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  • Inorganic Chemistry  (739)
  • EARTH RESOURCES AND REMOTE SENSING  (671)
  • Analytical Chemistry and Spectroscopy  (566)
  • Life and Medical Sciences  (346)
  • STRUCTURAL MECHANICS  (254)
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  • 1
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    Rapid interface flaw extension with friction (1976)
    In:  CASI
    Details
    Publikationsdatum: 2006-08-09
    Beschreibung: An idealized two-dimensional example of rapid interface flow extension is described. Initially undisturbed dissimilar isotropic, homogeneous, linearly elastic half-spaces are perfectly bonded along the interface y=0. Quantities associated with the half-space or = to 0 are denoted by the prime superscript or the subscripts 3 or 4 while those in y or = to 0 carry the subscripts 1 or 2. At time t=0 adjacent material points at x=0, y= + or - 0 are forced apart horizontally with a constant relative velocity delta v. This results in a zone of bond failure which extends symmetrically along the interface at a constant rate c. The newly created flaw surfaces are in sliding contact resisted by Coulomb friction. The friction coefficient is gamma.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Langley Res. Center Advan. in Eng. Sci., Vol. 1; p 239-246
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  • 2
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    Influence of a circular hole under uniform normal pressure on the stresses around a line crack in an infinite plate (1976)
    In:  CASI
    Details
    Publikationsdatum: 2006-08-09
    Beschreibung: Based on the two dimensional theory of elasticity and by the use of Muskhelishvili's technique, the influence of a circular hole, under uniform normal pressure, on the stresses around a line crack in an infinite plate subjected to tension is discussed. Numerical calculations were carried out, and the variation of the crack tip stress intensity factor due to the geometry was clarified.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Langley Res. Center Advan. in Eng. Sci., Vol. 1; p 275-282
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  • 3
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    Earth observations and photography experiment MA-136 (1976)
    In:  CASI
    Details
    Publikationsdatum: 2006-01-12
    Beschreibung: The primary objectives of the earth observations and photography experiment of the Apollo Soyuz Test Project were to photograph various terrestrial structures and to use the capabilities of man as a trained observer in visually studying earth features and phenomena. Man's special capabilities include the sensitivity of the eye to subtle color variations and the speed with which the eye/brain system can interpret what is seen and select targets for photography. Real time astronaut observations constitute a useful complement to orbital photographs and greatly aid in their interpretation. Targets for mapping and hand held photography were selected on the basis of their value to specialists in the earth sciences including geology, oceanography, desert study, hydrology, meteorology, and environmental science.
    Schlagwort(e): EARTH RESOURCES AND REMOTE SENSING
    Materialart: NASA. Lyndon B. Johnson Space Center Apollo-Soyuz Test Project; 64 p
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  • 4
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    A study of the effect of subcritical crack growth on the geometry dependence on nonlinear fracture toughness parameters (1976)
    In:  CASI
    Details
    Publikationsdatum: 2006-08-09
    Beschreibung: The effect of subcritical crack growth on the geometry dependence of nonlinear fracture toughness parameters was studied by comparing the toughness values for different specimen geometries at the onset of subcritical crack growth and at the initiation of unstable crack propagation. Center-cracked thin sheet specimens of 2024-T3 and 7075-T6 aluminum alloys were tested by varying the specimen length L, width w, and crack length-to-width ratio c/w. When the onset of unstable crack propagation was selected as the critical point, the nonlinear energy toughness and the R curve toughness increased with increasing w and decreasing L and c/w. However, when the onset of subcritical crack growth was taken as the critical point, energy toughness and the linear toughness values were independent of these geometrical variables.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Langley Res. Center Advan. in Eng. Sci., Vol. 1; p 257-266
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  • 5
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    Influence of specimen boundary on the dynamic stress intensity factor (1976)
    In:  CASI
    Details
    Publikationsdatum: 2006-08-09
    Beschreibung: The problem to be considered is the sudden appearance of a flaw or crack in a strip of material of finite height subjected to tensile loading. Stress waves are generated within the strip and are reflected from boundary to boundary. Of interest is the maximum value of the dynamic stress intensity factor at a given instance of time as the strip height to crack length ratio is varied.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Langley Res. Center Advan. in Eng. Sci., Vol. 1; p 205-214
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  • 6
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    Wave propagation in laminated orthotropic circular cylindrical shells (1976)
    In:  Other Sources
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    Publikationsdatum: 2011-08-17
    Beschreibung: An exact three-dimensional analysis of wave propagation in laminated orthotropic circular cylindrical-shells is developed. Numerical results are presented for three-ply shells, and for various axial wave lengths, circumferential wave numbers, and thicknesses. Results from a thin shell theory and a refined approximate theory are compared with the exact results.
    Schlagwort(e): STRUCTURAL MECHANICS
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  • 7
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    Plane-stress fracture of compact and notch-bend specimens (1976)
    In:  Other Sources
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    Publikationsdatum: 2011-08-17
    Beschreibung: Thin-gaged or high toughness materials containing cracks usually fail in a ductile manner with nominal failure stresses approaching the ultimate strength of the material. For such materials, a two-parameter fracture criterion was developed. An equation which related the linear elastic stress-intensity factor, elastic nominal stress, and two material parameters has previously been derived and has been used as a fracture criterion for surface- and through-cracked specimens under tensile loading. In the present paper the two-parameter fracture criterion was rederived in a more general form and was extended to compact and notch-bend fracture specimens. A close correlation was found between experimental and calculated failure stresses.
    Schlagwort(e): STRUCTURAL MECHANICS
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  • 8
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    The shear-stress intensity factor for a centrally cracked stiff-flanged shear web (1976)
    In:  Other Sources
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    Publikationsdatum: 2011-08-17
    Beschreibung: By use of the principle of superposition the stiff-flanged shear web is modeled mathematically by an infinite elastic strip with fixed longitudinal edges. The shear-stress intensity factor for a central longitudinal crack is calculated for various values of the ratio of strip width to crack length, h/a, in the range 0.1-10. The interaction of the crack with the boundaries is illustrated by boundary shear-stress distributions for three values of h/a. Some implications of the results for the design of damage-tolerant shear webs are discussed briefly.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: International Journal of Fracture; 12; Apr. 197
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  • 9
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    Earth-atmosphere system and surface reflectivities in arid regions from Landsat MSS data (1976)
    In:  Other Sources
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    Publikationsdatum: 2011-08-17
    Beschreibung: Previously developed programs for computing atmospheric transmission and scattering of the solar radiation are used to compute the ratios of the earth-atmosphere system (space) directional reflectivities in the nadir direction to the surface Lambertian reflectivity, for the four bands of the Landsat multispectral scanner (MSS). These ratios are presented as graphs for two water vapor levels, as a function of the surface reflectivity, for various sun elevation angles. Space directional reflectivities in the vertical direction are reported for selected arid regions in Asia, Africa, and Central America from the spectral radiance levels measured by the Landsat MSS. From these space reflectivities, surface reflectivities are computed applying the pertinent graphs. These surface reflectivities are used to estimate the surface albedo for the entire solar spectrum. The estimated albedos are in the range 0.34-0.52, higher than the values reported by most previous researchers from space measurements, but are consistent with laboratory and in situ measurements.
    Schlagwort(e): EARTH RESOURCES AND REMOTE SENSING
    Materialart: Remote Sensing of Environment; 5; 4, 19; 1976
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  • 10
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    The impact of earth resources exploration from space (1976)
    In:  Other Sources
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    Publikationsdatum: 2011-08-17
    Beschreibung: Remote sensing of the earth from satellite systems such as Landsat, Nimbus, and Skylab has demonstrated the potential influence of such observations on a number of major human concerns. These concerns include the management of food, water and fiber resources, the exploration and management of mineral and energy resources, the protection of the environment, the protection of life and property, and improvements in shipping and navigation.
    Schlagwort(e): EARTH RESOURCES AND REMOTE SENSING
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  • 11
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    Thermographic mosaic of Yellowstone National Park (1976)
    In:  Other Sources
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    Publikationsdatum: 2011-08-17
    Beschreibung: An uncontrolled aerial thermographic mosaic of Yellowstone National Park was assembled from the videotape record of 13 individual thermographs obtained with linescan radiometers. Post mission processing of the videotape record rectified the nadir line to a topographic map base, corrected for v/h variations in adjacent flight lanes, corrected for yaw and pitch distortions, and distortions produced by nonlinearity of the side-wise scan. One of the purposes of the thermographic study was to delineate the areas of thermal emission (hot springs, geysers, etc.) throughout the Park, a study which could have great value in reconnaissance surveys of geothermal areas in remote regions or regions of high relief.
