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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 1,621 records · Page 90

An Integrated Theory for Predicting the Hydrothermomechanical Response of Advanced Composite Structural Components

An integrated theory is developed for predicting the hydrothermomechanical (HDTM) response of fiber composite components. The integrated theory is based on a combined theoretical and experimental investigation. In addition to predicting the HDTM response of components, the theory is structured to assess the combined hydrothermal effects on the mechanical properties of unidirectional composites loaded along the material axis and off-axis, and those of angleplied laminates. The theory developed predicts values which are in good agreement with measured data at the micromechanics, macromechanics, laminate analysis and structural analysis levels.

Chamis, C. C.↗

Cygnus A at 99 GHz: Observations of the three principal components and interpretation of the central source

The three principal emission components of Cygnus A were observed at 99 GHz, the highest frequency at which radio measurements of this source have been accomplished. The observations show no definite indication of a high-frequency cutoff in the spectrum of the compact central component, which perhaps may be attributed to an optically thin synchrotron source that peaks at a frequency of several hundred GHz.

Hobbs, R. W.↗

An experimental test for the charge state of the 'anomalous' helium component

Observations of phase lags between intensity variations for various particle species and energy ranges in the low-energy galactic cosmic radiation during the general intensity decrease observed in 1974-1975 show that, for particles whose charge state is known (i.e., 'normal' cosmic-ray components), particles with higher rigidities respond more quickly to changes in modulation conditions than do those with lower rigidities. When compared with particles of known energy and charge, the behavior of the 'anomalous' low-energy helium component is consistent with these observations only if the helium is singly rather than doubly charged.

Mckibben, R. B.↗

Interpretation of Beta Lyrae. III - A study of the disk around the secondary component

Light curves of Beta Lyrae available in the far-ultraviolet, visual, and infrared regions of the spectrum at numerous phases in eclipse are analyzed in order to investigate the physical and radiative nature of the disk surrounding the secondary component. The results of this analysis together with those of other investigators lead to the proposal that the outer regions of the disk are dominated by free electrons. This electron-scattering envelope is most likely the source of infrared radiation as well as the cause of the observed polarization. However, the radiation in the region from the optical to the far-ultraviolet comes mainly from submerged layers where local thermodynamic equilibrium prevails. These layers represent the photosphere of either the disk or the secondary component itself.

Brown, D. A.↗

Cygnus A at 99 GHz - Observations of the three principal components and interpretation of the central source

The three principal emission components of Cygnus A have been observed at 99 GHz, the highest frequency at which radio measurements of this source have been accomplished. The observations show no definite indication of a high-frequency cutoff in the spectrum of the compact central component, which perhaps may be attributed to an optically thin synchrotron source that peaks at a frequency of several hundred GHz.

Hobbs, R. W.↗

Space Shuttle SRM metal case component fabrication

The 146 in. diam metal case components of the Space Shuttle Solid Rocket Motor (SRM) being developed have been successfully static-tested. The limitations placed on the program included current practice and facilities at the steel mills, forging suppliers, heat treaters, and machining operations. In addition, Thiokol had not previously fabricated metal components of this size with a minimum fracture toughness of 90 ksi-in. to 1/2 power. To insure that the SRM was producible within the established guidelines, it was necessary to coordinate all data heat by heat, forging by forging, and heat treat run by heat treat run. The basic fabrication sequences are outlined, and the data from the heat treat programs are presented.

Krummel, C. H.↗

The fluctuating and isotropic components of the cosmic X-ray background

Spatial fluctuations in the surface brightness of the extragalactic hard X-ray sky that are characteristic of distant unresolved discrete sources as well as the possible clumpiness of a hot universal plasma are being studied with the HEAO-1 A-2 experiment. The energy spectrum for this fluctuating component is directly compared to that of the isotropic background. The spectra of identified extragalactic objects recently obtained with experiments aboard both OSO-8 and HEAO-1 are used for examining the contribution of such sources to this fluctuating component of the background.

Boldt, E.↗

Structural Sizing of the EDIN0620 Body Components Using the APAS Structural Synthesis Computer Program

The use of a structural synthesis computer program to design components for a heavy lift launch vehicle is defined. A loads program was used to determine the vehicle shears, bending moments, and axial loads at two design loading conditions. A comparison was made between results from the structures program and the results of a weight estimating program which used historical data in determining component weights.

Nolte, W. E.↗

A reduction in ag./residential signature conflict using principal components analysis of Landsat temporal data

One important objective of a cooperative project between the U.S. Bureau of Census and NASA is to develop the ability to accurately delineate the types of land cover in the urban-rural transition zone of metropolitan areas. The application of principal components analysis to multidate Landsat imagery is being investigated as a method of reducing the overlap between residential and agricultural spectral signatures. The statistical concepts of principal components analysis are discussed, as well as the results of this analysis when applied to multidate Landsat imagery of the Washington, D.C. metropolitan area.

