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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 541 records · Page 30
All sourcesNASA NTRSDOE OSTI
NASA NTRS1987

Advanced turboprop wing installation effects measured by unsteady blade pressure and noise

A single rotation model propeller (SR-7A) was tested at simulated takeoff/approach conditions (Mach 0.2), in the NASA Lewis 9- by 15-Ft Anechoic Wind Tunnel. Both unsteady blade surface pressures and noise measurements were made for a tractor configuration with propeller/straight wing and propeller alone configurations. The angle between the wing chord and propeller axis (droop angle) was varied along with the wing angle of attack to determine the effects on noise and unsteady loading. A method was developed that uses unsteady blade pressure measurements to provide a quantitative indication of propeller inflow conditions, at least for a uniform (across the propeller disk) inflow angle. The wing installation caused a nearly uniform upwash at the propeller inlet as evidenced by the domination of the pressure spectra by the first shaft order. This inflow angle increased at a rate of almost 150 percent of that of the wing angle-of-attack for a propeller-wing spacing of 0.54 wing chords at a constant droop angle. The flyover noise, as measured by the maximum blade passing frequency level, correlates closely with the propeller inflow angle (approx. 0.6 dB per degree of inflow angle) for all droop angles and wing angles of attack tested, including the propeller alone data. Large changes in the unsteady pressure responses on the suction surface of the blade were observed as the advance ratio was varied. The presence of a leading edge vortex may explain this behavior since changes in the location of this vortex would change with loading (advance ratio).

Heidelberg, Laurence J.↗
NASA NTRS1988

Asymmetries in the location of the Venus ionopause

Four large data sets of Venus ionopause observations, based on different definitions and observations by Pioneer Venus Orbiter field and particle instruments, are compared. Regardless of the definition chosen, the ionopause is observed to be higher on average at dawn than at dusk. The results of an empirical ionosphere model and a data analysis technique which minimizes orbital bias are combined to show that most or all of this asymmetry results from the effects of orbital bias and uneven sampling of solar wind conditions. However, an additional asymmetry is found in which the ionopause is displaced in the direction opposite to the motional electric field of the solar wind. This effect is attributed to asymmetric pickup of exospheric ions by the electric and magnetic fields in the magnetosheath. This ion pickup interpretation can be understood in terms of a previous observed magnetosheath magnetic field asymmetry. Quantitative analysis indicates that the transverse momentum imparted by the solar plasma to pickup particles in their initial gyration is transmitted by the magnetosheath magnetic field to the ionosphere boundary.

Phillips, J. L.↗
NASA NTRS1988

The Franco-American macaque experiment

The details of studies to be carried out jointly by French and American teams on two rhesus monkeys prepared for future experiments aboard the Space Shuttle are discussed together with the equipment involved. Seven science discipline teams were formed, which will study the effects of flight and/or weightlessness on the bone and calcium metabolism, the behavior, the cardiovascular system, the fluid balance and electrolytes, the muscle system, the neurovestibular interactions, and the sleep/biorhythm cycles. New behavioral training techniques were developed, in which the animals were trained to respond to behavioral tasks in order to measure the parameters involving eye/hand coordination, the response time to target tracking, visual discrimination, and muscle forces used by the animals. A large data set will be obtained from different animals on the two to three Space Shuttle flights; the hardware technologies developed for these experiments will be applied for primate experiments on the Space Station.

Cipriano, Leonard F.↗
NASA NTRS1989

Medical-Information-Management System

Medical Information Management System (MIMS) computer program interactive, general-purpose software system for storage and retrieval of information. Offers immediate assistance where manipulation of large data bases required. User quickly and efficiently extracts, displays, and analyzes data. Used in management of medical data and handling all aspects of data related to care of patients. Other applications include management of data on occupational safety in public and private sectors, handling judicial information, systemizing purchasing and procurement systems, and analyses of cost structures of organizations. Written in Microsoft FORTRAN 77.

Alterescu, Sidney↗
NASA NTRS1988

Remote sensing information sciences research group

Research conducted under this grant was used to extend and expand existing remote sensing activities at the University of California, Santa Barbara in the areas of georeferenced information systems, matching assisted information extraction from image data and large spatial data bases, artificial intelligence, and vegetation analysis and modeling. The research thrusts during the past year are summarized. The projects are discussed in some detail.

Estes, John E.↗
NASA NTRS1989

Teledyne Taber 206-1000 and 2210-3000 pressure transducer proof test and burst test

The range accuracy and structural integrity of the Teledyne Taber 206-1000 and 2210-3000 pressure transducers are verified and multiple uses are studied to determine is they have a significant effect on the transducers. Burst pressure for these transducers was also established. The Teledyne Taber 206-1000 pressure transducer is used to measure chamber pressure on full-scale space shuttle rocket motors. The Teledyne Taber 2210-3000 pressure transducer is used to measure igniter pressure. The Teledyne Taber transducer has very good temperature stability and was used on all full-scale solid rocket motors, so there is a large data base established using this transducer.

