Estimation of wave heights during cyclonic conditions using wave propagation model     

Natesan  Usha  Rajalakshmi  P. R.  Ramana Murthy  M. V.  Ferrer  Vincent A. 《Natural Hazards》2013,69(3):1751-1766

Natural Hazards - Data from satellites are invaluable for applications including long-term climate studies and engineering design. Most present applications of wind-wave research for coastal...  相似文献   

Pot-hole Subsidence in Underground Coal Mining: Some Indian Experiences   总被引：1，自引：0，他引：1  

R. D. Lokhande  V. M. S. R. Murthy  K. B. Singh 《Geotechnical and Geological Engineering》2013,31(2):793-799

Subsidence is a gradual or sudden depression of the ground on the surface due to extraction of minerals from underground. It occurs in two forms, namely, trough and pot-hole subsidence. Trough subsidence is a depression covering a large surface area, whereas pot-hole subsidence is a localized phenomenon which occurs due to sudden collapse of overburden into the underground voids. Pot hole is extremely hazardous as it does not give any prior indication before its occurrence. Several pot-holes have occurred in the recent past in the coal mines of South Eastern Coalfield Limited and therefore the study assumes great importance. This paper presents the mechanism, behaviour and critical influencing parameters concerning pot-holes. Field investigations and analysis carried out on pot-holes which occurred in some of the Indian coal mines are presented for highlighting the importance of the same.  相似文献   

Prediction of Flyrock Distance in Open Pit Blasting Using Surface Response Analysis     

A. K. Raina  V. M. S. R. Murthy 《Geotechnical and Geological Engineering》2016,34(1):15-28

Flyrock is a rock thrown to greater distance than desired and is a dangerous and unwanted phenomenon in surface mines, particularly, when blasting is proceeding close to human occupation and dwellings. The prediction of flyrock distance is critical in defining the statutory danger zone of blasting and has evaded blasters for quite some time. Control of flyrock with its distance prediction involves identification of key variables and understanding their influence. Theoretical models though provide a good understanding of the phenomenon, the confidence that can be assigned to such models is still very less. This study presents novel method to identify, merge and consolidate independent variables into a simplified equation for flyrock distance prediction without compromising on the actual field applications. Field investigations were carried out in several mines and relevant data were generated relating to flyrock. The key parameters, namely, explosive, blast design and rock mass nature were characterized and analysed. An empirical model involving the key contributors for flyrock generation and distance prediction were assimilated and a new equation was developed based on actual data collected by employing surface response analysis. The developed model was found to be statistically significant and validated. Sensitivity analysis was conducted to ascertain the role of independent factors on flyrock distance.  相似文献   

Time-Space Relation between the Megacrystic Granites and Leptynites (Gar-Qtz-Plag Gneisses) in the Eastern Ghats Granulite Belt: Evidence for Peak-Metamorphic Anatectic Melting     

V. Divakara Rao  B.L. Narayana  N.N. Murthy 《Gondwana Research》2001,4(2)

  相似文献   

Aeromagnetic anomalies uncover the Precambrian basement in the Chhattisgarh basin area,Central India     

Bahadur Ram  Nagendra Pratap Singh  A. S. Krishna Murthy 《Acta Geophysica》2008,56(4):982-993

This paper presents aeromagnetic images for the Chhattisgarh basin region, in Central India, to provide a new window on Precambrian basement geology and structure. On the basis of aeromagnetic patterns, the Chhattisgarh basin is sub-divided into a northern low (negative) anomaly zone and a southern high (positive) anomaly zone. The northern portion of the main Chhattisgarh basin has been further divided into two subbasins, the Hirri sub-basin in the west, and Baradwar sub-basin in the east. A prominent negative anomaly delineates a NW-SE trending greenstone belt separating these sub-basins. Positive magnetic anomalies delineate the extent of the Dongargarh granite and equivalents, while the weak magnetic anomaly in the southeast of the Dongargarh granite and equivalents reflect granulite gneisses of the Eastern Ghat Mobile Belt. By applying the reduced-to-the-equator filter we enhanced the possible magnetic sources and structural lineaments within the Chhattisgarh basin. A new sketch map of structural elements was then compiled from aeromagnetic interpretation over the Chhattisgarh basin area. It includes possible faults, folds and an inferred lithological boundary.  相似文献   

Search for 12.6 millisecond periodicity in TeV gamma rays from Cygnus X-3     

P. N. Bhat  P. V. Ramana Murthy  P. R. Vishwanath 《Journal of Astrophysics and Astronomy》1988,9(3):155-160

Cygnus X-3, an X-ray binary with an orbital period 4.8 hr was seen to be emitting γ-rays with the same period at TeV energies by several groups. In addition the Durham group (Chadwicket al. 1985) published their observations on the existence of a pulsar in the Cyg X-3 system, emitting TeV γ-rays with a periodicity of approximately 12.6 ms. We observed this object during 1986 October-November and did not detect any pulsed emission of TeV γ-rays in the range of periods from 12.5850 to 12.5967 ms.  相似文献   

