On the periodicities of sunspots and solar strong hard X-ray bursts     

V. K. Verma  G. C. Joshi 《Solar physics》1987,114(2):415-418

In the present investigation, we have carried out power spectrum analysis of sunspot number and great hard x-ray (GHXR) burst (equal to or greater than 10,000 counts per second) for a period of about 6 years. The GHXR bursts show a periodicity of about 155 days. On the other hand, sunspot numbers do not show any periodicity. The GHXR burst periodicity confirms the existence of a 152–158 days periodicity in the occurrence of solar energetic events. Further, the GHXR bursts are showing periodicity independently indicating that the GHXR bursts are a separate class of X-ray flares.  相似文献   

The characteristics of asymmetric pedestrian behavior: A preliminary study using passive smartphone location data          下载免费PDF全文

Nick Malleson  Anthony Vanky  Behrooz Hashemian  Paolo Santi  Santosh K. Verma  Theodore K. Courtney  Carlo Ratti 《Transactions in GIS》2018,22(2):616-634

Understanding the movements of people is essential for the design and management of urban areas. This article presents a novel approach to understanding the asymmetry in route choice (i.e., the degree to which people choose different walking routes for their outbound and return journeys). The study utilizes a large volume of traces of individual routes, captured using a smartphone application. The routes are aggregated to a regular grid, and matrix statistics are developed to estimate the aggregate degree of route asymmetry for different types of route (shortest, longest, weekday, weekend, etc.). The results suggest that people change their route approximately 15% of the time. Although this varied little when observing trips made at the weekend or on a weekday, people taking journeys that deviated substantially from the shortest possible path were 6 percentage points less likely to change their routes than those taking journeys that were closest to the shortest path (14 and 20% asymmetry, respectively). The absolute length also impacted on the asymmetry of journeys, but not as substantially. This result is important because, for the first time, it reports a correlation between deviation from shortest route and aggregate pedestrian choice.  相似文献   

Fault rupture directivity of large earthquakes in Himalaya     

H. N. Srivastava  Mithila Verma  B. K. Bansal 《Journal of the Geological Society of India》2018,91(1):9-14

The paper examines the predominant fault rupture directivity during large earthquakes in different sectors of the Himalaya which influences strong ground motion and damage scenario. The nature of the faulting of earthquakes vis-à-vis their rupture directivity has been discussed. It is found that the rupture directivity near the Indo-Eurasian plate boundary varies from place to place i.e. either along the strike direction of the faults or at right angles to it. The secondary meizoseismal areas as observed for 1505 Dharchula, 1803 Uttarakhand, 1905 Kangra earthquakes in the Himalaya and 2001 Bhuj earthquake in stable continental region suggest that they are a fairly good indicator of predominant rupture directivity since the latter accentuates the site response up to a longer distance. The resulting larger ground motions, therefore, need to be incorporated in the design of engineering structures by suitable modifications in the BIS code.  相似文献   

Transition in Late Quaternary Paleoclimate in Schirmacher Region,East Antarctica as Revealed from Lake Sediments     

Hari B. Srivastava  Prakash K. Shrivastava  Sandip K. Roy  M. Javed Beg  Rajesh Asthana  Pawan Govil  Kamlesh Verma 《Journal of the Geological Society of India》2018,91(6):651-663

The lacustrine sediments are one of the best sources to provide information on climate change, specially in peri-glacial climatic region. Schirmacher Oasis, located on the Princess Astrid Coast in Queen Maud Land, is one of the few areas in East Antarctica that provides valuable information on paleoclimate of the region with various depositional features formed due to deglaciation process. This Oasis is dotted with more than 100 lakes of proglacial, land-locked and epi-shelf type. The multi-proxy sedimentological data, generated from the sediment cores from land-locked lakes and grab sample from a proglacial lake, lying in the same drainage line in the central part of Schirmacher region has provided better insight into the paleoclimatic evolution of the region. The immature and chemically unaltered lake sediments have shown restricted drainage pattern. Different phases of warmer and cooler intervals are highlighted by the patterns of fluctuations in different sedimentological and statistical parameters. The dominance of glacial signatures is very clear on the lake sediments as revealed by the surface textures of quartz grains. Physical weathering has mainly controlled the overall sediments and the composition of clay fraction. The clay minerals indicate a gradual shift in the weathering regime and therewith in climate from strongly glacial to fluvioglacial specially around 42 ka. This indicates beginning of warming of the area much before the LGM. But the warm period is not strong enough to alter the overall clay chemistry. Proxy records indicate short-period climatic oscillations during late Quaternary.  相似文献   

Gypsum–anhydrites in 1.9 Ga Vempalle Formation,Cuddapah basin,India: A note on the Palaeoproterozoic environment and diagenetic condition     

Purnajit Bhattacharjee  Sukanta Goswami  Sangeeta Bhagat  M B Verma 《Journal of Earth System Science》2018,127(8):114

The Cuddapah basin consists of generally well-preserved Palaeoproterozoic–Neoproterozoic sedimentary and associated volcanic rocks. The detailed lithological studies of sedimentary rocks of Vempalle Formation from the narrow linear belt of 15 km, in the southern margin, show the occurrence of layered gypsum in the cherty dolostone–shale intercalated facies, red shale and phosphatic dolostone facies of the Vempalle Formation. The petromineralogical studies reveal that gypsum is in close association with anhydrites. Microscopically, three different types of gypsum and anhydrite are identified, viz., lath-shaped, equant-shaped and anhedral-shaped grains. The equant variety corresponds to a granular gypsum, whereas the anhedral grains of gypsum exist as the granular and fibrous variety as seen in the hand specimen. The presence of gypsum/anhydrite has been confirmed by the petromineralogical, X-ray diffraction and chemical analytical data. The phosphatic dolostone is the host rock for stratabound type of uranium deposit at Tummalapalle, Cuddapah district, Andhra Pradesh, which is one of the most unique types of uranium mineralisation in the world. Abundant pseudomorphs of gypsum and anhydrite relicts and discontinuous gypsum layers within these dolostones, nodules of chert and gypsum indicate the interrelationship between the diagenesis and genesis of uranium mineralisation which indicates the carbonate precipitation in the sulphate-rich hypersaline environments.  相似文献   

