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  • EARTH RESOURCES AND REMOTE SENSING  (774)
  • ASTROPHYSICS  (432)
  • 2010-2014
  • 1980-1984
  • 1975-1979  (1,206)
  • 1925-1929
  • 1977  (1,206)
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  • 2010-2014
  • 1980-1984
  • 1975-1979  (1,206)
  • 1925-1929
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  • 1
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    In:  CASI
    Publication Date: 2006-08-09
    Description: Observations of cosmic and gamma radiation by SAS-2 satellite are summarized and analyzed to determine processes responsible for producing observed galactic radiation. In addition to the production of gamma rays in discrete galactic objects such as pulsars, there are three main mechanisms by which high-energy (greater than 100 MeV) radiation is produced by high-energy interactions involving cosmic rays in interstellar space. These processes, which produce what may be called diffuse galactic gamma-rays, are: (1) the decay of pi mesons produced by interactions of cosmic ray nucleons with interstellar gas nuclei; (2) the bremsstrahlung radiation produced by cosmic ray electrons interacting in the Coulomb fields of nuclei of interstellar gas atoms; and (3) Compton interactions between cosmic ray electrons and low-energy photons in interstellar space.
    Keywords: ASTROPHYSICS
    Type: The Struct. and Content of the Galaxy and Galactic Gamma Rays; p 315-346
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  • 2
    Publication Date: 2006-08-09
    Description: Gamma ray astronomy is now beginning to provide a new look at the galactic structure and the distribution of cosmic rays, both electrons and nucleons, within the galaxy. The observations are consistent with a galactic spiral-arm model in which the cosmic rays are linearly coupled to the interstellar gas on the scale of the spiral arms. The agreement between the predictions of the model and the observations for regions of the plane where both 21-cm and 2.6-mm CO surveys exist emphasizes the need to extend these observations to include the entire plane. Future gamma-ray observations with more sensitivity and better angular resolutions, combined with these radio surveys, should shed new light on the distribution of cosmic rays, the nature of the galaxy, and the location and intensity of the spiral arms.
    Keywords: ASTROPHYSICS
    Type: The Struct. and Content of the Galaxy and Galactic Gamma Rays; p 301-314
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  • 3
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    In:  CASI
    Publication Date: 2006-08-09
    Description: The density distributions of pulsars in luminosity, period, Z-distance, and galactocentric distance were derived, using a uniform sample of pulsars detected during a 408-MHz pulsar survey at Jodrell Bank. There are indications of a fine-scale structure in the spatial distributions and evidence that there is a general correlation with other galactic populations and the overall spiral structure. The electron layer in our galaxy is shown to be wider than the pulsar layer and uniform on a large scale. The number of pulsars in the galaxy has been estimated and used to derive the pulsar birthrate.
    Keywords: ASTROPHYSICS
    Type: NASA. Goddard Space Flight Center The Struct. and Content of the Galaxy and Galactic Gamma Rays; p 265-282
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  • 4
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    In:  CASI
    Publication Date: 2006-08-09
    Description: Thermal radiation associated with the explosion of supernovae is investigated. High temperature is required to produce copious gamma radiation of this sort. It appears that type 11 supernovae do not release much of their energy as gamma ray continuum radiation.
    Keywords: ASTROPHYSICS
    Type: NASA. Goddard Space Flight Center The Struct. and Content of the Galaxy and Galactic Gamma Rays; p 257-264
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  • 5
    Publication Date: 2006-08-09
    Description: The degree of saturation characterizing low altitude emission observations of H(I) and the optical depth corrections to the derived column and volume densities are discussed. The amount of fine-scale velocity and spatial structure diluted by the instrumental limitations of the presently available surveys are described. The general problem of detailed mapping of H(I) in the galaxy is explored. Comparison is made between the distribution of H(I) and that of CO and several other galactic tracers. Atomic hydrogen is unique in its distribution, instead of being typical of many Population I constituents. As defined by atomic hydrogen, the galactic disk has a diameter fully twice as large as that defined by the ionized and molecular states of hydrogen, as well as by other molecules, supernova remnants, pulsars, gamma-radiation, synchroton radiation, and the youngest stars. It is also less confined to the galactic equator than most of the other constituents. The degree of small scale structure apparent in the molecular observations is much greater than that in the H(I) observations.
    Keywords: ASTROPHYSICS
    Type: NASA. Goddard Space Flight Center The Struct. and Content of the Galaxy and Galactic Gamma Rays; p 163-188
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  • 6
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    In:  CASI
    Publication Date: 2006-08-09
    Description: Data from the SAS-2 high-energy gamma-ray experiment reveal the existence of four pulsars emitting photons above 35 MeV. An attempt is made to explain the gamma-ray emission from these pulsars in terms of an electron-photon cascade that develops in the magnetosphere of the pulsar. Although there is very little material above the surface of the pulsar, the very intense magnetic fields (10 to the 12th power gauss) correspond to many radiation lengths which cause electrons to emit photons by magnetic bremsstrahlung and which cause these photons to pair-produce. The cascade develops until the mean photon energy drops below the pair-production threshold which is in the gamma-ray range; at this stage, the photons break out from the source.
    Keywords: ASTROPHYSICS
    Type: NASA. Goddard Space Flight Center The Struct. and Content of the Galaxy and Galactic Gamma Rays; p 109-118
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  • 7
    Publication Date: 2006-08-09
    Description: Considerations made in developing a model of pulsars are explored. Observational data seems to support the argument that pulsar magnetospheres may contain large masses of plasma. The cascade process resulting from pair creation enables one to interpret the X-ray emission from the Crab and Vela pulsars as synchrotron radiation. On the other hand, the optical radiation from the Crab pulsar is best understood as coherent curvature radiation. Radio emission is interpreted as curvature radiation produced by charge bunches moving along magnetic-field lines. Certain tests of this model are proposed.
    Keywords: ASTROPHYSICS
    Type: NASA. Goddard Space Flight Center The Struct. and Content of the Galaxy and Galactic Gamma Rays; p 99-108
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  • 8
    Publication Date: 2011-08-17
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Earth and Planetary Science Letters; 37; 2, De; Dec. 197
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  • 9
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    In:  Other Sources
    Publication Date: 2011-08-17
    Description: A model for the appearance of the all-sky low-energy X-ray background on a fine angular scale is presented which is based on primeval hot gas clouds associated with the formation of clusters of galaxies according to the Sunyaev-Zel'dovich (1972) model. It is noted that the background could have both granular and diffuse components if it is due to such gas clouds. The observed appearance of the granular component is predicted along with the observable characteristics of collapsing protoclusters. The effects of distant X-ray-emitting QSOs, radio galaxies, and normal galaxies on the observations are considered, and these sources are shown not to interfere with the possibility of observing the protoclusters. It is concluded that if sufficient heating occurred in an intracluster medium within some clusters of galaxies at the protocluster epoch, the ensemble properties of protoclusters could be observed with an X-ray telescope, and the time at which protoclusters formed could perhaps be estimated.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 218
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  • 10
    Publication Date: 2011-08-17
    Description: The Delta Classifier defined as an agricultural crop classification scheme employing a temporal trend procedure is applied to more than 100 different Landsat data sets collected during the 1974-1975 growing season throughout the major wheat-producing regions of the United States. The classification approach stresses examination of temporal trends of the Landsat mean vectors of crops in the absence of corresponding ground truth information. It is shown that the resulting classifications compare favorably to ground truth estimates for wheat proportion in those cases where ground truth is available, and that the temporal trend procedure yields estimates of the wheat proportion that are comparable to the best results from maximum likelihood classification with photointerpreter-defined training fields.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Remote Sensing of Environment; 6; 4, 19; 1977
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  • 11
    Publication Date: 2011-08-17
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics; 61; 2, Oc; Oct. 197
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  • 12
    Publication Date: 2011-08-17
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics; 61; 1, Oc; Oct. 197
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  • 13
    Publication Date: 2011-08-17
    Description: Three incoherent synchrotron models are used to account for the very flat radio spectrum of the BL Lac object PKS 0735+178. The first interpretation is that the spectrum results from optically-thin synchrotron emission from relativistic electrons with a particular energy distribution. The second posits a single nonuniform, self-absorbed source generated by a wind flowing from a central object. The third suggests that sources with flat spectra are caused by the presence of multiple (three or more) discrete uniform components, and that the magnetic field and relativistic electron distribution for each source is correlated with the size of the individual components. It is proposed that the last model is the most tenable explanation of the phenomenon, and multi-frequency VLBI observations are suggested for the evaluation of the detailed structure of compact radio sources.