Williams, D. L.↗

Principal component greenness transformation in multitemporal agricultural Landsat data

A data compression technique for multitemporal Landsat imagery which extracts phenological growth pattern information for agricultural crops is described. The principal component greenness transformation was applied to multitemporal agricultural Landsat data for information retrieval. The transformation was favorable for applications in agricultural Landsat data analysis because of its physical interpretability and its relation to the phenological growth of crops. It was also found that the first and second greenness eigenvector components define a temporal small-grain trajectory and nonsmall-grain trajectory, respectively.

Abotteen, R. A.↗

The NASA Standard Telemetry and Command Components /STACC/

The Standard Telemetry and Command Components (STACC) were conceived by NASA for use on the Multimission Modular Spacecraft. The components have wider application, however, and already are being considered for many other spacecraft. A programmable Central Unit controls Remote Interface Units via a full duplex data bus, providing data acquisition and command distribution capability throughout the spacecraft. The Central Unit can meet any uplink, time code, and format requirements without hardware changes. Each remote unit can acquire any type of data (serial digital, bi-level, analog, or passive analog) on any channel. A third type of unit is an optional interface providing I/O capability to an on-board computer. The protocols used on the 1Mbps data bus are compatible with MSFC's 'Standard Interfaces for Digital Data, Multiplex Serial Data Acquisition and Distribution Systems (SIDD/MSDADS Standard)'. The bus design saves significant harness weight and simplifies the single point ground and isolation approaches.

Elliott, N. P.↗

Direct observation of a tangential electric field component at the magnetopause

Results are presented for direct, in situ measurements of the quasi-static electric field at and near the magnetopause, in the magnetosheath, bow shock, and solar wind, obtained by the ISEE-1 satellite. Both the large-scale average electric field and the fine-scale field observed during a magnetopause crossing show the existence of significant tangential electric field components on both sides of the magnetopause. The data in the satellite frame also show significant normal electric field components that point toward the magnetopause on both sides. The observed local level of power dissipation would correspond to a total power of 1 TW, if it existed over the entire front of the magnetopause.

Mozer, F. S.↗

Remote measurement of the transverse wind velocity component using a laser Doppler velocimeter

The wind speed transverse to the line-of-sight of a laser Doppler radar has been measured using the intensity fluctuations of the returned signal. These measurements were made at a range of 100 m with a CO2 CW laser Doppler velocimeter, which was simultaneously performing its design function of determining the radial velocity component. The transverse component measurements are compared with those obtained using a u, v, w Gill propeller anemometer.

Kennedy, L. Z.↗

Composite components on commercial aircraft

Commercial aircraft manufacturers are making production commitments to composite structure for future aircraft and modifications to current production aircraft. Flight service programs with advanced composites sponsored by NASA during the past 10 years are described. Approximately 2.5 million total composite component flight hours have been accumulated since 1970 on both commercial transports and helicopters. Design concepts with significant mass savings were developed, appropriate inspection and maintenance procedures were established, and satisfactory service was achieved for the various composite components. A major NASA/U.S. industry technology program to reduce fuel consumption of commercial transport aircraft through the use of advanced composites was undertaken. Ground and flight environmental effects on the composite materials used in the flight service programs supplement the flight service evaluation.

Dexter, H. B.↗

Advanced component technologies for energy-efficient turbofan engines

A cooperative government-industry effort, the Energy Efficient Engine Project, to develop the advanced technology base for future commercial development of a new generation of more fuel conservative turbofan engines for airline use is described. Engine configurations that are dependent upon technology advances in each major engine component are defined and current design and development of the advanced components are included.

Saunders, N. T.↗

Extension of similarity test procedures to cooled engine components with insulating ceramic coatings

Material thermal conductivity was analyzed for its effect on the thermal performance of air cooled gas turbine components, both with and without a ceramic thermal-barrier material, tested at reduced temperatures and pressures. The analysis shows that neglecting the material thermal conductivity can contribute significant errors when metal-wall-temperature test data taken on a turbine vane are extrapolated to engine conditions. This error in metal temperature for an uncoated vane is of opposite sign from that for a ceramic-coated vane. A correction technique is developed for both ceramic-coated and uncoated components.

Gladden, H. J.↗

An analysis method for multi-component airfoils in separated flow

The multi-component airfoil program (Langley-MCARF) for attached flow is modified to accept the free vortex sheet separation-flow model program (Analytical Methods, Inc.-CLMAX). The viscous effects are incorporated into the calculation by representing the boundary layer displacement thickness with an appropriate source distribution. The separation flow model incorporated into MCARF was applied to single component airfoils. Calculated pressure distributions for angles of attack up to the stall are in close agreement with experimental measurements. Even at higher angles of attack beyond the stall, correct trends of separation, decrease in lift coefficients, and increase in pitching moment coefficients are predicted.

Rao, B. M.↗

Improved components for engine fuel savings

The Engine Component Improvement (ECI) Project formulated to address near term improvements for current engines is described with emphasis on the development of component technologies to reduce the fuel consumption of CF6, JT9D, and JT8D engines. The technical and economical acceptability and the fuel saving potential of nine concepts are demonstrated. Descriptions of these concepts, results of testing, and the status as to entering airline service are presented. Also presented is the status of the remaining concepts still under development.

Antl, R. J.↗