Breakage assessment through cluster analysis of joint set orientations of exposed benches of opencast mines     

P. Pal Roy 《Geotechnical and Geological Engineering》1995,13(2):79-92

Summary This paper substantiates, through three different case studies, that the breakage assessment of opencast bench blasting can be made scientifically through the analysis of joint set orientations of different exposed benches in association with the corresponding face direction. Joint orientations, dip and strike of bedding planes have a significant influence on rock breakage. They can have decelerating effects on blasting performance, which may be rectified by geological mapping, and subsequently modifying the blast design parameters.  相似文献   

On love waves in heterogeneous media     

Tapan Kumar De 《Pure and Applied Geophysics》1968,70(1):18-21

Summary Love waves in a half space with one homogeneous elastic layer overlying a semiinfinite medium having elastic properties varying with depth has been considered. The frequency equation for small wave lengths has been obtained, considering general variation, and has been shown to involve the first three derivatives of the rigidity of the heterogeneous medium at its interface with the homogeneous layer.  相似文献   

Mean, interannual variability and trends in a regional climate change experiment over Europe. I. Present-day climate (1961–1990)     

F. Giorgi  X. Bi  J. S. Pal 《Climate Dynamics》2004,22(6-7):733-756

We present an analysis of a multidecadal simulation of present-day climate (1961–1990) over Europe with the regional climate model RegCM nested within the global atmospheric model HadAMH. Climatic means, interannual variability and trends are examined, with focus on surface air temperature and precipitation. The RegCM driven by HadAMH fields is able to reproduce the basic features of the observed mean surface climate over Europe, its seasonal evolution and the regional detail due to topographic forcing. Surface air temperature biases are mostly less than 1–2 °C and precipitation biases mostly within 10–20%. The RegCM has more intense vertical transport of temperature and water vapor than HadAMH, which results in lower surface air temperatures and greater precipitation than found in the HadAMH simulation. In some cases this is in the direction of greater agreement with observations, while in others it is in the opposite direction. The simulation shows a tendency to overestimate interannual variability of temperature and precipitation compared to observations, particularly during summer and over the Mediterranean regions. It is shown that in DJF, MAM and SON the RegCM interannual variability is primarily determined by the boundary forcing from HadAMH, while in JJA the internal model physics and resolution effects dominate over many subregions of the domain, and the RegCM has higher interannual variability than HadAMH. The precipitation trends simulated by the nested modeling system for the period 1961–1990 capture some features of the observed trends, in particular the cold season drying over the Mediterranean regions. Ensembles of simulations are, however, needed for a more robust assessment of the models capability to simulate climatic trends. Overall, this simulation is of good quality compared with previous nested RegCM experiments and will constitute the basis for the generation of climate change scenarios over the European region to be reported in future work.  相似文献   

Epigenetic Nature of the BIF-hosted Gold Mineralization at Ajjanahalli, Southern India: Evidence from Ore Petrography and Fluid Inclusion Studies: Reply     

Nabarun Pal  Biswajit Mishra   《Gondwana Research》2004,7(2):632-635

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Simulation of West African monsoon using the RegCM3. Part I: Model validation and interannual variability   总被引：1，自引：0，他引：1  

E. A. Afiesimama  J. S. Pal  B. J. Abiodun  W. J. Gutowski Jr  A. Adedoyin 《Theoretical and Applied Climatology》2006,86(1-4):23-37

Summary The West African monsoon oscillates each year with remarkable regularity but the interannual variability associated with the monsoon is not fully understood although much progress has been made in recent years. This study examines and evaluates the mean state and the interannual variability of the West African climate as simulated by the International Centre for Theoretical Physics (ICTP) Regional Climate Model version 3 (RegCM3) over the period 1979 through 1990 using the National Center for Environmental Prediction (NCEP)/National Center for Atmospheric Research (NCAR) reanalysis data as lateral boundary conditions. Our analysis shows that the averaged rainfall over the region is well represented by the model and demonstrates considerable skill in reproducing the extreme rainfall regimes. There is however a tendency to overestimate rainfall amounts along the Guinean coast, particularly around mountainous areas, and to underestimate it over the Soudano-Sahel. The increased rainfall along the coast is due to an enhanced low-level convergence of the moist southwesterly winds along the coast leading to a reduction of the moisture content in the atmosphere. The decrease over the Soudano-Sahel could be associated with the weakening of the land–sea temperature gradient and hence the decrease in the low level southerly flows. The spatial and temporal variations in temperature are well captured by the model except for slightly cold bias over the coastal region due to an overestimation of precipitation.  相似文献   