    Keywords: ASTROPHYSICS
    Type: Astronomical Journal; 82; Oct. 197
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  • 14
    Publication Date: 2011-08-17
    Description: A search for interstellar scintillation (ISS) of low-frequency variable radio sources is reported. Observations of 28 confirmed or suspected low-frequency variables, 21 nonvariable sources, and two pulsars were made at 408 MHz. As expected, the pulsars showed ISS, but scintillation was not detected in any other source. A typical upper limit to the rms modulation due to ISS is 150 mJy, giving lower limits to the apparent angular diameter of about 10 to the -6th arcsec. The possibilities that a true point source is broadened to an apparent angular diameter greater than or roughly equal to 10 to the -6th arcsec by scattering local to the source or in a general intergalactic medium are discussed.
    Keywords: ASTROPHYSICS
    Type: Astronomical Journal; 82; Oct. 197
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  • 15
    Publication Date: 2011-08-17
    Description: Observations at 90 GHz of a sample of 38 sources chosen to have flat or rising spectra between 0.318 and 5 GHz are reported. Roughly 25% of the sources were found to have flat or rising spectra between 5 and 90 GHz. The optical magnitude of each of the sources from the E print of the Palomar Sky Survey has also been estimated. Evidence is found for a correlation between the 90-GHz flux density and the optical magnitude, suggesting a relationship between the emission processes at these frequencies. Little evidence is found for a correlation between the low- and high-frequency spectral indices of the sources. This suggests that the sources tend to be opaque at centimeter wavelengths and optically thin at millimeter wavelengths. The properties of two of the more interesting sources are also discussed. Evidence is presented that strong millimeter activity may be generally associated with the BL Lac phenomenon.
    Keywords: ASTROPHYSICS
    Type: Astronomical Journal; 82; Oct. 197
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  • 16
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    Publication Date: 2011-08-17
    Description: This paper covers the topic of marine geodesy, its goals, and applications. Specifically discussed are position determination and establishment of geodetic control on the ocean bottom, ocean surface, and subsurface, and the determination of the geoid, a vertical reference surface. The various techniques used in position determination (including satellite, airborne, radio, inertial and acoustic techniques) are assessed in terms of accuracy, coverage, and contribution to the solution of specific problems associated with position and control. The results of several marine geodetic control experiments are presented. Classical techniques for the determination of the geoid are discussed and assessed, as are new techniques such as satellite altimetry. The outlook for marine geodetic measurements in the ocean is outlined in terms of what is being planned or considered for the next decade, and several recommendations are made.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
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  • 17
    Publication Date: 2011-08-17
    Description: An investigation is conducted concerning the possibility that observed Mg-26 anomalies in meteorites may be related to a nucleosynthetic event which preceded the formation of the solar system by at most a few million years. The Al-26, which decayed to form the observed excess Mg-26, could have been produced in either explosive carbon burning or in a high temperature carbon burning shell source immediately preceding the explosion. The results of supernova grain condensation calculations are presented and related to the hypothesis that a 'last event' supernova was indeed related to the formation of the solar system and thus might have created the observed isotopic anomalies in magnesium, oxygen, neon, and xenon.
    Keywords: ASTROPHYSICS
    Type: Nature; 269; Sept. 8
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  • 18
    Publication Date: 2011-08-17
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: American Mineralogist; 62; 1977
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  • 19
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    In:  Other Sources
    Publication Date: 2011-08-17
    Description: Questions concerning the origin of comets are considered. It is pointed out that the molecular composition of a dense interstellar cloud appears to have exactly the composition needed to produce the observed features of the visible cometary spectrum, which consists mainly of emission bands of unstable free radicals. A working model of cometary structure is discussed together with the classical observations which have led to it. The discussed model was originally described by Whipple (1951). It is emphasized that the model can serve only as a rough guide in efforts to interpret the evolution of cometary behavior. A survey is provided of new techniques which have only recently been applied to cometary observations, taking into account the spectrum of a comet, radio observations, and ultraviolet observations.
    Keywords: ASTROPHYSICS
    Type: American Scientist; 65; May-June
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  • 20
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    Publication Date: 2011-08-17
    Description: Pulsational eigenfrequencies and stability coefficients of the lowest modes of nonradial quadrupole (l = 2) oscillation have been obtained for chemically homogeneous stellar models constructed with Carson's (1976) radiative opacities. Instability is found to develop as a result of the same operation of the kappa-mechanism in the CNO ionization zone and at nearly the same stellar masses as was the case for the radial (l = 0) modes studied previously. A survey of the l = 5 modes indicates that the instability gradually declines with increasing degree of the spherical harmonics.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 214
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  • 21
    Publication Date: 2011-08-17
    Description: A rectangular (7 x 14 km) area 40 km S of Madrid was remote-sensed with a three-stage recognition process. Ground truth was established in the first phase, airborne sensing with a multispectral scanner and photographic cameras were used in the second phase, and Landsat satellite data were obtained in the third phase. Agronomic and hydrological photointerpretation problems are discussed. Color, black/white, and labeled areas are displayed for crop recognition in the land-use survey; turbidity, concentrations of pollutants and natural chemicals, and densitometry of the water are considered in the evaluation of water resources.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: IAA/Ingenieria Aeronautica y Astronautica; 29; Mar. 197
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  • 22
    Publication Date: 2011-08-17
    Description: Data on X-ray bursts recorded by the OSO-8 and SAS-3 satellites and criteria (rise time, duration, recurrence) for X-ray bursts are examined in a study of possible correlation between the galactic longitude distribution of X-ray burst sources and globular clusters. Correlations are weak, with only two X-ray bursts sources (NGC6624 and the rapid burster) coinciding with globular clusters, another seven possibly coinciding, most not correlated. Ad hoc explanations (globular clusters obscured by dust clouds, bursts associated with remnants of disrupted globular clusters evolved into supermassive black holes) are considered briefly.
    Keywords: ASTROPHYSICS
    Type: Nature; 267; May 5
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  • 23
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    Publication Date: 2011-08-17
    Description: Non-LTE calculations for the ultraviolet C I and Si I continuous opacity show that LTE results overestimate the importance of these sources of opacity and underestimate the emergent flux in Alpha Lyr. The largest errors occur between 1100 and 1160 A, where the predicted flux in non-LTE is as much as 50 times larger than in LTE, in reasonable accord with Copernicus observations. The discrepancy between LTE models and observations has been interpreted to result from the existence of a chromosphere. Until a self-consistent non-LTE model atmosphere becomes available, such an interpretation is premature.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 214
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  • 24
    Publication Date: 2011-08-17
    Description: Cygnus X-1 was observed on two occasions separated by a year by the same Goddard X-ray rocket payload. High-resolution temporal and spectral data reveal that Cyg X-1 was essentially unchanged in these two observations a year apart; the bursts of millisecond duration observed in the earlier flight were observed in the second as well. Analysis of these bursts has failed to reveal any internal temporal structure, either luminous or spectral. The shot-noise character of temporal fluctuations on time scales of at least 1 s can be explained by the presence of exponential pulses with a time constant of a fraction of a second and a rate near 8 per sec. The possible connection of these pulses with the bursts is examined.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 213
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  • 25
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    Publication Date: 2011-08-17
    Description: Envelope models for central stars of planetary nebulae have been constructed with Carson's (1976) radiative opacities. A stability analysis of these envelopes indicates that for a sufficiently high luminosity, the fundamental mode of radial pulsation is excited by the kappa mechanism operating in the CNO ionization zone. At somewhat higher luminosities the lowest overtones also become unstable. This may possibly explain the rapid variability that is observed in some central stars, if the time scale of the variations is minutes to hours.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 213
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  • 26
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    Publication Date: 2011-08-17
    Description: An analysis of the accretion process in an X-ray pulsar, whereby angular momentum is transferred to the star and its rotation period is changed, is presented, and an expression for the fractional rate of change of the pulse period in terms of X-ray luminosity and other star parameters is derived. It is shown that observed characteristic spin-up time scales for seven X-ray pulsars strongly support the view that in every source (1) the pulse period reflects the rotation period of a compact object, (2) the accretion is mediated by a disk surrounding the compact object and rotating in the same sense, and (3) the compact object is a neutron star rather than a white dwarf.
