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  • ASTROPHYSICS  (8)
  • AERODYNAMICS  (3)
  • NUMERICAL ANALYSIS  (2)
  • Astrophysics
  • Polymer and Materials Science
  • 1990-1994  (14)
  • 1992  (7)
  • 1991  (7)
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Verlag/Herausgeber
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  • 1990-1994  (14)
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  • 1
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Fire and Materials 16 (1992), S. 119-125 
    ISSN: 0308-0501
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Architektur, Bauingenieurwesen, Vermessung , Maschinenbau
    Notizen: This study is based on the use of integral, hybrid thermal barrier to protect the core of the composite structure. Thermal barrier treatments evaluated in this study include ceramic fabric, ceramic coating, intumescent coating, hybrid of ceramic and intumescent coating, silicone foam, and phenolic skin. The composite systems evaluated in combination with thermal barrier treatments included glass/vinyl ester, graphite/epoxy, graphite/bismaleimide, and graphite/phenolic. All configurations were tested for flammability characteristics. These included smoke density and combustion gas generation (ASTM E-662), residual flexural strength (ASTM D-790), heat release rate, and ignitability (ASTM E-1354). ASTM E-662 test method covers the determination of specific optical density of smoke generated by solid materials. ASTM D-790 test method covers the determination of flexural properties of composite materials in the form of rectangular bars. ASTM E-1354 (cone calorimeter) covers the measurement of the response of materials exposed to controlled levels of radiant heating with or without an external ignitor, and is used to determine the ignitability, heat release rates, mass loss rates, effective heat of combustion, and visible smoke development. Without any fire barrier treatments, all composite systems evaluated in this study failed to meet ignitability and peak heat release requirements of MIL-STD-2031 (SH) at radiant heat fluxes of 75 and 100 kW m-2, respectively. Intumescent coating and a hybrid system consisting of intumescent coating over ceramic coating were the most effective fire barrier treatments for composite systems evaluated in this study. Using either of these treatments, all composite systems met the ignitability requirements of 90 and 60 at 75 and 100 kW m-2, respectively. Except for glass/vinyl ester, all systems also met the peak and average heat release requirements of MIL-STD-2031 (SH) at radiant heat fluxes of 25, 75, and 100 kW m-2, respectively.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Publikationsdatum: 2013-08-31
    Beschreibung: A model of the spatial density distribution of large (m greater than 10(exp -3) g) cometary meteoroids in the inner solar system is obtained assuming that they have orbits closely associated with that of their parent comet. Distributions of the orbital parameters of the Taurid, Quadrantid and Perseid meteoroid streams are used in developing the model.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Lunar and Planetary Inst., Asteroids, Comets, Meteors 1991; p 403-406
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    facet.materialart.
    Unbekannt
    In:  CASI
    Publikationsdatum: 2013-08-31
    Beschreibung: We analyze the inner coma section of a CCD image of comet P/Halley taken at 1807 UT on 13 March 1986 using a C2 filter (wavelength 5000 to 5200A, half maximum) with the 3.8 m Anglo Australian Telescope at Siding Springs, Australia. Atmospheric turbulence leads to a spreading of the image detail and this produces a blander image of the inner coma region with a slower radial decrease of brightness in comparison to the unaffected image. We remove this smearing by utilizing the point spread function of a star on the same CCD image. Jets were then revealed by removing the average background. Analysis of the jet structure enabled us to estimate the lower limit of the parent molecule velocity. This is found to be 0.3 km s(exp -1).
    Schlagwort(e): ASTROPHYSICS
    Materialart: Lunar and Planetary Inst., Asteroids, Comets, Meteors 1991; p 89-92
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Publikationsdatum: 2019-06-28
    Beschreibung: Two projection operators are presented which employ a very efficient point-location algorithm. For a wide variety of practical problems, the projection cost was reduced by a substantial factor when compared with simpler procedures. Problems involving high levels of local refinement do not impede the point-location algorithm, and the extension of these concept to three dimensions has been implemented with no additional difficulty. Nodal interpolation is noted to be an excellent projection operator when cost is a criterion, while consistent-mass L2-projection furnishes the highest accuracy.
    Schlagwort(e): NUMERICAL ANALYSIS
    Materialart: In: Computational nonlinear mechanics in aerospace engineering (A93-12151 02-31); p. 175-204.
    Format: text
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  • 5
    Publikationsdatum: 2019-06-28
    Beschreibung: An FEM for the compressible Navier-Stokes equations is introduced. The discretization is based on entropy variables. The methodology is developed within the framework of a Galerkin/least-squares formulation to which a discontinuity-capturing operator is added. Results for three test cases selected among those of the Workshop on Hypersonic Flows for Reentry Problems are presented.
