排序方式: 共有57条查询结果,搜索用时 46 毫秒
41.
C. Konar M. Jamrozy M. J. Hardcastle J. H. Croston S. Nandi D. J. Saikia J. Machalski 《Journal of Astrophysics and Astronomy》2011,32(4):477-486
Relativistic and magnetized plasma ejected by radio loud AGNs through jets form the diffuse lobes of radio galaxies. The radiating
particles (electron/electron–positron) in lobes emit in radio via the synchrotron process and X-ray via inverse-Compton scattering
of cosmic microwave background photons. The thermal environment around radio galaxies emits X-rays via the thermal bremsstrahlung
process. By combining information from these processes we can measure physical conditions in and around the radio lobes and
thus study the dynamics of radio galaxies, including double–double radio galaxies. 相似文献
42.
M. L. Khabibullina O. V. Verkhodanov M. Singh A. Pyria S. Nandi N. V. Verkhodanova 《Astrophysical Bulletin》2011,66(2):171-182
We report the results of flux density measurements in the extended components of thirteen giant radio galaxies, made with
the RATAN-600 in the centimeter range. Supplementing them with the WENSS, NVSS and GB6 survey data we constructed the spectra
of the studied galaxy components. We computed the spectral indices in the studied frequency range and demonstrate the need
for a detailed account of the integral contribution of such objects into the background radiation. 相似文献
43.
M. L. Khabibullina O. V. Verkhodanov M. Singh A. Pirya S. Nandi N. V. Verkhodanova 《Astronomy Reports》2011,55(5):392-399
Results of RATAN-600 centimeter-wavelength flux-density measurements of the extended components in five giant radio galaxies
are reported. The spectra of the components of these radio galaxies have been constructed using the data of the WENSS, NVSS,
and GB6 surveys together with new RATAN-600 data. Spectral indices in the studied frequency range have been calculated. 相似文献
44.
Sourav Palit Sandip Kumar Chakrabarti Dipak Debnath A. R. Rao Anuj Nandi Vipin K. Yadav V. Girish 《Experimental Astronomy》2009,27(1-2):77-93
We present the results of simulations of shadows cast by a zone plate telescope which may have one to four pairs of zone plates. From the shadows we reconstruct the images under various circumstances. We discuss physical basis of the resolution of the telescope and demonstrate this by our simulations. We allow the source to be at a finite distance (diverging beam) as well as at an infinite distance (parallel beam) and show that the resolution is worsened when the source is nearby. By reconstructing the zone plates in a way that both the zone plates subtend the same solid angles at the source, we obtain back high resolution even for sources at a finite distance. We present simulated results for the observation of the galactic center and show that the sources of varying intensities may be reconstructed with accuracy. Results of these simulations would be of immense use in interpreting the X-ray images from recently launched CORONAS-PHOTON satellite. 相似文献
45.
Sahadeb Nandi 《Pure and Applied Geophysics》1973,105(1):825-835
Summary An exact solution of electrically conducting viscous incompressible flow in an annulus with porous walls under an external radial magnetic field is obtained when the motion is due to both longitudinal motion of the inner boundary and a constant axial pressure gradient, and the fluid injection rate at one wall is equal to the fluid withdrawal rate at the other. The fluid may be injected at the outer wall and sucked at the inner or vice versa. The solution for the hydromagnetic flow between two flat plates has also been obtained as a limiting case of the annulus problem. 相似文献
46.
Arpita Sharma Binoy K. Saikia Sarat Phukan Bimala P. Baruah 《Journal of the Geological Society of India》2016,88(5):609-619
The Tertiary North East Indian coals, classified as sub-bituminous rank, have found less industrial application owing to their physico-chemical attributes. These coals are characterized by low ash (<15%), high volatile matter (>35%) and high sulphur (2.9-4.46%). Majority of the sulphur occurs in organic form affixed to the coal matrix owing to marine influence, is difficult to remove. The coal maceral analysis shows the dominance of vitrinite (>75%) with lesser amounts of liptinite and inertinite. Reflectance measurements (Rmax) of these sub-bituminous coals fall in the range of 0.57 to 0.65. In this study, the petrographical (maceral), thermal and other physico-chemical analyses of some low rank Tertiary sub-bituminous coals from north-east India were carried out to assess their potential for combustion, liquefaction and coal bed methane formation. The petrofactor, conversion (%) and oil yield (%), combustion efficiency of the coal samples were determined. The respective linear correlations of conversion (%) of the coals with their vitrinite contents, petrofactor and oil yield values have been discussed. The relative combustion efficiency of the coals was measured from the thermo gravimetric analysis (TGA) of coals. The influence of maceral composition upon gas adsorption characteristics of these high volatile coals showed the increase in methane adsorption with vitrinite enrichment. Both the maceral and mineral matter contents were observed to have important influence on the gas adsorption characteristics. 相似文献
47.
