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  • THERMODYNAMICS AND COMBUSTION  (3)
  • GROUND SUPPORT SYSTEMS AND FACILITIES (SPACE)  (1)
  • Plasma and Beam Physics  (1)
  • captive breeding  (1)
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  • 1
    ISSN: 1573-7160
    Keywords: captive breeding ; in situ conservation ; ex situ conservation ; zoos ; protected areas
    Source: Springer Online Journal Archives 1860-2000
    Topics: Economics
    Notes: Abstract Growing deterministic and stochastic threats to many wild populations of large vertebrates have focused attention on the conservation significance of captive breeding and subsequent reintroduction. However, work on both gorillas and black rhinos questions this shift in emphasis. In these species, field-based conservation can be effective if properly supported and, although this is not cheap, per capita costs may still be considerably lower than for ex situ propagation in captivity. Here we attempt to broaden the scope of this debate by contrasting the breeding success and costs of in situ and captive programmes for a range of threatened mammals. Data are scarce, but we find that across nine large-bodied genera, in situ conservation achieves comparable rates of population growth to those seen in established captive breeding programmes. Moreover, comparing budgets of well-protected reserves with zoos' own estimates of maintenance costs and the costs of zoo adoption schemes, we find that per capita costs for effective in situ conservation are consistently lower than those of maintenance in captivity. Captive breeding may be more cost-effective for smaller-bodied taxa, and will often remain desirable for large mammals restricted to one or two vulnerable wild populations. However, our results, coupled with the fact that effective in situ conservation protects intact ecosystems rather than single species, lead us to suggest that zoos might maximize their contribution to large mammal conservation by investing where possible in well-managed field-based initiatives, rather than establishing additional ex situ breeding programmes.
    Type of Medium: Electronic Resource
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  • 2
    Publication Date: 2011-08-16
    Description: Analytical solutions were obtained for the thermal response of a transpiration- or sublimation-cooled spherical mirror coating exposed to convective and radiative heating. The solutions allow unlimited spectral detail to be accounted for. Results indicate that transpiration-cooled thick coatings (1 cm) may withstand up to 10 kW/sq cm on a steady basis without excessive temperature rise for quartzlike materials with an internal absorption coefficient of 0.01 per cm. On a transient basis, fluxes up to 20 kW/sq cm can be accommodated for a second (cW laser exposure time), 4 kW/sq cm for 5 sec (planetary entry heating time), and of the order of MW/sq cm for millisecond times (short-duration laser bursts) without transpiration cooling for a material with an absorption coefficient of 0.1 per cm. Proportionately higher fluxes can be accommodated with lower absorption coefficients. Thermal stresses produced by the heat pulse are found to be high but within the strength of the materials. The regime in which meaningful solutions may be obtained is mapped in detail.
    Keywords: THERMODYNAMICS AND COMBUSTION
    Type: AIAA Journal; 11; Jan. 197
    Format: text
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  • 3
    Publication Date: 2019-07-13
    Description: Utilizing a series of existing computer codes, ablation experiments in the Giant Planet Facility are numerically simulated. Of primary importance is the simulation of the low Mach number shock layer that envelops the test model. The RASLE shock-layer code, used in the Jupiter entry probe heat-shield design, is adapted to the experimental conditions. RASLE predictions for radiative and convective heat fluxes are in good agreement with calorimeter measurements. In simulating carbonaceous ablation experiments, the RASLE code is coupled directly with the CMA material response code. For the graphite models, predicted and measured recessions agree very well. Predicted recession for the carbon phenolic models is 50% higher than that measured. This is the first time codes used for the Jupiter probe design have been compared with experiments.
    Keywords: GROUND SUPPORT SYSTEMS AND FACILITIES (SPACE)
    Type: AIAA PAPER 79-1102 , American Institute of Aeronautics and Astronautics, Thermophysics Conference; Jun 04, 1979 - Jun 06, 1979; Orlando, FL
    Format: text
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  • 4
    Publication Date: 2019-06-27
    Description: The application of a 'two-flux' technique is considered for determining the reflective characteristics and approximate temperature distribution in highly backscattering materials characterized by a very small absorption coefficient. With respect to the transmitted internal radiation fields, the internal radiative emission is assumed to be negligible. A comparison of theory and experiment is presented.
    Keywords: THERMODYNAMICS AND COMBUSTION
    Type: AIAA Journal; 10; Sept
    Format: text
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  • 5
    Publication Date: 2011-08-16
    Description: The behavior of dielectric materials having densely packed internal scattering centers subject to extreme convective and radiative environments is analyzed. Experiments have shown that these materials act as volume reflectors of incident radiation even when the exposed surface is being eroded by thermochemical ablation. The analysis was applied to interpret experiments of subliming Teflon models exposed to combined radiative and convective fluxes up to 1.7 kW/sq cm for several seconds. Results show that, although the exposed surface receded at an apparently steady rate, the internal temperature climbed continually, due to internal absorption of radiation and would have caused failure internally if the test duration were extended a few seconds. Thus, performance is time-limited by the internal absorption coefficient. Results were obtained for larger configurations and other materials. Typically, Teflon shells may withstand radiant fluxes up to 20 kW/sq cm for about 5 sec and fritted quartz up to 50 kW/sq cm for about 8 sec (corresponding to the Jupiter entry).
    Keywords: THERMODYNAMICS AND COMBUSTION
    Type: AIAA Journal; 11; July 197
    Format: text
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  • 6
    Publication Date: 2018-03-24
    Description: Author(s): C. A. Lindstrøm, E. Adli, J. M. Allen, W. An, C. Beekman, C. I. Clarke, C. E. Clayton, S. Corde, A. Doche, J. Frederico, S. J. Gessner, S. Z. Green, M. J. Hogan, C. Joshi, M. Litos, W. Lu, K. A. Marsh, W. B. Mori, B. D. O’Shea, N. Vafaei-Najafabadi, and V. Yakimenko Hollow channel plasma wakefield acceleration is a proposed method to provide high acceleration gradients for electrons and positrons alike: a key to future lepton colliders. However, beams which are misaligned from the channel axis induce strong transverse wakefields, deflecting beams and reducing t... [Phys. Rev. Lett. 120, 124802] Published Fri Mar 23, 2018
    Keywords: Plasma and Beam Physics
    Print ISSN: 0031-9007
    Electronic ISSN: 1079-7114
    Topics: Physics
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