10,886 research outputs found
Field theoretic calculation of scalar turbulence
The cascade rate of passive scalar and Bachelor's constant in scalar
turbulence are calculated using the flux formula. This calculation is done to
first order in perturbation series. Batchelor's constant in three dimension is
found to be approximately 1.25. In higher dimension, the constant increases as
.Comment: RevTex4, publ. in Int. J. Mod. Phy. B, v.15, p.3419, 200
Radial Vibration of an Aeolotropic Cylindrical Shell of Varying Density in a Magnetic Field
In this paper, we have discussed the problem of vibration of cylindrical
shell of aelotropic material of variable density for two different cases-
first, when the density varies linearly and second, when it varies inversely
as the radius vecto
Structure of a Plane Boundary Shock Wave
Assuming the occurrence of a boundary shock wave as postulated by Martin, this paper studies its structure in conducting gas in presence of a magnetic field
Study of Distribution and Asymmetry of Solar Active Prominences During Solar Cycle 23
In this paper we present the results of a study of the spatial distribution
and asymmetry of solar active prominences (SAP) for the period 1996-2007 (solar
cycle 23). For more meaningful statistical analysis we have analysed the
distribution and asymmetry of SAP in two subdivisions viz. Group1 (ADF, APR,
DSF, CRN, CAP) and Group2 (AFS, ASR, BSD, BSL, DSD, SPY, LPS). The north-south
(N-S) latitudinal distribution shows that the SAP events are most prolific in
the 21-30degree slice in the northern and southern hemispheres and east-west
(E-W) longitudinal distribution study shows that the SAP events are most
prolific (best visible) in the 81-90degree slice in the eastern and western
hemispheres. It has been found that the SAP activity during this cycle is low
compared to previous solar cycles. The present study indicates that during the
rising phase of the cycle the number of SAP events were roughly equal on the
north and south hemispheres. However, activity on the southern hemisphere has
been dominant since 1999. Our statistical study shows that the N-S asymmetry is
more significant then the E-W asymmetry.Comment: 21 pages 5 figures; Published online; 02 October, 2009; Solar Physics
Journa
Seasonal and Interannual Varialbility in Evapotranspiration of Native Tallgrass Prairie and Cultivated Wheat Ecosystems, by G.G. Burba, S.B. Verma
James N. Green est un historien qui a toujours eu des liens étroits avec le Brésil, comme chercheur, mais aussi antérieurement comme militant des droits de l’homme. En 1998, durant un colloque, il dut faire face à une désagréable question. Pourquoi, lui demanda-t-on, les universitaires états-uniens ont si peu fait pour dénoncer les atrocités du régime militaire brésilien entre les années 1960 et le début des années 1980 ? De fait, le gouvernement des États-Unis a soutenu le régime militaire e..
Seasonal and Interannual Varialbility in Evapotranspiration of Native Tallgrass Prairie and Cultivated Wheat Ecosystems, by G.G. Burba, S.B. Verma
Behaviour of Sonic Waves in Dissociating Gases in the Presence of a Magnetic Field
This paper studies sonic waves in dissociating gases under the influence of a magnetic field. The conductivity of the medium has been taken to be finite since the temperature range considered is 1000 degree centigrade K to 7000 degree centigrade K. Since bodies travelling with hypersonic velocities meet with the phenomena of dissociation, this paper has a direct relevance to defence problems
Ice in the Antarctic polar stratosphere
On six occasions during the 1987 Airborne Antarctic Ozone Experiment, the Polar Stratospheric Cloud (PSC) ice crystals were replicated over the Palmer Peninsula at approximately 70 deg South. The sampling altitude was approximately 60 to 65 thousand feet, the temperature range was -83.5 to -72C and the atmosphere was subsaturated in all cases. The collected crystals were predominantly complete and hollow prismatic columns with maximum dimensions up to 217 microns. Evidence of scavenging of submicron particles was detected on several crystals. While the replicated crystal sizes were larger than anticipated, their relatively low concentration results in a total surface area less than one tenth that of the sampled aerosol particles. The presence of large crystals suggest that PSC ice crystals can play a very important role in stratospheric dehydration processes
Synthesis and Microstructural Characteristics of Tl-based High Temperature Superconducting Tapes
Energy fluxes in helical magnetohydrodynamics and dynamo action
Renormalized viscosity, renormalized resistivity, and various energy fluxes
are calculated for helical magnetohydrodynamics using perturbative field
theory. The calculation is to first-order in perturbation. Kinetic and magnetic
helicities do not affect the renormalized parameters, but they induce an
inverse cascade of magnetic energy. The sources for the the large-scale
magnetic field have been shown to be (1) energy flux from large-scale velocity
field to large-scale magnetic field arising due to nonhelical interactions, and
(2) inverse energy flux of magnetic energy caused by helical interactions.
Based on our flux results, a premitive model for galactic dynamo has been
constructed. Our calculations yields dynamo time-scale for a typical galaxy to
be of the order of years. Our field-theoretic calculations also reveal
that the flux of magnetic helicity is backward, consistent with the earlier
observations based on absolute equilibrium theory.Comment: REVTEX4; A factor of 2 corrected in helicit
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