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991.
The duration of strong motion has a significant influence on the severity of ground shaking. In this work, a combination of average values of four geophysical properties of site (Standard Penetration Test (SPT) blow count, primary wave velocity, shear wave velocity, and density of soil) including hypocentral distance of less than 50 km and magnitudes more than 5.0 from Japanese ground motion records were used for development of neural network model, to estimate duration of strong ground motion. Since majority of strong motion databases provide only average shear wave velocity for site characterization, an attempt has also been made to train the neural network with magnitude, hypocentral distance and average shear wave velocity as three input variables. Results obtained from this study show that the duration of strong motion is mostly dependent on average shear wave velocity rather than other geophysical properties of site. 相似文献
992.
Proper selection and ranking of Ground Motion Prediction Equations (GMPEs) is critical for successful logic-tree implementation
in probabilistic seismic hazard analysis. The present study explores this issue in predicting peak ground accelerations at
the rock sites in India. Macroseismic intensity data complemented with limited strong ground-motion recordings are used for
the purpose. The findings corroborate the possible conformity between the GMPEs developed for tectonically active shallow
crust across the globe. On the other hand, the relevant GMPEs in the intraplate regions cluster into two different groups
with the equations of lower ranks catering to higher ground motions. The earthquakes in the subduction zones have significant
regional implications. However, affinity in the ground-motion attenuations between the major interface events (M
W > 7.4) in Andaman-Nicobar, Japan and Cascadia, respectively, is noted. This can be also observed for the intraslab events
in the Hindukush and Taiwan respectively. Overall, we do not observe any significant advantage with the equations developed
using the regional data. These findings are expected to be useful in probabilistic seismic hazard analysis across the study
region. 相似文献
993.
To develop P management guidelines for poultry litter application in Oxisols of Brazil, the relationship between water soluble P (WSP), soil test P (STP), and degree of P saturation (DPS) needs to be established. The study examined this relationship in Oxisols of Brazil receiving poultry litter. Soils were analyzed for Mehlich‐1 P (M1‐P), WSP, P fractions, P sorption index (PSI), and P saturation based on Mehlich‐1 extractable P, Al, Fe (DPSM1), and PSI (DPSPSI). Surface water bodies in the catchment area were examined for inorganic and total P. All the surface water bodies in the catchment area of the sampled plots were highly enriched in inorganic and organic P. Enrichment of soil P fractions following poultry litter application followed the order HCl‐bound > NaOH‐bound > NaHCO3‐bound fraction. M1‐P was correlated to labile (NaHCO3‐Pi), and stable P pools (NaOH‐P and HCl‐P) and reflected the cumulative P accumulation in these soils. P saturation indices increased with cumulative P addition and increasing M1‐P. WSP increased with increasing DPS and a change point was noticed at 23% DPSPSI (equivalent to DPSM1 of 16.5%) corresponding to M1‐P of 44.5 mg P kg?1, which could be regarded as threshold for P loss in these soils. 相似文献
994.
This study examines the short-range forecast accuracy of the Pennsylvania State University-National Center for Atmospheric
Research Mesoscale Model (MM5) as applied to the July 2006 episode of the Indian summer monsoon (ISM) and the model's sensitivity
to the choice of different cumulus parameterization schemes (CPSs), namely Betts-Miller, Grell (GR) and Kain-Fritsch (KF).
The results showed that MM5 day 1 (0–24 h prediction) and day 2 (24–48 h prediction) forecasts using all three CPSs overpredicted
monsoon rainfall over the Indian landmass, with the larger overprediction seen in the day 2 forecasts. Among the CPSs, the
rainfall distribution over the Indian landmass was better simulated in forecasts using the KF scheme. The KF scheme showed
better skill in predicting the area of rainfall for most of the rainfall thresholds. The root mean square error (RMSE) in
day 1 and day 2 rainfall forecasts using different CPSs showed that rainfall simulated using the KF scheme agreed better with
the observed rainfall. As compared to other CPSs, simulation using the GR scheme showed larger RMSE in wind speed prediction
at 850 and 200 hPa over the Indian landmass. MM5 24-h temperature forecasts at 850 hPa with all the CPSs showed a warm bias
of the order of 1 K over the Indian landmass and the bias doubled in 48-h model forecasts. The mean error in temperature prediction
at 850 hPa over the Indian region using the KF scheme was comparatively smaller for all the forecast intervals. The model
with all the CPSs overpredicted humidity at 850 hPa. The improved prediction by MM5 with the KF scheme is well complemented
by the smaller error shown by the KF scheme in vertical distribution of heat and mean moist static energy in the lower troposphere.