    Schlagwort(e): EARTH RESOURCES AND REMOTE SENSING
    Materialart: Photogrammetric Engineering and Remote Sensing; 42; Oct. 197
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  • 12
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    Satellite measurement of mass of Sahara dust in the atmosphere (1976)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: Landsat 1 measurements of nadir radiance are used to obtain the mass of particulates in a vertical column of dust from the Sahara Desert. A radiative transfer model, constructed with knowledge of a few values of optical parameters measured from a ship, is developed to account for the measured radiance values. Measurement and model accuracies are discussed. It is found that the mass of particulates with smaller than a 10 micron radius in a vertical column is 1.6 g/sq m.
    Schlagwort(e): EARTH RESOURCES AND REMOTE SENSING
    Materialart: Applied Optics; 15; Oct. 197
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  • 13
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    Reliability and structural integrity (1976)
    In:  Other Sources
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    Publikationsdatum: 2011-08-17
    Beschreibung: An analytic model is developed to calculate the reliability of a structure after it is inspected for cracks. The model accounts for the growth of undiscovered cracks between inspections and their effect upon the reliability after subsequent inspections. The model is based upon a differential form of Bayes' Theorem for reliability, and upon fracture mechanics for crack growth.
    Schlagwort(e): STRUCTURAL MECHANICS
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  • 14
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    Flooding of Monroe County, Michigan - A comparison of three remote sensor data sets (1976)
    In:  Other Sources
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    Publikationsdatum: 2011-08-17
    Beschreibung: During the spring of 1973, three techniques were used to obtain remotely sensed data pertaining to the flooded shoreline of Monroe County, Michigan. Although digitized data from the Earth Resources Technology Satellite were available on magnetic tapes, analysis was based on interpretation methods normally used for aerial photography, since the black and white IR photography and side-looking airborne radar (SLAR) data were available only as images. Using IR photography as the standard, it was found that ERTS-1 Band 7 imagery had a 93% accuracy in detecting areas in the combined category of open water and flooded fields. X(HH) data from SLAR detected that built-up and wet areas were built-up (89 to 100% accuracy), but not that they were wet. It is suggested that these two sensors used in concert from orbital heights could provide information useful to relief organizations in flooded areas. It is considered likely that SLAR data will improve as higher resolution becomes available.
    Schlagwort(e): EARTH RESOURCES AND REMOTE SENSING
    Materialart: Michigan Academician; 8; Spring 1
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  • 15
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    Resizing procedure for structures under combined mechanical and thermal loading (1976)
    In:  Other Sources
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    Publikationsdatum: 2011-08-17
    Beschreibung: The fully-stressed design (FSD) appears to be the most widely used approach for sizing of flight structures under strength and minimum-gage constraints. Almost all of the experience with FSD has been with structures primarily under mechanical loading as opposed to thermal loading. In this method the structural sizes are iterated with the step size, depending on the ratio of the total stress to the allowable stress. In this paper, the thermal fully-stressed design (TFSD) procedure developed for problems involving substantial thermal stress is extended to biaxial stress members using a Von Mises failure criterion. The TFSD resizing procedure for uniaxial stress is restated and the new procedure for biaxial stress members is developed. Results are presented for an application of the two procedures to size a simplified wing structure.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: AIAA Journal; 14; Oct. 197
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  • 16
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    Don't waste waterweeds (1976)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: Experiments carried out at the NASA National Space Technology Laboratories indicate that water hyacinths can absorb organic chemicals, heavy metals, nutrients, and other materials from waste water while producing large quantities of biomass, which can be used to produce a gas containing 60-80% methane. When grown in sewage free of toxic materials, the biomass can be used as a potential source of fertilizer or animal feed supplements. The use of hot water from nuclear power plants to grow water hyacinths during the winter months is particularly attractive, since the hyacinths could act as an added safety filtration system for the removal of radioactive elements.
    Schlagwort(e): EARTH RESOURCES AND REMOTE SENSING
    Materialart: New Scientist; 71; Aug. 12
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  • 17
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    Paragenesis and petrogenesis of a corundum-bearing marble at Hunza /Kashmir/ (1976)
    In:  Other Sources
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    Publikationsdatum: 2011-08-17
    Schlagwort(e): EARTH RESOURCES AND REMOTE SENSING
    Materialart: Mineralium Deposita; 11; 1976
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  • 18
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    Effect of longitudinal or inplane deformation and inertia on the large amplitude flexural vibrations of slender beams and thin plates (1976)
    In:  Other Sources
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    Publikationsdatum: 2011-08-17
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: Journal of Sound and Vibration; 49; Dec. 8
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  • 19
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    Imaging radar applications to mapping and charting (1976)
    In:  Other Sources
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    Publikationsdatum: 2011-08-17
    Beschreibung: The paper outlines the major actual and potential radar mapping applications, gives an account of the present state of satellite radar imaging, and reviews the radargrammetric work achieved since 1972. Attention is focused on the mapping methods and accuracy regarding single-image radar mapping, stereo radargrammetry, and mapping from blocks of overlapping imagery. It is recommended that more radargrammetric expertise be applied in radar mapping projects so that full advantage may be taken of the metric information potential of imaging radar.
    Schlagwort(e): EARTH RESOURCES AND REMOTE SENSING
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  • 20
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    Precision processing of earth image data (1976)
    In:  Other Sources
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    Publikationsdatum: 2011-08-17
    Beschreibung: Precise corrections of Landsat data are useful for generating land-use maps, detecting various crops and determining their acreage, and detecting changes. The paper discusses computer processing and visualization techniques for Landsat data so that users can get more information from the imagery. The elementary unit of data in each band of each scene is the integrated value of intensity of reflected light detected in the field of view by each sensor. To develop the basic mathematical approach for precision correction of the data, differences between positions of ground control points on the reference map and the observed control points in the scene are used to evaluate the coefficients of cubic time functions of roll, pitch, and yaw, and a linear time function of altitude deviation from normal height above local earth's surface. The resultant equation, termed a mapping function, corrects the warped data image into one that approximates the reference map. Applications are discussed relative to shade prints, extraction of road features, and atlas of cities.
    Schlagwort(e): EARTH RESOURCES AND REMOTE SENSING
    Materialart: American Scientist; 64; Sept
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  • 21
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    Compensating for environmental variability in the thermal inertia approach to remote sensing of soil moisture (1976)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: A procedure is developed for removing data scatter in the thermal-inertia approach to remote sensing of soil moisture which arises from environmental variability in time and space. It entails the utilization of nearby National Weather Service air temperature measurements to normalize measured diurnal surface temperature variations to what they would have been for a day of standard diurnal air temperature variation, arbitrarily assigned to be 18 C. Tests of the procedure's basic premise on a bare loam soil and a crop of alfalfa indicate it to be conceptually sound. It is possible that the technique could also be useful in other thermal-inertia applications, such as lithographic mapping.
    Schlagwort(e): EARTH RESOURCES AND REMOTE SENSING
    Materialart: Journal of Applied Meteorology; 15; Aug. 197
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  • 22
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    Remote sensing of the surface emissivity at 9 microns over the globe (1976)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: The infrared spectral measurements made by the Nimbus 4 infrared interferometer spectrometer (Iris) for a period of about 10 months are used to study the surface emissivity properties over the globe. It is found that the surface emissivity at 9 microns, as measured by Iris with a circular field of view of about 100-km diameter, is significantly less than unity over arid and semiarid areas. The spectral features in the 8-12-micron window observed over these lands reveal emissivity characteristics essentially due to quartz (SiO2). It is found that these emissivity features are significantly weakened by the presence of clay, clay horizons, or pedogenic horizons in the soil. Low emissivity is observed over sandy or sandy loam areas (psamments) with no clay or pedogenic horizons.