    Keywords: ASTROPHYSICS
    Type: Nature; 266; Apr. 21
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  • 27
    Publication Date: 2011-08-17
    Description: Spectrophotometric observations from 2.1 to 4.1 microns of a variety of objects exhibiting the 3.3-micron emission feature (first detected in NGC 7027) are reported. The characteristics of the feature, the various environments in which it is found, and possible emission mechanisms are discussed in light of all the available observations of the feature to date. A resonance feature in solids is the most probable emission mechanism; however, no satisfactory identification has yet been made on the basis of infrared spectroscopy of terrestrial materials.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 213
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  • 28
    Publication Date: 2011-08-17
    Description: The infrared spectrum of the Kleinmann-Low nebula in M42 has been measured from 80 to 350 kaysers (approximately 29 to 125 microns) with a Michelson interferometer aboard the NASA Kuiper Airborne Observatory. The frequency spectrum peaks at about 185 kaysers. A simple model of the emission implies that the temperature is in the range 70-95 K and that the optical depth is at least 0.2 at the peak frequency. A possible absorption is seen at about 176 kaysers. Thermal emission by dust at a temperature of 71 K, with the absorption cross section proportional to frequency, provides a good fit to the data. Other thermal-emission models can also fit the spectrum. The data are compared with previous broad-band measurements. Upper limits are placed on expected line emission from the surrounding H II region at the position of the nebula.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 212
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  • 29
    Publication Date: 2011-08-17
    Description: It is suggested that the explosion of a Type II supernova triggered the collapse of a nearby interstellar cloud and led to the formation of the solar system. Estimates of the abundances resulting from nuclear processing of the supernova ejecta are presented. It appears promising that nucleosynthesis in this single supernova event can account for most isotopic anomalies and traces of extinct radioactivities in solar-system material.
    Keywords: ASTROPHYSICS
    Type: Icarus; 30; Mar. 197
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  • 30
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    Publication Date: 2011-08-17
    Description: Recent progress in the study of the pulse profiles of the nine known binary X-ray pulsars is discussed. The sources considered include SMC X-1, Her X-1, Cen X-3, A0535+26, GX1+4, 3U 0900-40, A1118-61, GX301-2, and 3U 0352+30. Sample X-ray profiles for these sources are provided, and general features exhibited by the profiles are identified. It is noted that the apparent existence of a gap in the period distribution of X-ray pulsars, in the range from about 5 to 100 sec, seems to be genuine within obvious statistical limitations and is probably not an observational effect. Two explanations for the production of X-ray pulsations are examined: one requiring a temporal modulation of mass accretion onto the surface of a neutron star and another requiring the funnelling of matter along magnetic field lines to the neutron star's surface.
    Keywords: ASTROPHYSICS
    Type: Nature; 266; Mar. 10
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  • 31
    Publication Date: 2011-08-17
    Description: The spectrum of comet West (1975 n) was recorded on March 7 and 11, 1976, in the wavelength interval from 5700 to 8200 A at an intermediate resolution. One hundred twenty-two emission lines are reported, with 78 lines having identifications with spectral features of NH2, H2O(+), C2, O I forbidden emission, and Na I.
    Keywords: ASTROPHYSICS
    Type: Astronomical Society of the Pacific; vol. 89
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  • 32
    Publication Date: 2011-08-17
    Description: A detailed study of the hydrostatic equilibrium of the gas-field system perpendicular to the galactic plane in the neighborhood of the sun, assuming that the magnetic field is parallel to the plane, has been carried out. It is found that the distribution of pressure due to cosmic rays and the magnetic field is different from that due to the gas. The observed radio spectrum in the direction of the galactic pole can be understood if one includes in the hydrostatic equilibrium the distribution of gas in the halo. The results of this analysis show that in the galactic plane, the cosmic-ray density is approximately 2 to 3 eV/cu cm with a magnetic-field strength of about 5 to 6 microgauss. It is inferred that cosmic rays are confined to a more extended volume in the Galaxy (with an equivalent thickness of at least 2 kpc in the solar neighborhood) than the gas disk, and the magnetic-field strength slowly decreases to a value of 1 microgauss only beyond about 5 kpc from the plane. Further, there is no evidence for a quasi-spherical radio halo, although the radio emission extends beyond the gas disk with scale height of at least 1 kpc. A lower limit of about 6 million years for the confinement of cosmic rays in the Galaxy has been set.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 212
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  • 33
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    Publication Date: 2011-08-17
    Description: The paper develops certain aspects of a model wherein a QSO is a massive black hole located in a dense galactic nucleus, with its growth and luminosity fueled by tidal disruption of passing stars. Cross sections for tidal disruptions are calculated, taking into account the thermal energy of stars, relativistic effects, and partial disruption removing only the outer layers of a star. Accretion rates are computed for a realistic distribution of stellar masses and evolutionary phases, the effect of the black hole on the cluster distribution is examined, and the red-giant disruption rate is evaluated for hole mass of at least 300 million solar masses, the cutoff of disruption of main-sequence stars. The results show that this black-tide model can explain QSO luminosities of at least 1 trillion suns if the black hole remains almost maximally Kerr as it grows above 100 million solar masses and if 'loss-cone' depletion of the number of stars in disruptive orbits is unimportant.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 212
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  • 34
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    Publication Date: 2011-08-17
    Description: The fractional abundances of the isotopic species of carbon monoxide in interstellar clouds are calculated on a basis of gas-phase ion-molecule reactions. The (C-13)O/(C-12)O ratio varies significantly with extinction of the ultraviolet radiation field, and in the outer regions of dark dense clouds (C-13)O may be enhanced by a factor of 10. The observational interpretation of the CO to H2 or interstellar-reddening relation and the isotopic abundances of carbon are complicated by these effects.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 212
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  • 35
    Publication Date: 2011-08-17
    Description: Measurements of the 104 sec pulse profile of A0535+26 at energies near 50 keV are reported. The data were obtained with a balloon-borne detector system which was launched on May 22, 1975 with the objective to observe transient or periodic emissions from X-ray or gamma-ray sources. The presence of the source was detected by a superposed epoch analysis. The pulse profile of A0535+26 in two energy channels is presented in a graph.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 212
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  • 36
    Publication Date: 2011-08-17
    Description: The All-Sky X-ray Monitor on board Ariel-5 has observed the 3-6 keV decline of the bright transient X-ray source A0620-00 on a virtually continuous basis during the period 1975 September-1976 March. The source behavior on time scales greater than about 100 minutes is characterized by smooth, exponential decays interrupted by substantial increases in October and February. The latter increase was an order-of-magnitude rise above the extrapolated exponential falloff, and was followed by a final rapid decline below a level of about 0.05 per sq cm per sec by late March. Upper limits of 2.5% and 10% were found for any periodicities in the range 0.2-10 days during the early and later decay phases, respectively. A probable correlation between the optical and 3-6 keV emission from A0620-00 has been noted, effectively ruling out models involving traditional optical novae in favor of Roche-lobe overflow in a binary system. The existing data on the transient X-ray sources are consistent with two distinct luminosity-lifetime classes of these objects.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 212
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  • 37
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    Publication Date: 2011-08-17
    Description: In order to understand the seemingly erratic V/R variations and radial velocity curves of emission edges and central absorption of some Be stars, we have advanced, for the changes of structure of the gaseous ring around these stars, a theory that is based on the interaction between the existing ring and the newly ejected matter from the star. It shows that the structural change of the ring is completely controlled by the angular-momentum input factor and the dissipation factor. In light of this understanding, we have gone on to interpret the observed results of Beta-1 Mon and Pi Aqr.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 212
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  • 38
    Publication Date: 2011-08-17
    Description: Recent analysis of laser data for determining variation of latitude have been based on apparent variations in the orbital inclination of the satellite derived from short orbital arcs of 6-8 hours. An alternative method, based on the daily adjustment of the station position to a much longer arc of 2 or 3 weeks has recently been developed and tested. In the new method a long orbital arc is derived from many days of data and is subsequently used as a reference orbit for the adjustment of the position of the station (only) on each day of the long arc for which tracking data are available. This new technique appears to give slightly better results when it is applied to a test period in August 1970, with the added advantage that earth rotation measurements can be derived from the same data at the same time. The results for the test period indicate a precision of 74 cm in variation of latitude and 0.81 ms in monitoring the earth's rotation with 6 hours of data.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Journal of Geophysical Research; 82; Feb. 10
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  • 39
    Publication Date: 2011-08-17
    Description: Ariel V All-Sky Monitor observations of Aql X-1 are reported and compared with previous observations that indicate the existence of 'low' and 'high' intensity states. All the data considered are shown to be consistent with flaring episodes having a mean flare interval of 435 days with an rms scatter of about 10%. It is suggested that the observations are most easily interpreted in terms of an 'X-ray dwarf nova' binary of the type proposed for the transient X-ray source A0620-00. Constraints on more detailed features of the source model are discussed.