Sruthi P Sreenivasan Melinda Kumar Bera Arpita Samanta Ravikant Vadlamani 《Journal of Earth System Science》2018,127(8):105
The exact magnitude of the carbon isotopic excursion (CIE) for the Palaeocene–Eocene Thermal Maximum (PETM) is essential for our understanding of the carbon cycle perturbation. Global compilation of the PETM CIE magnitudes indicates that the shallow-marine inorganic carbonate could be a potential candidate to decipher the actual CIE magnitude. The present study, therefore, made an attempt to explore the thick Palaeogene shallow-marine carbonate sequence of the Sylhet Limestone exposed in the Jaintia Hills of northeast (NE) India, in terms of the preservation and magnitude of the PETM CIE. Exploratory sampling carried out across the Sylhet Limestone suggests that this sequence was deposited during the Late Palaeocene and Early Eocene, as evident from the age-diagnostic foraminifera. The observed \({\sim }3.4\permille \) CIE at the top of the Lakadong Limestone, resting above the Miscellanea miscella and Ranikothalia nuttalli foraminifera-bearing horizon, can, therefore, be correlated with the PETM CIE. Although the magnitude of the CIE from our limited data set agrees well with the global compilation, the absence of a stepped profile questions the preservation of the CIE reported elsewhere from the Tethyan sequence. Further work is needed for a better understanding of the PETM interval in NE India. 相似文献
48.
We calculate the transport coefficients of low-density nuclear matter, especially the nuclear pasta phase, using quantum molecular dynamics simulations. The shear viscosity as well as the thermal and electrical conductivities are determined by calculating the static structure factor of protons for all relevant density, temperature and proton fractions, using simulation data. It is found that all the transport coefficients have similar orders of magnitude as found earlier without considering the pasta phase. Our results are thus in contrast to the common belief that the pasta layer is highly resistive and therefore have important astrophysical consequences. 相似文献
49.
Arpita Pankaj Pankaj Kumar Ajai Mishra 《Journal of the Indian Society of Remote Sensing》2012,40(4):725-734
Tons basin has the maximum share of glaciers, more than 50 glaciers, as well as glacierised area in Uttarakhand and Himachal Pradesh and the majority of the glaciers are of valley type. One of the important features of the glaciers of Tons valley is the presence of a thick mantle of supraglaciers moraine cover which can be attributed to the terrain characteristics, besides, the avalanche fed nature of the glaciers. The present study is the extraction of Glacio-geomorphological unit of Tons River basin based on the visual interpretation of remote sensing data. It was very much difficult in field, to extract all glacio-geomorphological units in glaciated area, but based on the remote sensing data, it becomes easy to identify. With the help of glacio-geomorphological map it has been found that four most important glaciers which fed the Tons River are Bandarpunch Glacier, Jaundar Bamak glacier, Jhajju Bamak and Tilku glacier. The tributaries of Tons River i.e. Harkidun Gad, Rupin Nadi and Supin Nadi are mainly fed by the mountain glaciers, valley glaciers and glacier lakes. The erosional terraces, glacio-fluvial terraces, open ??U?? shaped valleys, proglacial lake, lateral moraines, terminal moraines, palaeo-cirque and debris/talus cones are well developed in this glaciated regions. Glacio-geomorphic features are very much significant for palaeo-climatic reconstruction, showing variations, temporally and spatially. At the same time, these landforms, which are also altered by processes prevailing during interglacial period, helps in the geo-environment studies and glacier related problems like avalanches, global warming and cloudburst etc. 相似文献
50.