In this study, the KF scheme which explicitly resolve the downdrafts in the cloud column tended to produce more realistic
precipitation forecasts as compared to other schemes which did not explicitly incorporate downdraft effects. This is an important
result especially given that the area covered by monsoon-precipitating systems is largely from stratiform-type clouds which
are associated with strong downdrafts in the lower levels. This result is useful for improving the treatment of cumulus convection
in numerical models over the ISM region. 相似文献
995.
Pawan Govil Abhijit Mazumder Anoop Tiwari Sandeep Kumar 《Journal of the Geological Society of India》2011,78(1):30-35
A sediment core (L2) from Larsemann Hills, Antarctica was analyzed for Biogenic Silica (BSi), Sand (%) and Total Organic Carbon
(TOC). The 78 cm core length represents the time span of ∼8.3 cal ka BP. The values of BSi from the core show prominent high
productivity from ∼8.3 to ∼6 cal ka BP in comparison to less productivity in mid-late Holocene (∼6 cal ka BP to recent). Moreover,
high sand (%) infers the glacio-fluvial deposition from ∼8.3 to ∼5 cal ka BP TOC shows little variation through out the core,
except in the upper ∼10 cm (∼4 cal ka BP) part wherein it is comparatively high. The increased TOC in the upper part of the
core possibly indicates presence of algal mat due to exposure of the lake to the ice free (glacier free) conditions. 相似文献
996.
Sudhir Kumar Subrata Halder D. C. Singhal 《Journal of the Geological Society of India》2011,78(6):587-598
Groundwater utilization in Nadia district, West Bengal has been subjected to rapid exploitation in the wake of increasing
urbanization and production of agricultural commodities. It is, therefore, necessary to evaluate the existing trend and availability
of groundwater in time and space and its movement for proper planning in future. In the present study, an attempt has been
made develop a groundwater management model using Visual MODFLOW software. The groundwater flow model for the study area was
formulated by using input hydrogeological data and appropriate boundary conditions. The groundwater flow pattern of the study
area indicates the occurrence of base flow which feed both the Rivers Bhagirathi and Jalangi throughout the year. The computed hydraulic heads were calibrated by comparing with observed groundwater level data for years
2004 to 2006 and were verified with the data of 2007. The outcome of modeling shows that this model can be used for prediction
purpose in the future by updating input boundary conditions and hydrologic stresses during the preceding year. The model optimized
unit draft for deep tube well as 556.5 m3/day and the same for shallow tube well as 41 m3/day keeping the existing tube well structures in running condition and maintaining the present and recent past trends of
groundwater level. The model can be further improved if more spatial and temporal input parameters are available and can be
incorporated into the model for more realistic characterization of groundwater flow. 相似文献
997.
Chemical weathering of the Indo-Gangetic alluvium with special reference to release of fluoride in the groundwater,Unnao district,Uttar Pradesh 总被引:1,自引:0,他引:1
In the central part of Indo-Gangetic alluvium in the Unnao district, Uttar Pradesh there are many pockets where groundwater
shows high fluoride content. Drinking of fluorinated ground water has effected a large population and in many villages more
than 80% of the population is suffering from fluorosis. The source of this fluoride appears to be the alluvial sediments deposited
in the geological past as no hard rock terrain is present in the nearby areas. The area is dominantly made up of mud with
pockets of sand. The sand fraction is made up of quartz, plagioclase, microcline, muscovite and biotite along with some accessory
minerals like garnet, epidote, chlorite, tourmaline, hornblende, kyanite and a few opaque minerals. Moreover, the fluoride
content in the groundwater varies both spatially and with depth indicating a sporadic occurrence. The surface water is devoid
of high content of fluoride but is reported in hand pumps and in the dug wells. This paper deals with the geochemical study
of the sediments up to a depth of 45m as most of the hand pumps are up to this depth to understand the source of fluoride.