    Schlagwort(e): EARTH RESOURCES AND REMOTE SENSING
    Materialart: Journal of Geophysical Research; 81; July 20
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  • 23
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    The use of remote sensing imagery for environmental land use and flood hazard mapping (1976)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: Flood hazard maps have been constructed for Graham, Yuma, and Yavapai Counties in Arizona using remote sensing techniques. Watershed maps of priority areas were selected on the basis of their interest to the county planning staff and represented areas of imminent or ongoing development and those known to be subject to inundation by storm runoff. Landsat color infrared imagery at scales of 1:1,000,000, 1:500,000, and 1:250,000 was used together with high-altitude aerial photography at scales of 1:120,000 and 1:60,000 to determine drainage patterns and erosional features, soil type, and the extent and type of ground cover. The satellite imagery was used in the form of 70 mm chips for enhancement in a color additive viewer and in all available enlargement modes. Field checking served as the main backup to the interpretations. Areas with high susceptibility to flooding were determined with a high level of confidence from the remotely sensed imagery.
    Schlagwort(e): EARTH RESOURCES AND REMOTE SENSING
    Materialart: Journal of Environmental Sciences; 19; May-June
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  • 24
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    Static load-carrying capacity of circular rigid-plastic plates under Gaussian distribution of pressure (1976)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: International Journal of Solids and Structures; 12; 8, 19; 1976
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  • 25
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    Large amplitude free vibrations of tapered beams (1976)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: The Galerkin method is used to investigate the large-amplitude free vibrations of simply supported and clamped tapered beams of rectangular cross-section which are frequently encountered in practical structures. Two types of linear tapers are considered: breadth and depth tapers. Two solutions are obtained for each type of taper, using trigonometric and polynomial displacement distributions. Frequency-amplitude relationships are obtained for all these cases for the fundamental flexural mode. The results indicate good agreement between trigonometric and polynomial solutions for all cases. The nonlinearity is noted to be always of the hardening type and, as expected, it is severe for beams with depth taper as compared with beams with breadth taper.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: AIAA Journal; 14; Feb. 197
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  • 26
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    Applications of space technology to developing nations (1976)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: The use of imagery from the Landsat spacecraft for the monitoring and management of natural resources in developing countries is discussed. The Landsat imagery can be used to make cartographic maps at scales of 1:250,000 which meet the US National Map Accuracy Standards, providing a means of map updating to correct for river meanders or changing shorelines. The Landsat data can also be used in defining and measuring agricultural areas, identifying pest breeding areas, and monitoring irrigation practices and crop performance. Total volume estimates can be obtained in many cases for surface bodies of water, and subsurface water supplies can be detected from changes in vegetation in some instances.
    Schlagwort(e): EARTH RESOURCES AND REMOTE SENSING
    Materialart: COSPAR Information Bulletin; 75, A; Apr. 197
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  • 27
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    Remote profiling of lake ice using an S-band short-pulse radar aboard an all-terrain vehicle (1976)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: A short-pulse (one nanosecond) S-band radar system was developed to supplement the information obtained with the aid of the SLAR system of the Great Lakes ice information system. It is the objective of the ice information system to aid in extending the winter navigation season. The SLAR imagery cannot be interpreted directly to obtain information concerning the thickness of the ice. This information is to be provided by a remote ice measuring system utilizing nanosecond radar pulses. A description is given of investigations in which such a system was installed on a C-47 aircraft. In other studies reported an S-band short-pulse radar was mounted on an all-terrain vehicle.
    Schlagwort(e): EARTH RESOURCES AND REMOTE SENSING
    Materialart: Radio Science; 11; Apr. 197
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  • 28
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    Beaufort Sea ice zones as delineated by microwave imagery (1976)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: Microwave and infrared data were obtained from a research aircraft over the Beaufort Sea ice from the shoreline of Harrison Bay northward to a latitude of almost 81 deg N. The data acquired were compared with microwave data obtained on the surface at an approximate position of 75 deg N, 150 deg W. Over this north-south transect of the polar ice canopy it was discovered that the sea ice could be divided into five distinct zones. The shorefast sea ice was found to consist uniformly of first-year sea ice. The second zone was found to be a mixture of first-year sea ice, medium size multiyear floes, and many recently refrozen leads, polynyas, and open water; considerable shearing activity was evident in this zone. The third zone was a mixture of first-year and multiyear sea ice which had a uniform microwave signature. The fourth zone was found to be a mixture of first-year sea ice and medium-to-large size multiyear floes which was similar in composition to the second zone. The fifth zone was almost exclusively multiyear ice extending to the North Pole.
    Schlagwort(e): EARTH RESOURCES AND REMOTE SENSING
    Materialart: Journal of Geophysical Research; 81; Feb. 20
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  • 29
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    Ground location of satellite scanner data (1976)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: This paper presents simple and accurate mathematical formulation for determining the ground location of remote sensor data. The techniques used are based on elementary concepts of differential geometry and lead to the development of a relation that gives location as a function of surface ellipticity, satellite position, velocity, attitude, and scanner orientation. The formula lends itself to simply computer coding and will hopefully lead to a standardization of the various techniques which have been developed to solve this problem.
    Schlagwort(e): EARTH RESOURCES AND REMOTE SENSING
    Materialart: Photogrammetric Engineering and Remote Sensing; 42; Apr. 197
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  • 30
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    Structural optimization via a design space hierarchy (1976)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: Mathematical programming techniques provide a general approach to automated structural design. An iterative method is proposed in which design is treated as a hierarchy of subproblems, one being locally constrained and the other being locally unconstrained. It is assumed that the design space is locally convex in the case of good initial designs and that the objective and constraint functions are continuous, with continuous first derivatives. A general design algorithm is outlined for finding a move direction which will decrease the value of the objective function while maintaining a feasible design. The case of one-dimensional search in a two-variable design space is discussed. Possible applications are discussed. A major feature of the proposed algorithm is its application to problems which are inherently ill-conditioned, such as design of structures for optimum geometry.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: International Journal for Numerical Methods in Engineering; 10; 3, 19; 1976
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  • 31
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    Stall flutter and nonlinear divergence of a two-dimensional flat plate wing (1976)
    In:  Other Sources
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    Publikationsdatum: 2011-08-17
    Beschreibung: Tests were conducted in a small wind tunnel to study the torsional stall flutter behavior of a two-dimensional flat-plate wing pivoted about the midchord. The nonlinear static divergence equilibrium properties of the wing were well predicted from the measured static moment characteristics. Large amplitude limit cycles ranging from plus or minus 11 degrees to plus or minus 100 degrees were observed. Stall flutter occurred above a critical value of a reduced frequency of about 2. Self-excitation occurred for initial angles of attack between 0 and 8 degrees. Nondimensional harmonic coefficients were extracted from the free transient vibration tests for amplitudes up to 80 degrees.
    Schlagwort(e): STRUCTURAL MECHANICS
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  • 32
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    Geothermal flux through palagonitized tephra, Surtsey, Iceland - The Surtsey temperature-data-relay experiment via Landsat-1 (1976)
    In:  Other Sources
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    Publikationsdatum: 2011-08-17
    Beschreibung: The net geothermal flux through palagonitized basaltic tephra rims of the Surtur I and Surtur II craters at Surtsey, Iceland, in 1972, is estimated at 780 plus or minus 325 microcal/sq cm/s, indicating a decline since 1969 when a flux of 1500 microcal/sq cm/s was estimated. Heat flux in this range characterizes the postvolcanic environment on Surtsey in which the subaerial polagonitization of basaltic tephra is associated with mass transfer of hydrothermal vapor, either of meteoric or sea-water origin, only a few years after cessation of eruptive activity. The flux estimation is the result of the Surtsey data-relay experiment via Landsat-1 which was carried out in several phases. Temperature data were transmitted for a 38-day period in November and December 1972. A near-surface vertical gradient of 69.4 C/m was obtained, suggesting a mixed mechanism of heat transfer, partitioned between conduction and convection.
