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  • 1995-1999  (1)
  • 1985-1989  (4)
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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
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    In:  Other Sources
    Publication Date: 2019-06-28
    Description: Flow conditions corresponding to those of three previously conducted hypersonic axisymmetric flow experiments are presently treated by numerical solutions of the axisymmetric, thin layer Navier-Stokes equations with the Chemistry and Gasdynamic Implicit computer code's Version 2. While simulation and experimental results agree for ideal gas flows, the simulation for the case of a real gas flow reveals that the particular coupling of the gasdynamics and the chemistry used in the code degrades the convergence level obtainable, by comparison with ideal gas cases. The computed stagnation point heating is 60 percent lower than for the experiment.
    Keywords: AERODYNAMICS
    Type: AIAA PAPER 86-1285
    Format: text
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  • 3
    Publication Date: 2019-06-28
    Description: It is pointed out that further exploration of Titan, Saturn's largest moon, is of current interest to the scientific community, particularly from the standpoint of the organic chemical evolution of its atmosphere. For a suitable study of this Saturnian satellite, a mission involving a Titan atmospheric entry probe is to be conducted. The probe is to employ a deployable decelerator with the aim to allow scientific measurements in the haze layer. The present investigation is concerned with an assessment of the aerothermodynamic environment for the considered probe during its hypervelocity, low-Reynolds-number entry. Attention is given to the employed computational method, the Titan probe configuration, the Titan probe trajectory, the viscous-layer regime of the aerothermodynamic environment, and the incipient merged-layer regime.
    Keywords: AERODYNAMICS
    Type: AIAA PAPER 85-1063
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  • 4
    Publication Date: 2019-06-28
    Description: The Conservative Supra Characteristic Method (CSCM), an implicit upwind Navier-Stokes algorithm, is extended to the numerical simulation of flows in chemical equilibrium. The resulting computer code known as Chemistry and Gasdynamics Implicit - Version 2 (CAG12) is described. First-order accurate results are presented for inviscid and viscous Mach 20 flows of air past a hemisphere-cylinder. The solution procedure captures the bow shock in a chemically reacting gas, a technique that is needed for simulating high altitude, rarefied flows. In an initial effort to validate the code, the inviscid results are compared with published gasdynamic and chemistry solutions and satisfactorily agreement is obtained.
    Keywords: AERODYNAMICS
    Type: AIAA PAPER 85-0927
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  • 5
    Publication Date: 2019-06-28
    Description: Equilibrium, radiating viscous-shock-layer solutions are obtained for a number of trajectory points of the Fire II, Apollo 4, and PAET experimental flight vehicles. Convective heating rates calculated by a benchmark code agree well, except at high altitudes corresponding to low densities, with two engineering correlations. Calculated radiation intensities are compared with the flight radiometer data and with inviscid flow results. Differences as great as 70 percent are observed between measured data and the viscous calculations. Viscous effects reduce the intensity toward the wall, because of boundary-layer absorption, by as much as 30 percent, compared with inviscid intensities. Preliminary chemical and thermal nonequilibrium flow calculations along a stagnation streamline for a PAET trajectory predict enhancement of radiation owing to chemical relaxation. Stagnation point solutions are also presented for future air-assisted orbital transfer vehicle geometries with nose radii ranging from 0.3 to 15 m.
    Keywords: AERODYNAMICS
    Type: AIAA PAPER 85-1064
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