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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 397 records · Page 22
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NASA NTRS1992

Limb observations of the 12.32 micron solar emission line during the 1991 July total eclipse

The limb profile of the Mg I 12.32-micron emission line is determined by occultation in the July 11, 1991 total solar eclipse over Mauna Kea. It is shown that the emission peaks are very close to the 12-micron continuum limb, as predicted by recent theory for this line as a non-LTE photospheric emission. The increase in optical depth for this extreme limb-viewing situation indicates that most of the observed emission arises from above the chromospheric temperature minimum, and it is found that this emission is extended to heights well in excess of the model predictions. The line emission can be observed as high as 2000 km above the 12-micron continuum limb, whereas theory predicts it to remain observable no higher than about 500 km above the continuum limb. The substantial limb extension observed in this line is quantitatively consistent with limb extensions seen in the far-IR continuum, and it is concluded that it is indicative of departures from gravitational hydrostatic equilibrium, or spatial inhomogeneities, in the upper solar atmosphere.

Deming, Drake↗
NASA NTRS1992

Annual and interannual variations of earth-emitted radiation based on a 10-year data set

The method of empirical orthogonal functions (EOFs) was applied to a 10-yr data set of outgoing longwave radiation. Spherical harmonic functions are used as a basis set for producing equal area map results. The first EOF accounts for 66 percent of the variance. After that, each EOF accounts for only a small variance, forming a slowly converging series. The first two EOFs describe mainly the annual cycle. The third EOF is primarily the semiannual cycle although many other EOFs also contain significant semiannual parts. These results reaffirm those based on a shorter data set. In addition, a much stronger spring/fall mode was found in the central equatorial Pacific Ocean for the second EOF than was found earlier. The fourth EOF describes much of the 1976 to 1977 and 1982 to 1983 ENSO phenomena. There is typically a gap in the spectrum between a semiannual peak and the annual cycle for all but the first EOF. A semiannual OLR dipole straddles the Asian-Australian monsoon track.

Bess, T. D.↗
NASA NTRS1992

Boundary layer study on nozzle wall at hypersonic velocities

The boundary layer on the wall of the Hypervelocity Tunnel 9 was investigated with pitot pressure and total temperature measurements. Experimental results are presented for standard and supercooled Mach 14 runs. The boundary layer data at supercooled conditions are compared to numerical predictions made with a Navier-Stokes algorithm including vibrational nonequilibrium and intermolecular force effects. For standard tunnel conditions, the numerical solutions agree well with experimental data. For the supercooled cases, the numerical code predicts the total temperature but overpredicts the pitot pressure.

Jones, Kenneth M.↗
NASA NTRS1992

Buffet test in the National Transonic Facility

A buffet test of a commercial transport model was accomplished in the National Transonic Facility at the NASA Langley Research Center. This aeroelastic test was unprecedented for this wind tunnel and posed a high risk to the facility. This paper presents the test results from a structural dynamics and aeroelastic response point of view and describes the activities required for the safety analysis and risk assessment. The test was conducted in the same manner as a flutter test and employed onboard dynamic instrumentation, real time dynamic data monitoring, automatic, and manual tunnel interlock systems for protecting the model. The procedures and test techniques employed for this test are expected to serve as the basis for future aeroelastic testing in the National Transonic Facility. This test program was a cooperative effort between the Boeing Commercial Airplane Company and the NASA Langley Research Center.

Young, Clarence P., Jr.↗
NASA NTRS1993

Mapping Temperatures On Heat Pipes

Paints containing thermochromic liquid crystals (TLC's) used to map temperatures on heat pipes and thermosyphons. Color of thermally sensitive TLC coat changes reversibly upon heating or cooling. Each distinct color indicates particular temperature. Transient and steady-state isotherms become visible as colored bands. Positions and movements of bands yield information about startup transients, steady-state operation, cooler regions containing noncondensible gas, and other phenomena relevant to performance of heat pipe.

Gunnerson, Fred S.↗
NASA NTRS1993

Optical Shaft-Angle Encoder For Helicopter Rotor

Angular position of helicopter rotor blade determined precisely. Accomplished by use of optical shaft-angle encoder called "256 Ring" on rotor swashplate. Each 360 degree rotation of helicopter main rotor broken down into 256 reflective segments. As rotor rotates, beam of light reflected in turn from each segment into optoelectronic system. One of 256 segments reflects larger pulse than others do. Position of rotor determined by counting number of pulses after this reference pulse. While swashplate mounting requirements unique to each type of helicopter, concept applicable to all types of rotorcraft.

Golub, Robert A.↗
NASA NTRS1993

Experiments In Characterizing Vibrations Of A Structure

Report discusses experiments conducted to test methods of identification of vibrational and coupled rotational/vibrational modes of flexible structure. Report one in series that chronicle development of integrated system of methods, sensors, actuators, analog and digital signal-processing equipment, and algorithms to suppress vibrations in large, flexible structure even when dynamics of structure partly unknown and/or changing. Two prior articles describing aspects of research, "Autonomous Frequency-Domain Indentification" (NPO-18099), and "Automated Characterization Of Vibrations Of A Structure" (NPO-18141).

Yam, Yeung↗
NASA NTRS1993

Tracking Polymer Cure Via Embedded Optical Fibers

Fourier-transform infrared spectroscopy applied in interior of specimen of material by bringing infrared light through specimen in optical fiber. Light interacts with material via evanescent-wave effect. Spectra obtained in this way at various times during curing process also combined with data from ultrasonic, thermographic, and dielectric-impedance monitoring, and other measurement techniques to obtain more complete characterization of progress of curing process.