    Keywords: ASTROPHYSICS
    Type: Nature; 265; Feb. 17
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  • 40
    Publication Date: 2011-08-17
    Description: A survey of 73 sources has been made in the emission lines of N2H(+) and HCO(+), including detailed maps of four sources (Ori A, OMC-2, DR 21 OH, and NGC 6334). These data are combined with equally extensive data for HCN and CN to make a detailed study of the spatial relationship of these four species. Actual abundance ratios are shown to vary, often sharply, over small scale lengths (of the order of 1 arcmin) within the mapped sources. Excitation temperatures also vary. All four species appear to be subthermally excited. The abundance ratios and their spatial variations are interpreted in terms of ion-molecular formation and destruction processes. It is concluded that the relative abundances of CO may be considerably lower in some regions than previously believed. No evidence is found for variations in the C/O ratio over small scale lengths in Ori A. The degree of ionization of the Ori A molecular cloud may be significantly different from that of other molecular clouds.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 211
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  • 41
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    Publication Date: 2011-08-17
    Description: In connection with information considered by Illarianov and Sunyaev (1975) and van den Heuvel (1975), a simple physical model for an X-ray burst source in the galactic disk is proposed. The model includes an unevolved OB star with a relatively weak stellar wind and a compact object in a close binary system. For some reason, the stellar wind from the OB star is unable to accrete steadily on to the compact object. When the stellar wind is sufficiently weak, the compact object accretes irregularly, leading to X-ray bursts.
    Keywords: ASTROPHYSICS
    Type: Nature; 265; Jan. 20
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  • 42
    Publication Date: 2011-08-17
    Description: The structure and nature of 'discontinuities' in the interplanetary magnetic field at 1 AU in the period from March 18 to April 9, 1971, is determined by using high-resolution magnetic-field measurements from Explorer 43. The discontinuities that were selected for this analysis occurred under a variety of interplanetary conditions at an average rate of 0.5/hour. Both tangential and rotational discontinuities were identified. Tangential discontinuities were observed every day, even among Alfvenic fluctuations. In particular, on one day during which Alfvenic fluctuations were intense and persistent in a high-speed stream, tangential discontinuities (TD's) were seen throughout the day at an average rate of 0.5/hour; rotational discontinuities (RD's) were also observed during this day at a higher than usual rate, the ratio of TD's to RD's being approximately one. The structure of most of the current sheets was simple and ordered; i.e., the magnetic field usually changed smoothly and monotonically from one side of the current sheet to the other. The thickness distributions of the TD's and RD's with very smooth current sheets were similar. The average thickness of the RD's was 1200 km (13 proton Larmor radii), and the average thickness of the TD's was 1300 km (12 proton Larmor radii).
    Keywords: ASTROPHYSICS
    Type: Journal of Geophysical Research; 82; Aug. 1
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  • 43
    Publication Date: 2011-08-17
    Description: We have found that the rate of mass loss M increases with an increase in the period of pulsation for Mira-type variables. This result suggests that the rate of mass loss is accelerated with time until a maximum value is reached before the ejection of the outer envelope. The matter from the continuous mass loss during the evolution of the star produces supersonic shock waves that sweep up the interstellar gas upon encountering the interstellar medium, so that a shell is formed. This phenomenon may account for the observations of extended regions of emission that surround planetary nebulae.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 216
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  • 44
    Publication Date: 2011-08-17
    Description: The spectral region about the Mg II doublet lines near 2800 A of Be and shell stars has been observed. The star Gamma Cas shows narrow components to each resonance doublet line shifted 215 km/s toward shorter wavelengths. The resonance and subordinate lines of Zeta Tau are shifted toward shorter wavelengths by 75 km/s, and the subordinate lines are greatly strengthened. The star Kappa Dra, which is much later in spectral type, shows a comparatively normal doublet spectrum.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 216
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  • 45
    Publication Date: 2011-08-17
    Description: Generalized Einstein equations invariant under scale transformations are presented, and several astrophysical tests studied. It is assumed that the dynamics of atoms or clocks used as measuring apparatus is given a priori. Connection with gauge fields and broken symmetries is made through the cosmological constant.
    Keywords: ASTROPHYSICS
    Type: Physical Review Letters; 39; Aug. 22
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  • 46
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    Publication Date: 2011-08-17
    Description: A description is presented of an investigation involving the collection of Antarctic ice sheet surface topography data by means of balloons, floating at an altitude of about 12.5 km, which traversed the Antarctic during its 1975 summer. These balloons were part of 411 constant density balloons launched in the Southern Hemisphere during the Tropical Wind, Energy conversion and Reference Level Experiment. The three sensors carried by each balloon included a radio altimeter, a pressure sensor, and an ambient temperature sensor. Data transmitted by a balloon are received by a measuring system on board the Nimbus-6 satellite. A synoptic map is presented of the 150 mbar pressure surface at 1200 GMT, December 11, 1975.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Nature; 268; Aug. 11
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  • 47
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    Publication Date: 2011-08-17
    Description: The meaning of the term 'cometary nucleus' is discussed, taking into account observations of comets with different characteristics. It is pointed out that for some comets, there may be no nucleus to be seen at any time, while in others as the comet brightens or undergoes changes, a nucleus may develop to be seen for a time or even intermittently, while occasionally more than one nucleus may be seen to be present. On the basis of a study of observational reports it emerges that no more than about 30 per cent of comets exhibit anything resembling a starlike nucleus.
    Keywords: ASTROPHYSICS
    Type: Royal Astronomical Society; vol. 18
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  • 48
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    Publication Date: 2011-08-17
    Description: Swan-band emission from the C2 molecule provides important information for a study of the physical processes occurring in comets. It is, therefore, a disturbing factor that many quantitative Swan-band observations are in clear contradiction of predictions of resonance fluorescence excitation of the Swan bands. A description is presented of an investigation involving an application of resonance fluorescence theory to C2. The investigation takes into account all important electronic transitions which determine the population distribution of the lowest energy states. It is found that the previous discrepancy for the brighter band sequences disappears.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 216
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  • 49
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    Publication Date: 2011-08-17
    Description: The evolution of helium stars in the mass range from 4 to 15 solar masses has been followed from the initial helium main sequence to the end of carbon burning in the core, with the use of Carson's (1976) radiative opacities. As compared with earlier work based on smaller opacities, the main-sequence band in the H-R diagram is now both wider and cooler than before. If neutrino losses are neglected in the stellar models, the phase of carbon burning in the core occurs in the red-supergiant region; otherwise, it occurs, as it does in the earlier models with or without neutrino emission, close to the helium main sequence. Observational data for Wolf-Rayet stars and R Coronae Borealis variables are found to lend some support to the present models.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 216
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  • 50
    Publication Date: 2011-08-17
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics; 59; 2, Ju; July 197
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  • 51
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    Publication Date: 2011-08-17
    Description: One grain of uraninite was found in a single thin-section of Sierran granite. Electron and ion microprobe analysis were used to determine the composition. Since the U-Pb age calculated for the uraninite does not differ greatly from the K-Ar age of the unit in which it occurs, it is suggested that the mineral is primary and not reworked from a preexisting rock. No uraninite has been detected in heavy mineral concentrates from other rocks of the local area.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: American Mineralogist; 62; 1977
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  • 52
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    Publication Date: 2011-08-17
    Description: The rate of hydrogen production of Comet West is studied through rocket observation of solar Lyman-alpha radiation resonantly scattered by the escaping hydrogen atoms. Two sets of Lyman-alpha exposure sequences are used to obtain computer-smoothed brightness contour (isophote) maps covering a density range of 100:1. A simple radial outflow model is applied to the contour maps to determine the rate of hydrogen production (3.2 by 10 to the 30th power atoms/sec.) Discrepancies between the observed shape of the outer isophotes and predicted models may be explained by optical depth effects, or by the presence of small pieces of the comet's nucleus distributed along the orbit. Hydrogen, carbon, and oxygen production for Comet West and Comet Kohoutek are compared; differences may be accounted for by variations in the composition or evolution of the two comets.
