment of 20 kW S-band transmitter (1979)
    In:  CASI
    Details
    Publikationsdatum: 2006-06-01
    Beschreibung: The performance history of the 20-kW S-band transmitter, installed at three 64-meter antennas and six 26-meter antennas in the DSN, is reviewed. A number of failures and discrepancy reports are characteristic of the wearout phase of a failure curve. The type of failures are reviewed and four options toward reducing the number and cost of failures are reviewed. These are: existing (no change), refurbish, redesign and replacement. The options are compared on a ten year life cycle cost basis using FY77 expenditures for existing equipment as a base. It was concluded that benefits, in terms of reduction of outrage time, increase with an increase of expenditure toward improvement.
    Schlagwort(e): COMMUNICATIONS AND RADAR
    Materialart: The Deep Space Network; p 186-192
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 5
    facet.materialart.
    Unbekannt
    Microwave time delays in the DSN 34- and 64-meter antennas (1979)
    In:  CASI
    Details
    Publikationsdatum: 2006-06-01
    Beschreibung: The results and methods used to derive data for the recent changes to the DSN 34- and 64-m stations at both S- and X-band frequencies are presented.
    Schlagwort(e): COMMUNICATIONS AND RADAR
    Materialart: The Deep Space Network; p 183-185
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 6
    facet.materialart.
    Unbekannt
    DSS 13 antenna monitor system (1979)
    In:  CASI
    Details
    Publikationsdatum: 2006-06-01
    Beschreibung: The development of a monitor system for the DSS 13 antenna is presented. The system checks for accumulator pressures, differential pressures, wind velocity, power supplies, fluid temperatures, and fluid levels. It was concluded that the system performed properly in high winds and correctly reported all malfunctions.
    Schlagwort(e): COMMUNICATIONS AND RADAR
    Materialart: The Deep Space Network; p 138-140
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 7
    facet.materialart.
    Unbekannt
    Carrier tracking loop performance in the presence of strong CW interference (1979)
    In:  CASI
    Details
    Publikationsdatum: 2006-06-01
    Beschreibung: Research on the behavior of the carrier tracking loop exposed to a continuous wave irradiation along with Bruno's closed form of approximation for the loop phase error are described.
    Schlagwort(e): COMMUNICATIONS AND RADAR
    Materialart: The Deep Space Network; p 130-137
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 8
    facet.materialart.
    Unbekannt
    Costas loop demodulation of suppressed carrier BPSK signals in the DSN environment: Experimental results obtained at TDL (1979)
    In:  CASI
    Details
    Publikationsdatum: 2006-06-01
    Beschreibung: Suppressed carrier binary phase-shift keyed (BPSK) signalling is currently being considered as a design alternative for future DSN telemetry in the multimegabit range. Carrier tracking of such signals is usually achieved by a Costas loop, as opposed to the ordinary phase lock loop. A Costas loop capable of demodulating BPSK signals with data rates up to 1 Msps was designed and constructed and its Doppler tracking performance with respect to a Block 3 receiver was tested at the Telecommunications Development Laboratory (TDL). The compatibility of suppressed carrier signalling with the current radiometric system, specifically Doppler tracking and ranging, was investigated. The experimental results obtained to-date with respect to Doppler tracking are presented.
    Schlagwort(e): COMMUNICATIONS AND RADAR
    Materialart: The Deep Space Network; p 94-104
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 9
    facet.materialart.
    Unbekannt
    Feasibility of inertialess conscan utilizing modified DSN feedsystems (1979)
    In:  CASI
    Details
    Publikationsdatum: 2006-06-01
    Beschreibung: The closed-loop conical-scan (conscan) technique has proven to be a useful method for pointing the DSN antennas more accurately than is possible by open-loop methods. As presently implemented, the antenna beam is scanned about the received signal direction by physical movement of the antenna. While straightforward, this approach has at least two disadvantages. Firstly, because of structural distortions, finite angle encoder resolution, and drive servo response, the actual antenna beam direction only approximates the commanded beam direction. Secondly, because of the large mass moved during scan, the rate of scan is severely restricted. If there are significant gain or signal level variations during a scan period, the conscan system interprets these variations as antenna pointing error. Both of these disadvantages would be alleviated in an inertialess conscan system in which the beam scanning was performed electronically. Recently, standard JPL antenna feedhorn software was upgraded to calculate, among other things, asymmetric corrugated horn radiation patterns of the type that would be needed for electronic beam scan. The required horn excitation is discussed and the results were described.
    Schlagwort(e): COMMUNICATIONS AND RADAR
    Materialart: The Deep Space Network; p 85-93
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 10
    facet.materialart.
    Unbekannt
    Antenna feedhorn software upgrade (1979)
    In:  CASI
    Details
    Publikationsdatum: 2006-06-01
    Beschreibung: The HYBRIDHORN computer program was developed to serve as an item of general purpose antenna feedhorn design and analysis software. The formulation contains a small flare angle approximation which is subject to question for designs such as the S- and X-band feedhorn. Additionally, the original formulation did not allow azimuthal variation indexes other than unity. The HYBRIDHORN program was upgraded to correct both of these deficiencies. A large flare angle formulation was found. In the upgrade, all of the major program elements were converted to Univac 1108 compatible structured FORTRAN (SFTRAN) for ease of software maintenance. The small and large angle formulations are described and sample numerical results are presented.
    Schlagwort(e): COMMUNICATIONS AND RADAR
    Materialart: The Deep Space Network; p 75-84
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 11
    facet.materialart.
    Unbekannt
    Some effects of quantization on a noiseless phase-locked loop (1979)
    In:  CASI
    Details
    Publikationsdatum: 2006-06-01
    Beschreibung: If the VCO of a phase-locked receiver is to be replaced by a digitally programmed synthesizer, the phase error signal must be sampled and quantized. Effects of quantizing after the loop filter (frequency quantization) or before (phase error quantization) are investigated. Constant Doppler or Doppler rate noiseless inputs are assumed. The main result gives the phase jitter due to frequency quantization for a Doppler-rate input. By itself, however, frequency quantization is impractical because it makes the loop dynamic range too small.
    Schlagwort(e): COMMUNICATIONS AND RADAR
    Materialart: The Deep Space Network; p 58-66
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 12
    facet.materialart.
    Unbekannt
    Recovering the spectrum of a narrow-band process from syncopated samples (1979)
    In:  CASI
    Details
    Publikationsdatum: 2006-06-01
    Beschreibung: A nonuniform sampling strategy, phase quadrature sampling, in which a process of bandwith B is sampled at rate B in each of two channels where the two channels are pi/2 out of phase at frequency B is described. Phase quadrature sampling is a special case of sampling, where the phase between channels is fixed but arbitrary. A simple method for recovering the spectrum of the input process from syncopated samples is derived. The derivation indicates what values of phase between channels result in lossless sampling.
    Schlagwort(e): COMMUNICATIONS AND RADAR
    Materialart: The Deep Space Network; p 47-50
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 13
    facet.materialart.
    Unbekannt
    Effects of D region ionization on radio wave propagation (1979)
    In:  CASI
    Details
    Publikationsdatum: 2006-01-16
    Beschreibung: The effects of anomalous D region ionization upon radio wave propagation are described for the main types of disturbances: sudden ionospheric disturbances, relativistic electron events, magnetic storms, auroral disturbances, polar cap events, and stratospheric warmings. Examples of radio wave characteristics for such conditions are given for the frequencies between the extremely low (3-3000 Hz) and high (3-30 MHz) frequency domains. Statistics on the disturbance effects and radio wave data are given in order to contribute towards the evaluation of possibilities for predicting the radio effects.
    Schlagwort(e): COMMUNICATIONS AND RADAR
    Materialart: NASA. Marshall Space Flight Center Solar-Terrest. Predictions Proc., Vol. 2; p 617-654
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 14
    facet.materialart.
    Unbekannt
    Forecasts of geomagnetic activities and HF radio propagation conditions made at Hiraiso/Japan (1979)
    In:  CASI
    Details
    Publikationsdatum: 2006-01-16
    Beschreibung: The Hiraiso Branch of RRL prediction techniques are summarized separately for the 27 day recurrent storm and the flare-associated storm. The storm predictions are compared with the actual geomagnetic activities in two ways. The first one is the comparison on a day to day basis. In the second comparison, the accuracy of the storm predictions during 1965-1976 are evaluated. In addition to the storm prediction, short-term predictions of HF radio propagation conditions are conducted at Hiraiso. The HF propagation predictions are briefly described as an example of the applications of the magnetic storm prediction.
    Schlagwort(e): COMMUNICATIONS AND RADAR
    Materialart: NOAA Solar-Terrest. Predictions Proc., Vol. 1; p 182-204
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 15
    facet.materialart.
    Unbekannt
    Estimation of solar flame influence on radio circuit transmission loss (1979)
    In:  CASI
    Details
    Publikationsdatum: 2006-01-16
    Beschreibung: A provisional method for determining the hours and frequencies at which solar flares cause major radiopath absorption increase is presented. This technique is incorporated in a computer program for monthly radio propagation prediction.
