65 research outputs found

    Experimental study on the influence of wall heat effect on gas explosion and its propagation

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    In order to understand the mechanism and the influence degree of wall heat effect on gas explosion and its propagation, the influence of wall heat effect on gas explosion and its propagation is theoretically analyzed mainly from perspectives of the heat transportation and reaction process. Results show that the influence of wall heat loss on gas explosion strength is significant. In addition, the influences of wall heat effect on explosion wave and flame propagation velocity in the gas explosion process are experimentally investigated in the adiabatic condition and heat conduction. It is found that the wall heat effect can affect gas explosion strength, flame propagation velocity, peak overpressure and the peak flame propagation velocity, and their influence degree becomes more significant with the increase of the adiabatic degree. Therefore, it can be seen that the wall heat effect has an important influence on the gas explosion and its propagation. The influence of wall adiabatic condition on gas explosion with a higher combustion level is greater than the influence on gas explosion with low combustion levels

    Non-Gaussianity from false vacuum inflation: Old curvaton scenario

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    We calculate the three-point correlation function of the comoving curvature perturbation generated during an inflationary epoch driven by false vacuum energy. We get a novel false vacuum shape bispectrum, which peaks in the equilateral limit. Using this result, we propose a scenario which we call "old curvaton". The shape of the resulting bispectrum lies between the local and the false vacuum shapes. In addition we have a large running of the spectral index.Comment: 13 pages, 3 figures; v2 with minor revison; v3 final version to appear on JCA

    Quadra-Spectrum and Quint-Spectrum from Inflation and Curvaton Models

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    We calculate the quadra-spectrum and quint-spectrum, corresponding to five and six point correlation functions of the curvature perturbation. For single field inflation with standard kinetic term, the quadra-spectrum and quint-spectrum are small, which are suppressed by slow roll parameters. The calculation can be generalized to multiple fields. When there is no entropy perturbation, the quadra-spectrum and quint-spectrum are suppressed as well. With the presence of entropy perturbation, the quadra-spectrum and quint-spectrum can get boosted. We illustrate this boost in the multi-brid inflation model. For the curvaton scenario, the quadra-spectrum and quint-spectrum are also large in the small r limit. We also calculate representative terms of quadra-spectrum and quint-spectrum for inflation with generalized kinetic terms, and estimate their order of magnitude for quasi-single field inflation.Comment: 16 pages; v2: references added

    Temperature-programmed liquefaction of a low-rank coal

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