Ricks, G. A.↗
NASA NTRS1990

Portable High-Frequency Data-Acquisition System

Compact unit made of readily available solid-state components. Proposed system for acquisition of rapidly changing data self-contained and portable. Conceived for monitoring such aerodynamic effects as flutter, vibration, shock, sound, and pressure. Offers precise and fast acquisition of data and large data-storage capacity: has maximum sampling rate of 125 kHz, access time of 15 ns, and 1-million-bit memory. Measures time with "smart" (microprocessor-controlled) watch that maintains calendar time for more than 10 years without external power. Provides standby power from "smart" battery furnishing up to 1 ampere-hour of charge if power from main batteries lost.

Mustain, Roy W.↗
NASA NTRS1987

The effects of wall surface defects on boundary-layer transition in quiet and noisy supersonic flow

The design of supersonic vehicles with laminar flow control and vehicles such as the Space Shuttle requires information on allowable transition tolerances to fabrication defects such as discrete surface roughness and waviness. A relatively large data base on the effects of discrete roughness on transition exists for subsonic and supersonic speeds. The existing supersonic wind tunnel transition data are contaminated by wind tunnel noise emanating from the turbulent boundary layers on the nozzle walls. Roughness and waviness transition data obtained in a quiet Mach 3.5 supersonic wind tunnel are compared with those obtained in conventional noisy flows.

Morrisette, E. Leon↗
NASA NTRS1990

Low velocity instrumented impact testing of four new damage tolerant carbon/epoxy composite systems

Low velocity drop weight instrumented impact testing was utilized to examine the damage resistance of four recently developed carbon fiber/epoxy resin systems. A fifth material, T300/934, for which a large data base exists, was also tested for comparison purposes. A 16-ply quasi-isotropic lay-up configuration was used for all the specimens. Force/absorbed energy-time plots were generated for each impact test. The specimens were cross-sectionally analyzed to record the damage corresponding to each impact energy level. Maximum force of impact versus impact energy plots were constructed to compare the various systems for impact damage resistance. Results show that the four new damage tolerant fiber/resin systems far outclassed the T300/934 material. The most damage tolerant material tested was the IM7/1962 fiber/resin system.

Lance, D. G.↗
NASA NTRS1989

The indexed time table approach for planning and acting

A representation is discussed of symbolic temporal relations, called IxTeT, that is both powerful enough at the reasoning level for tasks such as plan generation, refinement and modification, and efficient enough for dealing with real time constraints in action monitoring and reactive planning. Such representation for dealing with time is needed in a teleoperated space robot. After a brief survey of known approaches, the proposed representation shows its computational efficiency for managing a large data base of temporal relations. Reactive planning with IxTeT is described and exemplified through the problem of mission planning and modification for a simple surveying satellite.

Ghallab, Malik↗
NASA NTRS1990

IRAS comet observations - The continuing saga

IRAS observations of comets include photometry, spectroscopy, and multiple wavelength imagery. The large beam of the IRAS detector array, which was well suited to detect faint extended emissions of cometary origin, has produced a large data set that is complex to analyze. Although some preliminary results of the IRAS comet photometry have been published, definitive analysis must explicitly account for the convolution of the emission source with the nonuniform spatial response of the detector array. This paper reviews the progress made toward the production and subsequent analysis of instrument-free comet images, and presents the current state of the art IRAS images of comet Kopff.

Walker, R. G.↗
NASA NTRS1989

Long-term variations in the gamma-ray background on SMM

Long-term temporal variations in the various components of the background radiation detected by the gamma-ray spectrometer on the Solar Maximum Mission are presented. The SMM gamma-ray spectrometer was launched in February, 1980 and continues to operate normally. The extended period of mission operations has provided a large data base in which it is possible to investigate a variety of environmental and instrumental background effects. In particular, several effects associated with orbital precession are introduced and discussed.

Kurfess, J. D.↗
NASA NTRS1989

Singular spectrum analysis in nonlinear dynamics, with applications to paleoclimatic time series

Two dimensions of a dynamical system given by experimental time series are distinguished. Statistical dimension gives a theoretical upper bound for the minimal number of degrees of freedom required to describe the attractor up to the accuracy of the data, taking into account sampling and noise problems. The dynamical dimension is the intrinsic dimension of the attractor and does not depend on the quality of the data. Singular Spectrum Analysis (SSA) provides estimates of the statistical dimension. SSA also describes the main physical phenomena reflected by the data. It gives adaptive spectral filters associated with the dominant oscillations of the system and clarifies the noise characteristics of the data. SSA is applied to four paleoclimatic records. The principal climatic oscillations and the regime changes in their amplitude are detected. About 10 degrees of freedom are statistically significant in the data. Large noise and insufficient sample length do not allow reliable estimates of the dynamical dimension.

