Genesis of Central Indian Ocean basin seamounts: morphological,petrological, and geochemical evidence     

Iyer  Sridhar D.  Amonkar  Ankeeta Ashok  Das  Pranab 《International Journal of Earth Sciences》2018,107(7):2517-2538

International Journal of Earth Sciences - We present the petrological investigation carried out of the seamounts located between water depths of 4300 and 5385 m in the Central Indian Ocean...  相似文献   

Laboratory Investigation of Hollow and Solid Shaft Helical Soil Nail by Displacement Controlled Pullout Testing     

Sharma  Pankaj  Rawat  Saurabh  Gupta  Ashok Kumar 《Geotechnical and Geological Engineering》2021,39(7):5291-5307

Geotechnical and Geological Engineering - A sequence of laboratory pullout tests was conducted to examine the installation and pullout behavior of hollow and solid shaft helical soil nails. The...  相似文献   

Stability analysis of a recurring soil slope failure along NH-5, Himachal Himalaya,India     

Ashok Kumar Singh  Jagadish Kundu  Kripamoy Sarkar 《Natural Hazards》2018,90(2):863-885

The repetitive soil slope failure along the National Highway (NH)-5 in Jhakri region of Himachal Pradesh, India draws frequent concern due to heavy damage and traffic disruption almost every year. Being only linking route from border district to the nearby land area, stability of the road-cut slopes along this highway is of major concern in regard to safe transportation. Absence of any previous stability investigation of this recurring slope failure calls for an integrated geotechnical and numerical approach in order to understand the instability factors. The geotechnical analysis has been performed to determine the inherent properties of soil materials which affect the stability of existing slope. An event-specific antecedent rainfall threshold has been suggested to quantify the relationship between rainfall and slope failure. A two-dimensional limit equilibrium method has also been executed to visualize the scenario of pre- and post-failure stability of the slope. On the basis of limit equilibrium analysis, it has been inferred that slope geometry is a major affecting parameter that influences the failure pattern. Moreover, preventive measures through benching and soil nailing have also been proposed and validated through limit equilibrium analysis for long-term stability and safe transportation.  相似文献   

Exploratory Study of Archaebacteria and their Habitat in Underground,Opencast Coal Mines and Coal Mine Fire Areas of Dhanbad     

D. Mukherjee  V. A. Selvi  J. Ganguly  L. C. Ram  R. E. Masto 《Journal of the Geological Society of India》2018,91(5):575-582

Coal contains abundant microbial genera which include archaebacteria. The study of archaea kingdom in coal mines is a significant tool for knowing the relationship between coal and archaebacteria, the major role in geochemical cycle and application for further coal bio–beneficiation. The present study related to exploration of archaebacteria and their habitat in coal mining area of Dhanbad with reference to their ecology and nutrient availability that have evolve to grow under extreme conditions. Total six different sites such as two underground coal mines (Sudamdih shaft and Chasnalla underground mine), two opencast coal mines (Chandan project and Bhowra abandoned mine), Jharia mine fire and Sudamdih coal washery of Dhanbad was selected. Seven gram negative obligate anaerobic bacteria were isolated from the selected sites. The isolated species were rod and cocci shaped and the colony was round, smooth, off white in colour and with entire margin and little are cluster of cocci in shape. The isolated species were identified as Methanococcus spp, Methanobacterium spp and Methanosarcina spp. Apart from that two thermoacidophilic sulfur oxidizing bacteria Sulfolobus spp was also isolated from Jharia Coal Mine Fire. The physicochemical and biological characterization of the habitat was also studied for the entire selected area.  相似文献   

Near-infrared photometry of the final helium shell flash object V4334 Sagittarii     

U. S. Kamath  N. M. Ashok 《Monthly notices of the Royal Astronomical Society》1999,302(3):512-514

  相似文献   

An entropy-based investigation into the variability of precipitation   总被引：3，自引：0，他引：3  

Ashok K. Mishra  Mehmet zger  Vijay P. Singh 《Journal of Hydrology》2009,370(1-4):139-154

