SEARCH · Engineering Papers
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.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
The procedures and techniques used in NASA's aerospace technology transfer program are reviewed for consideration in establishing priorities and bases for joint action by technicians and users of remotely sensed data in France. Particular emphasis is given to remote sensing in agriculture, forestry, water resources, environment management, and urban research.
Two experiments were performed in April and September 1976 to determine precise positions of radio sources using conventional Mark 2 VLBI techniques. Four stations in the continental United States observed at a wavelength of 18 cm. The recording bandwidth was 2 MHz. The preliminary results using analyses of fringe rate and delay are discussed and the source positions compared with the results of other measurements.
A sample of more than 150 redshifts, the majority new, is presented for galaxies brighter than an apparent photographic magnitude of 15.8 in a 28-square-deg field in Hercules containing the clusters A2151, A2152, and A2147. This sample populates a 60,000 cu Mpc conical volume. It contains a super-cluster centered near a radial velocity of 11,000 km/sec a large void of depth approximately 100 Mpc in front of the supercluster, and foreground structure at 4700 and 2300 km/sec the former associated with Seyfert's sextet.
Explore the source record for details and available documents.
The variable twist wing concept was used to investigate the relative effects of lift and turbulence distribution on the rolled up vortex wake. Several methods of reducing the vortex strength behind an aircraft were identified. These involve the redistribution of lift spanwise on the wing and drag distribution along the wing. Initial attempts to use the variable twist wing velocity data to validate the WAKE computer code have shown a strong correlation, although the vorticity levels were not exactly matched.
A comparison of data from Project MERIT Short Campaign is presented. The time delay weight matrix in VLBI geodetic parameter estimation was investigated. The utilization of range difference observations in geodynamics is discussed.
Fundamental problems encountered while attempting to develop automated techniques for applications of remote sensing are discussed under the following categories: (1) geometric and radiometric preprocessing; (2) spatial, spectral, temporal, syntactic, and ancillary digital image representation; (3) image partitioning, proportion estimation, and error models in object scene interference; (4) parallel processing and image data structures; and (5) continuing studies in polarization; computer architectures and parallel processing; and the applicability of "expert systems" to interactive analysis.
Results of two methods of extracting spectra from IUE images are compared. The first method, which is presently implemented, performs a geometric correction of the image followed by a photometric correction. The spectral data are then extracted using a slit with an effective width and sampling interval of 2.4A for the SWP camera and 3.7A for the LWR camera in low dispersion. The second method performs the photometric correction without doing a geometric correction. The spectral data are then extracted from the photometrically corrected image by an extraction slit, which follows the spectral orders in the nongeometrically corrected space, with an effective width and sampling interval 1/2 that of the present method.
The structural response to a given environment is described by the differential equations of motion of deformable bodies. Analytic solutions of such problems for a reasonably large class of structural configurations are not within the realm of the possible. Consequently, the mathematical problem is recast into a numerical problem for solution on the computer. New technology in the space and energy fields led to a growing demand for accurate analysis which at times cannot be met due to the limits set by available budgets for computer time. In response to this need for more efficient numerical analysis, the possibilities of reducing the number of freedoms in the system through a revival of the global function approach were explored.
The dynamic response of a stratified atmosphere permeated by a magnetic field to a sudden localized energy release (e.g., the onset of a flare) is examined in a physically self-consistent manner within the approximation of axisymmetric two-dimensional magnetohydrodynamics. In contrast to the previous plane analyses, with the inclusion of out-of-plane components of magnetic and velocity fields, it is shown that the presence of transverse waves leads to spiraling material motions and formation of ring current with open (mostly radial) magnetic field configuration. In the closed (mostly azimuthal) magnetic field, the evolutionary response of a magnetic field is shown to follow the typical sequence observed with a flare, namely, the relaxations of magnetic shear toward the potential configuration. The details of the results are described with discussions on their physical significance.