Vautard, R.↗
NASA NTRS1990

IUE and Einstein survey of late-type giant and supergiant stars and the dividing line

Results are presented on an IUE UV survey of 255 late-type G, K, and M stars, complementing the Maggio et al. (1990) Einstein X-ray survey of 380 late-type stars. The large data sample of X-ray and UV detections make it possible to examine the activity relationship between the X-ray and the UV emissions. The results confirm previous finding of a trend involving a steeply-dropping upper envelope of the transition region line fluxes, f(line)/f(V), as the dividing line is approached. This suggests that a sharp decrease in maximum activity accompanies the advancing spectral type, with the dividing line corresponding to this steep gradient region. The results confirm the rotation-activity connection for stars in this region of the H-R diagram.

Haisch, Bernhard M.↗
NASA NTRS1990

Flight demonstration of a self repairing flight control system in a NASA F-15 fighter aircraft

Battle damage causing loss of control capability can compromise mission objectives and even result in aircraft loss. The Self Repairing Flight Control System (SRFCS) flight development program directly addresses this issue with a flight control system design that measures the damage and immediately refines the control system commands to preserve mission potential. The system diagnostics process detects in flight the type of faults that are difficult to isolate post flight, and thus cause excessive ground maintenance time and cost. The control systems of fighter aircraft have the control power and surface displacement to maneuver the aircraft in a very large flight envelope with a wide variation in airspeed and g maneuvering conditions, with surplus force capacity available from each control surface. Digital flight control processors are designed to include built-in status of the control system components, as well as sensor information on aircraft control maneuver commands and response. In the event of failure or loss of a control surface, the SRFCS utilizes this capability to reconfigure control commands to the remaining control surfaces, thus preserving maneuvering response. Correct post-flight repair is the key to low maintainability support costs and high aircraft mission readiness. The SRFCS utilizes the large data base available with digital flight control systems to diagnose faults. Built-in-test data and sensor data are used as inputs to an Onboard Expert System process to accurately identify failed components for post-flight maintenance action. This diagnostic technique has the advantage of functioning during flight, and so is especially useful in identifying intermittent faults that are present only during maneuver g loads or high hydraulic flow requirements. A flight system was developed to test the reconfiguration and onboard maintenance diagnostics concepts on a NASA F-15 fighter aircraft.

Urnes, James M.↗
NASA NTRS1991

Active region mass motions observed in soft X-ray lines

Significant coronal mass motions are deduced from soft X-ray line broadening observed in solar active regions even during quiescent periods. A large data base of Mg XI resonance line profiles near 9.17 A has been acquired with the SMM Flat Crystal Spectrometer for a variety of active region conditions and disk locations. For the X-ray bright areas, the typical profiles have an excess line width equal to or greater than the thermal Doppler width for Mg ions at the observed coronal temperatures (3-4 MK). The equivalent excess velocities of 40-60 km/s are higher than those reported previously for cooler lines in other wavebands. The excess velocities show a correlation with magnetic field strength or gradient, but no obvious dependence on the angular distance from sun center.

Saba, J. L. R.↗
NASA NTRS1991

Space Observations for Global Change

There is now compelling evidence that man's activities are changing both the composition of the atmospheric and the global landscape quite drastically. The consequences of these changes on the global climate of the 21st century is currently a hotly debated subject. Global models of a coupled Earth-ocean-atmosphere system are still very primitive and progress in this area appears largely data limited, specially over the global biosphere. A concerted effort on monitoring biospheric functions on scales from pixels to global and days to decades needs to be coordinated on an international scale in order to address the questions related to global change. An international program of space observations and ground research was described.

Rasool, S. I.↗
NASA NTRS1992

IMF draping around the geotail - IMP 8 observations

The draping pattern for the full range of IMF directions is mapped in the GSM yz-plane using a large data set for studying magnetic field draping around the tail. Based on the maps, it is concluded that the dominant pattern is draping as found by Ohtani and Kokubun (1991) and Sanchez and Siscoe (1990). A new finding is that the draping pattern is rotated relative to the plane formed by the IMF and the aberrated x-axis, with the degree of rotation varying from zero for strongly northward and southward IMF to a peak of 17 deg for moderately southward IMF. It is also found that the tail radius is bigger for southward IMF than for northward IMF.

Kaymaz, Zerefsan↗