Employing the entropy concept spatial and temporal variability of precipitation time series were investigated for the State of Texas, USA. Marginal entropy was used to investigate the variability associated with monthly, seasonal and annual time series. Also, apportionment entropy and intensity entropy were used for investigating the intra-annual and decadal distributions of monthly and annual precipitation amounts and numbers of rainy days within a year and decade respectively. Finally, the Hurst exponent and the Mann–Kendall test were used to evaluate the long-term persistence and trend in the variability of precipitation. Distinct spatial patterns in annual series and different seasons were observed. The variability of precipitation amount as well as number of rainy days within a year increased from east to west of Texas. The results also indicated that highly disorderliness in the amount of precipitation and number of rainy days caused severe droughts during the 1950’s in whole of Texas.  相似文献   

Organochlorine contaminants in the muscle of striped bass illegally harvested from shad gill nets in the Hudson River Estuary     

Deshpande AD  Doyle SA  Dockum BW  Tesolin-Gee A 《Marine pollution bulletin》2008,56(12):2088-2093

  相似文献   

Simulation of Monsoon Disturbances in a GCM     

K. Ashok  M. K. Soman  V. Satyan 《Pure and Applied Geophysics》2000,157(9):1509-1539

--A large part of the rainfall over India during the summer monsoon season (June-September) is contributed by synoptic scale disturbances such as monsoon depressions. To study the evolution of such disturbances in Atmospheric General Circulation Models (AGCM), the Hadley Centre AGCM (HadAM2b) has been integrated for 15 summer monsoons (1979-1993) and the output was examined for the presence of synoptic scale disturbances such as monsoon depressions, low pressure areas, land lows and land depressions over the Indian summer monsoon region. The atmospheric initial condition for each of these integrations was of 23rd May and observed Sea Surface Temperatures (SST) were described as a boundary condition.¶Although the horizontal resolution of the AGCM used in this study is only 2.5° 2 3.75° lat. long., the model is able to simulate a few monsoon disturbances. The important features of these simulated disturbances are presented. The features of the simulated disturbances are realistic. The morphologies of a well simulated monsoon depression and a simulated low pressure area are presented as examples. The frequency of the simulated monsoon depressions is less than the climatological frequency of the depressions during all four monsoon months.  相似文献   

Evaluation of multiple stochastic rainfall generators in diverse climatic regions   总被引：1，自引：0，他引：1  

Tue?M.?Vu  Ashok?K.?MishraEmail author  Goutam?Konapala  Di?Liu 《Stochastic Environmental Research and Risk Assessment (SERRA)》2018,32(5):1337-1353

Long term synthetic precipitation data are useful for water resources planning and management. Commonly stochastic weather generator (SWG) models are useful to produce synthetic time series of unlimited length of weather data based on the statistical characteristics of observed weather at a given location. However, it is difficult to find a single model which works best for all weather (climate) patterns. The objective of this study is to evaluate five different SWG models namely CLIGEN, ClimGen, LARS-WG, RainSim and WeatherMan to generate precipitation at three diverse climatic regions: a Mediterranean climate of western USA, temperate climate of eastern Australia and tropical monsoon region in northern Vietnam. The performance of SWG models to generate precipitation characteristics (i.e., precipitation occurrence; wet and dry spell; and precipitation intensity on wet days) varies between three selected climatic regimes. It was observed that the second order Markov chain (ClimGen and WeatherMan) performed well for all three selected regions in generating precipitation occurrence statistics. All models are able to simulate the ratio of wet/dry spell lengths with respect to observed precipitation. The RainSim performed well in reproducing wet/dry spell lengths in comparison to other models for wetter regions in Australia and Vietnam. ClimGen and WeatherMan are the two best models in simulating precipitation in the western USA, followed by CLIGEN and LARS. Similarly, ClimGen and WMAN are the two best models for synthetic precipitation generation for eastern Australian and northern Vietnam stations, but CLIGEN performs poorly over these regions. All SWG model performed differently with respect to climatic regimes, therefore careful validation is required depending on the weather pattern as well as its application in different water resources sectors. Although our findings are preliminary in nature, however, in order to generalize the performance of SWG’s in a given climate type, it is recommended that more number of stations needs to be evaluated in future studies.  相似文献   

Elasmobranch fauna from the upper most part of the Cretaceous Bagh Group,Narmada valley,India          下载免费PDF全文

Guntupalli V. R. Prasad  Vishal Verma  Ashok Sahni  Ranjit S. Lourembam  Priyadarshini Rajkumari 《Island Arc》2017,26(5)

  相似文献