    Schlagwort(e): COMMUNICATIONS AND RADAR
    Materialart: NOAA Solar-Terrest. Predictions Proc., Vol. 1; p 67-71
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 16
    facet.materialart.
    Unbekannt
    PROPHET: An applicaton of propagation forecasting principles (1979)
    In:  CASI
    Details
    Publikationsdatum: 2006-01-16
    Beschreibung: A propagation assessment and forecasting terminal, PROPHET, is described. The terminal is a key element of the environmental prediction and assessment system which uses real time solar/geophysical data to provide real time knowledge of propagation conditions. The terminal uses models to translate data from satellite and ground based sources into performance predictions for specific systems.
    Schlagwort(e): COMMUNICATIONS AND RADAR
    Materialart: NOAA Solar-Terrest. Predictions Proc., Vol. 1; p 312-321
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 17
    facet.materialart.
    Unbekannt
    Radio disturbance warning issuance system (1979)
    In:  CASI
    Details
    Publikationsdatum: 2006-01-16
    Beschreibung: A radio disturbance warning issuance system was introduced in the Hiraiso Branch of the Radio Research Laboratories in 1972 to reconstruct the current radio disturbance warning service as a social information service. A description of the new ideas which were experimentally systematized by means of an electronic computer is presented.
    Schlagwort(e): COMMUNICATIONS AND RADAR
    Materialart: NOAA Solar-Terrest. Predictions Proc., Vol. 1; p 223-228
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 18
    facet.materialart.
    Unbekannt
    A simplified method of evaluating the stress wave environment of internal equipment (1979)
    In:  CASI
    Details
    Publikationsdatum: 2006-01-16
    Beschreibung: A simplified method called the transfer function technique (TFT) was devised for evaluating the stress wave environment in a structure containing internal equipment. The TFT consists of following the initial in-plane stress wave that propagates through a structure subjected to a dynamic load and characterizing how the wave is altered as it is transmitted through intersections of structural members. As a basis for evaluating the TFT, impact experiments and detailed stress wave analyses were performed for structures with two or three, or more members. Transfer functions that relate the wave transmitted through an intersection to the incident wave were deduced from the predicted wave response. By sequentially applying these transfer functions to a structure with several intersections, it was found that the environment produced by the initial stress wave propagating through the structure can be approximated well. The TFT can be used as a design tool or as an analytical tool to determine whether a more detailed wave analysis is warranted.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: Shock and Vibration Inform. Center The Shock and Vibration Bull., Pt. 1; p 89-96
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 19
    facet.materialart.
    Unbekannt
    High G pyrotechnic shock simulation using metal-to-metal impact (1979)
    In:  CASI
    Details
    Publikationsdatum: 2006-01-16
    Beschreibung: A technique for simulating high g level pyrotechnic shocks is described and the results of applying the technique to obtain the MIL-STD-1540A shock spectrum with a maximum acceleration of 18,000g at 2,000 Hz are presented. Designing the resonant beam and plate on which the test unit is mounted, and generating a proper impulsive load on them, were the essentials of the technique. One dimensional stress wave and Euler equations were employed in the design. A metal pendulum hammer was used to generate the impulsive load.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: Shock and Vibration Inform. Center The Shock and Vibration Bull., Pt. 1; p 97-100
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 20
    facet.materialart.
    Unbekannt
    Probability of failure prediction for step-stress fatigue under sine or random stress (1979)
    In:  CASI
    Details
    Publikationsdatum: 2006-01-16
    Beschreibung: A previously proposed cumulative fatigue damage law is extended to predict the probability of failure or fatigue life for structural materials with S-N fatigue curves represented as a scatterband of failure points. The proposed law applies to structures subjected to sinusoidal or random stresses and includes the effect of initial crack (i.e., flaw) sizes. The corrected cycle ratio damage function is shown to have physical significance.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: Shock and Vibration Inform. Center The Shock and Vibration Bull., Pt. 1; p 31-41
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 21
    facet.materialart.
    Unbekannt
    Ionosphere-reflected propagation (1979)
    In:  CASI
    Details
    Publikationsdatum: 2006-01-16
    Beschreibung: The predictability of those ionospheric parameters relevant to ionosphere-reflected communications is considered along with their optimum utilization. Several excellent original articles and review papers which have been published from time to time dealing with the long term and short term forecasting of ionospheric parameters, radio systems, and modelling needs for ionospheric communications, are covered.
    Schlagwort(e): COMMUNICATIONS AND RADAR
    Materialart: NASA. Marshall Space Flight Center Solar-Terrest. Predictions Proc., Vol. 2; p 203-216
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 22
    facet.materialart.
    Unbekannt
    Transionospheric propagation predictions (1979)
    In:  CASI
    Details
    Publikationsdatum: 2006-01-16
    Beschreibung: The current status and future prospects of the capability to make transionospheric propagation predictions are addressed, highlighting the effects of the ionized media, which dominate for frequencies below 1 to 3 GHz, depending upon the state of the ionosphere and the elevation angle through the Earth-space path. The primary concerns are the predictions of time delay of signal modulation (group path delay) and of radio wave scintillation. Progress in these areas is strongly tied to knowledge of variable structures in the ionosphere ranging from the large scale (thousands of kilometers in horizontal extent) to the fine scale (kilometer size). Ionospheric variability and the relative importance of various mechanisms responsible for the time histories observed in total electron content (TEC), proportional to signal group delay, and in irregularity formation are discussed in terms of capability to make both short and long term predictions. The data base upon which predictions are made is examined for its adequacy, and the prospects for prediction improvements by more theoretical studies as well as by increasing the available statistical data base are examined.
    Schlagwort(e): COMMUNICATIONS AND RADAR
    Materialart: NASA. Marshall Space Flight Center Solar-Terrest. Predictions Proc., Vol. 2; p 217-245
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 23
    facet.materialart.
    Unbekannt
    Radio propagation prediction services in Japan (1979)
    In:  CASI
    Details
    Publikationsdatum: 2006-01-16
    Beschreibung: Japanese prediction services for HF radio communications are outlined in relation to prediction method, performance and evaluation. The current prediction is based on the CCIR interim method with some modifications matching to a computer system. The principal service is the monthly median prediction issued regularly three months in advance for various communication circuits. A daily prediction for short distance circuits is being prepared by using real time ionospheric sounding data. An evaluation theory and practice is expected to be introduced in the future prediction service.
    Schlagwort(e): COMMUNICATIONS AND RADAR
    Materialart: NOAA Solar-Terrest. Predictions Proc., Vol. 1; p 212-222
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 24
    facet.materialart.
    Unbekannt
    Long term solar activity and ionospheric prediction services rendered by the National Physical Laboratory, New Delhi (1979)
    In:  CASI
    Details
    Publikationsdatum: 2006-01-16
    Beschreibung: The data base used in solar and ionospheric prediction services is described. Present prediction techniques are discussed and compared with actual observations. Future prediction techniques using computers are also discussed.
    Schlagwort(e): COMMUNICATIONS AND RADAR
    Materialart: NOAA Solar-Terrest. Predictions Proc., Vol. 1; p 118-133
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 25
    facet.materialart.
    Unbekannt
    The French short term radiopropagation predictions in the decameter band (1979)
    In:  CASI
    Details
    Publikationsdatum: 2006-01-16
    Beschreibung: Weekly and daily predictions of the ionospheric characteristics relevant to radio propagation are considered. A description of the techniques involved is given as well as examples showing how the prediction messages are prepared. The short term predictions are confined to restricted geographical areas and are relevant to radio circuits whose terminators are both located inside the same zone. They can be used with a reasonable approximation for circuits less than 3000 km of length whose reflection point lies within a given zone.
    Schlagwort(e): COMMUNICATIONS AND RADAR
    Materialart: NOAA Solar-Terrest. Predictions Proc., Vol. 1; p 12-24
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 26
    facet.materialart.
    Unbekannt
    Mechanics of fracture - Fundamentals and some recent developments (1979)
    In:  Other Sources
    Details
    Publikationsdatum: 2011-08-18
    Beschreibung: An overview is presented of the fundamental aspects of and recent developments in fracture mechanics. Reference is made to linear elastic fracture mechanics including the state of stresses and displacements in the vicinity of cracks, effects of crack geometry and orientation on stress intensity factors, energy balance of Griffith, Irwin's stress intensity concept, and linear elastic fracture mechanics testing for fracture toughness. Other aspects of this paper include the non-linear behavior of materials and their influence on fracture mechanics parameters, consideration of viscoelasticity and plasticity, non-linear fracture toughness parameters as C.O.D., R-curve and J-integral, and a non-linear energy method, proposed by Liebowitz. Finite element methods applied to fracture mechanics problems are indicated. Also, consideration has been given to slow crack growth, dynamic effects on K(IC), Sih's criterion for fracture, Lee and Liebowitz's criterion relating crack growth with plastic energy, and applications of fracture mechanics to aircraft design. Suggestions are offered for future research efforts to be undertaken in fracture mechanics.