    Keywords: ASTROPHYSICS
    Type: Icarus; 31; Aug. 197
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  • 53
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    Publication Date: 2011-08-17
    Description: Data obtained from the Copernicus Orbiting Astronomical Observatory, launched in 1972 and still obtaining information, are used in a discussion of the interstellar medium. The Copernicus instruments have facilitated direct estimates for the density and temperature of individual interstellar clouds, and improved the ability to determine where along the line of sight a cloud lies with respect to background stars. The physical characteristics of hydrogen molecules are considered, with attention to the formation and destruction of interstellar hydrogen. The differences between 'thin' clouds, in which molecular hydrogen is optically thin, and 'thick' clouds are examined. Several features of the interstellar medium are described.
    Keywords: ASTROPHYSICS
    Type: American Scientist; 65; July-Aug
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  • 54
    Publication Date: 2011-08-17
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 215
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  • 55
    Publication Date: 2011-08-17
    Description: The atmospheric properties of seven planetary nuclei which have O or Of-type spectra were determined by use of the Zanstra method and by analysis of the visual line spectra. One finding is that the O-type spectral sequence may extend to effective temperatures of 90,000 kelvins or more, if the results of the Zanstra method are to be believed. However, there are some indications of internal inconsistency in the Zanstra method and some outstanding discrepancies between the effective temperatures indicated by the Zanstra method and those indicated from analysis of the visual line spectra. Two ways to resolve these discrepancies are to postulate an excess of extreme-UV stellar flux or to postulate a hot binary companion for some central stars. In either case the validity of the Harmon-Seaton evolutionary sequence for central stars becomes questionable.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 215
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  • 56
    Publication Date: 2011-08-17
    Description: The concept that cosmic-ray density is related to the matter to which cosmic rays are dynamically coupled through magnetic fields on the scale of galactic arm segments is considered with specific reference to gamma-ray astronomy. A model of the galactic-matter and cosmic-ray distributions is developed on the basis of 21-cm radio surveys and recent observations of the 2.6-mm CO emission line by assuming that cosmic rays are galactic in origin, their column density is proportional to the total interstellar-gas column density, their scale height is considerably larger than that of the matter, and the Galaxy is a spiral with an arm/interarm density ratio of about 3 to 1. It is found that there is a good correlation between the observed gamma-ray intensity and that predicted on the basis of essentially complete coupling of cosmic rays to the best estimate of atomic and molecular hydrogen in the Galaxy. Individual maxima observed in gamma-radiation from the central region of the Galaxy are shown to be well correlated with those predicted to result from certain spiral-arm tangents if all the matter is assumed to be modulated in a particular spiral-arm segment pattern.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 215
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  • 57
    Publication Date: 2011-08-17
    Description: The X-ray spectrum of Her X-1 was observed in the energy range from 2 to 24 keV from August 29 to September 3, 1975. Emission features are observed near the K-alpha iron-line energy which exhibit both broadening and a double line structure. The total luminosity in these features is about 4 by 10 to the 35th power ergs/s. Iron line fluorescence from an opaque cool (not exceeding 1 million K) shell of material at the Alfven surface provides the necessary luminosity in this feature. The double line structure and the line energy width can be due to Doppler shifts if the shell is forced to corotate with the pulsar at a radius of at least 800 million cm. Implications of this model regarding physical conditions near Her X-1 are discussed.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 215
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  • 58
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    Publication Date: 2011-08-17
    Description: Mass loss from an accretion disk around a supermassive (of the order of 100 million solar masses) black hole is proposed as the origin of the broad permitted lines of Seyfert galaxies and QSOs. The material is expelled by ionizing radiation emitted near the center of the disk and striking it at a radius of approximately 10 to the 16.5 power cm. The escaping gas initially has a density of about 1 trillion per cu cm, high enough for radiation pressure to accelerate the gas to high radial velocities. The model leads to line emission from tiny dense filaments moving at about 10,000 km/s in a region roughly 10 to the 17th power cm across. This agrees with the observed broad line widths, variability time scales, and the absence of broad forbidden-line emission.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Letters; 18; 3, 19; 1977
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  • 59
    Publication Date: 2011-08-17
    Description: The paper reports the observation of pulsed fractions in the primary and secondary peaks, as well as in the interpulse region, of the high-energy X-ray light curve of NP 0532. A statistical analysis of light-curve data is performed, and a similar analysis is carried out using simulated data. It is concluded that a previously reported third peak in the light curve was transient in nature.
    Keywords: ASTROPHYSICS
    Type: Nature; 266; Mar. 31
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  • 60
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    Publication Date: 2011-08-17
    Description: The large numbers hypothesis (LNH) linking the magnitude of large dimensionless ratios in physics (on the order of 10 to the 40th power) to cosmic time is examined. The LNH is checked against evidence on 3K background radiation of the universe and the (log N, log S)-relation for radio galaxies. Earlier criticisms of LNH by Gamow and Teller are examined, and alternative hypotheses put forth by Dicke and Carter (1974) are discussed. The discussion covers: continuous (additive or multiplicative) creation of matter, the Einstein metric and the atomic metric, and general cosmological and local astronomical implications of LNH. LNH is also viewed in relation to solar evolution and pulsar physics.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; 211; Jan. 15
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  • 61
    Publication Date: 2011-08-17
    Description: The observed transitions at energies above 20 keV show that the spectrum of Cyg XR-1 exhibits the pivoting effect during intensity transitions expected from two-temperature accretion disk models of the X-ray emitting region. Cyg XR-1 was observed with the high-energy X-ray spectrometer on board the OSO-8 satellite from November 11-19, 1975 and from October 27 to November 15, 1976 (excluding the period from November 1 to November 7, 1976).
    Keywords: ASTROPHYSICS
    Type: Nature; 267; June 30
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  • 62
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    Publication Date: 2011-08-17
    Description: The thermal response of a substance to a time-varying surface power input is determined by its thermal inertia. Remote sensing (e.g., from satellites) can be utilized to measure this property, which is related to surface composition or to near-surface soil moisture. An algorithm is developed which relates thermal inertia to remote measurements of surface temperature and reflectance. Application to geosynchronous satellite data illustrates the contrast between irrigated and desert areas in the region north of the Gulf of California. The effect of local weather conditions (latent and sensible heat transfer to the atmosphere) must be estimated before precise values for thermal inertia can be specified.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Journal of Geophysical Research; 82; June 20
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  • 63
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    Publication Date: 2011-08-17
    Description: The accretion-disk model for the optical continuum of QSOs has been investigated using the standard viscous-stress ('alpha-P') formalism. It is found that with a maximum allowable mass of 10 billion solar masses, the standard model with sub-Eddington flow falls a factor of 10 short of the luminosity of the brightest QSOs. Models with the higher mass-flow rates required to reach the maximum luminosities produce most of their energy in an optically thin region which has not yet been self-consistently treated. The disk model with sub-Eddington flow has difficulty in producing a power law of the correct slope over the optical band. It is suggested that nonthermal processes may be needed to explain the optical properties of QSOs.
