The Experts below are selected from a list of 48123 Experts worldwide ranked by ideXlab platform

Oleg A Godin - One of the best experts on this subject based on the ideXlab platform.

  • Anomalous transmission of infrasound through air-water and air-ground Interfaces
    The Journal of the Acoustical Society of America, 2012
    Co-Authors: Oleg A Godin
    Abstract:

    Sound speed and especially mass density exhibit large relative changes at gas-liquid and Gas-Solid Interfaces. Sound transmission through an interface with a strong impedance contrast is normally very weak. However, diffraction effects can lead to the phenomenon of anomalous transparency of gas-liquid or Gas-Solid Interfaces, where most of the acoustic power generated by a compact, low-frequency source located within the liquid or within the solid is radiated into the gas. Contrary to the conventional wisdom based on ray-theoretical predictions and observations at higher frequencies, infrasonic energy from compact waterborne and underground sources can be effectively transmitted into air. This paper reviews the theory and emerging experimental evidence of the anomalous transparency. Physical mechanisms responsible for enhanced sound transmission at low frequencies are discussed. The phenomenon of anomalous transparency can have significant implications, in particular, for localization of buried objects an...

  • Low-frequency sound transmission through a Gas-Solid interface.
    The Journal of the Acoustical Society of America, 2011
    Co-Authors: Oleg A Godin
    Abstract:

    Sound transmission through Gas-Solid Interfaces is usually very weak because of the large contrast in wave impedances at the interface. Here, it is shown that diffraction effects can lead to a dramatic increase in the transparency of Gas-Solid Interfaces at low frequencies, resulting in the bulk of energy emitted by compact sources within a solid being radiated into a gas. The anomalous transparency is made possible by power fluxes in evanescent body waves and by excitation of interface waves. Sound transmission into gas is found to be highly sensitive to absorption of elastic waves within a solid.

  • Low-frequency sound transmission through a gas–liquid interface
    The Journal of the Acoustical Society of America, 2008
    Co-Authors: Oleg A Godin
    Abstract:

    Sound transmission through gas–solid Interfaces is usually very weak because of the large contrast in wave impedances at the interface. Here, it is shown that diffraction effects can lead to a dramatic increase in the transparency of gas–solid Interfaces at low frequencies, resulting in the bulk of energy emitted by compact sources within a solid being radiated into a gas. The anomalous transparency is made possible by power fluxes in evanescent body waves and by excitation of interface waves. Sound transmission into gas is found to be highly sensitive to absorption of elastic waves within a solid.

Hans-dieter Wiemhöfer - One of the best experts on this subject based on the ideXlab platform.

  • Sensing effects at Gas-Solid Interfaces
    Solid State Ionics, 1995
    Co-Authors: Hans-dieter Wiemhöfer
    Abstract:

    Abstract Sensing effects at Gas-Solid Interfaces are discussed and compared with emphasis on solid ionic conductors. Energy schemes or band diagrams for ions and electrons are useful for discussing the thermodynamic and electrical properties of Gas-Solid Interfaces in equilibrium. Absolute electrode potentials are defined and illustrated with results for oxygen electrodes on yttria-stabilized zirconia. Atomistic properties of Gas-Solid interactions are discussed with regard to the reactions and elementary steps during chemisorption, electrode reaction and electron or charge transfer between solid and adsorbate. Apart from equilibria, nonequilibrium processes can be used for gas sensing. Examples are given for the application of different catalytic properties of electrode materials.

Yongping Chen - One of the best experts on this subject based on the ideXlab platform.

  • Temperature jump at rough gas–solid interface in Couette flow with a rough surface described by Cantor fractal
    International Journal of Heat and Mass Transfer, 2014
    Co-Authors: Chengbin Zhang, Zilong Deng, Yongping Chen
    Abstract:

    Abstract A lattice Boltzmann simulation of heat transfer for gas flowing in microchannels incorporating surface roughness as characterized by fractal Cantor structure is conducted to investigate the temperature jump at rough gas–solid Interfaces in the slip flow regime. The gas temperature jump at rough interface as quantified by the temperature jump length is evaluated and compared with smooth interface. It is indicated that the temperature jump at a rough gas–solid interface is mainly dependent on Knudsen number, Prandtl number, and surface roughness. The presence of roughness is beneficial to the energy exchange at the gas–solid interface and introduces a smaller temperature jump when compared with a smooth surface. The local gas temperatures in the valley of rough surface are approximately equal to the corresponding surface temperatures while an obvious interfacial temperature jump is detected over the peaks of the rough surface. In addition, increase in Prandtl number, roughness height, surface fractal dimension as well as the decrease in Knudsen number can lead to the reduction of interface temperature jump for gas convection heat transfer in microchannels. Interestingly, in microchannels, the roughness height play a considerable role in the temperature jump at the gas–solid interface, however, the effect of fractal dimension on interfacial temperature jump is not so significant.

Chathan M. Cooke - One of the best experts on this subject based on the ideXlab platform.

  • SURFACE FLASHOVER OF GAS/SOLID Interfaces
    Gaseous Dielectrics III, 2013
    Co-Authors: Chathan M. Cooke
    Abstract:

    ABSTRACT Surface flashover along a gas/solid interface is an important limiting factor for the withstand voltage and the reliability of compressed-gas-insulated equipment. The flashover process may be viewed as comprised of two parts: inception and propagation. Both of these have been studied and are shown to be influenced by the applied field and its perpendicular and tangential components at the insulator surface. Surface electric charge accumulations and contaminate particles are thus found to be influential when they significantly perturb the surface fields. The flashover path will follow the surface from electrode to electrode, or, when perpendicular component fields are high, may jump from the surface through the gas or into the solid itself. Experimental results in systems where the applied surface field distribution was controllable are used to confirm the basic phenomena and models.

Abderrahmane Beroual - One of the best experts on this subject based on the ideXlab platform.

  • Creeping Discharges at Liquid/solid and Gas/Solid Interfaces: Analogies and Involving Mechanisms
    2019 IEEE 20th International Conference on Dielectric Liquids (ICDL), 2019
    Co-Authors: Abderrahmane Beroual
    Abstract:

    This paper is a synthesis of acquired results by my group on creeping discharges at fluid/solid Interfaces during the last two decades. It aims to evidence the analogies between the characteristic parameters of surface discharges propagating on liquid/solid and gas/solid Interfaces (namely, shape, stopping length, current/electrical charge, fractal dimension) and the dependency of these characteristics on the same physical parameters. It also evidences the influence of the capacitive effects on these characteristics under different types of voltage waveforms namely AC, DC and lightning impulse voltages.