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排序方式: 共有118条查询结果,搜索用时 218 毫秒
51.
Aliyar Qurban Dhungana Santosh Shrestha Sangam 《Theoretical and Applied Climatology》2022,147(1-2):605-626
Theoretical and Applied Climatology - The civil war, harsh climate, tough topography, and lack of accurate meteorological stations have limited observed data across Afghanistan. To fulfill the gap,... 相似文献
52.
In this paper a study on the improvement of liquefaction strength of fly ash by reinforcing with randomly distributed geosynthetic fiber/mesh elements is reported. A series of stress controlled cyclic triaxial tests were carried out on fly ash samples reinforced with randomly distributed fiber and mesh elements. The liquefaction resistance of reinforced fly ash is defined in-terms of pore pressure ratio. The effects of parameters such as fiber content, fiber aspect ratio, confining pressure, cyclic stress ratio, on liquefaction resistance of fly ash have been studied. Test results indicate that the addition of fiber/mesh elements increases the liquefaction strength of fly ash significantly and arrests the initiation of liquefaction even in samples of loose initial condition and consolidated with the low confining pressure. 相似文献
53.
Abstract Estimation of snowmelt runoff is very important in the Western Himalayan rivers in India where it is required to plan for hydropower generation and the water management during the non‐monsoon season. An attempt has been made to estimate snowmelt runoff on a 10 day average basis in Beas Basin up to Pandoh Dam during May, 1998 and November, 1999 using a Snowmelt Runoff Model (SRM), which is a degree day method. The input parameters for the model are derived from existing maps, satellite data, metrological and hydrological data. The relief of the basin is divided into 12 elevation zones of 500 m each. The temperature was extrapolated to these elevation zones using temperature lapse rate calculated using the observed temperature at seven stations within the basin. Snow covered area in the basin was determined using Indian Remote Sensing Satellites IRS ‐ 1C / 1D Wide Field Sensor (WIFS). The runoff from the snow covered area and snow free area was separately calculated in each elevation zone. The model parameter degree‐day factor is taken from literature and runoff coefficients for snow and rain are derived using the observed data. The total discharge at the dam site is computed by a weighted sum of runoff components from all the elevation zones. There is a good agreement between the observed and computed runoff with a coefficient of determination of 0.854 and the difference in volume is + 4.6 %. 相似文献
54.
This study was carried out to analyze groundwater quality in selected villages of Nalbari district, Assam, India, where groundwater
is the main source of drinking water. 40 groundwater samples collected from hand pumps and analyzed for pH, EC, TDS, Ca2+, Mg2+, Na+, K+, HCO3
−, SO4
2−, Cl− and F−. Chemical analysis of the groundwater showed that mean concentration of cations in (mg/L) is in the order Ca2+ > Mg2+ > Na+ > K+ while for anions it is HCO3
− > Cl− > SO4
2− > F−. Fluoride concentration was recorded in the range of 0.02–1.56 mg/L. As per the desirable and maximum permissible limits
for fluoride in drinking water recommended by WHO and by Bureau of Indian Standards (BIS), which is 1.5 mg/L, the groundwater
of about 97% of the samples were found to be suitable for drinking purpose. The suitability of the groundwater for irrigation
purpose was investigated by some determining factors such as sodium adsorption ratio, soluble sodium percentage, Kelly’s ratio
and electrical conductivity. The value of the sodium absorption ratio and electrical conductivity of the groundwater samples
were plotted in the US Salinity laboratory diagram for irrigation water. Most of the groundwater samples fall in the field
of C2S1 and C3S1 indicating medium to high salinity and low sodium water, which can be used for irrigation on almost all types
of soil with little doubt of exchangeable sodium. The hydrochemical facies shows that the groundwater is Ca-HCO3 type. 相似文献
55.
56.
R Elangovan Kumar Krishna Neeraj Vishwakarma K R Hari M Ram Mohan 《Journal of Earth System Science》2017,126(7):92
Field and petrographic studies are carried out to characterize the interactions of mafic and felsic magmas from Pithora region of the northeastern part of the Bastar Craton. The MMEs, syn-plutonic mafic dykes, cuspate contacts, magmatic flow textures, mingling and hybridization suggest the coeval emplacement of end member magmas. Petrographic evidences such as disequilibrium assemblages, resorption textures, quartz ocelli, rapakivi and poikilitic textures suggest magma mingling and mixing phenomena. Such features of mingling and mixing of the felsic and mafic magma manifest the magma chamber processes. Introduction of mafic magmas into the felsic magmas before initiation of crystallization of the latter, results in hybrid magmas under the influence of thermal and chemical exchange. The mechanical exchange occurs between the coexisting magmas due to viscosity contrast, if the mafic magma enters slightly later into the magma chamber, then the felsic magma starts to crystallize. Blobs of mafic magma form as MMEs in the felsic magma and they scatter throughout the pluton due to convection. At a later stage, if mafic magma enters the system after partial crystallization of felsic phase, mechanical interaction between the magmas leads to the formation of fragmented dyke or syn-plutonic mafic dyke. All these features are well-documented in the study area. Field and petrographic evidences suggest that the textural variations from Pithora region of Bastar Craton are the outcome of magma mingling, mixing and hybridization processes. 相似文献
57.