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics; 59; 1, Ju; July 197
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  • 64
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    Publication Date: 2011-08-17
    Description: Radiative acceleration as a mechanism for ejection of matter from quasistellar objects is considered, and calculations are presented showing that a strongly beamed outflow will result if the source of the driving radiation is a disk. The net forces exerted by an infinitesimally thin, optically thick disk emitting thermal radiation with given intensity on clouds or particles is calculated, and conditions for beaming are obtained. Apparently it is possible to establish strong beaming within a distance of the order of the disk radius.
    Keywords: ASTROPHYSICS
    Type: Nature; 266; Apr. 21
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  • 65
    Publication Date: 2011-08-17
    Description: The paper studies the detailed spectral characteristics of the planetary nebulae N97 and N153 in the Large Magellanic Cloud (LMC), the planetary nebula N67 in the Small Magellanic Cloud (SMC), and the small H II regions N9, N61, and N81 in the SMC. Electron temperatures and densities for each nebula are derived from emission-line strengths determined by photographic spectrophotometry, and relative abundances are estimated for H, He, N, O, Ne, Ar, and S. The results show that: (1) N67 has a 60% overabundance in He/H while N97 and N153 have approximately normal He/H values; (2) all three planetaries have N/H values comparable to those of galactic planetaries but substantially higher than found in the H II regions of their respective Cloud; (3) the O/H values in the planetaries are similar to or lower than those in the H II regions of the respective Cloud; (4) the O/Ne, O/S, and O/Ar ratios in the two LMC planetaries are comparable to those in galactic planetaries; (5) the compositions of the small H II regions in the SMC are nearly identical to those of previously studied large H II regions in the same Cloud; and (6) the He/H ratio of the interstellar gas in the SMC is about 25% less than that in the Galaxy. It is concluded that most of the N abundance in both Clouds arose from nucleosynthesis sources other than planetary nebulae.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; 211; Jan. 1
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  • 66
    Publication Date: 2011-08-17
    Description: Areas in which LANDSAT satellite imagery were found most useful include regional interpretations of geological structure, updating verifying of geologic maps, mineral and petroleum exploration, and the monitoring of natural hazards such as large-scale erosion and seismicity. Investigations in these areas of application demonstrated the wide variety of uses presently undertaken or envisioned for the future.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: NASA. John F. Kennedy Space Center Remote Sensing and the Earth; p 194-204
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  • 67
    Publication Date: 2011-08-17
    Description: The use of recutting remote sensing was demonstrated for location of shipwrecks in the Florida Keys, using selected films and filters for improved water penetration.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: NASA. John F. Kennedy Space Center Remote Sensing and the Earth; p 341-350
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  • 68
    Publication Date: 2011-08-17
    Description: Various types of films were used to detect pre-Columbian archaeological sites in South Dakota. Natural color and color IR films (scale 1/10,000) provided the best interpretation medium.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: NASA. John F. Kennedy Space Center Remote Sensing and the Earth; p 172-180
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  • 69
    Publication Date: 2011-08-17
    Description: A network of sampling sites throughout the annual grassland region was established to correlate plant growth in stages and forage production to climatic and other environmental factors. Plant growth and range conditions were further related to geographic location and seasonal variations. A sequence of LANDSAT data was obtained covering critical periods in the growth cycle. Data were analyzed by both photointerpretation and computer aided techniques. Image characteristics and spectral reflectance data were then related to forage production, range condition, range site, and changing growth conditions.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: NASA. John F. Kennedy Space Center Remote Sensing and the Earth; p 77-101
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  • 70
    Publication Date: 2011-08-17
    Description: A method is proposed for using clear lakes as dark backgrounds against which the atmospheric path radiance can be determined from satellite observations. If the path radiance can be determined to sufficient accuracy, the atmospheric extinction can be inferred with suitable radiative transfer models. An extensive program of observation was made to determine the magnitude and variability of the various contributors to the total radiance observed by a satellite. It is shown that the volume and surface reflectance contributions (in the absence of sunglint) are small, constant, and can be modeled accurately enough to make these an insignificant source of error. The sunglint radiance observed in this investigation may be a significant source of error. It is shown that atmospheric extinction can be inferred from the path radiance observation after systematic differences between the model and observations are removed.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: ERIM Proc. of the 11th Intern. Symp. on Remote Sensing of Environment, Vol. 1; p 731-755
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  • 71
    Publication Date: 2011-08-17
    Description: Remote sensor data (primarily LANDSAT) was analyzed by photogeologic and computer-assisted enhancement techniques to evaluate the metallic mineral potential of Baja California. Overlays were prepared at 1:1,000,000 and 1:500,000 and included known geologic relationships and mineral occurrences, lineament, drainage and structural patterns, tonal anomalies, and enhancement results. Computer-assisted enhancement and classification of the test sites was performed using the IMAGE 100 system to identify subtle tonal anomalies thought related to mineralization using known sites as analysis guides. Mineral potential maps of Baja California were generated from these analyses and the ten highest priority targets visited. Preliminary assay results (atomic absorption analysis) for the samples recovered showed moderate to high geochemical anomalies for Copper (10 of 12 samples), Zinc (3 of 12 samples) and Lead (4 of 12 samples).
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: ERIM Proc. of the 11th Intern. Symp. on Remote Sensing of Environment, Vol. 1; p 683-691
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  • 72
    Publication Date: 2011-08-17
    Description: Some of the main aspects that need to be considered in a remote sensing sampling design are: (1) the frequency that any one land use type (on the ground) is erroneously attributed to another class by the interpreter; (2) the frequency that the wrong land use (as observed on the ground) is erroneously included in any one class by the remote sensing interpreter; (3) the proportion of all land (as determined in the field) that is mistakenly attributed by the interpreter; and (4) the determination of whether the mistakes are random (so that the overall proportions are approximately correct) or subject to a persistent bias. A sampling and statistical testing procedure is presented which allows an approximate answer to each of these aspects. The concept developed and described incorporates the probability of making incorrect interpretations at particular prescribed accuracy levels, for a certain number of errors, for a particular sample size. It is considered that this approach offers a meaningful explanation of the interpretation accuracy level of an entire remote sensing land use survey.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: ERIM Proc. of the 11th Intern. Symp. on Remote Sensing of Environment, Vol. 1; p 615-623
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  • 73
    Publication Date: 2011-08-17
    Description: A demonstration of the utility of LANDSAT imagery for quickly and cheaply estimating irrigated land area was conducted in the Klamath River basin of Oregon. LANDSAT color composite images, at 1:250,000 scale and acquired on two dates during the 1975 growing season, were interpreted. Irrigated lands were delineated manually, and the irrigated area was estimated, based on dot-grid sampling of the manually delineated lands. The image interpretation estimate of irrigated area was then adjusted by a comparison of interpretation results with ground data on 45 sample plots, each 2.6 square kilometers in size. Two interpreters independently estimated the irrigated area. Their adjusted estimates were 115,000 hectares and 108,000 hectares respectively, with corresponding 95 percent confidence intervals of + or - 7,880 hectares and + or - 14,000 hectares.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: ERIM Proc. of the 11th Intern. Symp. on Remote Sensing of Environment, Vol. 1; p 515-524
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  • 74
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    Publication Date: 2011-08-17
    Description: A digital processing and analysis scheme for use with digitized synthetic aperture radar data was developed. Using data from a four channel system, the imagery is preprocessed using specially designed software and then analyzed using preexisting facilities originally intended for use with MSS type data. Geometric and radiometric correction may be performed if desired, as well as classification analysis, Fast Fourier transform, filtering and level slice and display functions. The system provides low cost output in real time, permitting interactive imagery analysis. System information flow diagrams as well as sample output products are shown.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Proc. of the 11th Intern. Symp. on Remote Sensing of Environment, Vol. 1; p 563-570
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  • 75
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    Publication Date: 2011-08-17
    Description: The Large Area Crop Inventory Experiment (LACIE) is a project designed to demonstrate the applicability of remote sensing technology to monitor globally an important world food crop - wheat. The need for more timely and reliable monitoring of food and fiber supplies is discussed, and the monitoring systems currently utilized are reviewed. The fundamentals involved in assessing the impact of variable weather and economic conditions on wheat acreage, yield, and production are elucidated. The experiment's approach to production monitoring is described, and its status is reviewed. Examples of acreage and yield monitoring in the Soviet Union are used to illustrate the experiment's approach.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: ERIM Proc. of the 11th Intern. Symp. on Remote Sensing of Environment, Vol. 1; p 429-465
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  • 76