14C dates of calcretes have suggested that the 45 m thick succession must have been formed in about 45000 years. 相似文献
998.
N.?NatarajanEmail author G.?Suresh Kumar 《Geotechnical and Geological Engineering》2011,29(4):477-491
In this study, the behavior of thermal fronts along the fracture is studied in the presence of fracture-skin in a coupled
fracture-matrix system. Cold water is injected into the fracture, which advances gradually towards production well, while
extracting heat from the surrounding reservoir matrix. The heat conduction into the fracture-skin and the rock-matrix from
the high permeability fracture is assumed to be one dimensional perpendicular to the axis of fluid flow along the fracture.
Constant temperature cold water is injected through an injection well at the fracture inlet. The fluid flow takes place along
the horizontal fracture which ensures connectivity between the injection and production wells. Since the rock-matrix is assumed
to be tight, the permeability of fracture-skin as well as the rock-matrix is neglected. The present study focuses on the heat
flux transfer at the fracture-skin interface as against the earlier studies on fracture-matrix interface, and the sensitivity
of additional heterogeneity in the form of fracture skin in a conventional fracture-matrix coupled system is studied. The
behavior of thermal fronts for various thermal conductivity values of the fracture-skin and rock-matrix is analyzed. Spatial
moment analysis is performed on the thermal distribution profiles resulting from numerical studies in order to investigate
the impact on mobility and dispersion behavior of the fluid in the presence of fracture-skin. The presence of fracture skin
affects the heat transfer significantly in the coupled fracture-matrix system. The lower order spatial moments indicate that
the effective thermal velocity increases with increase in skin thermal conductivity and a significant thermal dispersion is
observed at the inlet of the fracture owing to the high thermal conductivity of the fracture-skin at the early stages. Furthermore
the higher spatial moments indicate that the asymmetricity increases with decrease in skin thermal conductivity unlike the
case with half fracture aperture and fluid velocity and the kurtosis is maximum with higher skin thermal conductivity which
implies enhanced heat extraction from the fracture-skin into the fracture. Results suggest that the amount of heat extraction
by the circulating fluid within the fracture from the reservoir not only depends on the rock-matrix module of the reservoir
characteristics but also the fracture-skin characteristics of the system and subsequently influence the reservoir efficiency. 相似文献
999.
The role of biofilm proteins in modulating cyprid metamorphosis is not well understood. In the present investigation this possibility was explored by disrupting biofilm proteins using commercially available protease. The influence of natural biofilm and artificial biofilms of Aeromonas salmonicida salmonicida and Bacillus brevis and their culture supernatants and exopolysaccharides obtained under different nutritional conditions was evaluated. Natural biofilm facilitated cyprid metamorphosis in Balanus amphitrite, whereas monospecies biofilms did not. The treatment of biofilms with protease resulted in a decline in metamorphosis, except in B. brevis, where although metamorphosis was negated initially, it increased with the protease concentration and observation days. As the response of cyprids to exopolysaccharides produced by A. salmonicida salmonicida was dependent on protein concentration, protease treatment resulted in a decrease in metamorphosis, whereas in case of B. brevis biofilms, protease hydrolysis products could be important in providing settlement cues. Thus, biofilm bacterial components play an important role in the cyprid metamorphosis of Balanus amphitrite. 相似文献
1000.
Halder Debjani Kheroar Shyamal Srivastava Rajiv Kumar Panda Rabindra Kumar 《Theoretical and Applied Climatology》2020,140(3):823-838
Theoretical and Applied Climatology - Temperature and CO2 are the two most important climate parameters that affect crop yield directly. In this study, the impact of these two parameters on the... 相似文献