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Sk. Saiyad Ali Somnath Bharadwaj Samir Choudhuri Abhik Ghosh Nirupam Roy 《Journal of Astrophysics and Astronomy》2016,37(4):35
The Diffuse Galactic Syncrotron Emission (DGSE) is the most important diffuse foreground component for future cosmological 21-cm observations. The DGSE is also an important probe of the cosmic ray electron and magnetic field distributions in the turbulent interstellar medium (ISM) of our galaxy. In this paper we briefly review the Tapered Gridded Estimator (TGE) which can be used to quantify the angular power spectrum C ? of the sky signal directly from the visibilities measured in radio-interferometric observations. The salient features of the TGE are: (1) it deals with the gridded data which makes it computationally very fast, (2) it avoids a positive noise bias which normally arises from the system noise inherent to the visibility data, and (3) it allows us to taper the sky response and thereby suppresses the contribution from unsubtracted point sources in the outer parts and the side lobes of the antenna beam pattern. We also summarize earlier work where the TGE was used to measure the C ? of the DGSE using 150 MHz GMRT data. Earlier measurements of C ? are restricted to \(\ell \le \ell _{\max } \sim 10^{3}\) for the DGSE, the signal at the larger ? values is dominated by the residual point sources after source subtraction. The higher sensitivity of the upcoming SKA1 Low will allow the point sources to be subtracted to a fainter level than possible with existing telescopes. We predict that it will be possible to measure the C ? of the DGSE to larger values of \(\ell _{\max }\) with SKA1 Low. Our results show that it should be possible to achieve \(\ell _{\max }\sim 10^{4}\) and ~105 with 2 minutes and 10 hours of observations respectively. 相似文献
104.
Aly Marwa M. Refay Neveen H. Elattar Hoda Morsy Karim M. Bandala Erick R. Zein Samir A. Mostafa Mohamed K. 《Natural Hazards》2022,111(2):1107-1119
Natural Hazards - This article aims to provide a thorough assessment of water quality and quantity incorporating the estimation of future patterns as a result of climate change from economic,... 相似文献
105.
RésuméDans cette étude, on a fait appel à la télédétection et aux systèmes d’information géographiques (SIG) pour évaluer et cartographier l’érosion hydrique en utilisant l’équation universelle des pertes en sol USLE dans le bassin versant de l’Oued Mina en Algérie. Ce bassin est caractérisé par une grande irrégularité dans les précipitations, une forte pente, une lithologie essentiellement marneuse et une couverture végétale très faible ce qui le rend très vulnérable à l’érosion. L’USLE est la combinaison de six facteurs spécifiques qui décrivent les caractéristiques du bassin versant. Les données de télédétection multi-temporelles et les SIG sont utilisés pour évaluer et cartographier chaque facteur individuellement. L’intégration des cartes thématiques des facteurs du modèle USLE dans le SIG permet de cerner l’impact de chaque facteur dans les pertes en sol, de classer par importance relative les zones d’érosion, et de quantifier les pertes en sol dans le bassin.Editeur Z.W. KundzewiczCitation Toumi, S., Meddi, M., Mahé, G., et Brou, Y.T., 2013. Cartographie de l’érosion dans le bassin versant de l’Oued Mina en Algérie par télédétection et SIG. Hydrological Sciences Journal 58 (7), 1542–1558. 相似文献
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Samir Mankabady 《Marine Policy》1979,3(3):225-231
The author examines the various methods of finance for LNG carriers at each stage of funding. First, he describes the various factors involved in the funding of LNG carriers, and continues by highlighting the different methods of finance. He concludes by summarizing the prospects for shipping finance in a severely depressed ship sale and purchase market. 相似文献
108.
A parametric study was performed of electron temperature variation in the wake of a conducting sphere in a streaming plasma. The flow conditions were varied as follows: the ambient electron temperatures in the range 850–2450 K; the ambient electron densities in the range 5 × 104?7 × 105/cm3; and body potentials relative to plasma potential in the range of + 1.7 to ?2.8 V for an ion beam energy of ~4 eV. Electron temperature enhancements were observed which ranged up to 200 per cent above ambient in the nearest proximity of the body surface. The magnitude of the enhancement depends upon the ambient density, temperature and body potential. 相似文献
109.
Dynamic stability of elastic multistorey frame structures subjected to vertical earthquake ground accelerations is studied. Different stationary, non-stationary, white and non-white random models for earthquake strong motion are considered. The concepts of mean-square and almost-sure stability are reviewed and the corresponding stability theorems are presented. Several general criteria regarding the dynamic stability of the equilibrium state of multistorey frames subjected to random excitations are developed. A few examples concerning the stability of single and multi-degree-of-freedom structures under earthquake excitations are presented. The stability of motion of frames under combined horizontal–vertical acceleration is also briefly discussed. 相似文献
110.
Samir Ranjan Roy 《Pure and Applied Geophysics》1971,90(1):15-22
Summary The paper is concerned with the investigation of the disturbances of a finite elastic rod within the framework of relativistic mechanics of continua and of relativistic electrodynamics under specified boundary conditions. 相似文献