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    Publication Date: 2011-08-17
    Description: Monitoring of pollutants within the troposphere is discussed. Selected specific techniques were investigated and it was shown how the use of these techniques fits into the overall national strategy for air pollution abatement.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: ERIM Proc. of the 11th Intern. Symp. on Remote Sensing of Environment, Vol. 1; p 353-359
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  • 77
    Publication Date: 2011-08-17
    Description: To realize the maximum potential benefits of remote sensing, the technology must be applied by personnel responsible for the management of natural resources and the environment. In Canada and the United States, these managers are often in local offices and are not those responsible for the development of systems to acquire, preprocess, and disseminate remotely sensed data, nor those leading the research and development of techniques for analysis of the data. However, the latter organizations have recognized that the technology they develop must be transferred to the management agencies if the technology is to be useful to society. Problems of motivation and communication associated with the technology transfer process, and some of the methods employed by Federal, State, Provincial, and local agencies, academic institutions, and private organizations to overcome these problems are explored.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: ERIM Proc. of the 11th Intern. Symp. on Remote Sensing of Environment, Vol. 1; p 325-331
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  • 78
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    Publication Date: 2011-08-17
    Description: The actual and the desirable roles of remote sensing in dealing with current forestry issues, such as national forest policy, supply and demand for forest products and competing demands for forest land are discussed. Topics covered include wood shortage, regional timber inventories, forests in tropical and temperate zones, Skylab photography, forest management and protection, available biomass studies, and monitoring.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: ERIM Proc. of the 11th Intern. Symp. on Remote Sensing of Environment, Vol. 1; p 267-276
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  • 79
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    Publication Date: 2011-08-17
    Description: The use of data from environmental satellites and other remote sensing platforms in some of NOAA's operational services are described. Topics discussed include: hurricanes; severe local storms and tornadoes; forest guidance; weather forecasting; hydrology; space program support; oceanography; search and rescue; and wildlife management. Applications which have become routine, and those which are in advanced field test are included. Some applications yield a clear cut economic benefit. In other cases, benefits -- if any -- are obscure. In yet other cases, benefits in one sector may be offset by detriments in another. Illustrative examples are given.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: ERIM Proc. of the 11th Intern. Symp. on Remote Sensing of Environment, Vol. 1; p 221-228
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  • 80
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    Publication Date: 2011-08-17
    Description: Obstacles or deficiencies in on-going satellites that impede operational use of data are described. Because spectral and spatial characteristics of LANDSAT D sensors are different from earlier satellites, they deter operational planning and data use, and an operational program operated in parallel with experimental technology development is needed. Particular attention is given to the satellite sensor readout system, its current applications, and needs for the future.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: ERIM Proc. of the 11th Intern. Symp. on Remote Sensing of Environment, Vol. 1; p 229-235
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  • 81
    Publication Date: 2011-08-17
    Description: Beginning with a survey of the state-of-the-art of processing remotely sensed data in early 1975, significant developments between that time and the present are chronicled, and technologies for early 1979 are projected. Current technical issues discussed include: training selection and labeling; classification and mensuration; use of satellite indicators to supplement predictions; small scale field structures; physical factors; ancillary data; geometric quality; and the cost of processing.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Proc. of the 11th Intern. Symp. on Remote Sensing of Environment, Vol. 1; p 125-135
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  • 82
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    Publication Date: 2011-08-17
    Description: A perspective on the implementation of microwave sensors in future airborne and spaceborne observations of hydrologic parameters is presented. The rationale is based on a review of the status and future trends of active (radar) and passive (radiometer) microwave research as applied to the remote sensing of soil moisture content, snowpack water equivalent, freeze/thaw boundaries, lake ice thickness, surface water area, and the specification of watershed runoff coefficients. Analyses and observations based on data acquired from ground based, airborne and spaceborne platforms, and an evaluation of advantages and limitations of microwave sensors are included.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: ERIM Proc. of the 11th Intern. Symp. on Remote Sensing of Environment, Vol. 1; p 67-86
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  • 83
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    Publication Date: 2011-08-17
    Description: The baryon symmetric big-bang cosmologies offer an explanation of the present photon-baryon ratio in the universe, the best present explanation of the diffuse gamma-ray background spectrum in the 1 to 200 MeV range, and a mechanism for galaxy formation. In the context of an open universe model, the value of omega which best fits the present gamma-ray data is omega equals approx. 0.1 which does not conflict with upper limits on Comptonization distortion of the 3K background radiation. In regard to He production, evidence is discussed that nucleosynthesis of He may have taken place after the galaxies were formed.
    Keywords: ASTROPHYSICS
    Type: ESA Recent Advan. in Gamma-Ray Astronomy; p 201-206
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  • 84
    Publication Date: 2011-08-17
    Description: Remote sensing was applied to a preliminary study of suspended solids in the Requena Dam. Aerial and terrestrial photographs were analyzed by photointerpretation and microdensitometry. Field measurements and sampling were also made. A relationship between ground data for the concentration of suspended solids and the transmissibility of the aerial infrared film was suggested.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: ERIM Proc. of the 11th Intern. Symp. on Remote Sensing of Environment, Vol. 1; p 495-504
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  • 85
    Publication Date: 2011-08-17
    Description: The cooperation and assistance of industrialized nations and the United Nations and its agencies in promoting the transfer of remote sensing technology in developing nations was discussed. Training programs, workshops, and seminars as well as on-going globally scattered demonstration projects were evaluated and it was suggested that emphasis should shift from centralized training to scheduled regional training programs, resulting in larger local participation and on-the-spot application of the technology to solve local problems.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: ERIM Proc. of the 11th Intern. Symp. on Remote Sensing of Environment, Vol. 1; p 339-351
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  • 86
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    Publication Date: 2011-08-17
    Description: Current applications and products from existing operational satellites, are reviewed. The future data and information that will become available before the end of this decade are described with emphasis on global oceanic data.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: ERIM Proc. of the 11th Intern. Symp. on Remote Sensing of Environment, Vol. 1; p 279-297
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  • 87
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    Publication Date: 2011-08-17
    Description: A variety of photographic and nonphotographic sensors are briefly described which were used for remote sensing purposes.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Remote Sensing and the Earth; p 26-41
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  • 88
    Publication Date: 2011-08-17
    Description: The ability of Landsat multispectral digital data to differentiate among 62 combinations of rock and alteration types at the Goldfield mining district of Western Nevada was investigated by using statistical techniques of cluster and discriminant analysis. Multivariate discriminant analysis was not effective in classifying each of the 62 groups, with classification results essentially the same whether data of four channels alone or combined with six ratios of channels were used. Bivariate plots of group means revealed a cluster of three groups including mill tailings, basalt and all other rock and alteration types. Automatic hierarchical clustering based on the fourth dimensional Mahalanobis distance between group means of 30 groups having five or more samples was performed. The results of the cluster analysis revealed hierarchies of mill tailings vs. natural materials, basalt vs. non-basalt, highly reflectant rocks vs. other rocks and exclusively unaltered rocks vs. predominantly altered rocks. The hierarchies were used to determine the order in which sets of multiple discriminant analyses were to be performed and the resulting discriminant functions were used to produce a map of geology and alteration which has an overall accuracy of 70 percent for discriminating exclusively altered rocks from predominantly altered rocks.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: ERIM Proc. of the 11th Intern. Symp. on Remote Sensing of Environment, Vol. 1; p 783-790
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  • 89
    Publication Date: 2011-08-17
    Description: A survey of several offshore islands, rocks and shoals on the Labrador Coast was performed, using LANDSAT imagery to assist in the location of uncharted hydrographic features. Several satellite coverages of the coast were studied prior to the survey, and suspected shoal points identified. Using map-derived control points and monocomparator measurements of the LANDSAT images, the positions of these points were determined by mathematical adjustment to an estimated position accuracy of 150 meters. As a result, on the survey, an uncharted island and eight uncharted drying rocks, which might easily have escaped detection from a survey ship, were verified and positioned. To check the accuracy of the coordinates derived from LANDSAT, three islands were positioned by standard ground survey methods. The positional differences, all less than 150 meters, are not plottable at the scale of the existing offshore charts. The LANDSAT positions were also used to control aerial photography of a shoal area for office compilation of a hydrographic chart.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: ERIM Proc. of the 11th Intern. Symp. on Remote Sensing of Environment, Vol 1; p 775-781