    Schlagwort(e): EARTH RESOURCES AND REMOTE SENSING
    Materialart: U.S. Geological Survey; vol. 4
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  • 33
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    Exploration for porphyry copper deposits in Pakistan using digital processing of Landsat-1 data (1976)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: Rock-type classification by digital-computer processing of Landsat-1 multispectral scanner data has been used to select 23 prospecting targets in the Chagai District, Pakistan, five of which have proved to be large areas of hydrothermally altered porphyry containing pyrite. Empirical maximum and minimum apparent reflectance limits were selected for each multispectral scanner band in each rock type classified, and a relatively unrefined classification table was prepared. Where the values for all four bands fitted within the limits designated for a particular class, a symbol for the presumed rock type was printed by the computer at the appropriate location. Drainage channels, areas of mineralized quartz diorite, areas of pyrite-rich rock, and the approximate limit of propylitic alteration were very well delineated on the computer-generated map of the test area. The classification method was used to evaluate 2,100 sq km in the Mashki Chah region. The results of the experiment show that outcrops of hydrothermally altered and mineralized rock can be identified from Landsat-1 data under favorable conditions.
    Schlagwort(e): EARTH RESOURCES AND REMOTE SENSING
    Materialart: U.S. Geological Survey; vol. 4
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  • 34
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    Lattice theory of three-dimensional cracks (1976)
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    Publikationsdatum: 2011-08-16
    Beschreibung: The problem of the stability of a three-dimensional crack is analyzed within a lattice-statics approximation. The consequence of introducing a jog into the crack face as well as the effects of various nonlinear-force laws are studied. The phenomenon of lattice trapping (upper and lower bounds on the applied stress for an equilibrium crack of given length) is again obtained. It is possible to obtain some physical insight into which aspects of the force law are critical for crack stability. In particular, the inadequacy of a thermodynamic approach - which relates the critical stress to a surface energy corresponding to the area under the cohesive-force-vs-displacement curve - is demonstrated. Surface energy is a global property of the cohesive-force law. Crack stability is sensitive to much more refined aspects of the cohesive-force law. Crack healing is sensitive to the long-range portion of the cohesive force. Crack expansion is sensitive to the position of the maximum in the cohesive-force relation.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: Journal of Applied Physics; 47; Feb. 197
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  • 35
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    ERTS-1 data applied to strip mining (1976)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: Two coal basins within the western region of the Potomac River Basin contain the largest strip-mining operations in western Maryland and West Virginia. The disturbed strip-mine areas were delineated along with the surrounding geological and vegetation features by using ERTS-1 data in both analog and digital form. The two digital systems employed were (1) the ERTS analysis system, a point-by-point digital analysis of spectral signatures based on known spectral values and (2) the LARS automatic data processing system. These two systems aided in efforts to determine the extent and state of strip mining in this region. Aircraft data, ground-verification information, and geological field studies also aided in the application of ERTS-1 imagery to perform an integrated analysis that assessed the adverse effects of strip mining. The results indicated that ERTS can both monitor and map the extent of strip mining to determine immediately the acreage affected and to indicate where future reclamation and revegetation may be necessary.
    Schlagwort(e): EARTH RESOURCES AND REMOTE SENSING
    Materialart: Photogrammetric Engineering and Remote Sensing; 42; Feb. 197
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  • 36
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    Remote measurement of water color (1976)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: This paper contains a discussion of the requirements and approaches which can be taken in the development of techniques for the analysis of remote multispectral imagery of natural bodies of water. There are two general approaches which can be used in the analysis of multispectral water color data collected by aircraft or satellite remote sensors. With the theoretical modeling approach, optically important constituents of natural waters are mathematically related to the upwelling radiance spectrum received by the remote sensor. With the empirical approach, the relationships are determined empirically by comparing remote sensing data with surface truth data. There are several levels of mathematical sophistication which can be applied to both approaches. The two approaches are discussed in some detail and it is concluded that the two approaches are closely related and should be pursued simultaneously for maximum utilization of the laboratory and field measurement data which will be needed. A set of minimum surface truth measurement parameters and techniques is suggested.
    Schlagwort(e): EARTH RESOURCES AND REMOTE SENSING
    Materialart: Remote Sensing of Environment; 5; 1, 19; 1976
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  • 37
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    Side-looking radar mosaicking experiment (1976)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: A block of 24 overlapping synthetic aperture side-looking radar images flown over a well mapped area of about 90,000 sq km provided an opportunity to evaluate the mapping accuracy achieved in current radar mosaicking projects. The maps of scale 1:24,000 that are available in the imaged area permitted the study of the geometric errors of the radar mosaics and of individual radar strips. An estimate was obtained for the effect of the distribution and density of ground control points and for the accuracy of different mosaicking methods that are currently employed with synthetic aperture radar images. It is shown that a successful radar mosaicking process requires the elimination of image errors of up to several kilometers. These errors are introduced as a result of the limited precision of the inertial aircraft navigation. An example of a radar mapping effort in which the navigation errors could be eliminated is presented. The resulting radar mosaics have residual RMS mapping errors of planimetry of about plus or minus 150 m.
    Schlagwort(e): EARTH RESOURCES AND REMOTE SENSING
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  • 38
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    Symmetric stiffness matrix for incompressible hyperelastic materials (1976)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: Symmetric structure matrices are derived for solving plane strain and axisymmetric problems involving incompressible hyperelastic materials. An infinite hollow cylinder subjected to internal pressure is considered as an example. Displacement and hydrostatic pressure profiles are calculated using the Newton-Raphson iteration technique. The results are in good agreement with the exact curves.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: AIAA Journal; 14; Mar. 197
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  • 39
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    Dynamic response of membranes with finite elements (1976)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: A general set of finite-element equations is developed for treating the nonlinear dynamic response of membranes consisting of complex nonlinear materials. The approach proposed by Key (1974) for a most complete treatment of the finite-element method to the nonlinear dynamic analysis of solids is used in developing the nonlinear equations of motion for membranes with cubic quadrilateral finite elements. The computations are kept general with respect to material modeling by computing the deformation gradient and requiring a constitutive subroutine to supply the Cauchy stress. An example calculation of the vibration of a square membrane demonstrates the accuracy of the formulation for small deformation theory and shows the nonlinear effect of large deformations.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: American Society of Civil Engineers; Journal
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  • 40
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    Disjoint design spaces in the optimization of harmonically excited structures (1976)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: The paper deals with a method of optimizing harmonically or dynamically excited structures which removes the frequency constraint (that specifies that the structure's first natural frequency of vibration must be greater than the excitation frequency), replaces the displacement constraint by an inequality constraint on the allowable stress and applies finite element approximations to the continuous one-dimensional structures. When the problem is posed in this manner, the feasible design space is disconnected or 'disjoint'. An attempt is made to explain this disjointness by studying the optimal design of a thin-walled cantilevered rod subjected to steady, simple harmonic torsional excitation. The finite element method is applied to the optimization of a harmonically excited structure with an arbitrary number of design variables, with the disjointness of the design space, a complicating factor.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: AIAA Journal; 14; Feb. 197
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  • 41
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    NASTRAN used in a production environment (1976)
    In:  CASI
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    Publikationsdatum: 2016-06-07
    Beschreibung: A finite element analysis procedure built around the NASTRAN system is assessed. A number of support programs that were either written or modified to interface with NASTRAN and some improvements that were made to NASTRAN itself are noted. Some typical models are analyzed and an actual schedule is followed for constructing and analyzing the models to support a large design program.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Ames Res. Center NASTRAN: User's Experiences; p 531-554
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  • 42
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    Modal seismic analysis of a nuclear power plant control panel and comparison with SAP 4 (1976)
    In:  CASI
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    Publikationsdatum: 2016-06-07
    Beschreibung: The application of NASTRAN to seismic analysis by considering the example of a nuclear power plant control panel was considered. A modal analysis of a three-dimensional model of the panel, consisting of beam and quadri-lateral membrane elements, is performed. Using the results of this analysis and a typical response spectrum of an earthquake, the seismic response of the structure is obtained. ALTERs required to the program in order to compute the maximum modal responses as well as the resultant response are given. The results are compared with those obtained by using the SAP IV computer program.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Ames Res. Center MATRAN: User's Experiences; p 515-530
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  • 43
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    Some applications of the NASTRAN level 16 subsonic flutter analysis capability (1976)
    In:  CASI
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    Publikationsdatum: 2016-06-07
    Beschreibung: The Level 16 flutter analysis capability was applied to an aspect-ratio-6.8 subsonic transport type wing, an aspect-ratio-1.7 arrow wing, and an aspect-ratio-1.3 all movable horizontal tail with a geared elevator. The transport wing and arrow wing results are compared with experimental results obtained in the Langley transonic dynamic tunnel and with other calculated results obtained using subsonic lifting surface (kernel function) unsteady aerodynamic theory.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASTRAN: User's Experiences; p 495-512
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  • 44
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    A postprocessor system for the data reduction and post analysis of NASTRAN results (1976)
    In:  CASI
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    Publikationsdatum: 2016-06-07