    Schlagwort(e): STRUCTURAL MECHANICS
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 27
    facet.materialart.
    Unbekannt
    NASA-Langley Research Center's participation in a round-robin comparison between some current crack-propagation prediction methods (1979)
    In:  Other Sources
    Details
    Publikationsdatum: 2011-08-18
    Beschreibung: A round-robin study was conducted which evaluated and compared different methods currently in practice for predicting crack growth in surface-cracked specimens. This report describes the prediction methods used by the Fracture Mechanics Engineering Section, at NASA-Langley Research Center, and presents a comparison between predicted crack growth and crack growth observed in laboratory experiments. For tests at higher stress levels, the correlation between predicted and experimentally determined crack growth was generally quite good. For tests at lower stress levels, the predicted number of cycles to reach a given crack length was consistently higher than the experimentally determined number of cycles. This consistent overestimation of the number of cycles could have resulted from a lack of definition of crack-growth data at low values of the stress intensity range. Generally, the predicted critical flaw sizes were smaller than the experimentally determined critical flaw sizes. This underestimation probably resulted from using plane-strain fracture toughness values to predict failure rather than the more appropriate values based on maximum load.
    Schlagwort(e): STRUCTURAL MECHANICS
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 28
    facet.materialart.
    Unbekannt
    A review and assessment of the stress-intensity factors for surface cracks (1979)
    In:  Other Sources
    Details
    Publikationsdatum: 2011-08-18
    Beschreibung: The stress-intensity factor solutions proposed for a surface crack in a finite plate subjected to uniform tension are reviewed. Fourteen different solutions obtained over the past 16 years using approximate analytical methods, experimental methods, and engineering estimates are compared. The accuracy of the various solutions is assessed by correlating fracture data on surface-cracked tension specimens made of a brittle epoxy material. Fracture of the epoxy material was characterized by a constant value of stress-intensity factor as failure. Thus, the correctness of various solutions is judged by the variations in the stress-intensity factors at failure. The solutions were ranked in order of minimum standard deviation. The highest ranking solutions correlated 95% of data analyzed within + or - 10% whereas the lowest ranking solutions correlated 95% of data analyzed within + or - 20%. Some solutions could be applied to all data considered, whereas others were limited with respect to crack shapes and crack sizes that could be analyzed.
    Schlagwort(e): STRUCTURAL MECHANICS
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 29
    facet.materialart.
    Unbekannt
    Airborne East Coast/Midwest urban survey at 121.5/243 MHz (1979)
    In:  Other Sources
    Details
    Publikationsdatum: 2011-08-17
    Beschreibung: Results of an airborne RF interference measurement survey of the emergency-distress, Search and Rescue frequency bands at 121.5 and 243 MHz at an altitude of 25,000 ft over the U.S. East Coast and Midwest urban areas are presented. Included are a series of minutely median profile plots of antenna-noise temperature computed from RF interference power measurements at the output terminal of a quarter-wavelength monopole antenna, for both daytime and nighttime observations. The greatest value, 450,000 K, of minutely median temperature was recorded over New York City at 121.5 MHz during the day. East Coast urban areas exhibited a day-night effect at 121.5 MHz, where nighttime observations had a median value of 8.6-dB below daytime values; Midwest counterparts did not exhibit a significant day-night effect at 121.5 MHz.
    Schlagwort(e): COMMUNICATIONS AND RADAR
    Materialart: IEEE Transactions on Electromagnetic Compatibility; EMC-21; May 1979
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 30
    facet.materialart.
    Unbekannt
    Solving the current element problem over lossy half-space without Sommerfeld integrals (1979)
    In:  Other Sources
    Details
    Publikationsdatum: 2011-08-17
    Beschreibung: An approach is presented for efficient computation of the vector potentials arising in the problem of a current element radiating over a lossy half-space. The present approach departs from the conventional ones in that it works primarily with the transform domain representations rather than with the Sommerfeld integrals which are the corresponding spatial domain counterparts. The key step in the present method is to approximate the transforms using a suitable approximation which is valid for a wide range of parameters of practical interest. The approximated transforms can be inverted in a closed form for the horizontal component of the vector potentials and can be expressed in a computationally efficient form for the vertical component. Numerical results illustrating the accuracy of the method are presented and some estimates of comparative computational times are also included.
    Schlagwort(e): COMMUNICATIONS AND RADAR
    Materialart: IEEE Transactions on Antennas and Propagation; AP-27; Nov. 197
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 31
    facet.materialart.
    Unbekannt
    Finite dynamic element formulation for a plane triangular element (1979)
    In:  Other Sources
    Details
    Publikationsdatum: 2011-08-17
    Beschreibung: Higher order correction terms for the stiffness and inertia matrices associated with a triangular plane stress-strain finite dynamic element are developed in detail. Numerical results are presented which indicate that the adoption of these matrices along with a suitable quadratic matrix eigenproblem solver effects a significant economy in the free vibration solution of structure when compared with the analysis based on the usual finite element procedure. Finally, a FORTRAN IV computer program listing of the various relevant matrices is given.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: International Journal for Numerical Methods in Engineering; 14; 10, 1; 1979
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 32
    facet.materialart.
    Unbekannt
    Digital techniques for ULF wave polarization analysis (1979)
    In:  Other Sources
    Details
    Publikationsdatum: 2011-08-17
    Beschreibung: Digital power spectral and wave polarization analysis are powerful techniques for studying ULF waves in the earth's magnetosphere. Four different techniques for using the spectral matrix to perform such an analysis have been presented in the literature. Three of these techniques are similar in that they require transformation of the spectral matrix to the principal axis system prior to performing the polarization analysis. The differences in the three techniques lie in the manner in which determine this transformation. A comparative study of these three techniques using both simulated and real data has shown them to be approximately equal in quality of performance. The fourth technique does not require transformation of the spectral matrix. Rather, it uses the measured spectral matrix and state vectors for a desired wave type to design a polarization detector function in the frequency domain. The design of various detector functions and their application to both simulated and real data will be presented.
    Schlagwort(e): COMMUNICATIONS AND RADAR
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 33
    facet.materialart.
    Unbekannt
    Calculated scan characteristics of a large spherical reflector antenna (1979)
    In:  Other Sources
    Details
    Publikationsdatum: 2011-08-17
    Beschreibung: A previously published numerical method to calculate the radiation properties of parabolic reflectors has been modified to also include very large spherical reflectors. The method has been verified by comparing the calculated and the measured results for a 120-wavelength spherical reflector.
    Schlagwort(e): COMMUNICATIONS AND RADAR
    Materialart: IEEE Transactions on Antennas and Propagation; AP-27; May 1979
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 34
    facet.materialart.
    Unbekannt
    False lock performance of quadriphase receivers (1979)
    In:  Other Sources
    Details
    Publikationsdatum: 2011-08-17
    Beschreibung: Quadriphase receivers, like biphase receivers, have the ability to false lock on a sideband on the data modulation. The theory associated with this phenomenon for receivers of binary phase-shift-keying (BPSK), using Costas loop demodulation, has recently been documented in the literature. This paper considers the corresponding theory for receivers of balanced quadriphase-shift-keying (QPSK) employing a quadriphase Costas loop (or equivalent fourth-power loop) for demodulation. Specific closed form expressions for false lock performance are developed and numerically evaluated for the particular case of single pole arm filters and an NRZ data format for each of the two statistically independent quadrature modulations.
    Schlagwort(e): COMMUNICATIONS AND RADAR
    Materialart: IEEE Transactions on Communications; COM-27; Nov. 197
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 35
    facet.materialart.
    Unbekannt
    Analysis of beam-like lattice trusses (1979)
    In:  Other Sources
    Details
    Publikationsdatum: 2011-08-17
    Beschreibung: A simple procedure is presented for predicting the thermoelastic and free vibration responses of large repetitive beam-like trusses. The procedure is based on replacing the original lattice structure by an equivalent continuum beam model and obtaining closed-form (exact) solutions for the beam model. The equivalent beam model accounts for warping and shear deformation in the plane of the cross-section and is characterized by its thermoelastic strain and kinetic energies, from which the equations of motion and constitutive relations can be derived. The high accuracy of the results obtained by the proposed approach is demonstrated by means of numerical examples.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: Computer Methods in Applied Mechanics and Engineering; 20; Oct. 197
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 36
    facet.materialart.
    Unbekannt
    Digital and analog communication systems (1979)
    In:  Other Sources
    Details
    Publikationsdatum: 2011-08-17
    Beschreibung: The book presents an introductory treatment of digital and analog communication systems with emphasis on digital systems. Attention is given to the following topics: systems and signal analysis, random signal theory, information and channel capacity, baseband data transmission, analog signal transmission, noise in analog communication systems, digital carrier modulation schemes, error control coding, and the digital transmission of analog signals.
