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  • MECHANICAL ENGINEERING  (6)
  • LUNAR AND PLANETARY EXPLORATION  (4)
  • Astronomy
  • 1985-1989  (10)
  • 1
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    Solid-state ice volcanism on the satellites of Uranus (1988)
    In:  Other Sources
    Details
    Publikationsdatum: 2011-08-19
    Beschreibung: Voyager images of the Uranian satellites Ariel and Miranda show flow features with morphologies indicating that ice has been extruded to the satellites' surfaces in the solid state. These images provide the first observational evidence for solid-state ice volcanism in the solar system. Topographic profiles have been measured across a number of flow features on Ariel. With a simple model of extrusion, spreading, and cooling of a viscous flow, the initial viscosity of the flow material is found to have been no more than about 10 to the 16th poise, far lower than expected for H2O ice at the ambient surface temperatures in the Uranian system. Sharply reduced viscosities may have resulted from incorporation of ices like NH3 or CH4 in the Uranian satellites.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Science (ISSN 0036-8075); 241; 1322-132
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 2
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    Evidence for pigmentary hematite on Mars based on optical, magnetic, and Moessbauer studies of superparamagnetic (nanocrystalline) hematite (1989)
    In:  Other Sources
    Details
    Publikationsdatum: 2011-08-19
    Beschreibung: Samples containing variable amounts of superparamagnetic hematite (sp-Hm) were prepared by a method in which the sp-Hm particles were dispersed throughout larger particles of silica gel, and the optical and magnetic properties of these samples were compared with those of larger-diameter hematite (bulk-Hm). It is shown that the optical properties of sp-Hm are different from those of bulk-Hm. Implications of the results for mineralogical interpretations of spectral data for the Martian surface and its terrestrial analogues are discussed. It is concluded that features resulting from ferric iron in the Martian spectral data and the results of the Viking magnetic properties experiment are both consistent with hematite present as both sp-Hm and bulk-Hm; the hematite particles most likely occur in pigmentary form, i.e., as particles dispersed throughout the volume of a spectrally neutral material.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Journal of Geophysical Research (ISSN 0148-0227); 94; 2760-277
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 3
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    Spectral characterization of Martian soil analogues (1987)
    In:  CASI
    Details
    Publikationsdatum: 2013-08-31
    Beschreibung: As previously reported, reflectance spectra of iron oxide precipitated as ultrafine particles, unlike ordinary fine grained hematite, have significant similarities to reflectance spectra from the bright regions of Mars. These particles were characterized according to composition, magnetic properties, and particle size distribution. Mossbauer, magnetic susceptibility, and optical data were obtained for samples with a range of concentrations of iron oxide in silica gel of varying pore diameters. To analyze the Mossbauer spectra, a versatile fitting program was enhanced to provide user friendly screen input and theoretical models appropriate for the superparamagnetic spectra obtained.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: NASA. Lyndon B.; NASA. Lyndon B. John
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 4
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    Vibration characteristics of OH-58A helicopter main rotor transmission (1987)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-28
    Beschreibung: Experimental vibration tests covering a range of torque and speed conditions were performed on the OH-58A helicopter main rotor transmission at the NASA Lewis Research Center. Signals from accelerometers located on the transmission housing were analyzed by using Fourier spectra, power spectral density functions, and averaging techniques. Most peaks of the Fourier spectra occurred at the spiral bevel and planetary gear mesh harmonics. The highest level of vibration occurred at the spiral bevel meshing frequency. Transmission speed and vibration measurement location had a significant effect on measured vibration; transmission torque and measurement direction had a small effect.
    Schlagwort(e): MECHANICAL ENGINEERING
    Materialart: NASA-TP-2705 , E-3368 , NAS 1.60:2705 , AVSCOM-TR-86-C-42 , AD-A180364
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 5
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    Helicopter transmission testing at NASA Lewis Research Center (1987)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-28
    Beschreibung: The helicopter has evolved into a highly valuable air mobile vehicle for both military and civilian needs. The helicopter transmission requires advanced studies to develop a technology base for future rotorcraft advances. A joint helicopter transmission research program between the NASA Lewis Research Center and the U.S. Army Aviation Systems Command has existed since 1970. Program goals are to reduce weight and noise and to increase life and reliability. The current experimental activities at Lewis consist of full-scale helicopter transmission testing, a base effort in gearing technology, and a future effort in noise reduction technology. The experimental facilities at Lewis for helicopter transmission testing are described. A description of each of the rigs is presented along with some significant results and near-term plans.
