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81.
Precise measurement of the coronal properties of Active Galactic Nuclei (AGN) requires the availability of high signal-to-noise ratio data covering a wide range of X-ray energies. The Nuclear Spectroscopic Telescope Array (NuSTAR) which is highly sensitive to earlier missions in its operational energy range of 3–79 keV, allows us to arrive at precise estimates of the coronal parameters such as cut-off energy (\(E_\mathrm{cut}\)), coronal temperature (\(\textit{kT}_e\)) and geometry of the corona at least for sources that have \(E_\mathrm{cut}\) within the energy range of NuSTAR. In this paper, we present our preliminary results on the spectral analysis of two Seyfert galaxies namely 3C 120 and NGC 4151 using NuSTAR observations in the 3–79 keV band. We investigated the continuum and coronal parameters, the photon index \(\Gamma \), \(E_\mathrm{cut}\) and \(\textit{kT}_{e}\). By fitting the X-ray spectrum of 3C 120 and NGC 4151 with a simple phenomenological model, we found that both the sources showed a clear cut-off in their spectrum. 相似文献
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S. B. Singh B. Veeraiah R. L. Dhar B. A. Prakash M. Tulasi Rani 《Hydrogeology Journal》2011,19(2):355-366
Exploration and exploitation of groundwater in sedimentary areas are reasonably simple. However, the problem of salinity in coastal areas makes the job very difficult, especially when the freshwater aquifers are not extensive and are entrapped between saline aquifers. States along the eastern coast of India, particularly Orissa with respect to the Mahanadi basin, have acute problems with groundwater salinity. It has been possible to locate horizons of fresh groundwater entrapped between deep saline aquifers in the southwestern part of Mahanadi delta, with the help of deep resistivity soundings along the Delang-Puri profile. This finding has been validated through boreholes and checked with electrical logs of this region. Three freshwater aquifers have been detected: one at shallow depth between 20 and 60?m, the second in the depth range of 90??60?m, and the third in the fractured/weathered basement. The second freshwater aquifer has the most potential; it has a thickness range of 20??0?m and it could be exploited to overcome problematic salinity issues. In general, the depth to basement is variable and it increases seaward. 相似文献
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D. Bala Subrahamanyam Radhika Ramachandran S. Indira Rani S. Sijikumar T. J. Anurose Asish Kumar Ghosh 《Natural Hazards》2012,61(3):893-910
Accurate knowledge of different meteorological parameters over a launch site is very crucial for efficient management of satellite
launch operations. Local weather over the Indian satellite launch site located at Sriharikota High Altitude Range (SHAR: 13.72°N,
80.22°E) is very much dependent on the atmospheric circulation prevailing over the Bay of Bengal oceanic region and topography-induced
convective activities. With a view to providing severe weather threat prediction in terms of launch commit criteria (LCC),
two numerical atmospheric models namely high-resolution regional model (HRM) and advanced regional prediction system (ARPS)
are made operational over SHAR in a synoptic and mesoscale domain, respectively. In the present research article, two launch
campaigns through Polar Satellite Launch Vehicle (PSLV-C11 and PSLV-C12) when contrasting weather conditions prevailed over
the launch site are chosen for demonstration of potential of two models in providing location-specific short-to-medium-range
weather predictions meeting the needs of LCC. In the case of PSLV-C11 campaign, when the launch site underwent frequent thundershower-associated
rainfall, ARPS model–derived meteorological fields were effectively used in prediction of probability of the wet spells. On
the other hand, Bay of Bengal underwent severe cyclonic storm during PSLV-C12 campaign, and its formation was reasonable captured
through HRM simulations. It is concluded that a combination of HRM and ARPS provide reliable short-to-medium-range weather
prediction over SHAR, which has got profound importance in launch-related activities. 相似文献
88.
The emission from blazars is known to be variable at all wavelengths. The flux variability is often accompanied by spectral changes. Spectral energy distribution (SED) changes must be associated with changes in the spectra of emitting electrons and/or the physical parameters of the jet. Meaningful modeling of blazar broadband spectra is required to understand the extreme conditions within the emission region. Not only is the broadband SED crucial, but also information about its variability is needed to understand how the highest states of emission occur and how they differ from the low states. This may help in discriminating between models. Here we present the results of our SED modeling of the blazar S5 0716+714 during various phases of its activity. The SEDs are classified into different bins depending on the optical brightness state of the source. 相似文献
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Consolidation of a poroelastic half-space with anisotropic permeability and compressible constituents by axisymmetric surface loading 总被引：1，自引：0，他引：1
The fully coupled Biot quasi-static theory of linear poroelasticity is used to study the consolidation of a poroelastic half-space
caused by axisymmetric surface loads. The fluid and solid constituents of the poroelastic medium are compressible and its
permeability in the vertical direction is different from its permeability in the horizontal direction. An analytical solution
of the governing equations is obtained by taking the displacements and the pore pressure as the basic state variables and
using a combination of the Laplace and Hankel transforms. The problem of an axisymmetric normal load is discussed in detail.
An explicit analytical solution is obtained for normal disc loading. Detailed numerical computations reveal that the anisotropy
in permeability as well as the compressibilities of the fluid and solid constituents of the poroelastic medium have significant
effects on the consolidation of the half-space. The anisotropy in permeability may accelerate the consolidation process and
may lead to a dilution in the theoretical prediction of the Mandel-Cryer effect. The compressibility of the solid constituents
may also accelerate the consolidation process. 相似文献