    Schlagwort(e): COMMUNICATIONS AND RADAR
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 37
    facet.materialart.
    Unbekannt
    Some observations regarding the statistical determination of stress rupture regression lines (1979)
    In:  Other Sources
    Details
    Publikationsdatum: 2011-08-17
    Beschreibung: Observations concerning the statistical evaluation of creep data are presented. Methods currently employed in the determination of stress rupture regression lines can result in conflicting and necessarily invalid results. Anomalous behavior is principally associated with the selection of the dependent variable. However, it is the least squares method of curve fitting which introduces regression bias. Methods to improve the validity of least squares regressions are suggested.
    Schlagwort(e): STRUCTURAL MECHANICS
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 38
    facet.materialart.
    Unbekannt
    Buckling of rotating beams (1979)
    In:  Other Sources
    Details
    Publikationsdatum: 2011-08-17
    Beschreibung: The stability of a beam subjected to compressive centrifugal forces arising from steady rotation about an axis which does not pass through the clamped end of the beam is analyzed to determine the critical rotational speeds for buckling in the inplane and out-of-plane directions. The differential equations of motion are solved numerically using an integrating matrix method in combination with an eigenanalysis to determine the eigenvalues from which stability is assessed. The results clarify several differences which have been identified in the literature relating to the proper behavior of the critical rotational speed for buckling as the radius of rotation of the clamped end of the beam is reduced.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: International Journal of Mechanical Sciences; 21; 12, 1; 1979
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 39
    facet.materialart.
    Unbekannt
    Simple spline-function equations for fracture mechanics calculations (1979)
    In:  Other Sources
    Details
    Publikationsdatum: 2011-08-17
    Beschreibung: The paper presents simple spline-function equations for fracture mechanics calculations. A spline function is a sequence of piecewise polynomials of degree n greater than 1 whose coefficients are such that the function and its first n-1 derivatives are continuous. Second-degree spline equations are presented for the compact, three point bend, and crack-line wedge-loaded specimens. Some expressions can be used directly, so that for a cyclic crack propagation test using a compact specimen, the equation given allows the cracklength to be calculated from the slope of the load-displacement curve. For an R-curve test, equations allow the crack length and stress intensity factor to be calculated from the displacement and the displacement ratio.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: International Journal of Fracture; 15; Oct. 197
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 40
    facet.materialart.
    Unbekannt
    A quarter-century of progress in the development of correlation and extrapolation methods for creep rupture data (1979)
    In:  Other Sources
    Details
    Publikationsdatum: 2011-08-17
    Beschreibung: Developments in the analysis of creep-rupture data are reviewed with particular reference to time temperature relations for the correlation and extrapolation of creep and stress rupture data, the minimum commitment method, and successive regression methods. Some contributions to the development of time-temperature parameters are noted.
    Schlagwort(e): STRUCTURAL MECHANICS
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 41
    facet.materialart.
    Unbekannt
    Wave propagation in transversely impacted composite laminates (1979)
    In:  Other Sources
    Details
    Publikationsdatum: 2011-08-17
    Beschreibung: An experimental study was conducted to determine the wave-propagation characteristics, transient strains and residual properties of unidirectional and angle-ply boron/epoxy and graphite/epoxy laminates impacted with silicon-rubber projectiles at velocities up to 250 m/sec. Results include the following: (1) the predominant wave is the flexural wave propagating at different velocities in different directions; (2) peak strains and strain rates in the transverse to the (outer) fiber direction are much higher than those in the direction of the fibers; (3) strain rates up to 640/sec were measured; and (4) unidirectional laminates under impact showed appreciable modulus and strength degradation in the direction transverse to fibers.
    Schlagwort(e): STRUCTURAL MECHANICS
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 42
    facet.materialart.
    Unbekannt
    Analysis of misalignment in the tension test (1979)
    In:  Other Sources
    Details
    Publikationsdatum: 2011-08-17
    Beschreibung: Many experimenters fail to appreciate the significance of test system alignment during a tensile test. Poor alignment can increase data scatter and significantly influence some of the test results. In this paper a comprehensive analytical study of the misalignment problem in the plastic strain range is presented and errors caused by misalignment estimated. The results show that the stress-strain curve is not significantly affected by misalignment. However, the strains at the outermost fibers of the specimen cross-section are strongly affected by misalignment. Therefore, the effect of misalignment is most important when properties sensitive to local strain concentrations are being investigated.
    Schlagwort(e): STRUCTURAL MECHANICS
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 43
    facet.materialart.
    Unbekannt
    Non-linear dynamic response of a wind turbine blade (1979)
    In:  Other Sources
    Details
    Publikationsdatum: 2011-08-17
    Beschreibung: The paper outlines the nonlinear dynamic analysis of an isolated three-degree flap-lag-feather wind turbine blade under a gravity field and with shear flow. Lagrangian equations are used to derive the nonlinear equations of motion of blade for arbitrarily large angular deflections. The limit cycle analysis for forced oscillations and the determination of the principal parametric resonance of the blade due to periodic forces from the gravity field and wind shear are performed using the harmonic balance method. Results are obtained first for a two-degree flap-lag blade, then the effect of the third degree of freedom (feather) is studied. The self-excited flutter solutions are obtained for a uniform wind and with gravity forces neglected. The effects of several parameters on the blade stability are examined, including coning angle, structural damping, Lock number, and feather frequency. The limit cycle flutter solution of a typical configuration shows a substantial nonlinear softening spring behavior.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: Journal of Sound and Vibration; 63; Mar. 22
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 44
    facet.materialart.
    Unbekannt
    Recent finite element studies in plasticity and fracture mechanics (1979)
    In:  Other Sources
    Details
    Publikationsdatum: 2011-08-17
    Beschreibung: The paper reviews recent work on fundamentals of elastic-plastic finite-element analysis and its applications to the mechanics of crack opening and growth in ductile solids. The presentation begins with a precise formulation of incremental equilibrium equations and their finite-element forms in a manner valid for deformations of arbitrary magnitude. Special features of computational procedures are outlined for accuracy in view of the near-incompressibility of elastic-plastic response. Applications to crack mechanics include the analysis of large plastic deformations at a progressively opening crack tip, the determination of J integral values and of limitations to J characterizations of the intensity of the crack tip field, and the determination of crack tip fields in stable crack growth.
    Schlagwort(e): STRUCTURAL MECHANICS
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 45
    facet.materialart.
    Unbekannt
    Stress-intensity factors for a wide range of semi-elliptical surface cracks in finite-thickness plates (1979)
    In:  Other Sources
    Details
    Publikationsdatum: 2011-08-17
    Beschreibung: Surface cracks are among the more common flaws in aircraft and pressure vessel components. Several calculations of stress-intensity factors for semi-elliptical surface cracks subjected to tension have appeared in the literature. However, some of these solutions are in disagreement by 50-100%. In this paper, stress-intensity factors for shallow and deep semi-elliptical surface cracks in plates subjected to tension are presented. To verify the accuracy of the three-dimensional finite-element models employed, convergence was studied by varying the number of degrees of freedom in the models from 1500 to 6900. The 6900 degrees of freedom used here were more than twice the number used in previously reported solutions. Also, the stress-intensity variations in the boundary-layer region at the intersection of the crack with the free surface were investigated.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: Engineering Fracture Mechanics; 11; 4, 19; 1979
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 46
    facet.materialart.
    Unbekannt
    Interim radio spectrum surveillance station (1979)
    In:  Other Sources
    Details
    Publikationsdatum: 2011-08-17
    Beschreibung: Radio frequency interference at NASA's deep space stations has become a serious problem. A radio spectrum surveillance capability at these stations is needed to determine the sources of interference so that preventative measures can be taken. The first phase of a program to develop this capability was the development of a low-cost surveillance station now in operation at the Goldstone Space Communication Complex near Barstow, California. This interim surveillance station is described and findings from the use of this equipment are presented.
    Schlagwort(e): COMMUNICATIONS AND RADAR
    Materialart: The Deep Space Network; p 99-107
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 47
    facet.materialart.
    Unbekannt
    Minimizing the RMS surface distortions from gravity loadings of the 34-m HA-DEC antenna for deep space missions (1979)
    In:  Other Sources
    Details
    Publikationsdatum: 2011-08-17
    Beschreibung: The computer analysis of the 34-m HA-DEC antenna by the IDEAS program provided the rms distortions of the surface panels support points for full gravity loadings in the three directions of the basic coordinate system of the computer model. The rms distortions for the gravity vector not in line with any of the three basic directions were solved and contour plotted starting from three surface panels setting declination angle. By inspections of the plots, it was concluded that the setting or rigging angle of -15 degrees declination minimized the rms distortions for sky coverage of plus or minus 22 declination angles to 10 degrees of ground mask.
    Schlagwort(e): COMMUNICATIONS AND RADAR
    Materialart: The Deep Space Network; p 94-98
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 48
    facet.materialart.
