Influence of surface layers on the seismic estimate of the solar radius     

Tripathy  S.C.  Antia  H.M. 《Solar physics》1999,186(1-2):1-11

Possible systematic errors in determining the solar radius from the f-mode frequencies are studied to find that the input physics governing the structure of outermost layers of the Sun has significant influence on the estimated radius. It is investigated how treatment of convection and low temperature opacity may influence the determination of radius and it is found that it may be changed by as much as 100 km. The best estimate of the solar radius is found to be 695.77±0.1 Mm, where the error bars represent estimate of systematic errors, while the statistical errors are very small (1 km).  相似文献   

Nonlinear shock structure in a weakly ionised magnetoplasma     

C. B. Dwivedi  S. C. Tripathy 《Annales Geophysicae》1994,12(12):1139-1143

The formation of a neutral induced weak nonlinear shock structure in a weakly ionised magnetoplasma has been analytically investigated. Using the reductive perturbation method, basic dynamical equations of a three-component (electron, ion and neutral) plasma have been reduced to a well-known Burger equation which can support a weak shock solution. Its stationary and initial value solutions have been derived to describe the characteristics of the weak shock profile. Asymptotic behavior of the Burger solution results in a saw-tooth structure which has a practical implication to predict the nonlinear steepened structure of the nighttime irregularity in the lower portion of the Earth’s ionosphere. Accordingly, it is suggested that the observation of saw-tooth shape of nighttime irregularity at 92 km could be attributed to the nonlinear saturation of the NILF mode instability as proposed by Dwivedi and Das in 1992. However, exact experimental verification of this suggestion requires more data on nighttime irregularity in the mesosphere and lower thermosphere (80-95 km) for a wide range of scale sizes extending up to about 1 km and above.  相似文献   

Time dependent viscous string cloud cosmological models     

S. K. Tripathy  S. K. Nayak  S. K. Sahu  T. R. Routray 《Astrophysics and Space Science》2009,323(1):91-96

Bianchi type-I string cosmological models are studied in Saez-Ballester theory of gravitation when the source for the energy momentum tensor is a viscous string cloud coupled to gravitational field. The bulk viscosity is assumed to vary with time and is related to the scalar expansion. The relationship between the proper energy density ρ and string tension density λ are investigated from two different cosmological models.  相似文献   

How Good are the Predictions for Oscillation Frequencies     

Jain  Kiran  Tripathy  S.C.  Bhatnagar  A. 《Solar physics》2002,206(2):213-217

We have used available intermediate degree p-mode frequencies for solar cycle 23 to check the validity of previously derived empirical relations for frequency shifts (Jain et al., 2000). We find that the calculated and observed frequency shifts during the rising phase of cycle 23 are in good agreement. The observed frequency shift from minimum to maximum of this cycle as calculated from MDI frequency data sets is 251±7 nHz and from GONG data is 238±11 nHz. These values are in close agreement with the empirically predicted value of 271±22 nHz.  相似文献   

Delineation of fluoride contaminated groundwater around a hot spring in Nayagarh, Orissa, India using geochemical and resistivity studies     

N. Kundu  M. Panigrahi  S. Sharma  S. Tripathy 《Environmental Geology》2002,43(1-2):228-235

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Trace element chemistry of major rivers in Orissa State, India   总被引：1，自引：1，他引：1  

K. O. Konhauser  M. A. Powell  W. S. Fyfe  F. J. Longstaffe  S. Tripathy 《Environmental Geology》1997,29(1-2):132-141

 Geochemical analyses of surface waters from rivers flowing through Orissa State, India, indicated that trace element concentrations were extremely variable and consistently higher than world river average. The Brahmani River was the most solute-rich river studied, followed by the Baitarani and Mahanadi Rivers. Although all three rivers drain similar geology, the Brahmani River catchment is heavily industrialized, and water samples collected upstream and downstream from industries indicated that anthropogenic activity directly influenced its chemical composition. Samples collected from several towns, in all three river systems, did not invariably show similar patterns, with various elements having higher dissolved concentrations upstream. Because the concentration of total solids increased downstream, this implied that some components of the sewage had effectively sequestered available elements from solution and converted them to particulate material. Although the impact of pollution is clearly recognizable in water samples collected in proximity to the anthropogenic source, there are only slight elemental accumulations in the lower reaches of the Mahanadi River, with no accumulation in the Brahmani River. Apparently for these large rivers, discharged effluent becomes rapidly diluted, while complexation and sedimentation further removes trace elements from the water column. However, in the less voluminous Baitarani River, elementar enrichment near the river's mouth suggests that in this secondary river, where dilution effects are less, the concerns over regional water quality may be more prevalent. Received: 1 April 1995 · Accepted: 30 August 1995  相似文献   

