On the temperature distribution in the solar corona     

H. P. Mital  Udit Narain 《Solar physics》1978,56(1):121-123

An improved value of coronal temperature is obtained by the degree of ionization method taking various processes into consideration. Comparison with some of the existing results has also been made.  相似文献   

On distribution of CMEs speed in solar cycle 23     

Nishant Mittal  Joginder Sharma  Vivek Tomar  Udit Narain 《Planetary and Space Science》2009,57(1):53-57

We have analyzed the data for more than 12900 coronal mass ejections (CMEs) which were obtained by SOHO/LASCO during the period of 1996-2007. The online CME catalogue contains all major CMEs detected by LASCO C2 and C3 coronagraphs. Basically we determine the CME speeds from the linear and quadratic fits to the height-time measurements. It is found that linear (constant speed) fit is preferable for 90% of the CMEs. The distribution of speeds of CMEs in solar cycle 23 is presented along with those obtained by others. As expected, the speeds decrease in the decay phase of the cycle 23. There is an unusual drop in speed in the year 2001 and an abnormal increase in speed in the year 2003 due to the high concentration of CMEs, X-class soft X-ray flares, solar energetic particle (SEP) events and interplanetary shocks observed during October-November period called Halloween events.  相似文献   

Propagator matrix formulation of heat transfer in spherically stratified media     

Janardan G. Negi  Rishi Narain Singh 《Pure and Applied Geophysics》1968,70(1):74-80

Summary In the paper we have transformed the steady and unsteady conductive heat transfer differential equation in spherical coordinates into a system of first order differential equations and processed them by method of propagator matrices to extrapolate the known surface heat flux and temperature to any desired depth. The elements of propagator matrices have been summarised for various piecewise continuous conductivity and rate of heat generation functions to approximate inhomogeneities in the earth. In the analysis the rate of heat generation is either assumed to depend linearly upon temperature or correspond to first order irreversible chemical reactions.  相似文献   

Radioactive heat generation and heat flow in the Indian shield     

R.U.M. Rao  G.V. Rao  Hari Narain 《Earth and Planetary Science Letters》1976,30(1):57-64

Using a laboratory gamma-ray spectrometer, 160 rock samples from different heat flow sites in India have been analysed for their U, Th and K contents. Heat generation has been estimated for the significant rock types. Of the six regions covered by this study, correction due to heat generation contrast and geologic structure was found necessary and has been applied in two regions. Heat flow/heat generation plots for two regions in the southernmost part of the shield follow the line characteristic of a normal continental heat flow province. The plots for the other four regions indicate a heat flow province with an intercept of 0.92 HFU and a slope of 14.8 km. From data available at present, these parameters are higher compared to those from the other shields. The higher parameters imply a higher temperature and heat flow at the Moho, indicating a region of “hotter” upper mantle in the Indian shield.  相似文献   

Structure of the lithosphere along the deep seismic sounding profile: Tien Shan—Pamirs—Karakorum—Himalayas     

V. V. Beloussov  N. A. Belyaevsky  A. A. Borisov  B. S. Volvovsky  I. S. Volkovsky  D. P. Resvoy  B. B. Tal-Virsky  I. Kh. Khamrabaev  K. L. Kaila  H. Narain  A. Marussi  J. Finetti 《Tectonophysics》1980,70(3-4):193-221

During 1973–1977, as part of the International Geodynamic Project, some seismic investigations of the Earth's crust have been carried out by geotraverses of the Tien Shan—Pamirs—Karakorum—Himalayas. The seismic data obtained together with other geophysical information, allow the construction and interpretation of the lithospheric section through the Pamirs-Himalayas structure. This section includes thick crust with complex layering, supra-asthenospheric and asthenospheric layers of the upper mantle. The thickness of the Earth's crust increases from 50–55 km in the north, in the Ferghana depression (Tien Shan), to 70–75 km in the south, near the Karakul Lake (Northern Pamir). It varies within 60–65 km for the Central and Southern Pamir, Karakorum and the Inner Himalayas. Its thickness is least (35–37 km) in the south, under the outer margin of the Himalayan foredeep. Extreme gravity minima and depressions on the geoid surface correspond to the regions with maximum thickness of the Earth's crust. The centers of the disturbing masses on the geoid surface are located in the vicinity of the asthenosphere's upper layer; this determines the effect of the whole lithospheric layer, including its asthenospheric layer, at intense changes of gravity anomalies. The asthenospheric upper layer is recorded at a depth of about 120 km, its base at a depth of 200 km, in the northern and southern regions, and 300 km in its central part (Southern Pamir, Karakorum). In the middle asthenospheric layer, wave velocities decrease to 7.5 km/sec, under the base they increase to 8.4 km/sec and reach 9.4 km/sec at a depth of about 400 km. In the supra-asthenospheric layer of the upper mantle, longitudinal and shear wave-velocities slightly increase (by less than 0.1 km/sec) towards its base.  相似文献   

Propagation of Rayleigh waves on cylindrical surfaces of transversely isotropic material and of varying density in a magnetic field     

Surya Narain  B. G. Verma 《Pure and Applied Geophysics》1972,98(1):13-25

Summary Three dimensional magneto-elastic equations pertaining to the problem of propagation of axial Rayleigh waves on the surface of elastic cylinder of isotropic material have been solved. Two cases have been considered — first, when the density varies linearly and second, when it varies inversely as the radius vector and frequency equations for both the cases have been obtained.  相似文献   

On temperatures in the crust: The effect of temperature dependence of conductivity     

Rishi Narain Singh  Sheel Chandra Jain 《Pure and Applied Geophysics》1970,80(1):267-270

Summary An analysis is made to ascertain the effect of conductivity variation with temperature on the temperatures within the crust. It shows that this effect is very small and can safely be neglected.  相似文献   

    

Udit Narain  Rakesh Kumar Sharma 《Solar physics》1998,181(2):287

We quantitatively re-examine the nonlinear viscous damping of surface Alfvén waves in polar coronal holes, using recently reported observational data on electron density and temperature and the magnetic field spreading near the edges. It is found that in the nonlinear regime the viscous damping of surface Alfvén waves becomes a viable mechanism of solar coronal plasma heating when strong spreading of magnetic field is taken into account. Our estimations confirm that coronal heating is more pronounced in the nonlinear case than in the linear one in presence of magnetic field spreading.  相似文献   

Fluid Institutions: Commons in Transition in the Periurban Interface     

Aditya Kumar Singh  Vishal Narain 《社会与自然资源》2019,32(5):606-615

Amidst growing concern about the decline of the commons, this case underscores the importance of understanding how the commons are refashioned and remade to address emerging challenges in periurban spaces. This article describes how institutions surrounding the use of common property resources get transformed and evolve in periurban contexts. What were once johads – common property village ponds – undergo a change in their usage from storing rainwater to storing waste water of the city for irrigation. This emerges as a collective response to the uncertainty attached to the availability of waste water. New institutions evolve with regard to contributions to waste water infrastructure, as well as the appropriation of waste water. Further research should document the changing use of village commons and the emergence of new institutions governing them.  相似文献   

Self-gravitating fluids in cylindrically-symmetric non-static space-time     

S. Narain 《Astrophysics and Space Science》1985,116(2):389-394

In this paper we have obtained a cylindrically symmetric non-static model of the perfect fluid distribution, satisfying one of the Petrov type D conditions. This turned out to be a FRW model.  相似文献