    Unbekannt
    Preliminary report on DSN system performance under local weather effects (1979)
    In:  Other Sources
    Details
    Publikationsdatum: 2011-08-17
    Beschreibung: Local effects of precipitation are studied, and a simplified working model is developed. Experimental results obtained by simulation are in good agreement with the model, showing that it could be an important contribution to system degradation. If this is confirmed, some suggestions for improvement are presented.
    Schlagwort(e): COMMUNICATIONS AND RADAR
    Materialart: The Deep Space Network; p 82-88
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 49
    facet.materialart.
    Unbekannt
    New X-band antenna feeds for the DSN 64-meter stations (1979)
    In:  Other Sources
    Details
    Publikationsdatum: 2011-08-17
    Beschreibung: New X-band antenna feed assemblies with dual-polarization capability are being implemented in the DSN 64-meter stations. Together with dual X-band traveling wave masers, they permit the simultaneous reception of right- and left-hand circular polarization from the Voyager spacecraft. The new feed also includes a dual hybrid mode feedhorn which increases the antenna gain by 0.36 dB over the present feedhorn.
    Schlagwort(e): COMMUNICATIONS AND RADAR
    Materialart: The Deep Space Network; p 71-74
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 50
    facet.materialart.
    Unbekannt
    A generalization of binary minimum shift keying and staggered quadriphase shift keying modulation (1979)
    In:  Other Sources
    Details
    Publikationsdatum: 2011-08-17
    Beschreibung: A generalized modulation scheme, which includes minimum shift keying (MSK) and staggered quadriphase shift keying (SQPSK) as special cases, is analyzed. The general modulator is realized as a one-input, two-output sequence transducer whose outputs select the carrier signal for each band. This form of the modulator has the practical advantage of not requiring any RF filtering since there is no actual mixing of the carriers with the modulating signals. It is shown that the optimum demodulator (whether hard-decision or soft-decision) always can make its decisions from the received waveform over two bands when the interference is additive white Gaussian noise, thus generalizing a well-known result for hard decision demodulation of MSK and SQPSK signals. The power spectra of MSK and SQPSK signals are derived to isolate the role played by coherency between the modulating signals and the carriers.
    Schlagwort(e): COMMUNICATIONS AND RADAR
    Materialart: The Deep Space Network; p 26-40
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 51
    facet.materialart.
    Unbekannt
    Radio frequency carrier arraying for near maximum carrier signal-to-noise ratio improvement (1979)
    In:  Other Sources
    Details
    Publikationsdatum: 2011-08-17
    Beschreibung: Radio frequency arraying of several receiving systems provides signal-to-noise ratio improvement relative to a single receiving system. This report considers radio frequency carrier arraying which provides near maximum signal-to-noise ratio improvement for carrier reception and demodulation.
    Schlagwort(e): COMMUNICATIONS AND RADAR
    Materialart: The Deep Space Network; p 99-106
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 52
    facet.materialart.
    Unbekannt
    Coding for optical channels (1979)
    In:  Other Sources
    Details
    Publikationsdatum: 2011-08-17
    Beschreibung: In a previous paper Pierce considered the problem of optical communication from a novel viewpoint, and concluded that performance will likely be limited by issues of coding complexity rather than by thermal noise. This paper reviews the model proposed by Pierce and presents some results on the analysis and design of codes for this application.
    Schlagwort(e): COMMUNICATIONS AND RADAR
    Materialart: The Deep Space Network; p 70-77
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 53
    facet.materialart.
    Unbekannt
    Submicrosecond comparison of intercontinental clock synchronization by VLBI and the NTS satellite (1979)
    In:  Other Sources
    Details
    Publikationsdatum: 2011-08-17
    Beschreibung: The intercontinental clock synchronization capabilities of Very Long Baseline Interferometry (VLBI) and the Navigation Technology Satellite (NTS) were compared in May 1978 by using both methods to synchronize the cesium clocks at the NASA Deep Space Net complexes at Madrid, Spain, and Goldstone, California. The VLBI experiments used the Wideband VLBI Data Acquisition System. The Navigation Technology Satellites were used with NTS Timing Receivers developed by the Goddard Space Flight Center. The two methods agreed at about the one-half microsecond level. The VLBI system also obtained long-term stability information on the HP5061A004 cesium standards by measuring delta T/T over four 3- to 4-day intervals, obtaining stability estimates of (1 + or - 1)x10 to the -13th power for the combined timing systems.
    Schlagwort(e): COMMUNICATIONS AND RADAR
    Materialart: The Deep Space Network; p 64-69
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 54
    facet.materialart.
    Unbekannt
    Comparison of phase modulation systems (1979)
    In:  Other Sources
    Details
    Publikationsdatum: 2011-08-17
    Beschreibung: Comparison of the energy to noise ratio necessary to obtain a given modulation bit error probability has indicated that three-phase modulation is about 0.75 db superior to four-phase. It is shown that this apparent superiority results entirely from the greater bandwidth required by the three-phase system for the same bit transmission rate. Two further comparison criteria are proposed, which are based on the cut-off rate R sub 0 of the discrete channel created by the modulation system. For the criterion which constrains both the bandwidth and transmitted power, it is shown that four-phase modulation is always superior to three-phase modulation. The conclusion is that three-phase modulation offers no practical advantage over four-phase modulation.
    Schlagwort(e): COMMUNICATIONS AND RADAR
    Materialart: The Deep Space Network; p 57-63
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 55
    facet.materialart.
    Unbekannt
    DSN ground communications facility (1979)
    In:  Other Sources
    Details
    Publikationsdatum: 2011-08-17
    Beschreibung: A functional description of the Ground Communications Facilities and its relationships with other elements of the Deep Space Network and NASA Communications Network is presented together with development objectives and goals and comments on implementation activities in support of flight projects.
    Schlagwort(e): COMMUNICATIONS AND RADAR
    Materialart: The Deep Space Network; p 19-28
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 56
    facet.materialart.
    Unbekannt
    DSN command system Mark 3-78 (1979)
    In:  Other Sources
    Details
    Publikationsdatum: 2011-08-17
    Beschreibung: The Deep Space Network Command System Mark III-78 implementation and functional operation are described. Software upgrade enables expanded storage capacity in the Deep Space Station Command Processor Assembly. Store-and-forward command data handling is operational for Voyager and Helios. Near-real-time command data handling was retained for Viking and Pioneer.
    Schlagwort(e): COMMUNICATIONS AND RADAR
    Materialart: The Deep Space Network; p 11-18
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 57
    facet.materialart.
    Unbekannt
    The NASA radar entomology program at Wallops Flight Center (1979)
    In:  Other Sources
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: NASA contribution to radar entomology is presented. Wallops Flight Center is described in terms of its radar systems. Radar tracking of birds and insects was recorded from helicopters for airspeed and vertical speed.
    Schlagwort(e): COMMUNICATIONS AND RADAR
    Materialart: Radar, Insect Population Ecology, and Pest Management; p 161-169
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 58
    facet.materialart.
    Unbekannt
    Quantitative Analysis of Radar Returns from Insects (1979)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: When a number of flying insects is low enough to permit their resolution as individual radar targets, quantitative estimates of their aerial density are developed. Accurate measurements of heading distribution using a rotating polarization radar to enhance the wingbeat frequency method of identification are presented.
    Schlagwort(e): COMMUNICATIONS AND RADAR
    Materialart: NASA. Wallops Flight Center Radar, Insect Population Ecology, and Pest Management; p 131-158
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 59
    facet.materialart.
    Unbekannt
    Radar program at Western Cotton Research Laboratory (1979)
    In:  Other Sources
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: An entomological radar similar to those used in England is developed. The radar will detect insects in flight and the data will be used for studying insect dispersal.
    Schlagwort(e): COMMUNICATIONS AND RADAR
    Materialart: NASA. Wallops Flight Center Radar, Insect Population Ecology, and Pest Management; p 159-160
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 60
    facet.materialart.
    Unbekannt
    Radar observation of known and unknown clear echoes (1979)
    In:  Other Sources
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: Target cross-section as a function of wavelength for known insects, known bird, and dot targets is presented. Tracking data using the time series analysis was tabulated for known birds. Examples were selected from these early works to give entomologists some indication of the types of information that are available by radar as well as examples of the different sources of clear-air radar backscatter.
    Schlagwort(e): COMMUNICATIONS AND RADAR
    Materialart: NASA. Wallops Flight Center Radar, Insect Population Ecology, and Pest Management; p 113-130
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 61
    facet.materialart.