    Beschreibung: NASTRAN analysis results are scanned to determine maximum and minimum displacements, forces and stresses. Allowables and margins of safety are computed, and in the case of multiple loading conditions, envelopes for displacements, forces, stresses and margins of safety are also produced for specified element sets. Graphical plots of the reduced or the regular NASTRAN results may be obtained superimposed either of a developed fuselage strip or on a projection of any specified part of the finite element model. The use of the data reduction, post analysis and graphical plotting capabilities provide the analyst with a fast and convenient tool for the study of NASTRAN analysis results and their presentation for project documentation.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Ames Res. Center NASTRAN: User's Experiences; p 555-580
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  • 45
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    Addition of higher order plate elements to NASTRAN (1976)
    In:  CASI
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    Publikationsdatum: 2016-06-07
    Beschreibung: Two plate elements, the linear strain triangular membrane element CTRIM6 and the higher order plate bending element CTRPLT1, were added to NASTRAN Level 16.0. The theoretical formulation, programming details, and bulk data information pertaining to the addition of these elements are discussed. Sample problems illustrating the use of these elements are presented.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Ames Res. Center NASTRAN: User's Experiences; p 439-478
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  • 46
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    Implementation on a nonlinear concrete cracking algorithm in NASTRAN (1976)
    In:  CASI
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    Publikationsdatum: 2016-06-07
    Beschreibung: A computer code for the analysis of reinforced concrete structures was developed using NASTRAN as a basis. Nonlinear iteration procedures were developed for obtaining solutions with a wide variety of loading sequences. A direct access file system was used to save results at each load step to restart within the solution module for further analysis. A multi-nested looping capability was implemented to control the iterations and change the loads. The basis for the analysis is a set of mutli-layer plate elements which allow local definition of materials and cracking properties.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Ames Res. Center NASTRAN: User's Experiences; p 479-494
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  • 47
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    The quarter-point quadratic isoparametric element as a singular element for crack problems (1976)
    In:  CASI
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    Publikationsdatum: 2016-06-07
    Beschreibung: The quadratic isoparametric elements which embody the inverse square root singularity are used for calculating the stress intensity factors at tips of cracks. The strain singularity at a point or an edge is obtained in a simple manner by placing the mid-side nodes at quarter points in the vicinity of the crack tip or an edge. These elements are implemented in NASTRAN as dummy elements. The method eliminates the use of special crack tip elements and in addition, these elements satisfy the constant strain and rigid body modes required for convergence.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Ames Res. Center NASTRAN: User's Experiences; p 419-438
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  • 48
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    Analysis of the Learjet 35/36 Wing and Correlation with Experimental Results (1976)
    In:  CASI
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    Publikationsdatum: 2016-06-07
    Beschreibung: Two NASTRAN models of the Gates Learjet Corporation Model 35/36 Wing were developed. The models and the problems encountered in their development are discussed. A skin buckling analysis used for the ultimate loading conditions is presented. A discussion of the static tests and the correlation of the static test with the NASTRAN results and the results of a supplementary semimonocoque beam analysis are also included.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Ames Res. Center NASTRAN: User's Experiences; p 331-352
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  • 49
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    Application of NASTRAN to large space structures (1976)
    In:  CASI
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    Publikationsdatum: 2016-06-07
    Beschreibung: The application of NASTRAN to design studies of two very large-area lightweight structures is described. The first is the Satellite Solar Power Station, while the second is a deployable three hundred meter diameter antenna. A brief discussion of the operation of the SSPS is given, followed by a description of the structure. The use of the NASTRAN program for static, vibration and thermal analysis is illustrated and some results are given. Next, the deployable antenna is discussed and the use of NASTRAN for static analysis, buckling analysis and vibration analysis is detailed.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Ames Res. Center NASTRAN: User's Experiences; p 295-330
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  • 50
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    NASTRAN as an analytical research tool for composite mechanics and composite structures (1976)
    In:  CASI
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    Publikationsdatum: 2016-06-07
    Beschreibung: Selected examples are described in which NASTRAN is used as an analysis research tool for composite mechanics and for composite structural components. The examples were selected to illustrate the importance of using NASTRAN as an analysis tool in this rapidly advancing field.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASTRAN: User's Experiences; p 381-418
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    A summary of NASTRAN fluid/structure interaction capabilities (1976)
    In:  CASI
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    Publikationsdatum: 2016-06-07
    Beschreibung: A summary of fluid/structure interaction capabilities for the NASTRAN computer program is presented. Indirect applications of the program towards solving this class of problem were concentrated on. For completeness and comparitive purposes, direct usage of NASTRAN is briefly discussed. The solution technology addresses both steady state and transient dynamic response problems.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Ames Res. Center NASTRAN: User's Experiences; p 229-250
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    A finite element-analytical method for modeling a structure in an infinite fluid (1976)
    In:  CASI
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    Publikationsdatum: 2016-06-07
    Beschreibung: A method is described from which the interaction of an elastic structure with an infinite acoustic fluid is determined. The displacements of the structure and the pressure field of the immediate surrounding fluid are modeled by finite elements, and the remaining pressure field of the infinite fluid region is given by an analytical expression. This method yields a frequency dependent boundary condition for the outer fluid boundary when applied to the frequency response of an elastic beam in contact with an acoustic fluid. The frequency response of the beam is determined using NASTRAN, and compares favorably to the exact solution which is also presented. The effect of the fluid on the response of the structure at low and high frequencies is due to added mass and damping characteristics, respectively.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Ames Res. Center NASTRAN: User's Experiences; p 251-272
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    Deformations of thick two-material cylinder under axially varying radial pressure (1976)
    In:  CASI
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    Publikationsdatum: 2016-06-07
    Beschreibung: Stresses and deformations in thick, short, composite cylinder subjected to axially varying radial pressure are studied. Effect of slippage at the interface is examined. In the NASTRAN finite element model, multipoint constraint feature is utilized. Results are compared with theoretical analysis and SAP-IV computer code. Results from NASTRAN computer code are in good agreement with the analytical solutions. Results suggest a considerable influence of interfacial slippage on the axial bending stresses in the cylinder.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Ames Res. Center NASTRAN: User's Experiences; p 161-176
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  • 54
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    A comparison of the two NASTRAN differential stiffness techniques (1976)
    In:  CASI
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    Publikationsdatum: 2016-06-07
    Beschreibung: NASTRAN contains two techniques to solve the differential stiffness problems. One is incorporated in a new static analysis rigid format and the other is contained in a new normal modes analysis rigid format. The two techniques relative to computational accuracy and time of execution are compared.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Ames Res. Center NASTRAN: User's Experiences; p 149-160
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    A NASTRAN implementation of the doubly asymptotic approximation for underwater shock response (1976)
    In:  CASI
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    Publikationsdatum: 2016-06-07
    Beschreibung: A detailed description is given of how the decoupling approximation known as the doubly asymptotic approximation is implemented with NASTRAN to solve shock problems for submerged structures. The general approach involves locating the nonsymmetric terms (which couple structural and fluid variables) on the right hand side of the equations. This approach results in coefficient matrices of acceptable bandwidth but degrades numerical stability, requiring a smaller time step size than would otherwise be used. It is also shown how the structure's added (virtual) mass matrix, is calculated with NASTRAN.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Ames Res. Center NASTRAN: User's Experiences; p 207-228
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  • 56
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    The GSFC NASTRAN thermal analyzer new capabilities (1976)
    In:  CASI
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    Publikationsdatum: 2016-06-07
    Beschreibung: An overview of four analysis capabilities, which developed and integrated into the NASTRAN Thermal Analyzer, is given. To broaden the scope of applications, these additions provide the NTA users with the following capabilities: (1) simulating a thermal louver as a means of the passive thermal control, (2) simulating a fluid loop for transporting energy as a means of the active thermal control, (3) condensing a large sized finite element model for an efficient transient thermal analysis, and (4) entering multiple boundary condition sets in a single submission for execution in steady state thermal analyses.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASTRAN: User's Experiences; p 119-126
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    Real eigenvalue analysis in NASTRAN by the tridiagonal reduction (FEER) method (1976)
    In:  CASI
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    Publikationsdatum: 2016-06-07
    Beschreibung: Implementation of the tridiagonal reduction method for real eigenvalue extraction in structural vibration and buckling problems is described. The basic concepts underlying the method are summarized and special features, such as the computation of error bounds and default modes of operation are discussed. In addition, the new user information and error messages and optional diagnostic output relating to the tridiagonal reduction method are presented. Some numerical results and initial experiences relating to usage in the NASTRAN environment are provided, including comparisons with other existing NASTRAN eigenvalue methods.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASTRAN" User's Experiences; p 127-148
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  • 58
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    Thermal analyses of the International Ultraviolet Explorer (IUE) scientific instrument using the NASTRAN thermal analyzer (NTA): A general purpose summary (1976)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: The NTA Level 15.5.2/3, was used to provide non-linear steady-state (NLSS) and non-linear transient (NLTR) thermal predictions for the International Ultraviolet Explorer (IUE) Scientific Instrument (SI). NASTRAN structural models were used as the basis for the thermal models, which were produced by a straight forward conversion procedure. The accuracy of this technique was sub-sequently demonstrated by a comparison of NTA predicts with the results of a thermal vacuum test of the IUE Engineering Test Unit (ETU). Completion of these tasks was aided by the use of NTA subroutines.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASTRAN: User's Experiences; p 99-118
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  • 59
