8,717 research outputs found

    Interval structure of the Pieri formula for Grothendieck polynomials

    Get PDF
    We give a combinatorial interpretation of a Pieri formula for double Grothendieck polynomials in terms of an interval of the Bruhat order. Another description had been given by Lenart and Postnikov in terms of chain enumerations. We use Lascoux's interpretation of a product of Grothendieck polynomials as a product of two kinds of generators of the 0-Hecke algebra, or sorting operators. In this way we obtain a direct proof of the result of Lenart and Postnikov and then prove that the set of permutations occuring in the result is actually an interval of the Bruhat order.Comment: 27 page

    Computation of Kolmogorov's Constant in Magnetohydrodynamic Turbulence

    Get PDF
    In this paper we calculate Kolmogorov's constant for magnetohydrodynamic turbulence to one loop order in perturbation theory using the direct interaction approximation technique of Kraichnan. We have computed the constants for various Eu(k)/Eb(k)E^u(k)/E^b(k), i.e., fluid to magnetic energy ratios when the normalized cross helicity is zero. We find that KK increases from 1.47 to 4.12 as we go from fully fluid case (Eb=0)(E^b=0) to a situation when Eu/Eb=0.5% E^u/E^b=0.5, then it decreases to 3.55 in a fully magnetic limit (Eu=0)(E^u=0). When Eu/Eb=1E^u/E^b=1, we find that K=3.43K=3.43.Comment: Latex, 10 pages, no figures, To appear in Euro. Phys. Lett., 199

    On the Performance of Slider Bearing under Fluctuating Speed using a Non-Newtonian Visco-Elastic Fluid as Lubricant

    Get PDF
    In the present paper effect of fluctuations on the performance of a slider bearing has been considered using a non-Newtonian viscoelastic fluid as lubricant. It has been obtained that load-carrying capacity of the hearing always exceeds its value in steady case except for a brief initial period. The effect of visco-elasticity has been found to be advantageous for the increase of load-carrying capacity

    On the Performance of Slider Bearing under Fluctuating Speed using a Non-Newtonian Visco-Elastic Fluid as Lubricant

    Get PDF
    In the present paper effect of fluctuations on the performance of a slider bearing has been considered using a non-Newtonian viscoelastic fluid as lubricant. It has been obtained that load-carrying capacity of the hearing always exceeds its value in steady case except for a brief initial period. The effect of visco-elasticity has been found to be advantageous for the increase of load-carrying capacity

    Biochemical genetic profile of the Indian mackerel Rastreliger kanagurta of mud bank and post-mud bank period

    Get PDF
    An attempt was made to study the genetic profile of the Indian mackerel Rastrelliger kanagurta, an economically important fish species of India. The genetic profile of the mackerel caught during the mud bank period was compared to that of the post mud bank period

    High-resolution imaging and near-infrared spectroscopy of penumbral decay

    Full text link
    Combining high-resolution spectropolarimetric and imaging data is key to understanding the decay process of sunspots as it allows us scrutinizing the velocity and magnetic fields of sunspots and their surroundings. Active region NOAA 12597 was observed on 24/09/2016 with the 1.5-m GREGOR solar telescope using high-spatial resolution imaging as well as imaging spectroscopy and near-infrared (NIR) spectropolarimetry. Horizontal proper motions were estimated with LCT, whereas LOS velocities were computed with spectral line fitting methods. The magnetic field properties were inferred with the SIR code for the Si I and Ca I NIR lines. At the time of the GREGOR observations, the leading sunspot had two light-bridges indicating the onset of its decay. One of the light-bridges disappeared, and an elongated, dark umbral core at its edge appeared in a decaying penumbral sector facing the newly emerging flux. The flow and magnetic field properties of this penumbral sector exhibited weak Evershed flow, moat flow, and horizontal magnetic field. The penumbral gap adjacent to the elongated umbral core and the penumbra in that penumbral sector displayed LOS velocities similar to granulation. The separating polarities of a new flux system interacted with the leading and central part of the already established active region. As a consequence, the leading spot rotated 55-degree in clockwise direction over 12 hours. In the high-resolution observations of a decaying sunspot, the penumbral filaments facing flux emergence site contained a darkened area resembling an umbral core filled with umbral dots. This umbral core had velocity and magnetic field properties similar to the sunspot umbra. This implies that the horizontal magnetic fields in the decaying penumbra became vertical as observed in flare-induced rapid penumbral decay, but on a very different time-scale.Comment: 14 pages, 11 figures, Accepted to be published in Astronomy and Astrophysic
    corecore