    Schlagwort(e): AERODYNAMICS
    Materialart: In: Hypersonic flows for reentry problems. Vol. 2 (A93-42576 17-02); p. 181-200.
    Format: text
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  • 6
    Publikationsdatum: 2019-06-28
    Beschreibung: A finite element method for the compressible Navier-Stokes equations is introduced. The discretization is based on entropy variables. The methodology is developed within the framework of a Galerkin/least-squares formulation to which a discontinuity-capturing operator is added. Results for four test cases selected among those of the Workshop on Hypersonic Flows for Reentry Problems are presented.
    Schlagwort(e): AERODYNAMICS
    Materialart: In: Hypersonic flows for reentry problems. Vol. 2 (A93-42576 17-02); p. 427-450.
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    Publikationsdatum: 2019-07-12
    Beschreibung: A space-time element method is presented for solving the compressible Euler and Navier-Stokes equations. The proposed formulation includes the variational equation, predictor multi-corrector algorithms and boundary conditions. The variational equation is based on the time-discontinuous Galerkin method, in which the physical entropy variables are employed. A least-squares operator and a discontinuity-capturing operator are added, resulting in a high-order accurate and unconditionally stable method. Implicit/explicit predictor multi-corrector algorithms, applicable to steady as well as unsteady problems, are presented; techniques are developed to enhance their efficiency. Implementation of boundary conditions is addressed; in particular, a technique is introduced to satisfy nonlinear essential boundary conditions, and a consistent method is presented to calculate boundary fluxes. Numerical results are presented to demonstrate the performance of the method.
    Schlagwort(e): AERODYNAMICS
    Materialart: Computer Methods in Applied Mechanics and Engineering (ISSN 0045-7825); 89; 3-Jan; 141-219
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    Publikationsdatum: 2019-07-12
    Beschreibung: A Fourier stability and accuracy analysis of the space-time Galerkin/least-squares method as applied to a time-dependent advective-diffusive model problem is presented. Two time discretizations are studied: a constant-in-time approximation and a linear-in-time approximation. Corresponding space-time predictor multi-corrector algorithms are also derived and studied. The behavior of the space-time algorithms is compared to algorithms based on semidiscrete formulations.
    Schlagwort(e): NUMERICAL ANALYSIS
    Materialart: Computer Methods in Applied Mechanics and Engineering (ISSN 0045-7825); 87; 1 Ma; 35-58
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    Publikationsdatum: 2019-07-12
    Beschreibung: The X-ray spectrum of the distant galaxy cluster A2163 was measured in the energy range 1-18 keV with the Ginga satellite. A combined analysis of these data with data previously obtained with the Einstein Observatory is presented. The mean temperature and X-ray luminosity derived are exceptionally high compared to other clusters: kT = 12.9 keV, L(x) (2-10 keV) = 3.5 x 10 exp 45 ergs/s for z = 0.15, as are the gas mass (6.7 x 10 exp 14 solar mass) and binding mass (25 x 10 exp 14 solar mass). The very existence of such a cluster can provide interesting constraints on the relative distribution of 'visible' mass and dark matter, an important parameter in cold dark matter models for formation of structure in the universe.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal, Part 1 (ISSN 0004-637X); 390; 2 Ma; 345-349
    Format: text
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  • 10
    Publikationsdatum: 2019-07-12
    Beschreibung: A semiempirical method for establishing lower limits on the thermal conductivity of hot gas in clusters of galaxies is described. The method is based on the observation that the X-ray imaging data (e.g., Einstein IPC) for clusters are well described by the hydrostatic-isothermal beta model, even for cooling flow clusters beyond about one core radius. In addition, there are strong indications that noncooling flow clusters (like the Coma Cluster) have a large central region (up to several core radii) of nearly constant gas temperature. This suggests that thermal conduction is an effective means of transporting and redistributing the thermal energy of the gas. This in turn has implications for the extent to which magnetic fields in the cluster are effective in reducing the thermal conductivity of the gas. Time-dependent hydrodynamic simulations for the gas in the Coma Cluster under two separate evolutionary scenarios are presented. One scenario assumes that the cluster potential is static and that the gas has an initial adiabatic distribution. The second scenario uses an evolving cluster potential. These models along with analytic results show that the thermal conductivity of the gas in the Coma Cluster cannot be less than 0.1 of full Spitzer conductivity. These models also show that high gas conductivity assists rather than hinders the development of radiative cooling in the central regions of clusters.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal, Part 1 (ISSN 0004-637X); 394; 2 Au; 452-458
    Format: text
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