17,280 research outputs found

    Classical String in Curved Backgrounds

    Get PDF
    The Mathisson-Papapetrou method is originally used for derivation of the particle world line equation from the covariant conservation of its stress-energy tensor. We generalize this method to extended objects, such as a string. Without specifying the type of matter the string is made of, we obtain both the equations of motion and boundary conditions of the string. The world sheet equations turn out to be more general than the familiar minimal surface equations. In particular, they depend on the internal structure of the string. The relevant cases are classified by examining canonical forms of the effective 2-dimensional stress-energy tensor. The case of homogeneously distributed matter with the tension that equals its mass density is shown to define the familiar Nambu-Goto dynamics. The other three cases include physically relevant massive and massless strings, and unphysical tahyonic strings.Comment: 12 pages, REVTeX 4. Added a note and one referenc

    Active vibration isolator for flexible bodies Patent

    Get PDF
    Vibration control of flexible bodies in steady accelerating environmen

    Improved active vibration isolator

    Get PDF
    Active vibration isolator simultaneously isolates a flexible structure or payload from disturbances, attenuates the response of a flexible structure to transient disturbances, and maintains the equilibrium position of the payload within predetermined limits over a wide range of steady loads and accelerators

    Separator development for a heat sterilizable battery

    Get PDF
    Coating procedure for tape separator of heat sterilizable batter

    Separator development for a heat sterilizable battery Quarterly report, 1 Jan. - 31 Mar. 1968

    Get PDF
    Dip coating method for manufacturing sterilizable battery tape separator

    Separator development for a heat sterilizable battery Quarterly report, 1 Apr. - 30 Jun. 1968

    Get PDF
    Flame absorption spectroscopic analysis of support tape

    Separator development for a heat sterilizable battery Quarterly report, Oct. 1 - Dec. 31, 1967

    Get PDF
    Zirconium oxide loadings and coating methods varied to improve separators for heat sterilizable batter

    Modelling the local and global cloud formation on HD 189733b

    Get PDF
    Context. Observations suggest that exoplanets such as HD 189733b form clouds in their atmospheres which have a strong feedback onto their thermodynamical and chemical structure, and overall appearance. Aims. Inspired by mineral cloud modelling efforts for Brown Dwarf atmospheres, we present the first spatially varying kinetic cloud model structures for HD 189733b. Methods. We apply a 2-model approach using results from a 3D global radiation-hydrodynamic simulation of the atmosphere as input for a detailed, kinetic cloud formation model. Sampling the 3D global atmosphere structure with 1D trajectories allows us to model the spatially varying cloud structure on HD 189733b. The resulting cloud properties enable the calculation of the scattering and absorption properties of the clouds. Results. We present local and global cloud structure and property maps for HD 189733b. The calculated cloud properties show variations in composition, size and number density of cloud particles which are strongest between the dayside and nightside. Cloud particles are mainly composed of a mix of materials with silicates being the main component. Cloud properties, and hence the local gas composition, change dramatically where temperature inversions occur locally. The cloud opacity is dominated by absorption in the upper atmosphere and scattering at higher pressures in the model. The calculated 8{\mu}m single scattering Albedo of the cloud particles are consistent with Spitzer bright regions. The cloud particles scattering properties suggest that they would sparkle/reflect a midnight blue colour at optical wavelengths.Comment: Accepted for publication (A&A) - 21/05/2015 (Low Resolution Maps
    • …
    corecore