A planar, fixed-orbit model of the rotation of the planet Mercury is analyzed. The model includes only the solar torques on the planet's permanent asymmetry and its solar tidal bulge. For this model, it is shown that the zero of the averaged tidal torque corresponds to an asymptotically stable periodic solution of the second kind which, for two tidal torque representations, is close to the asymptotically stable equilibrium point corresponding to an exact 32 spin-orbit resonance. A conjecture that the current rotation state of Mercury is due to transfer from capture by the zero of the averaged tidal torque to 32 resonance capture with changes in the eccentricity of the planet's orbit is discussed briefly. 相似文献
58.
Praveen K. Thakur Sreyasi Maiti Nanette C. Kingma V. Hari Prasad S. P. Aggarwal Ashutosh Bhardwaj 《Natural Hazards》2012,61(2):501-520
Vulnerability assessment of natural disasters is a crucial input for risk assessment and management. In the light of increasing
frequency of disasters, societies must become more disaster resilient. This research tries to contribute to this aim. For
risk assessment, insight is needed into the hazard, the elements at risk and their vulnerabilities. This study focused on
the estimation of structural vulnerability due to flood for a number of structural elements at risk in the rural area of Orissa,
India (Kendrapara), using a community-based approach together with geospatial analysis tools. Sixty-three households were
interviewed about the 2003 floods in 11 villages and 166 elements at risk (buildings) were identified. Two main structural
types were identified in the study area, and their vulnerability curves were made by plotting the relationships between flood
depth and vulnerability for each structural type. The vulnerability ranges from 0 (no damage) to 1 (collapse/total damage).
Structural type-1 is characterized by mud wall/floor material and a roof of paddy straw, and structural type-2 is characterized
by reinforced cement concrete (RCC) walls/floor and a RCC roof. The results indicate that structural type-1 is most vulnerable
for flooding. Besides flood depth, flood duration is also of major importance. Houses from structural type-1 were totally
collapsed after 3 days of inundation. Damage of the houses of structural type-2 began after 10 days of inundation. 相似文献
59.
Hari Om Vats M. R. Deshpansde O. P. N. Calla N. M. Vadher B. M. Darji V. Sukumaran 《Earth, Moon, and Planets》1996,73(2):125-132
This article reports the observations of microwave emission from Jupiter during the impact of K, N, P2 and S fragments of the comet Shoemaker-Levy 9. The comparison of microwave bursts intensities produced by these impacts with the impact class and the size of the impactors reveals no correlation. This is in conformity with other observations at microwave frequencies and indicates that the process of burst emission is very complex. The impacts K and N produced three microwave bursts which could possibly be due to further fragmentation of these fragments. The results are discussed in the perspective of synchrotron emission from Jupiter and possible enhancements due to an increase in the radial diffusion coefficient. However, this model does not fully explain the observations. 相似文献
60.
S. K. Roy Bhowmik Soma Sen Roy Kuldeep Srivastava B. Mukhopadhay S. B. Thampi Y. K. Reddy Hari Singh S. Venkateswarlu Sourav Adhikary 《Meteorology and Atmospheric Physics》2011,111(3-4):133-147
This paper demonstrates the usefulness of Indian Doppler Weather Radar (DWR) data for nowcasting applications, and assimilation into a mesoscale Numerical Weather Prediction (NWP) model. Warning Decision Support System Integrated Information (WDSS-II) developed by National Severe Storm Laboratory (NSSL) and Advanced Regional Prediction System (ARPS) developed at the Centre for Analysis and Prediction, University of Oklahoma are used for this purpose. The study reveals that the WDSS-II software is capable of detecting and removing anomalous propagation echoes from the Indian DWR data. The software can be used to track storm cells and mesocyclones through successive scans. Radar reflectivity mosaics are created for a land-falling tropical cyclone??Khaimuk of 14 November 2008 over the Bay of Bengal using observations from three DWR stations, namely, Visakhapatnam, Machilipatnam and Chennai. Assimilation of the quality-controlled radar data (DWR, Chennai) of the WDSS-II software in a very high-resolution NWP model (ARPS) has a positive impact for improving mesoscale prediction. This has been demonstrated for a land-falling tropical cyclone Nisha of 27 November 2008 of Tamil Nadu coast. This paper also discusses the optimum scan strategy and networking considerations. This work illustrates an important step of transforming research to operation. 相似文献