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    Automated fully-stressed design with NASTRAN (1976)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: An automated strength sizing capability is described. The technique determines the distribution of material among the elements of a structural model. The sizing is based on either a fully stressed design or a scaled feasible fully stressed design. Results obtained from the application of the strength sizing to the structural sizing of a composite material wing box using material strength allowables are presented. These results demonstrate the rapid convergence of the structural sizes to a usable design.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Ames Res. Center NASTRAN: User's Experiences; p 53-66
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  • 60
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    On modeling and the use of the NASTRAN thermal analyzer (1976)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: Eight alternative modeling techniques to specify prescribed temperature at grid or scalar points for transient thermal analyses are presented. Four cases are for constant temperatures, and the others are time varying temperature functions. Theoretical explications and detailed listing of input data cards used for illustrating different modelings are given. It is shown that the NTA is exploited to extend beyond its normal capabilities through innovative modeling techniques. In addition, the effect of node valency on the energy distribution grid points is illustrated and discussed. Guidelines to delineate this effect are given.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASTRAN: User's Experiences; p 3-20
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  • 61
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    Efficient reanalysis of structures by a direct modification method (1976)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: A procedure for the local stiffness modifications of large structures is described. It enables structural modifications without an a priori definition of the changes in the original structure and without loss of efficiency due to multiple loading conditions. The solution procedure, implemented in NASTRAN, involved the decomposed stiffness matrix and the displacement vectors of the original structure. It solves the modified structure exactly, irrespective of the magnitude of the stiffness changes. In order to investigate the efficiency of the present procedure and to test its applicability within a design environment, several real and large structures were solved. The results of the efficiency studies indicate that the break-even point of the procedure varies between 8% and 60% stiffness modifications, depending upon the structure's characteristics and the options employed.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Ames Res. Center NASTRAN: User's Experiences; p 21-52
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  • 62
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    Application of NASTRAN to large deflection supersonic flutter of panels (1976)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: Flat panel flutter at high supersonic Mach number is analyzed using NASTRAN Level 16.0 by means of modifications to the code. Two-dimensional plate theory and quasi-steady aerodynamic theory are employed. The finite element formulation and solution procedure are presented. Modifications to the NASTRAN code are discussed. Convergence characteristics of the iteration processes are also briefly discussed. Effects of aerodynamic damping, boundary support condition and applied in-plane loading are included. Comparison of nonlinear vibration and linear flutter results with analytical solutions demonstrate that excellent accuracy is obtained with NASTRAN.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASTRAN: User's Experiences; p 67-98
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  • 63
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    NASA's plans for future NASTRAN capability (1976)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: Improvements in the NASTRAN systems management office are presented. Among the improvements are the following items: (1) the FEER eigenmethod and its extension to complete eigenvalue problems; (2) the addition of a supersonic flutter package which allows gust response calculations and active control effects as membrane In addition to capabilities mentioned, an error correction information system is also introduced.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASTRAN: User's Experiences; p 1-2
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  • 64
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    Loads technology for supersonic cruise aircraft (1976)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: A flight program to measure atmospheric turbulence at high altitudes (long wavelengths) in a variety of meteorological conditions is described and some results obtained in high altitude wind shear are discussed. Results are also presented from wind tunnel test programs to measure fluctuating pressures associated with over-the-wing configurations. A flexible aircraft take off and landing analysis and an active control landing gear analysis, are developed and their capabilities are described. Efforts to validate these analyses with experimental data are also discussed as well as results obtained from parametric studies.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: Proc. of the SCAR Conf., Pt. 2,; 22 p
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  • 65
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    Simulation of the atmospheric boundary layer in the wind tunnel for modeling of wind loads on low-rise structures (1976)
    In:  Other Sources
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: The lower part of the atmospheric boundary layer (strong wind conditions) was simulated in low speed wind tunnel for the modeling of wind loads on low-rise structures. The turbulence characteristics of the turbulent boundary layer in the wind tunnel are compared with full scale measurements and with measurements made at NASA Wallops Flight Center. Wind pressures measured on roofs of a 1:70 scale model of a small single family dwelling were compared with results obtained from full scale measurements. The results indicate a favorable comparison between full scale and model pressure data as far as mean, r.m.s. and peak pressures are concerned. In addition, results also indicate that proper modeling of the turbulence is essential for proper simulation of the wind pressures.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Langley Res. Center Advan. in Eng. Sci., Vol. 3; p 1167-1176
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  • 66
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    Sound radiation from randomly vibrating beams of finite circular cross section (1976)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: The radiation of sound from vibrating cylindrical beams is analyzed based on the frequency of the beam vibrations and the physical characteristics of the beam and its surroundings. A statistical analysis of random beam vibrations allows this result to be independent of the boundary conditions at the ends of the beam. The acoustic power radiated by the beam can be determined from a knowledge of the frequency band vibration data without a knowledge of the individual modal vibration amplitudes. A practical example of the usefulness of this technique is provided by the application of the theoretical calculations to the prediction of the octave band acoustic power output of the picking sticks of an automatic textile loom. Calculations are made of the expected octave band sound pressure levels based on measured acceleration data. These theoretical levels are subsequently compared with actual sound pressure level measurements of loom noise.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Langley Res. Center Advan. in Eng. Sci., Vol. 3; p 1071-1081
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  • 67
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    On the radiation of sound from baffled finite panels (1976)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: Theoretical and experimental research on structural-acoustic interaction is reviewed. The emphasis is upon the radiation from and acoustic loading of baffled rectangular plates and membranes. The topics discussed include a criterion for strong radiation loading, the mass law for a finite panel, numerical calculation of the radiation impedance of a finite panel in the presence of a parallel mean flow, and experimental determination of the effect of vibration amplitude and Mach number upon panel radiation efficiency.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Langley Res. Center Advan. in Eng. Sci., Vol. 3; p 1043-1055
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  • 68
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    The prediction and measurement of sound radiated by structures (1976)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: Theories regarding the radiation of sound are reviewed and the implementation in strategies for explaining or measuring the sound produced by practical strucutres are discussed. Particular attention is given to those aspects that relate to the determination of the relative amounts of sound generated by various parts of a machine or structure, which can be very useful information for noise reduction efforts.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Langley Res. Center Advan. in Eng. Sci., Vol. 3; p 1031-1042
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  • 69
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    Stress concentration factors around a circular hole in laminated composites (1976)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: Stress concentration factors around a circular hole in a composite laminate are determined. The specific case investigated is a four layer (-45/45/45/-45 degs) graphite epoxy laminate. The factors are determined experimentally by means of electrical resistance strain gages, and analytically by using a hybrid finite element analysis.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Langley Res. Center Advan. in Eng. Sci., Vol. 2; p 711-720
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  • 70
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    Stress intensity at a crack between bonded dissimilar materials (1976)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: The contour integral method is extended to general boundary value problems involving imperfect bonding of dissimilar materials. The loading and restraints are shown to have a significant effect on the stress intensity. Example problems are presented to illustrate the results.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Langley Res. Center Advan. in Eng. Sci., Vol. 2; p 699-709
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  • 71
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    A study on the forced vibration of a Timoshenko beam (1976)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: By using Galerkin's variational method an approximate solution is developed for a system of two differential equations with linear partial derivatives of the second order. This system of differential equations corresponds to the physical model, known in the literature as the Timoshenko Beam. The results obtained are applied to two particular cases representing respectively: the case of a beam with a rectangular section, with a constant height and a basis with a linear variation; and the case of a beam with a constant basis and a height with cubic variation.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: Advan. in Eng. Sci., Vol. 2; p 671-685
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  • 72
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    Neutral elastic deformations (1976)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: Elastic bodies or systems may not require external energy for certain finite and continuous deformations. Conditions providing these kinds of effortless, or neutral, deformations are discussed.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Langley Res. Center Advan. in Eng. Sci., Vol. 2; p 665-670
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  • 73
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    Thermal stresses in a spherical pressure vessel having temperature-dependent, transversely isotropic, elastic properties (1976)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: Rayleigh-Ritz and modified Rayleigh-Ritz procedures are used to construct approximate solutions for the response of a thick-walled sphere to uniform pressure loads and an arbitrary radial temperature distribution. The thermoelastic properties of the sphere are assumed to be transversely isotropic and nonhomogeneous; variations in the elastic stiffness and thermal expansion coefficients are taken to be an arbitrary function of the radial coordinate and temperature. Numerical examples are presented which illustrate the effect of the temperature-dependence upon the thermal stress field. A comparison of the approximate solutions with a finite element analysis indicates that Ritz methods offer a simple, efficient, and relatively accurate approach to the problem.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Langley Res. Center Advan. in Eng. Sci., Vol. 2; p 639-651
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  • 74
