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81.
Magnetized accretion flows around black holes which include standing or oscillating shock waves can produce very realistic
spectrum till a few MeV. These shocks accelerate hot electrons which produce power-law spectrum. The post-shock region intercepts
soft-photons from an external source, namely, a Keplerian disk and also from distributed sources such as the synchrotron photons
emitted from thermal and non-thermal electrons originated in the pre-shock and post-shock flow. These photons are inverse
Comptonized by the thermal and the non-thermal electrons present in the CENBOL region. Computations show that the emitted
radiation is extended till a few MeV. We include the bulk motion Comptonization as well and discuss its importance vis-a-vis
the power-law spectrum produced by non-thermal electrons.
相似文献
82.
83.
The tremendous increase in offshore operational activities demands improved wave forecasting techniques. With the knowledge of accurate wave conditions, it is possible to carry out the marine activities such as offshore drilling, naval operations, merchant vessel routing, nearshore construction, etc. more efficiently and safely. This paper describes an artificial neural network, namely recurrent neural network with rprop update algorithm and is applied for wave forecasting. Measured ocean waves off Marmugao, west coast of India are used for this study. Here, the recurrent neural network of 3, 6 and 12 hourly wave forecasting yields the correlation coefficients of 0.95, 0.90 and 0.87, respectively. This shows that the wave forecasting using recurrent neural network yields better results than the previous neural network application. 相似文献
84.
85.
Rajendra Singh P. K. Mandal A. K. Singh R. Kumar A. Sinha 《Rock Mechanics and Rock Engineering》2008,41(3):421-444
Summary Considering ground instability problems of underground coal mines at shallow covers, this paper reviews and describes problems
of optimal extraction of coal stuck below surface/subsurface constraints at Indian coal fields. Importance of thickness and
quality of inter-burden between the working horizon and surface/subsurface constraints is discussed from a ground movement
point of view during optimisation of coal recovery by underground mining beneath the constraints. A CIMFR, formerly CMRI idea,
known as Wide Stall Method, was found suitable to overcome the limitations of non-effective-width based optimisation of recovery
of coal, trapped in pillars below surface/subsurface objects, at shallow cover. The involved rock mechanics concept and three
successful field trials of the Wide Stall Method under three different geo-mining conditions of the country are also briefly
given in this paper.
Author’s address: Rajendra Singh, Central Institute of Mining and Fuel Research (CIMFR, formerly CMRI), Barwa Road, Dhanbad,
826001 Jharkhand, India 相似文献
86.
Considering different mechanical cutting tools for excavation of rock, drilling and blasting is said to be inexpensive and
at the same time most acceptable and compatible to any geo-excavation condition. Depending upon strength properties of in-situ
rock mass, characteristics of joint pattern and required quality of blasting, control blasting techniques viz., pre-split
and smooth blasting are commonly implemented to achieve an undamaged periphery rock-wall. To minimize magnitude of damage
or overbreak, the paper emphasized that in-situ stresses and re-distribution of stresses during the process of excavation
should be considered prior to selection of explosive parameters and implementation of any suitable blast pattern. Rock structure
being not massive in nature, the paper firstly explains the influence of discontinuities and design parameters on smooth-wall
blasting. Considering the empirical equations for estimation of stress wave’s magnitude and its attenuation characteristics
through transmitting medium, the paper has put forward a mathematical model for smooth blasting pattern. The model firstly
illustrates that rock burden for each hole should be sub-divided into thin micro strips/slabs to understand the characteristics
of wave transmission through the medium and lastly with the help of beam theory of structural dynamics have put forward a
mathematical model to analyze and design an effective smooth blasting pattern to achieve an undamaged periphery rock-wall. 相似文献
87.
Climate change vulnerability to agrarian ecosystem of small Island: evidence from Sagar Island,India
Mandal S. Satpati L. N. Choudhury B. U. Sadhu S. 《Theoretical and Applied Climatology》2018,132(1-2):451-464
Theoretical and Applied Climatology - The present study assessed climate change vulnerability in agricultural sector of low-lying Sagar Island of Bay of Bengal. Vulnerability indices were estimated... 相似文献
88.
S. K. Sharma T. K. Mandal A. K. De N. C. Deb Srishti Jain Mohit Saxena S. Pal A. K. Choudhuri Saraswati 《Journal of Atmospheric Chemistry》2018,75(2):219-233
Ambient concentrations of organic carbon (OC), elemental carbon (EC) and water soluble inorganic ionic components (WSIC) of PM10 were studied at Giridih, Jharkhand, a sub-urban site near the Indo Gangatic Plain (IGP) of India during two consecutive winter seasons (November 2011–February 2012 and November 2012–February 2013). The abundance of carbonaceous and water soluble inorganic species of PM10 was recorded at the study site of Giridih. During winter 2011–12, the average concentrations of PM10, OC, EC and WSIC were 180.2?±?46.4; 37.2?±?6.2; 15.2?±?5.4 and 18.0?±?5.1 μg m?3, respectively. Similar concentrations of PM10, OC, EC and WSIC were also recorded during winter 2012–13. In the present case, a positive linear trend is observed between OC and EC at sampling site of Giridih indicates the coal burning, as well as dispersed coal powder and vehicular emissions may be the source of carbonaceous aerosols. The principal components analysis (PCA) also identifies the contribution of coal burning? +?soil dust, vehicular emissions?+?biomass burning and seconday aerosol to PM10 mass concentration at the study site. Backward trajectoy and potential source contributing function (PSCF) analysis indicated that the aerosols being transported to Giridih from upwind IGP (Punjab, Haryana, Uttar Pradesh and Bihar) and surrounding region. 相似文献
89.
90.
An isotopic and chemical study was conducted on precipitation, spring water, streams, groundwater wells and submarine groundwater discharge (SGD) to constrain the recharge areas and flow paths of SGD. The isotopic values of precipitation were used to determine the local meteoric water lines (LMWLs) of Rishiri Island. The d-excess values of precipitation showed seasonal variation, with lows of 2.5‰ in the summer and highs of 24.2‰ in the winter. The d-excess values of spring water, streams, groundwater wells and SGD ranged from 12.5‰ to 23.0‰, indicating that the resulting waters were a mix of two seasons of precipitation. The isotopic composition of the groundwater wells sampled along the coast and SGD showed more negative values than that of the spring water sampled along the coast. This indicated that SGD recharged at high altitudes and flowed into the sea. The isotopic and chemical composition of SGD indicated unidirectional flow from land to sea. 相似文献