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  • 90
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    Publication Date: 2011-08-17
    Description: System specifications are proposed for an imaging radar whose primary objective is to provide useful information for land applications including hydrology, agriculture and geology.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: ERIM Proc. of the 11th Intern. Symp. on Remote Sensing of Environment, Vol. 1; p 407-425
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  • 91
    Publication Date: 2011-08-17
    Description: The Tennessee Valley Authority was created in 1933 as a resource development agency and was charged with the basic mission of improving the economy of a depressed region through power production, flood control, and navigation. Those programs which availed themselves of remotely monitored data, either directly or indirectly supporting this mission, were examined.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: ERIM Proc. of the 11th Intern. Symp. on Remote Sensing of Environment, Vol. 1; p 385-392
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  • 92
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    Publication Date: 2011-08-17
    Description: The transfer of technology from industrialized countries to the third world is a very complicated process and one that requires a great deal of research and development. The political and social obstacles to this transfer are generally greater than the technical obstacles, but technical assistance programs have neither the competence nor the inclination to deal with these factors adequately. Funding for technical assistance in remote sensing is now expanding rapidly, and there is a growing need for institutions to study and promote the effective use of this technology for economic development. The United Nations, the Food and Agriculture Organization, the World Bank, the United States Agency for International Development and the Canadian technical assistance agencies take different approaches to the problem and deal with the political pressures in different ways.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: ERIM Proc. of the 11th Intern. Symp. on Remote Sensing of Environment, Vol. 1; p 333-338
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  • 93
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    Publication Date: 2011-08-17
    Description: During the past decade, there has been a rapid expansion of remote sensing research and technology development related to coastal wetlands. As a result of this research, all of the 23 coastal states have ongoing or completed wetland inventories, most utilizing aerial photographs as the data source for producing a variety of map products with varying scales, formats, classification systems and intended uses. The U.S. Geological Survey is increasing emphasis on map production and revision for the coastal zone. The new U.S. Fish and Wildlife Service National Wetland Inventory is intended to provide a standardized method for comparison of wetlands on a national basis - it too will use available aerial photographs as a basic data source. At present, satellite data is not used for operational mapping of coastal wetlands because of resolution and geometric constraints. In the future, however, satellite data may provide an accurate reliable and economical source to update wetland inventories and to monitor or evaluate coastal wetlands. The technological improvements accompanying the development and launch of Landsat C and D and the space shuttle promise to make satellite digital data a more powerful tool to supply information for future management decisions for coastal wetlands.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: ERIM Proc. of the 11th Intern. Symp. on Remote Sensing of Environment, Vol. 1; p 301-323
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  • 94
    Publication Date: 2011-08-17
    Description: Problems arising from remote sensing of the earth by satellites have been the subject of indepth research and analysis by the United Nations. Every aspect of this multidisciplinary subject has been explored in more than 100 reports and papers published as UN documents dealing with all the implications of remote sensing: scientific, technological, institutional, political, economic, cultural, and legal. National, regional and international situations have been analyzed, and the General Assembly has passed resolutions requesting that the Committee on the Peaceful Uses of Outer Space give a high priority to remote sensing. The identification and analysis of issues has been going on for several years, the objective being international agreement on general principles to guide nations in the conduct of their remote sensing activities.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: ERIM Proc. of the 11th Intern. Symp. on Remote Sensing of Environment, Vol. 1; p 247-256
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  • 95
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    Publication Date: 2011-08-17
    Description: Most of the remote sensing related work in hydrologic modeling has centered on modifying existing models to take advantage of the capabilities of new sensor techniques. There has been enough success with this approach to insure that remote sensing is a powerful tool in modeling the watershed processes. Unfortunately, many of the models in use were designed without recognizing the growth of remote sensing technology. Thus, their parameters were selected to be map or field crew definable. It is believed that the real benefits will come through the evolution of new models having new parameters that are developed specifically to take advantage of our capabilities in remote sensing. The ability to define hydrologically active areas could have a significant impact. The ability to define soil moisture and the evolution of new techniques to estimate evoportransportation could significantly modify our approach to hydrologic modeling. Still, without a major educational effort to develop an understanding of the techniques used to extract parameter estimates from remote sensing data, the potential offered by this new technology will not be achieved.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: ERIM Proc. of the 11th Intern. Symp. on Remote Sensing of Environment, Vol. 1; p 87-99
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  • 96
    Publication Date: 2011-08-17
    Description: The design of general remote sensing-aided methodologies was studied to provide the estimates of several important inputs to water yield forecast models. These input parameters are snow area extent, snow water content, and evapotranspiration. The study area is Feather River Watershed (780,000 hectares), Northern California. The general approach involved a stepwise sequence of identification of the required information, sample design, measurement/estimation, and evaluation of results. All the relevent and available information types needed in the estimation process are being defined. These include Landsat, meteorological satellite, and aircraft imagery, topographic and geologic data, ground truth data, and climatic data from ground stations. A cost-effective multistage sampling approach was employed in quantification of all the required parameters. The physical and statistical models for both snow quantification and evapotranspiration estimation was developed. These models use the information obtained by aerial and ground data through appropriate statistical sampling design.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: ERIM Proc. of the 11th Intern. Symp. on Remote Sensing of Environment, Vol. 1; p 795-806
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  • 97
    Publication Date: 2011-08-17
    Description: The effects of soil water deficit on spruce and pine seedling canopy reflectance, needle reflectance and transmittance, and canopy density were measured in a greenhouse with a diffuse source of radiant flux. A potential for early or pre-visual detection of plant water stress was not supported by these measurements made at visible, and reflected infrared wavelengths to 1950 nm. Needles were found to transmit approximately thirty percent of the radiant flux incident on them at 780 nm, ten percent at 700 nm, and were found to be opaque at 450, 550, 600 and 650 nm.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: ERIM Proc. of the 11th Intern. Symp. on Remote Sensing of Environment, Vol. 1; p 719-728
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  • 98
    Publication Date: 2011-08-17
    Description: Multispectral data analysis was incorporated with multiseasonal data analysis based on a spectral radiance data-set. Concepts include comparing data types, exploring relationships between periodicity of LANDSAT and the seasonal sense of the Orientals, and derivation of a method to register the acquired data. Examples include a quality investigation of a paddy field by seasonal LANDSAT data, a progress check of the field in harvest season, and a detailed survey of the vegetational environment by summer and winter LANDSAT data.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: ERIM Proc. of the 11th Intern. Symp. on Remote Sensing of Environment, Vol. 1; p 545-561
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  • 99
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    Publication Date: 2011-08-17
    Description: A linear classifier is developed. The classifier algorithm derives, from the picture element (pixel) response values, the response values for a point (called footpoint) consisting of determined proportions of distinct and operator defined land surfaces. The algorithm decides whether the pixel contains the content of the defined surfaces by testing the footpoint to pixelpoint distance against an operator specified threshold value. The test can be either of statistical or geometric form. Those pixels which give a positive result to the test are subclassified according to the proportions of the distinct land surfaces. The practical characteristics of the classifier are discussed and the classification results achieved, in a number of test areas, are described. The artificial nature of the classifier assumptions relate to certain land surface conditions. Testing the suitability of the classifier for other conditions is discussed.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: ERIM Proc. of the 11th Intern. Symp. on Remote Sensing of Environment, Vol. 1; p 535-543
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  • 100
    Publication Date: 2011-08-17
    Description: Efforts of the Agency for International Development to stimulate interest in remote sensing and the use of operational data are described.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: ERIM Proc. of the 11th Intern. Symp. on Remote Sensing of Environment, Vol. 1; p 243-246
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