Dean, David L.↗
NASA NTRS1993

Autonomous Frequency-Domain System-Identification Program

Autonomous Frequency Domain Identification (AU-FREDI) computer program implements system of methods, algorithms, and software developed for identification of parameters of mathematical models of dynamics of flexible structures and characterization, by use of system transfer functions, of such models, dynamics, and structures regarded as systems. Software considered collection of routines modified and reassembled to suit system-identification and control experiments on large flexible structures.

Yam, Yeung↗
NASA NTRS1992

Experimental validation of boundary element methods for noise prediction

Experimental validation of methods to predict radiated noise is presented. A combined finite element and boundary element model was used to predict the vibration and noise of a rectangular box excited by a mechanical shaker. The predicted noise was compared to sound power measured by the acoustic intensity method. Inaccuracies in the finite element model shifted the resonance frequencies by about 5 percent. The predicted and measured sound power levels agree within about 2.5 dB. In a second experiment, measured vibration data was used with a boundary element model to predict noise radiation from the top of an operating gearbox. The predicted and measured sound power for the gearbox agree within about 3 dB.

Seybert, A. F.↗
NASA NTRS1991

Source gases: Concentrations, emissions, and trends

Source gases are defined as those gases that influence levels of stratospheric ozone (O3) by transporting species containing halogen, hydrogen, and nitrogen to the stratosphere. Examples are the CFC's, methane (CH4), and nitrous oxide (N2O). Other source gases that also come under consideration in an atmospheric O3 context are those that are involved in the O3 or hydroxyl (OH) radical chemistry of the troposphere. Examples are CH4, carbon monoxide (CO), and nonmethane hydrocarbons (NMHC's). Most of the source gases, along with carbon dioxide (CO2) and water vapor (H2O), are climatically significant and thus affect stratospheric O3 levels by their influence on stratospheric temperatures. Carbonyl sulphide (COS) could affect stratospheric O3 through maintenance of the stratospheric sulphate aerosol layer, which may be involved in heterogeneous chlorine-catalyzed O3 destruction. The previous reviews of trends and emissions of source gases, either from the context of their influence on atmospheric O3 or global climate change, are updated. The current global abundances and concentration trends of the trace gases are given in tabular format.

Fraser, Paul J.↗
NASA NTRS1992

Enterprise storage report for the 1990's

Data processing has become an increasingly vital function, if not the most vital function, in most businesses today. No longer only a mainframe domain, the data processing enterprise also includes the midrange and workstation platforms, either local or remote. This expanded view of the enterprise has encouraged more and more businesses to take a strategic, long-range view of information management rather than the short-term tactical approaches of the past. This paper will highlight some of the significant aspects of data storage in the enterprise for the 1990's.

Moore, Fred↗
NASA NTRS1992

Spaceflight payload design flight experience G-408

Worcester Polytechnic Institute's first payload of spaceflight experiments flew aboard Columbia, STS-40, during June of 1991 and culminated eight years of work by students and faculty. The Get Away Special (GAS) payload was installed on the GAS bridge assembly at the aft end of the cargo bay behind the Spacelab Life Sciences (SLS-1) laboratory. The Experiments were turned on by astronaut signal after reaching orbit and then functioned for 72 hours. Environmental and experimental measurements were recorded on three cassette tapes which, together with zeolite crystals grown on orbit, formed the basis of subsequent analyses. The experiments were developed over a number of years by undergraduate students meeting their project requirements for graduation. The experiments included zeolite crystal growth, fluid behavior, and microgravity acceleration measurement in addition to environmental data acquisition. Preparation also included structural design, thermal design, payload integration, and experiment control. All of the experiments functioned on orbit and the payload system performed within design estimates.

Durgin, William W.↗
NASA NTRS1991

Enterprise storage report for the 1990's

Data processing has become an increasingly vital function, if not the most vital function, in most businesses today. No longer only a mainframe domain, the data processing enterprise also includes the midrange and workstation platforms, either local or remote. This expanded view of the enterprise has encouraged more and more businesses to take a strategic, long-range view of information management rather than the short-term tactical approaches of the past. Some of the significant aspects of data storage in the enterprise for the 1990's are highlighted.

Moore, Fred↗
NASA NTRS1991

Network accessible multi-terabyte archive

The viewgraphs of a discussion on Network Accessible Multi-terabyte Archive presented at the National Space Science Data Center (NSSDC) Mass Storage Workshop is included. Topics covered in the presentation include the rotary storage system (RSS) including RSS data access, data management, administration, and hardware and software architecture.

Rybczynski, Fred↗
NASA NTRS1991

ATL Products Division's entries into the computer mass storage marketplace

The viewgraphs of a discussion on ATL Products Division's entries into the computer mass storage marketplace presented at the National Space Science Data Center (NSSDC) Mass Storage Workshop is included. Topics covered are product evolution including robotics; aperture storage module library; Broadcast Division's TCS2000 Video Cart and TCS90 Videocart System; high density systems business product lines; and storage and library management.

Zeiler, Fred↗
NASA NTRS1992

Network accessible multi-terabyte archive

Features of the Rotary Storage System (RSS), developed by Metrum Information Storage, are presented in vugraph format. The RSS makes use of the T-120 Super-VHS media with 10.4 GB per cartridge. Other features of the RSS are as follows: (1) Very Large Data Store (VLDS) tape drives; (2) robots with on-line capacity to 6.2 TB; (3) bar code reader; (4) data management computer; and (5) network accessible.

Rybczynski, Fred↗