On the role of resolution and topography in the simulation of East Asia precipitation   总被引：13，自引：0，他引：13  

Xuejie Gao  Ying Xu  Zongci Zhao  J. S. Pal  F. Giorgi 《Theoretical and Applied Climatology》2006,86(1-4):173-185

Summary In this paper, we investigate the role that horizontal resolution plays in the simulation of East Asia precipitation. Two sets of numerical experiments are performed using the Regional Climate Model (RegCM2) nested in one-way mode within the CSIRO global coupled atmosphere-ocean model. In the first set we use the actual RegCM2 topography at the selected model resolutions, which are 45, 60, 90, 120, 180, 240 and 360 km. In the second set of the experiments, the same coarse CSIRO model topography is used in all simulations using the different resolutions of the first set. The results demonstrate that the simulation of East Asian precipitation improves as the horizontal resolution is increased. Moreover, it is shown that the simulations using a higher resolution along with the coarse CSIRO topography perform better than the simulations using a coarser model resolution with corresponding model topography. This suggests that over East Asia adequate spatial resolution to resolve the physical and dynamical processes is more important than topography. Lastly, the results indicate that model resolutions of 60 km or higher are needed to accurately simulate the distribution of precipitation over China and East Asia.  相似文献   

Nature, origin and evolution of the granitoid-hosted early Proterozoic copper-molybdenum mineralization at Malanjkhand, Central India – a reply     

S. C. Sarkar  S. Kabiraj  S. Bhattacharya  A. B. Pal 《Mineralium Deposita》1997,32(6):622-622

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Prediction of peak particle velocity and peak air pressure generated by buried explosion     

R. N. Gupta  P. Pal Roy  B. Singh 《Geotechnical and Geological Engineering》1988,6(1):15-26

Summary Three sets of different formulae expressed as functions of dynamic elastic constants of rock and some design parameters involved in a buried explosion are derived explicitly for the prediction of peak particle velocity (PPV) and peak air pressure (PAP). Separate equations are derived to estimate PPV and PAP for inside, outside, and at the boundary of the crater zone. The equations incorporate the physical parameters including (i) longitudinal wave velocity, (ii) shear wave velocity, (iii) density of rock, (iv) characteristic impedance of air, (v) detonation pressure of explosive, (vi) depth of hole, (vii) radius of hole, (viii) distance of the measuring transducer. Suggested equations are tested for a few hard and medium-hard rocks. Characteristic features and important conclusions are described.  相似文献   

Cyclone track prediction using INSAT data     

P. K. Pal  B. M. Rao  C. M. Kishtawal  M. S. Narayanan  G. Rajkumar 《Journal of Earth System Science》1989,98(4):353-364

INSAT visible and infrared imageries of three cyclones in the Bay of Bengal during the period 1984–1987 were analysed with a view to improve the cyclone track prediction in this region. It was observed that the rotation in the major structural cloud features (as seen from the cloud-top temperature maps) associated with these cyclones in the Bay of Bengal is followed with a change in direction of their movement. This method is seen to be particularly effective when the cyclone is severe and when the major cloud features persist for a reasonably longer time. In the present study, only the direction of movement is forecast assuming a uniform speed of the cyclone.  相似文献   

Beryllium-10 contents of core samples from the St. Severin meteorite     

C. Tuniz  C.M. Smith  R.K. Moniot  T.H. Kruse  W. Savin  D.K. Pal  G.F. Herzog  R.C. Reedy 《Geochimica et cosmochimica acta》1984,48(9):1867-1872

Eleven samples taken from along the 35-cm core AIII of the LL-chondrite St. Severin have ¹⁰Be contents ranging from 20 to 28 dpm/kg and averaging 24.5 ± 0.9 dpm/kg. The ¹⁰Be contents increase with depth in the outermost 8 cm while at depths greater than 8 cm the ¹⁰Be contents change little. Calculations based on cross sections for proton-induced reactions that make ¹⁰Be disagree seriously with the measured values. Relatively large cross sections were constructed for neutron-induced reactions below 1 GeV. They give calculated ¹⁰Be production rates that agree with the measured values to within 10%. Cosmogenic ¹⁰Be in stony meteorites is better described as a medium-energy product than as a high-energy one.  相似文献