Geological and geomorphological studies of a part of Ganjam district,Orissa by remote sensing techniques     

J K Tripathy  R C Panigrahy  K Vinod Kumar 《Journal of the Indian Society of Remote Sensing》1996,24(3):169-177

Geological and geomorphological mapping was carried out for a part of Ganjam district, Orissa through visual interpretation of IRS-IB LISS II flase colour composites. Various lithounits such as khondalites, charnockites and granites of Archaean age were mapped. The study area is traversed by two sets of vertical joints — one trending in NE-SW direction and the other in NW-SE direction. Three sets of lineaments in the study area trending in NE-SW, NW-SE and ENE-WSW suggest that the study area was subject to very high degree of deformation in the past. Major geomorphic units delineated are, Hills, Pediments, Valley Fills, New Flood Plains, Old Flood Plains, New Coastal Plains and Old Coastal Plains. Different landforms under each geomorphic unit are also mapped.  相似文献   

Detection of Hα Intensity Oscillations in Solar Flares     

Jain  Rajmal  Tripathy  S. C. 《Solar physics》1998,181(1):113-120

We report here the first direct evidence for detection of H intensity oscillations in two extended flares of 15 November 1989 and 20 April 1991. The relative intensity variations measured with time at 18 different flare and chromospheric locations were analysed to obtain the oscillation modes. The analysis shows prominent 5- and 3-min modes in flares in addition to their existence in the chromosphere. However, there exists a frequency difference between the flare and chromospheric modes. This frequency deviation of about 300 µHz is proposed as an influence of higher magnetic field, location of the measurements (height) in chromosphere, and high temperature in the flare.  相似文献   

Qualitative stability assessment of cut slopes along the National Highway-05 around Jhakri area,Himachal Pradesh,India     

Jagadish Kundu  Kripamoy Sarkar  Ashutosh Tripathy  T N Singh 《Journal of Earth System Science》2017,126(8):112

Several deformation phases in tectonically active Himalayas have rendered the rock masses very complex in terms of structure, lithology and degree of metamorphism. Again, anthropogenic activities such as roads, tunnels and other civil engineering constructions have led to a state of disequilibrium which in many cases, results in failure of rock masses. National Highway-05 around Jhakri area in India is a major connecting route to the China border in the hilly terrains of the state Himachal Pradesh. It cuts through the Himalayan rocks and has a hazardous history of landslides destroying human lives and interrupting communication very frequently. As a contribution towards the mitigation process, a study has been carried out along the highway to analyse kinematic stability and qualitative estimation of rock mass condition through rock mass classification systems. The kinematic analysis shows that the rock slopes are prone to planar and wedge failure. Rock mass rating for most of the locations lies between 7 and 34, representing a poor rock mass quality (Class IV), whereas slope mass rating is more disperse and ranges from 11 to 52 for most of the slopes (Class III, IV and V).  相似文献   

Geochemical studies to delineate topsoil contamination around an ash pond of a coal-based thermal power plant in India     

T.?PraharajEmail author  S.?Tripathy  M.?A.?Powell  B.?R.?Hart 《Environmental Geology》2003,45(1):86-97

In the present study, an attempt was made to delineate soil contamination around the ash pond of a coal-based thermal power plant. The topsoil in the study area was found to be contaminated to varying degrees from ash disposal. The soil drawn from various profiles was largely contaminated by ash fall out, predominantly in the prevalent wind direction. Pb, Zn, Cu, Ni, Co, Mn, Cr, V and Ba were found to be enriched in the topsoil around the ash pond with respect to the crust as well as the background, while Mn, V, Cr, Co and Ni were enriched compared to their maximum permissible concentrations prescribed for agricultural soils. These observations have been further strengthened from the contamination index map and lognormal distribution pattern of the elements. As a consequence of this contamination, many of the important physicochemical properties of topsoil in the direction of the wind have been modified significantly.Electronic Supplementary Material Supplementary material is available in the online version of this article at  相似文献