Mission analyses indicated that by extracting oxygen from the Martian atmosphere, which consists primarily of carbon dioxide, the launch mass of a spacecraft can be reduced by such an amount that samples from the planet can be returned to earth. The solid electrolyte process for producing O2 from CO2 was investigated. A model of the thermodynamic and electrochemical processes in the electrolyte cell was postulated, thereby establishing the parameters influencing the effectiveness and efficiency of an in situ O2 production system. The major operating parameters were investigated over a wide range of temperature and pressure. Operating limits imposed by the solid electrolyte material, 8% yttria stabilized zirconia, were determined as a function of the operating temperature.
The technique of range differencing with Lageos ranges to obtain more accurate estimates of baseline lengths and polar motion variation was studied. Differencing quasi simultaneous range observations eliminate a great deal of orbital biases. Progress is reported on the definition and maintenance of a conventional terrestrial reference system.
The set of computer programs described allows for data definition, data input, and data transfer between the LSI-11 microcomputers and the VAX-11/780 minicomputer. Program VAXCOM allows for a simple method of textual file transfer from the LSI to the VAX. Program LSICOM allows for easy file transfer from the VAX to the LSI. Program TTY changes the LSI-11 operators console to the LSI's printing device. Program DICTIN provides a means for defining a data set for input to either computer. Program DATAIN is a simple to operate data entry program which is capable of building data files on either machine. Program LEDITV is an extremely powerful, easy to use, line oriented text editor. Program COPYSBF is designed to print out textual files on the line printer without character loss from FORTRAN carriage control or wide record transfer.
The use of an International Standards Organization (ISO) Open Systems Interconnection (OSI) Reference Model and its relevance to interconnecting an Applications Data Service (ADS) pilot program for data sharing is discussed. A top level mapping between the conjectured ADS requirements and identified layers within the OSI Reference Model was performed. It was concluded that the OSI model represents an orderly architecture for the ADS networking planning and that the protocols being developed by the National Bureau of Standards offer the best available implementation approach.
The effects of space ionizing radiation on polymers is investigated in terms of operative physical and chemical processes. A useful model of charged particle impact with a polymer was designed. Principle paths of molecular relaxation were identified and energy handling processes were considered. The focus of the study was on energy absorption and the immediately following events. Further study of the radiation degradation of polymers is suggested.
A theoretical investigation of three dimensional relativistic klystron action is described. The relativistic axisymmetric equations of motion are derived from the time-dependent Lagrangian function for a charged particle in electromagnetic fields. An analytical expression of the fringing RF electric and magnetic fields within and in the vicinity of the interaction gap and the space-charge forces between axially and radially elastic deformable rings of charges are both included in the formulation. This makes an accurate computation of electron motion through the tunnel of the cavities and the drift tube spaces possible. Method of analysis is based on Lagrangian formulation. Bunching is computed using a disk model of electron stream in which the electron stream is divided into axisymmetric disks of equal charge and each disk is assumed to consist of a number of concentric rings of equal charges. The Individual representative groups of electrons are followed through the interaction gaps and drift tube spaces. Induced currents and voltages in interacting cavities are calculated by invoking the Shockley-Ramo theorem.
The general principles of remote sensing techniques as applied to agriculture and the methods of data analysis are described. the theoretical spectral responses of crops; reflectance, transmittance, and absorbtance of plants; interactions of plants and soils with reflectance energy; leaf morphology; and factors which affect the reflectance of vegetation cover are dicussed. The methodologies of visual and computer-aided analyses of LANDSAT data are presented. Finally, a case study wherein infrared film was used to detect crop anomalies and other data applications are described.
A description is presented of the computational procedures used to obtain spatial fields of relative vorticity, advection of vorticity, horizontal divergence, and vertical motion. An investigation is conducted of the effectiveness of these procedures to reduce the effects of deliberately introduced random errors, giving attention to the confidence which can be placed on values of the derived parameters. It is concluded that fields of 500 mb vorticity and 700 mb vertical velocity, which are frequently used in synoptic scale forecasting schemes, show minimal effects of the deliberately introduced errors. Vorticity advection is found to be the most sensitive term to input data errors. Large fluctuations in fields of this parameter are evident both statistically and qualitatively.