    Schlagwort(e): MECHANICAL ENGINEERING
    Materialart: NASA-TM-89912 , E-3603 , NAS 1.15:89912 , AVSCOM-TR-87-C-10
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 6
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    Predicted effect of dynamic load on pitting fatigue life for low-contact-ratio spur gears (1986)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-28
    Beschreibung: How dynamic load affects the surface pitting fatigue life of external spur gears was predicted by using the NASA computer program TELSGE. Parametric studies were performed over a range of various gear parameters modeling low-contact-ratio involute spur gears. In general, gear life predictions based on dynamic loads differed significantly from those based on static loads, with the predictions being strongly influenced by the maximum dynamic load during contact. Gear mesh operating speed strongly affected predicted dynamic load and life. Meshes operating at a resonant speed or one-half the resonant speed had significantly shorter lives. Dynamic life factors for gear surface pitting fatigue were developed on the basis of the parametric studies. In general, meshes with higher contact ratios had higher dynamic life factors than meshes with lower contact ratios. A design chart was developed for hand calculations of dynamic life factors.
    Schlagwort(e): MECHANICAL ENGINEERING
    Materialart: NASA-TP-2610 , E-2989 , NAS 1.60:2610 , AD-A170906 , AVSCOM-TR-86-C-21
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 7
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    Helicopter transmission research at NASA Lewis Research Center (1988)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-28
    Beschreibung: A joint helicopter transmission research program between NASA Lewis Research Center and the U.S. Army Aviation Systems Command has existed since 1970. Program goals are to reduce weight and noise and to increase life and reliability. Reviewed are significant advances in technology for gears and transmissions and the experimental facilities at NASA Lewis for helicopter transmission testing are described. A description of each of the rigs is presented along with some significant results from the experiments.
    Schlagwort(e): MECHANICAL ENGINEERING
    Materialart: NASA-TM-100962 , E-4181 , AVSCOM-TM-88-C-003 , NAS 1.15:100962 , AD-A242220
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 8
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    Automated acoustic intensity measurements and the effect of gear tooth profile on noise (1987)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-28
    Beschreibung: Acoustic intensity measurements were made at NASA Lewis Research Center on a spur gear test apparatus. The measurements were obtained with the Robotic Acoustic Intensity Measurement System developed by Cleveland State University. This system provided dense spatial positioning, and was calibrated against a high quality acoustic intensity system. The measured gear noise compared gearsets having two different tooth profiles. The tests evaluated the sound field of the different gears for two speeds and three loads. The experimental results showed that gear tooth profile had a major effect on measured noise. Load and speed were found to have an effect on noise also.
    Schlagwort(e): MECHANICAL ENGINEERING
    Materialart: NASA-TM-100155 , E-3718 , AVSCOM-TR-87-C-24 , NAS 1.15:100155 , AD-A184071
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 9
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    On the obliquity and tidal heating of Triton (1989)
    In:  Other Sources
    Details
    Publikationsdatum: 2019-07-12
    Beschreibung: Although tidal heating is generally associated with spin-locked satellites on eccentric orbits, a satellite with a large obliquity can undergo substantial heating due to obliquity tides, even on a circular orbit. The near-100-deg obliquity of the Neptune moon, Triton, could generate significant tidal heating and eventually lead to a damping of its orbital inclination to 180 deg. Ground-based observations of Triton have tentatively found a synchronous rotational state that is consistent with despinning times of about 10,000 years, indicating that Triton is almost certainly rotating synchronously.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Icarus (ISSN 0019-1035); 80; 211-219
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 10
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    Effect of advanced component technology on helicopter transmissions (1989)
    In:  CASI
    Details
    Publikationsdatum: 2019-07-13
    Beschreibung: Experimental tests were performed on the NASA/Bell Helicopter Textron (BHT) 500 hp advanced technology transmission (ATT) at the NASA Lewis Research Center. The ATT was a retrofit of the OH-58C helicopter 236 kW (317 hp) main rotor transmission, upgraded to 373 kW (500 hp), with a design goal of retaining long life with a minimum increase in cost, weight, and size. Vibration, strain, efficiency, deflection, and temperature experiments were performed and the results were compared to previous experiments on the OH-58A, OH-58C, and UH-60A transmissions. The high-contact-ratio gears and the cantilevered-mounted, flexible ring gear of the ATT reduced vibration compared to that of the OH-58C. The ATT flexible ring gear improved planetary load sharing compared to that of the rigid ring gear of the UH-60A transmission. The ATT mechanical efficiency was lower than that of the OH-58A transmission, probably due to the high-contact-ratio planetary gears.
    Schlagwort(e): MECHANICAL ENGINEERING
    Materialart: NASA-TM-101431 , E-4531 , NAS 1.15:101431 , AVSCOM-TR-87-C-38 , AD-A219265 , International Power Transmission and Gearing Conference; Apr 25, 1989 - Apr 27, 1989; Chicago, IL; United States
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
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