A design study of atmospheric Cerenkov radiation telescope for very high energy gamma-ray astronomy     

S. K. Gupta  P. V. Ramana Murthy  S. C. Tonwar  P. R. Vishwanath 《Astrophysics and Space Science》1985,115(1):163-183

Detection of cosmic sources of very high energy gamma rays based on the atmospheric Cerenkov technique is discussed. Very high energy gamma-rays initiate, on entering the terrestrial atmosphere, electron-photon cascade showers with in turn produce Cerenkov photons in the air. Parabolic reflectors are used to focus these photons onto fast photomultipliers. Two methods of deployment of parabolic reflectors are in vogue: one in which all the reflectors are located close to each other in a compact array and the other in which the reflectors are spread out farther apart forming a distributed array. In the latter mode, the arrival direction of individual showers can be determined accurately by using the measured relative arrival times between different detectors. Detailed studies with the distributed array helped us to understand the various parameters in the two designs and evaluate their relative merits in reaching the ultimate goals of lowering the energy threshold and improving the signal to background ratio for the detection of gamma-ray sources. It is found that the relative superiority among the two types of arrays is a function of the exponent assumed for the differential power law energy spectrum for the gamma ray source. It is also seen that with the type of reflectors commonly used in atmospheric Cerenkov work, lower energy thresholds can be achieved with use of larger aperture.  相似文献   

The Effect of Spatial Correlation of Cone Tip Resistance on the Bearing Capacity of Shallow Foundations     

G. L. Sivakumar Babu  Satyanarayana Murthy Dasaka 《Geotechnical and Geological Engineering》2008,26(1):37-46

The effect of directional behaviour of correlation structure of cone tip resistance on the bearing capacity of shallow strip footing resting on cohesionless soil deposit in 2-D random field is analysed using probabilistic approach. The results obtained from the analysis show that the assumption of perfect (or infinite) correlation of cone tip resistance data leads to lower values of probability of failure. In contrast, the isotropic assumption of correlation behaviour based on vertical scale of fluctuation leads to higher values of probability of failure. The results also show that the transformation model would play a major role in the evaluation of variability of design property. In conclusion, the need for a proper evaluation methodology for calculation of correlation lengths of soil properties and their influence in foundation design is highlighted.  相似文献   

On the impossibility of the co-existence of monsoons and severe storm surges in the Bay of Bengal     

Tad S. Murty  Venkata R. Neralla 《Natural Hazards》1992,6(3):281-285

The problem of storm surges is introduced briefly. The utility of passive microwave observations to study this phenomenon is pointed out. The reasons for the nonoccurrence of severe surges in the Bay of Bengal, during monsoon regimes, is discussed in this paper. It was demonstrated that the predominant reason for lack of severe surges over the Bay of Bengal coast is due to the absence of weak wind shear during monsoon seasons.Atmospheric Environment Service, Ice Center, Environment Canada, 373 Sussex Drive, Ottawa, Ontario, Canada K1A OH3.  相似文献   

Performance of image classification on hyperspectral imagery for lithological mapping   总被引：1，自引：0，他引：1  

Nisha Rani  Venkata Ravibabu Mandla  Tejpal Singh 《Journal of the Geological Society of India》2016,88(4):440-448

SVM and SAM classifiers for the lithological mapping using Hyperion data in parts of Gadag schist belt of western Dharwar craton, Karnataka, India were used. The main objective of the present study is to assess and compare the potential use of Hyperion data set for lithological mapping. Accuracy assessment of the derived thematic maps was based on the analysis of the confusion matrix statistics computed for each classification map. For consistency, the same set of validation points were used in evaluating the accuracy of the lithological thematic maps produced. On the basis of the accuracy assessment results, it appears that SVM generally outperformed the SAM classifier in both OA accuracy and individual classes’ accuracies. OA accuracy and Kc for SVM is 96.93% and 0.9655, whereas for SAM it is 74.02% and 0.7085 respectively. SVM classification is the best in describing the spatial distribution and the cover density of each lithology, as was also indicated from the statistics of the individual class results. The individual class accuracy were also analyzed for the SVM and the result show that PA ranges from 87% to 100% and UA ranges from 91% to 100%, whereas for SAM ranges from 15% to 95%, and from 31% to 100% respectively. The SVM method could effectively classify and improve on the existing geological map for the Gadag schist belt (GSB) using hyperspectral data. The results could be validated through field visits. Therefore, it is concluded that hyperspectral remote sensing data can be efficiently used to improve existing maps, especially in areas where same rock types show variable degree of alteration over smaller spatial scales.  相似文献