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    Fluid-plasticity of thin cylindrical shells (1976)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: Dynamic plastic response of a thin cylindrical shell, immersed in a potential fluid initially at rest and subjected to internal pressure pulse of arbitrary shape and duration, is examined. The shell is assumed to respond as a rigid-perfectly plastic material while the fluid is taken as inviscid and incompressible. The fluid back pressure is incorporated into the equation of motion of the shell as an added mass term. Since arbitrary pulses can be reduced to equivalent rectangular pulses, the equation of motion is solved only for a rectangular pulse. The influence of the fluid in reducing the final plastic deformation is demonstrated by a numerical example.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Langley Res. Center Advan. in Eng. Sci., Vol. 2; p 627-637
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  • 75
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    Large deflections of shallow conical membrane (1976)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: Large deflections of a shallow elastic conical membrane fixed at the outer edge and loaded by either uniform or hydrostatic pressure are investigated. The overning equations were solved by the method of matched asymptotic expansions and by a finite difference method. Agreement between the two methods was excellent for the small values of the perturbation parameter.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Langley Res. Center Advan. in Eng. Sci., Vol. 2; p 575-584
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  • 76
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    Gaussian ideal impulsive loading of rigid viscoplastic plates (1976)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: The response of a thin, rigid, viscoplastic plate subjected to a spatially axisymmetric Gaussian ideal impulse loading was studied analytically. The Gaussian ideal impulse distribution instantaneously imparts a Gaussian initial velocity distribution to the plate, except at the fixed boundary. The plate deforms with monotonically increasing deflections until the initial dynamic energy is completely dissipated in plastic work. The simply supported plate of uniform thickness obeys the von Mises yield criterion and a generalized constitutive equation for rigid, viscoplastic materials. For the small deflection bending response of the plate, neglecting the transverse shear stress in the yield condition and rotary inertia in the equations of dynamic equilibrium, the governing system of equations is essentially nonlinear. A proportional loading technique, known to give excellent approximations of the exact solution for the uniform load case, was used to linearize the problem and obtain analytical solution in the form of eigenvalue expansions. The linearized governing equations required the knowledge of the collapse load of the corresponding static problem.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: Advan. in Eng. Sci., Vol. 2; p 595-616
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  • 77
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    The staging system: Display and edit module (1976)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: The Display and Edit (D and E) Module described is one of six major modules being developed for the STAGING (STructural Analysis through Generalized INteractive Graphics) System. Several remarks are included concerning the computer environment and the architecture of the data base. The utility of this module is emphasized.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Langley Res. Center Advan. in Eng. Sci., Vol. 2; p 543-553
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  • 78
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    An optimal structural design algorithm using optimality criteria (1976)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: An algorithm for optimal design is given which incorporates several of the desirable features of both mathematical programming and optimality criteria, while avoiding some of the undesirable features. The algorithm proceeds by approaching the optimal solution through the solutions of an associated set of constrained optimal design problems. The solutions of the constrained problems are recognized at each stage through the application of optimality criteria based on energy concepts. Two examples are described in which the optimal member size and layout of a truss is predicted, given the joint locations and loads.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Langley Res. Center Advan. in Eng. Sci., Vol. 2; p 521-530
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  • 79
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    Optimum vibrating beams with stress and deflection constraints (1976)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: The fundamental frequency of vibration of an Euler-Bernoulli or a Timoshenko beam of a specified constant volume is maximized subject to the constraint that under a prescribed loading the maximum stress or maximum deflection at any point along the beam axis will not exceed a specified value. In contrast with the inequality constraint which controls the minimum cross-section, the present inequality constraints lead to more meaningful designs. The inequality constraint on stresses is as easily implemented as the minimum cross-section constraint but the inequality constraint on deflection uses a treatment which is an extension of the matrix partitioning technique of prescribing displacements in finite element analysis.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Langley Res. Center Advan. in Eng. Sci., Vol. 2; p 509-519
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  • 80
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    Optimal design against collapse after buckling (1976)
    In:  CASI
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    Publikationsdatum: 2016-06-07
    Beschreibung: After buckling, statically indeterminate trusses, beams, and other strictly symmetric structures may collapse under loads which reach limiting magnitudes. Optimal design is discussed for prescribed values of these collapse loads.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Langley Res. Center Advan. in Eng. Sci., Vol. 2; p 501-508
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  • 81
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    Variational theorems for superimposed motions in elasticity, with application to beams (1976)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: Variational theorems are presented for a theory of small motions superimposed on large static deformations and governing equations for prestressed beams on the basis of 3-D theory of elastodynamics. First, the principle of virtual work is modified through Friedrichs's transformation so as to describe the initial stress problem of elastodynamics. Next, the modified principle together with a chosen displacement field is used to derive a set of 1-D macroscopic governing equations of prestressed beams. The resulting equations describe all the types of superimposed motions in elastic beams, and they include all the effects of transverse shear and normal strains, and the rotatory inertia. The instability of the governing equations is discussed briefly.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Langley Res. Center Advan. in Eng. Sci., Vol. 2; p 481-490
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  • 82
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    Vibrations and stresses in layered anisotropic cylinders (1976)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: An equation describing the radial displacement in a k layered anisotropic cylinder was obtained. The cylinders are initially unstressed but are subjected to either a time dependent normal stress or a displacement at the external boundaries of the laminate. The solution is obtained by utilizing the Vodicka orthogonalization technique. Numerical examples are given to illustrate the procedure.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Langley Res. Center Advan. in Eng. Sci., Vol. 2; p 459-472
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  • 83
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    Response of long, flexible cantilever beams applied root motions (1976)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: Results are presented for an analysis of the response of long, flexible cantilever beams to applied root rotational accelerations. Maximum values of deformation, slope, bending moment, and shear are found as a function of magnitude and duration of acceleration input. Effects of tip mass and its eccentricity and rotatory inertia on the response are also investigated. It is shown that flexible beams can withstand large root accelerations provided the period of applied acceleration can be kept small relative to the beam fundamental period.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: Advan. in Eng. Sci., Vol. 2; p 491-499
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  • 84
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    Incremental analysis of large elastic deformation of a rotating cylinder (1976)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: The effect of finite deformation upon a rotating, orthotropic cylinder was investigated using a general incremental theory. The incremental equations of motion are developed using the variational principle. The governing equations are derived using the principle of virtual work for a body with initial stress. The governing equations are reduced to those for the title problem and a numerical solution is obtained using finite difference approximations. Since the problem is defined in terms of one independent space coordinate, the finite difference grid can be modified as the incremental deformation occurs without serious numerical difficulties. The nonlinear problem is solved incrementally by totaling a series of linear solutions.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Langley Res. Center Advan. in Eng. Sci., Vol. 2; p 473-480
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  • 85
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    Dynamic inelastic response of thick shells using endochronic theory and the method of nearcharacteristics (1976)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: The endochronic theory of plasticity originated by Valanis was applied to study the axially symmetric motion of circular cylindrical thick shells subjected to an arbitrary pressure transient applied at its inner surface. The constitutive equations for the thick shells were obtained. The governing equations are solved by means of the nearcharacteristics method.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Langley Res. Center Advan. in Eng. Sci., Vol. 2; p 449-458
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  • 86
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    Free vibrations of laminated composite elliptic plates (1976)
    In:  CASI
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    Publikationsdatum: 2016-06-07
    Beschreibung: The free vibrations are studied of laminated anisotropic elliptic plates with clamped edges. The analytical formulation is based on a Mindlin-Reissner type plate theory with the effects of transverse shear deformation, rotary inertia, and bending-extensional coupling included. The frequencies and mode shapes are obtained by using the Rayleigh-Ritz technique in conjunction with Hamilton's principle. A computerized symbolic integration approach is used to develop analytic expressions for the stiffness and mass coefficients and is shown to be particularly useful in evaluating the derivatives of the eigenvalues with respect to certain geometric and material parameters. Numerical results are presented for the case of angle-ply composite plates with skew-symmetric lamination.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Langley Res. Center Advan. in Eng. Sci., Vol. 2; p 425-438
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  • 87
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    Coriolis effects on nonlinear oscillations of rotating cylinders and rings (1976)
    In:  CASI
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    Publikationsdatum: 2016-06-07
    Beschreibung: The effects which moderately large deflections have on the frequency spectrum of rotating rings and cylinders are considered. To develop the requisite solution, a variationally constrained version of the Lindstedt-Poincare procedure is employed. Based on the solution developed, in addition to considering the effects of displacement induced nonlinearity, the role of Coriolis forces is also given special consideration.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Langley Res. Center Advan. in Eng. Sci., Vol. 2; p 409-416
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  • 88
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    On the stability of a class of implicit algorithms for nonlinear structural dynamics (1976)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: Stability in energy for the Newmark beta-family of time integration operators for nonlinear material problems is examined. It is shown that the necessary and sufficient conditions for unconditional stability are equivalent to those predicted by Fourier methods for linear problems.