Simplified SMA-inspired 1-parameter SCS-CN model for runoff estimation     

Sangeeta Verma  Pushpendra Kumar Singh  Surendra Kumar Mishra  Sanjay Kumar Jain  Ronny Berndtsson  Anju Singh  Ravindra Kumar Verma 《Arabian Journal of Geosciences》2018,11(15):420

This study proposes a simplified 1-parameter SCS-CN model (M5) based on Mishra-Singh (2002) model and soil moisture accounting (SMA) procedure for surface runoff estimation and compares its performance with the existing SCS-CN method (SCS, 1956) (M1), Michel 1-P model (Water Resour Res 41:1-6, 2005) (M2), Sahu 1-P model (Hydrol Process 21:2872-2881, 2007) (M3), and Ajmal et al. model (J Hydrol 530:623-633, 2015) (M4) using large rainfall–runoff dataset of 48,763 events from123 USDA-ARS watersheds. The performance of models was evaluated using three statistical error indices such as Nash-Sutcliffe efficiency (NSE), root mean square error (RMSE), percentage bias (PBIAS), and rank and grading system (RGS). Based on the results obtained, the models can be ranked as follows: M5?>?M4?>?M3?>?M1?>?M2, i.e., model M5 outperformed all the remaining four models M1–M4 and hence is recommended for field applications.  相似文献   

Analysis of thermo-hydrologic-mechanical impact of repository for high-level radioactive waste in clay host formation: an Indian reference disposal system     

Avi Dutt  M. S. Saini  T. N. Singh  A. K. Verma  R. K. Bajpai 《Environmental Earth Sciences》2012,66(8):2327-2341

In our study, a coupled hydrologic-mechanical analysis is done of the excavation damaged zone, before the emplacement of nuclear waste. This is followed by a coupled thermal-hydrologic-mechanical analysis to evaluate the impact of nuclear waste repository in porous water containing rock mass. This analysis has been under taken in accordance with the Indian reference disposal system. The paper considers the changes in pore pressure and stresses due to excavation of disposal holes. A critical study of rock mass permeability, porosity, thermally induced stresses, strains, and temperature distribution after the emplacement of nuclear spent fuels in disposal holes has also been done. Coupling to the mechanical constitutive equations is done via ??effective?? normal strain rates.  相似文献   

Changes in climate extremes by the use of CMIP5 coupled climate models over eastern Himalayas     

Vishal Singh  Manish Kumar Goyal 《Environmental Earth Sciences》2016,75(9):839

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Geomorphic control on the formation of mixed layer clays by progressive degradation of biotite: A case study from Jutulsessen Gjelsvikfjella,East Antarctica     

Kamlesh Verma  Sanjeeb Bhattacharya  A. M. Asim Ansari  Prakash K. Srivastava  Amit Dharwadkar 《Journal of the Geological Society of India》2014,83(5):532-534

Eleven glacial sediment samples collected from different elevation of Jutulsessen Nunatak, Gjelsvikfjella of East Antarctica were studied for the clay mineralogical analysis using X-ray diffraction technique. The result shows prominent peak at 10, and 3.34 Å suggesting the presence of biotite possibly derived from the catchment where biotite rich granite gneisses are exposed. The detailed investigation on the shape of biotite peak of certain samples shows the signs of alteration of biotite in to a mixed layer containing tri-octahedral smectite (low charge vermiculite). The presence of mixed layer along with the biotite is found to be associated with the samples of lower geomorphic level. The progressive alteration of clay sized biotite to form a mixed layer in the lower horizons of Jutulsessen Nunatak is probably due to the periodic accumulation of melt-water during the austral summer.  相似文献   

Modified biomass of Phanerochaete chrysosporium immobilized on luffa sponge for biosorption of hexavalent chromium     

D. K. Verma  S. H. Hasan  D. Ranjan  R. M. Banik 《International Journal of Environmental Science and Technology》2014,11(7):1927-1938

Phanerochaete chrysosporium, a white rot basidiomycete, was immobilized over Luffa cylindrica sponge discs, treated with 0.1 N HCl and its potentiality for the removal of hexavalent chromium [Cr(VI)] from water was investigated in both batch and in up-flow fixed-bed bioreactor. The acid treatment of biomass increased the uptake capacity and percentage removal of Cr(VI) from 33.5 to 46.5 mg g^?1 and 67 to 92 %, respectively. Maximum uptake of Cr(VI) was achieved at pH 2, temperature 40 °C after 100 min of contact time. The Cr(VI) sorption on the biomass was better explained by Langmuir isotherm. Thermodynamic studies indicated that the process was spontaneous and endothermic. Sorption kinetic study showed that pseudo-second-order model best correlates the Cr(VI) sorption on the biomass as compare to pseudo-first-order kinetic model. The performance of fixed-bed bioreactor was evaluated at different bed heights (5, 15 and 25 cm) and flow rates (1.66, 4.98 and 8.33 mL min^?1) by using bed depth service time model. Response surface methodology statistical method was applied for optimizing the process parameters. FTIR analysis showed that amino groups were mainly involved in adsorption of Cr(VI).  相似文献