    Unbekannt
    Theoretical modelling and experimental data matching for active and passive microwave remote sensing of Earth terrain (1979)
    In:  CASI
    Details
    Publikationsdatum: 2017-10-02
    Beschreibung: Two theoretical models were developed to characterize terrain media: a random medium with a variance, a horizontal correlation length; and a homogeneous dielectric containing discrete scatterers. The earth terrain is modelled as layers of such scattering media bounded by air above and half-space below. Matching the theoretical results with experimental data collected from vegetation and snow-ice fields shows that: (1) for observation angles near nadir, rough surface effects are important; (2) for snow-ice field the horizontal correlation length is greater than the vertical correlation length whereas for vegetation field their relative sizes depend on the types of vegetation; (3) the vertically polarized backscattering cross-section is always larger than the horizontally polarized backscattering cross-section for half-space scattering media; (4) for snow field displaying diurnal change, a three-layer model including a thin top layer caused by sunlight illumination must be used; and (5) for a random medium with equal horizontal and vertical correlation lengths, the measured data can also be matched with a corresponding discrete scatterer model.
    Schlagwort(e): COMMUNICATIONS AND RADAR
    Materialart: AGARD Terrain Profiles and Contours in Electromagnetic Wave Propagation; 8 p
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 62
    facet.materialart.
    Unbekannt
    Space Shuttle Orbiter AFT heat shield seal (1979)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: The evolution of the orbiter aft heat shield seal (AHSS) design, which involved advancing mechanical seal technology in severe thermal environment is discussed. The baseline design, various improvements for engine access, and technical problem solution are presented. It is a structure and mechanism at the three main propulsion system (MPS) engine interfaces to the aft compartment structure. Access to each MPS engine requires disassembly and removal of the AHSS. Each AHSS accommodates the engine movement, is exposed to an extremely high temperature environment, and is part of the venting control of the aft compartment.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Johnson Space Center The 13th Aerospace Mech. Symp.; p 251-259
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 63
    facet.materialart.
    Unbekannt
    Hydrazine monopropellant reciprocating engine development (1979)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: A hydrazine fueled piston engine for providing 11.2 kW was developed to satisfy the need for an efficient power supply in the range from 3.7 to 74.6 kW where existing nonair-breathing power supplies such as fuel cells or turbines are inappropriate. The engine was developed for an aircraft to fly to 21.3 km and above and cruise for extended periods. A remotely piloted aircraft and the associated flight control techniques for this application were designed. The engine is geared down internally (2:1) to accommodate a 1.8 m diameter propeller. An alternator is included to provide electrical power. The pusher-type engine is mounted onto the aft closure of the fuel tank, which also provides mounting for all other propulsion equipment. About 20 hrs of run time demonstrated good efficiency and adequate life. One flight test to 6.1 km was made using the engine with a small fixed-pitch four-bladed propeller. The test was successful in demonstrating operational characteristics and future potential.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: The 13th Aerospace Mech. Symp.; p 1-14
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 64
    facet.materialart.
    Unbekannt
    Summary of the Orbiter mechanical systems (1979)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: Major mechanical systems of the Orbiter space vehicle are summarized with respect to general design details, manner of operation, expected performance, and, where applicable, unique features. A synopsis of data obtained during the five atmospheric flight tests of spacecraft OV-101 and status of the systems for the first orbital spacecraft STS-1 are presented.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: The 13th Aerospace Mech. Symp.; p 219-234
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 65
    facet.materialart.
    Unbekannt
    Helical grip for the cable cars of San Francisco (1979)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: A helical cable car grip to minimize high maintenance costs of San Francisco's cable car operation is presented. The grip establishes a rolling contact between the cable and grip to reduce sliding friction and associated cable wear. The design, development, and testing of the helical cable car grip are described.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Johnson Space Center The 13th Aerospace Mech. Symp.; p 83-93
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 66
    facet.materialart.
    Unbekannt
    Space Shuttle Orbiter payload bay door mechanisms (1979)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: The opening, closing, and latching of the first large clamshell door to operate in space presented some unusual challenges for the mechanism designer of the Space Shuttle Program. The requirements, hardware configuration, design trade-offs, and qualification testing in process to meet the challenge and to make the system operational for the Shuttle orbiter's approaching first orbital flight are described.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Johnson Space Center The 13th Aerospace Mech. Symp.; p 261-269
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 67
    facet.materialart.
    Unbekannt
    Tests of a protective shell passive release mechanism for hypersonic wind-tunnel models (1979)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: A protective shell mechanism for wind tunnel models was developed and tested. The mechanism is passive in operation, reliable, and imposes no new structural design changes for wind tunnel models. Methods of predicting the release time and the measured loads associated with the release of the shell are given. The mechanism was tested in a series of wind tunnel tests to validate the removal process and measure the pressure loads on the model. The protective shell can be used for wind tunnel models that require a step input of heating and loading such as a thin skin heat transfer model. The mechanism may have other potential applications.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Johnson Space Center The 13th Aerospace Mech. Symp.; p 167-181
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 68
    facet.materialart.
    Unbekannt
    Reliability breakthrough: An antenna deployment/positioning mechanism with electrical and mechanical redundancy (1979)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: An Antenna Positioner Mechanism (APM) was developed for deployment of an antenna reflector and for fine granularity closed loop tracking of the antenna in response to RF beacon error signals. By utilizing permanent magnet stepper motors, spur gearheads, irreversible single threat worm/wheel assemblies and a miter gear differential, full electrical and mechanical redundancy was realized. Two versions of this design were generated: one is a weight-optimized design with a clutch for overload protection and one is a more rugged unit without a clutch.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Johnson Space Center The 13th Aerospace Mech. Symp.; p 137-149
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 69
    facet.materialart.
    Unbekannt
    Load proportional safety brake (1979)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: This brake is a self-energizing mechanical friction brake and is intended for use in a rotary drive system. It incorporates a torque sensor which cuts power to the power unit on any overload condition. The brake is capable of driving against an opposing load or driving, paying-out, an aiding load in either direction of rotation. The brake also acts as a no-back device when torque is applied to the output shaft. The advantages of using this type of device are: (1) low frictional drag when driving; (2) smooth paying-out of an aiding load with no runaway danger; (3) energy absorption proportional to load; (4) no-back activates within a few degrees of output shaft rotation and resets automatically; and (5) built-in overload protection.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Johnson Space Center The 13th Aerospace Mech. Symp.; p 95-110
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 70
    facet.materialart.
    Unbekannt
    A two-axis pointing system for an orbiting astronomical instrument (1979)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: The system described was built for incorporation into a solar flare X-ray instrument due to be orbited as one of a number of instruments on the NASA Solar Maximum Mission (SMM) satellite in late 1979. It enables the instrument to be rotated about 2 mutually perpendicular axes in 5 arc-second steps within a range of 7 arc-minutes, thus giving the instrument the capability to map areas of the sun.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Johnson Space Center The 13th Aerospace Mech. Symp.; p 27-38
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 71
    facet.materialart.
    Unbekannt
    Automatic in-orbit assembly of large space structures (1979)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: The automated assembly of a large number of components required for the on-orbit erection of large tetrahedral space platforms is described. The assembly machine is a huge jig in which a multitude of mechanisms must operated continuously in the thermo vacuum environment of space and under the control of computers programmed to command every step of each motion. The concepts are presented to determine the most reliable solution. Continuous operation of mechanisms in space presents many unresolved problems, with regard to lubrication of unprotected devices, such as chain drives, which must maintain reasonable positioning tolerances.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Johnson Space Center The 13th Aerospace Mech. Symp.; p 283-291
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 72
    facet.materialart.
    Unbekannt
    IUSThrust Vector Control (TVC) servo system (1979)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: The IUS TVC SERVO SYSTEM which consists of four electrically redundant electromechanical actuators, four potentiometer assemblies, and two controllers to provide movable nozzle control on both IUS solid rocket motors is developed. An overview of the more severe IUS TVC servo system design requirements, the system and component designs, and test data acquired on a preliminary development unit is presented. Attention is focused on the unique methods of sensing movable nozzle position and providing for redundant position locks.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Johnson Space Center The 13th Aerospace Mech. Symp.; p 271-281
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 73
    facet.materialart.
    Unbekannt
    Payload installation and deployment aid for Space Shuttle Orbiter spacecraft remote manipulator system (1979)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: An aid concept known as the PIDA (Payload Installation and Deployment Aid) is presented as a way to assist the RMS (Remote Manipulator System) by relaxing the accuracy required during payload handling in the payload bay. The aid concept was designed and developed to move payloads through a prescribed path between the confined quarters of the payload bay and a position outside the critical maneuvering area of the Orbiter. A description of the design requirements and the modes of operation of the various functions of the deployment and the docking mechanisms are covered.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: The 13th Aerospace Mech. Symp.; p 235-249
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 74
    facet.materialart.
    Unbekannt
    Magnetic spring in oscillating mirror linear scanner for satellite camera (1979)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: One of the main difficulties encountered in the development of a multispectral scanner is the realization of an oscillating mechanical device. A magnetic device which is characterized by the absence of friction is presented. The main developments concern the analysis of magnetic forces. A preliminary project of a device which could be used in a satellite is presented.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Johnson Space Center The 13th Aerospace Mech. Symp.; p 183-193
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 75
    facet.materialart.