    Schlagwort(e): STRUCTURAL MECHANICS
    Materialart: NASA. Langley Res. Center Advan. in Eng. Sci., Vol. 2; p 385-391
    Format: application/pdf
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  • 89
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    Thematic mapper studies: Data quality analysis (1976)
    In:  Other Sources
    Details
    Publikationsdatum: 2019-06-28
    Schlagwort(e): EARTH RESOURCES AND REMOTE SENSING
    Materialart: NASA-TM-80715
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
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  • 90
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    Design specification for color coded spectral plots (1976)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: There are no author-identified significant results in this report.
    Schlagwort(e): EARTH RESOURCES AND REMOTE SENSING
    Materialart: E80-10245 , NASA-CR-160706 , LEC-9924 , JSC-11851
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
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  • 91
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    Thematic mapper studies band correlation analysis (1976)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: Spectral data representative of thematic mapper candidate bands 1 and 3 to 7 were obtained by selecting appropriate combinations of bands from the JSC 24 channel multispectral scanner. Of all the bands assigned, only candidate bands 4 (.74 mu to .80 mu) and 5 (.80 mu to .91 mu) showed consistently high intercorrelation from region to region and time to time. This extremely high correlation persisted when looking at the composite data set in a multitemporal, multilocation domain. The GISS investigations lend positive confirmation to the hypothesis, that TM bands 4 and 5 are redundant.
    Schlagwort(e): EARTH RESOURCES AND REMOTE SENSING
    Materialart: NASA-TM-80716
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
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  • 92
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    Final design specification for LARSYS modification/Fisher F-distribution thresholding (1976)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: There are no author-identified significant results in this report.
    Schlagwort(e): EARTH RESOURCES AND REMOTE SENSING
    Materialart: E80-10210 , NASA-CR-160648 , LEC-9963 , JSC-11864
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
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  • 93
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    As-built design specification for Metro data edit program (1976)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: There are no author-identified significant results in this report.
    Schlagwort(e): EARTH RESOURCES AND REMOTE SENSING
    Materialart: E80-10201 , NASA-CR-160620 , LEC-9888 , JSC-11838
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
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  • 94
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    Transfer of Interactive Report Extracted Data (TIRED) requirements specification (1976)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: There are no author-identified significant results in this report.
    Schlagwort(e): EARTH RESOURCES AND REMOTE SENSING
    Materialart: E80-10221 , NASA-CR-160611 , LEC-8841-REV-A , JSC-11365-REV-A
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
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  • 95
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    As-built specification for the ERIM tape conversion to LARSYS 2 program (ECTL2) (1976)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: There are no author-identified significant results in this report.
    Schlagwort(e): EARTH RESOURCES AND REMOTE SENSING
    Materialart: E80-10202 , NASA-CR-160614 , LEC-9857 , JSC-11833
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
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  • 96
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    PDP 11/45 LACIE phase 11/111 automatic status and tracking system functional design specification (1976)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: There are no author-identified significant results in this report.
    Schlagwort(e): EARTH RESOURCES AND REMOTE SENSING
    Materialart: E80-10222 , NASA-CR-160613 , LEC-9861 , JSC-11835
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
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  • 97
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    Unbekannt
    Transfer of Interactive Report Extracted Data (TIRED) requirements specification (1976)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: There are no author-identified significant results in this report.
    Schlagwort(e): EARTH RESOURCES AND REMOTE SENSING
    Materialart: E80-10219 , NASA-CR-160615 , LEC-8841 , JSC-11365
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
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  • 98
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    A computer analysis of ERTS data of the Lake Gregory area of South Australia with particular emphasis on its role in terrain classification for engineering (1976)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-28
    Beschreibung: A digital computer and multivariate statistical techniques were used to analyze 4-band multispectral data. A representation of the original data for each of the four bands allows a certain degree of terrain interpretation; however, variations in appearance of sites within and between bands, without additional criteria for deciding which representation should be preferred, create difficulties for classification. Investigation of the video data groups produced by principal components analysis and cluster analysis techniques shows that effective correlations with classifications of terrain produced by conventional methods could be carried out. The analyses also highlighted underlying relationships between the various elements. The approach used allows large areas (185 cm by 185 cm) to be classified into fundamental units within a matter of hours and can be applied to those parts of the Earth where facilities for conventional studies are poor or lacking.
    Schlagwort(e): EARTH RESOURCES AND REMOTE SENSING
    Materialart: E83-10178 , NASA-CR-169785 , NAS 1.26:169785
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
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  • 99
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    Image processing system performance prediction and product quality evaluation (1976)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: The author has identified the following significant results. A new technique for image processing system performance prediction and product quality evaluation was developed. It was entirely objective, quantitative, and general, and should prove useful in system design and quality control. The technique and its application to determination of quality control procedures for the Earth Resources Technology Satellite NASA Data Processing Facility are described.
    Schlagwort(e): EARTH RESOURCES AND REMOTE SENSING
    Materialart: E78-10062 , NASA-CR-156654 , ZE-5185-M-2
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
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  • 100
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    Forest land management by satellite: LANDSAT-derived information as input to a forest inventory system (1976)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: The author has identified the following significant results. Analysis of LANDSAT temporal data, specifically the digitally merged winter and summer scenes, provided the best overall classification results. Comparison of temporal classification results with available ground truth reveal a 94% agreement in the delineation of hardwood categories, a 96% agreement for the combined pine category, and a greater than 50% agreement for each individual pine subcategory. For nearly 1000 acres, compared clearcut acreage estimated with LANDSAT digital data differed from company inventory records by only 3%. Through analysis of summer data, pine stands were successfully classified into subcategories based upon the extent of crown closure. Maximum spectral separability of hardwood and pine stands was obtained from the analysis of winter data.
    Schlagwort(e): EARTH RESOURCES AND REMOTE SENSING
    Materialart: E78-10038 , NASA-CR-155259
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
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