8,717 research outputs found
Interval structure of the Pieri formula for Grothendieck polynomials
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
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 , i.e., fluid to magnetic energy ratios
when the normalized cross helicity is zero. We find that increases from
1.47 to 4.12 as we go from fully fluid case to a situation when , then it decreases to 3.55 in a fully magnetic limit .
When , we find that .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
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
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
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
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
- …