    Unbekannt
    Unfolding the air vanes on a supersonic air-launched missile (1979)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: ASALM (Advanced Strategic Air-Launched Missile) is a supersonic air vehicle designed to be air-launched from a carrier aircraft. The four aft aerodynamic control vanes are folded to maximize the number of missiles carried on-board. The unfolding (erection) system must be small, energetic, fast, and strong. The materials selected and problems that arose during development of the unfolding system are described.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Johnson Space Center The 13th Aerospace Mech. Symp.; p 207-217
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 76
    facet.materialart.
    Unbekannt
    On the design of an adjustable high precision latching hinge (1979)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: The design and test details of a high precision hinge and locking mechanism created principally in support of the Lockheed space deployable Flexrib Parabolic Antenna concept are presented. These developed improvements in the detail design of ultra-precise rib hinge and contour adjustment mechanisms will allow radio frequency antenna reflectors to expand into the 15-50 meter diameter size class and to support the .013 mm. deployment repeatability tolerance required to support the 12+ GHz frequency range.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Johnson Space Center The 13th Aerospace Mech. Symp.; p 127-136
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 77
    facet.materialart.
    Unbekannt
    A telescopic jib for continuous adjustment (1979)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: For special space applications, e.g. for experiments distant from any orbital platforms or manipulators a new kind of jibs with extreme extension capacity has to be designed. Considering the requirements, the telescopic principle is found to be the most promising. For the choice of the stiff structure, design criteria are evaluated. Special effort deals with the drive system. An electromechanical system can satisfy the requirements. First results of the development of such a drive are presented. The most significant features are: A telescopic assembly of tubes which can be mutually moved by a short spindle in the center of the package. An elastically suspended screw is located at the bottom of each tube. For the jib extension, these screws will be linked with the spindle. The control of their sequence and the adjustment of tubes in mutual end positions are performed by latches. A functional model proved the basic idea.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Johnson Space Center The 13th Aerospace Mech. Symp.; p 49-58
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 78
    facet.materialart.
    Unbekannt
    Development of the Trident 1 aerodynamic saike mechanism (1979)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: The Aerospike drag reduction mechanism was designed and developed for use on the Trident I submarine launched ballistic missile. This mechanism encounters a unique combination of environments necessitating unique design solutions to ensure satisfactory operation over its design life. The development of the Aerospike is reviewed emphasizing the unique and interesting problems encountered and their solutions.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Johnson Space Center The 13th Aerospace Mech. Symp.; p 39-48
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 79
    facet.materialart.
    Unbekannt
    Gimbal bearing design considerations and friction control (1979)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: The design considerations of bearing selection, bearing fits, bearing installation, and thermal control are discussed for a gimbal with a high stiffness, low friction torque requirement. Tradeoffs between a quad set of small diameter spread apart or a large diameter bearing pair resulted in a cleaner, lighter, stiffer unit with the latter selection. Bearing fits were designed to eliminate clearances with tolerances of .00127 mm 00005 in) on the bearing shafts and housings. The problems in metrology are discussed and a perferred technique for measurement of small cross-section bearings described. A technique for installation to assure proper seating of the bearing is offered. Where transient thermal conditions are involved, a method of controlling bearing friction by active control of bearing temperature gradients including the use of bearing unload test curves is described.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Johnson Space Center The 13th Aerospace Mech. Symp.; p 71-81
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 80
    facet.materialart.
    Unbekannt
    Development of a beam builder for automatic fabrication of large composite space structures (1979)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: The composite material beam builder which will produce triangular beams from pre-consolidated graphite/glass/thermoplastic composite material through automated mechanical processes is presented, side member storage, feed and positioning, ultrasonic welding, and beam cutoff are formed. Each process lends itself to modular subsystem development. Initial development is concentrated on the key processes for roll forming and ultrasonic welding composite thermoplastic materials. The construction and test of an experimental roll forming machine and ultrasonic welding process control techniques are described.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Johnson Space Center The 13th Aerospace Mech. Symp.; p 293-304
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 81
    facet.materialart.
    Unbekannt
    The impact of rare earth cobalt permanent magnets on electromechanical device design (1979)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: Specific motor designs which employ rare earth cobalt magnets are discussed with special emphasis on their unique properties and magnetic field geometry. In addition to performance improvements and power savings, high reliability devices are attainable. Both the mechanism and systems engineering should be aware of the new performance levels which are currently becoming available as a result of the rare earth cobalt magnets.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Johnson Space Center The 13th Aerospace Mech. Symp.; p 195-206
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 82
    facet.materialart.
    Unbekannt
    Development of drive mechanisms for communicaton satellites (1979)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: A distinguished pedigree is an important asset in the development of Aerospace mechanisms. Four drives recently developed for communication satellites are outgrowths of a previously-proven drive configuration. Pedigree by itself, however is not enough to generate success. Inevitably, design changes which are thought to be minor, are generally introduced to fine tune the pedigreed hardware to meet particular requirements of a specific new application. Such design changes are often viewed too casually and are not thoroughly tested in the early development stages of the program. Two areas of design change are described on the solar array drive applied to the Japanese Broadcast Satellite which led to subsequent problems during the development phase of the program. The methods applied to establish the cause and the solution of these problems are described as well as the testing approach adapted to prevent similar occurrences on the current Communication Satellite Program, The Defense System Communications Satellite III.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Johnson Space Center The 13th Aerospace Mech. Symp.; p 151-166
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 83
    facet.materialart.
    Unbekannt
    Design of a piezoelectric shaker for centrifuge testing (1979)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: The design of a prototype piezoelectric shaker and its development to date is described. Although certain design problems remain to be solved, the piezoelectric system shows promise for adaptation to a larger payload system, such as the proposed geotechnical centrifuge at the Ames Research Center.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Johnson Space Center The 13th Aerospace Mech. Symp.; p 59-70
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 84
    facet.materialart.
    Unbekannt
    Design and development of a motion compensator for the RSRA main rotor control (1979)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: The RSRA, an experimental helicopter, is equipped with an active isolation system that allows the transmission to move relative to the fuselage. The purpose of the motion compensator is to prevent these motions from introducing unwanted signals to the main rotor control. A motion compensator concept was developed that has six-degree-of-freedom capability. The mechanism was implemented on RSRA and its performance verified by ground and flight tests.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Johnson Space Center The 13th Aerospace Mech. Symp.; p 15-25
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 85
    facet.materialart.
    Unbekannt
    Computer-aided fracture mechanics life prediction analysis (1979)
    In:  Other Sources
    Details
    Publikationsdatum: 2019-06-28
    Beschreibung: The fracture mechanics analysis and computer logic used to perform design life predictions is described. Initial part-through crack defects are analyzed under the conditions of constant-amplitude loading to predict the number of loading cycles applied before breakthrough or failure. A criterion is provided to predict the transition from part-through crack growth characteristics to through crack growth characteristics. A breakthrough criterion is also provided.
    Schlagwort(e): STRUCTURAL MECHANICS
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 86
    facet.materialart.
    Unbekannt
    Satellite-aided mobile radio concepts study: Concept definition of a satellite-aided mobile and personal radio communication system (1979)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-28
    Beschreibung: The satellite system requires the use of a large satellite antenna and spacecraft array power of about 12 kW or more depending on the operating frequency. Technology developments needed include large offset reflector multibeam antennas, satellite electrical power sybsystems providing greater than 12 kW of power, signal switching hardware, and linearized efficient solid state amplifiers for the satellite-aided mobile band. Presently there is no frequency assignment for this service, and it is recommended that an allocation be pursued. The satellite system appears to be within reasonable extrapolation of the state of the art. It is further recommended that the satellite-aided system spacecraft definition studies and supporting technology development be initiated.
    Schlagwort(e): COMMUNICATIONS AND RADAR
    Materialart: NASA-CR-166646
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 87
    facet.materialart.
    Unbekannt
    A preliminary study of a very large space radiometric antenna (1979)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-28
    Beschreibung: An approach used to compute the size of a special radiometric reflector antenna is presented. Operating at 1 GHz, this reflector is required to produce 200 simultaneous contiguous beams, each with a 3 dB footprint of 1 km from an assumed satellite height of 650 km. The overall beam efficiency for each beam is required to be more than 90%.
    Schlagwort(e): COMMUNICATIONS AND RADAR
    Materialart: NASA-TM-80047
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 88
    facet.materialart.
    Unbekannt
    NASA electronic message experiment and study: Detailed test plans (1979)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-28
    Beschreibung: A methodology for evaluating the utility of high speed digital facsimile as a component of the projected NASA-wide electronic message network is presented. Equipment checkout, operator familiarization, pretest calibration, and the development of procedures are addressed. An experimental test program of the facsimile message service which will carry duplicates of the actual messages sent by other means is highlighted. Also, an operational test program during which messages will be sent on a regular basis in order to accumulate the information that will be used to evaluate system performance and project future growth is described.
    Schlagwort(e): COMMUNICATIONS AND RADAR
    Materialart: NASA-CR-160007
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 89
    facet.materialart.
    Unbekannt
    A tactile-output paging communication system for the deaf-blind (1979)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-28
    Beschreibung: A radio frequency paging communication system that has coded vibrotactile outputs suitable for use by deaf-blind people was developed. In concept, the system consists of a base station transmitting and receiving unit and many on-body transmitting and receiving units. The completed system has seven operating modes: fire alarm; time signal; repeated single character Morse code; manual Morse code; emergency aid request; operational status test; and message acknowledge. The on-body units can be addressed in three ways: all units; a group of units; or an individual unit. All the functions developed were integrated into a single package that can be worn on the user's wrist. The control portion of the on-body unit is implemented by a microcomputer. The microcomputer is packaged in a custom-designed hybrid circuit to reduce its physical size.
    Schlagwort(e): COMMUNICATIONS AND RADAR
    Materialart: NASA-CR-152332
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 90
    facet.materialart.
    Unbekannt
    Design of a 24-channel transmultiplexer (1979)
    In:  Other Sources
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: The design of a transmultiplexer capable of performing the bilateral conversion between one 1544 kbit/s digital signal (which represents 24 PCM coded voice channels) and two analog group signals (each one containing 12 voice channels in the 60-108 kHz band) is investigated. It is shown that an FIR filter bank required as part of such a transmultiplexer can be realized efficiently by cascading a discrete cosine transform processor and a weighting network. Fast convolution algorithms are derived for evaluating the cosine transform. A method of using the symmetry conditions to reduce the computation rate in the weighting network and an elegant hardware configuration for implementing it are also discussed.
    Schlagwort(e): COMMUNICATIONS AND RADAR
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 91
    facet.materialart.
    Unbekannt
    Note on the effect of transverse shear deformation in laminated anisotropic plates (1979)
    In:  Other Sources
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: The paper describes the development of some computer methods in applied mechanics. It begins with a distribution of primary stresses in laminated plates, followed by a determination of the associated statically consistent transverse shearing stress. The last section deals with the use of an energy principle for the utilization of these expressions for primary and transverse stresses. The purpose of this is to obtain two-dimensional constitutive equations involving transverse shear deformations and transverse shear stress resultants.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: AD-A098868 , Computer Methods in Applied Mechanics and Engineering; 20; Nov. 197
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 92
    facet.materialart.
    Unbekannt
    Optimum design of laminated plates under shear (1979)
    In:  Other Sources
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: This paper is concerned with the optimum design of plates with orthotropic layers under shear. The plates considered are the laminates of N orthotropic layers whose principal material axes coincide with the plate axes. Each layer is assumed to have the same thickness and an equal number of fibers in the direction of + alpha sub i and - alpha sub i with respect to the plate axis. The fiber directions which give the highest shear buckling stress are found by utilizing a mathematical optimization technique.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: Journal of Composite Materials; 13; Oct. 197
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 93
    facet.materialart.
    Unbekannt
    On the limitations of the concept of space frequency equivalence (1979)
    In:  Other Sources
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: A narrow-band correlation interferometer using directive (large) antennas is equivalent to a wideband correlation interferometer employing isotropic (small) antennas. This concept of space frequency equivalence, due to Kock and Stone, is reexamined and is shown to hold exactly only for the mean or expected values of the correlation interferometer outputs. If their variances are considered, the equivalence disappears, with the variance fo the wideband system always equal to or greater than that of the narrow-band system.
    Schlagwort(e): COMMUNICATIONS AND RADAR
    Materialart: Radio Science; 14; Nov
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 94
    facet.materialart.
    Unbekannt
    Crosstalk cancellation on linearly and circularly polarized communications satellite links (1979)
    In:  Other Sources
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: The paper discusses the cancellation network approach for reducing crosstalk caused by depolarization on a dual-polarized communications satellite link. If the characteristics of rain depolarization are sufficiently well known, the cancellation network can be designed in a way that reduces system complexity, the most important parameter being the phase of the cross-polarized signal. Relevant theoretical calculations and experimental data are presented. The simplicity of the cancellation system proposed makes it ideal for use with small domestic or private earth terminals.
    Schlagwort(e): COMMUNICATIONS AND RADAR
    Materialart: Radio Science; 14; Nov
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 95
    facet.materialart.
    Unbekannt
    Effect of transverse shear and material orthotropy in a cracked spherical cap (1979)
    In:  Other Sources
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: The elastostatic problem for a relatively thin-walled spherical cap containing a through crack is considered. The problem is formulated for a specially orthotropic material within the confines of a linearized, shallow shell theory. The theory used is equivalent to Reissner's theory of flat plates and hence permits the consideration of all five physical conditions on the shell boundaries separately. The solution of the problem is reduced to that of a pair of singular integral equations and the asymptotic stress state around the crack tips is investigated. The numerical solution of the problem is given for an isotropic shell and for two specially orthotropic shells. The results indicate that the material orthotropy as well as the shell curvature and thickness may have a considerable effect on the stress intensity factors at the crack tips.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: International Journal of Solids and Structures; 15; 12, 1; 1979
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 96
    facet.materialart.
    Unbekannt
    The effect of transverse shear in a cracked plate under skew-symmetric loading (1979)
    In:  Other Sources
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: The problem of an elastic plate containing a through crack and subjected to twisting moments or transverse shear loads is considered. By using a bending theory which allows the satisfaction of the boundary conditions on the crack surface regarding the normal and the twisting moments and the transverse shear load separately, it is found that the resulting asymptotic stress field around the crack tip becomes identical to that given by the elasticity solutions of the plane strain and antiplane shear problems. The problem is solved for uniformly distributed or concentrated twisting moment or transverse shear load and the normalized Mode II and Mode III stress-intensity factors are tabulated. The results also include the effect of the Poisson's ratio and material orthotropy for specially orthotropic materials on the stress-intensity factors.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: ASME PAPER 79-WA/APM-16
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 97
    facet.materialart.
    Unbekannt
    The role of crack blunting in sustained load crack growth (1979)
    In:  Other Sources
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: Sustained load crack growth occurs in metals following critical crack extension above KIc and in aggressive environments while maintaining a constant load below KIc. In this paper, crack arrest measurements are performed on precracked, 0.0254-m thick, side-grooved WOL specimens exposed to 34.5 MN/sq m hydrogen at ambient temperature. The specimens are loaded inside a pressure vessel while in contact with the high pressure hydrogen environment. Crack growth is observed with each loading increment. The crack blunting observed in the fracture mechanics tests on 321 stainless steel is found to be similar to that produced in the 321 stainless steel tensile specimens. Rounding and branching of the crack decreases the effective stress intensity at the crack tip. It is possible, for materials in which cracks tend to blunt or branch in hydrogen, that although cracks will arrest at a relatively high stress intensity in decreasing stress intensity test, a crack may begin to grow at a lower stress intensity when loaded in hydrogen, and the crack may continue to grow when the stress intensity is continually increasing.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: Scripta Metallurgica; 13; Oct. 197
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 98
    facet.materialart.
    Unbekannt
    Finite-strain large-deflection elastic-viscoplastic finite-element transient response analysis of structures (1979)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: A method of analysis for thin structures that incorporates finite strain, elastic-plastic, strain hardening, time dependent material behavior implemented with respect to a fixed configuration and is consistently valid for finite strains and finite rotations is developed. The theory is formulated systematically in a body fixed system of convected coordinates with materially embedded vectors that deform in common with continuum. Tensors are considered as linear vector functions and use is made of the dyadic representation. The kinematics of a deformable continuum is treated in detail, carefully defining precisely all quantities necessary for the analysis. The finite strain theory developed gives much better predictions and agreement with experiment than does the traditional small strain theory, and at practically no additional cost. This represents a very significant advance in the capability for the reliable prediction of nonlinear transient structural responses, including the reliable prediction of strains large enough to produce ductile metal rupture.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA-CR-159874 , ASRL-TR-154-15
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 99
    facet.materialart.
    Unbekannt
    The 18/30 GHz fixed communications system service demand assessment. Volume 1: Executive summary (1979)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: The total demand for voice, video, and data communications services, and satellite transmission services at the 4/6 GHz, 12/14 GHz, and 18/30 GHz frequencies is discussed. Major study objectives, overall methodology, results, and general observations about a satellite systems market characteristics and trends are summarized.
    Schlagwort(e): COMMUNICATIONS AND RADAR
    Materialart: NASA-CR-159546
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 100
    facet.materialart.
    Unbekannt
    Study of advanced sunflower precision deployable antenna (1979)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: The maximum deployed diameter stowable in shuttle was determined for the original concept and for new more efficient concepts. Estimates of weight, surface accuracy and cost were made for the various configurations. Five critical technologies were identified which would be required to manufacture large solid deployable reflectors. These technologies are concerned with surface accuracy improvement and verification.
    Schlagwort(e): COMMUNICATIONS AND RADAR
    Materialart: NASA-CR-162631 , MEL-79-B-126
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
Schließen ⊗
Diese Webseite nutzt Cookies und das Analyse-Tool Matomo. Weitere Informationen finden Sie hier...