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71.
72.
Twenty-nine elements have been determined by INAA in two impact glasses and four basalts from Lonar Crater, India. The glasses are remarkably similar to the underlying core basalt samples in major, minor and trace element abundances. This suggests that impact-induced chemical fractionation during formation of the glasses from basalt is minimal for many of the principal rock and mineral-forming elements. It should be recognized that many of the most volatile trace elements were not determined in this study. Differences in the volatile trace element contents of the glasses and basalts due to either impact-induced fractionation, or incorporation of material from a volatile-rich impacting body, can not yet be excluded. 相似文献
73.
Wetlands are one of the most important sources of atmospheric methane (CH4) contributing about 22% to the global methane budget. But to improve estimates of CH4 emission at regional and global scales there is a need to observe the sources such as wetlands frequently and develop process-based
models. In this regard, wetland inventory using satellite remote sensing data has conventionally been carried out by analysis
of optical data. Due to thermal inertia differences emittive thermal channels data has shown promise to provide highly critical
information about wetlands such as water spread, aquatic vegetation and mud flats etc. Thermal channels data of MODIS (Moderate
Resolution Imaging Spectroradiometer) sensor with a spatial resolution of 1km and swath of 2330 km is emerging as the key
source of remote sensing data for global/ regional wetland estimation and assessment of green house gas emission. In the present
study MODIS thermal channels (31 and 32) and optical channels (1,2, and 3) data have been used for evaluating methane emission
from wetlands in Gujarat. An empirical model based on temperature and productivity has been used to investigate the response
of methane emission from different sources. Model has the potential to estimate country level methane emission based on satellite
remote sensing in conjunction with collateral data/information. In this study. MODIS data of two dates pertaining to Gujarat
have been analyzed and results compared with respect to methane emission. 相似文献
74.
Use of fuzzy synthetic evaluation for assessment of groundwater quality for drinking usage: a case study of Southern Haryana,India 总被引:1,自引:0,他引:1
Bhupinder Singh Sudhir Dahiya Sandeep Jain V. K. Garg H. S. Kushwaha 《Environmental Geology》2008,54(2):249-255
A method based on concept of fuzzy set theory has been used for decision-making for the assessment of physico-chemical quality
of groundwater for drinking purposes. Conventional methods for water quality assessment do not consider the uncertainties
involved either in measurement of water quality parameters or in the limits provided by the regulatory bodies. Fuzzy synthetic
evaluation model gives the certainty levels for the quality class of the water based on the prescribed limit of various regulatory
bodies and opinion of the experts from the field of drinking water quality. In this paper, application of fuzzy rule based
optimization model is illustrated with twenty groundwater samples from Sohna town of Gurgaon district of Southern Haryana,
India. These samples were analysed for 15 different physico-chemical parameters, out of them nine important parameters were
used for the quality assessment using fuzzy synthetic evaluation approach. From this study, it has been concluded that all
the water samples are in acceptable category whose certainty level ranges from 44 to 100%. Water from these sources can be
used for the drinking purposes if alternate water source is not available without any health concern on the basis of physico-chemical
characteristics. 相似文献
75.
76.
The fatigue life of critical members, such as hangers, floor-beams and stringers in a single track, open deck railroad truss bridge, was investigated for various unit freight trains, operating at different speeds. A partial bridge model was used, along with a three-car train, to determine the stress cycles. For determining the fatigue lives of critical members, four fully-loaded trains per day were assumed to pass over the bridge. Each train was assumed to consist of one hundred 70-ton cars or seventy 100-ton cars. The 100-ton freight cars cause large stress ranges, and consequently shorter fatigue lives than the 70-ton freight cars. For the hundred-car train, with 70-ton and 100-ton cars mixed in various proportions, the fatigue lives became shorter as the percentage of 100-ton cars in the consist was increased. The impact percentages were also studied. 相似文献
77.
A new vehicle model and the partial bridge model were used to study the dynamic interaction between an open deck steel truss bridge and a moving freight train. The responses in terms of dynamic stresses in certain critical members in the bridge were generated to predict their fatigue lives by using a reliability-based methodology. 相似文献
78.
79.
T. K. Manual Ateef Khan Y. Nazeer Ahammed R. S. Tanwar R. S. Parmar K. S. Zalpuri Prabhat K. Gupta S. L. Jain Risal Singh A. P. Mitra S. C. Garg A. Suryanarayana V. S. N. Murty M. Dileep Kumar Andrew J. Shepherd 《Journal of Earth System Science》2006,115(4):473-484
Characteristics of trace gases (O3, CO, CO2, CH4 and N2O) and aerosols (particle size of 2.5 micron) were studied over the Arabian Sea, equatorial Indian Ocean and southwest part
of the Bay of Bengal during the monsoon transition period (October–November, 2004). Flow of pollutants is expected from south
and southeast Asia during the monsoonal transition period due to the patterns of wind flow which are different from the monsoon
period. This is the first detailed report on aerosols and trace gases during the sampled period as the earlier Bay of Bengal
Experiment (BOBMEX), Arabian Sea Monsoon Experiment (ARMEX) and Indian Ocean Experiments (INDOEX) were during monsoon seasons.
The significant observations during the transition period include: (i) low ozone concentration of the order of 5 ppbv around
the equator, (ii) high concentrations of CO2, CH4 and N2O and (iii) variations in PM2.5 of 5–20μg/m3. 相似文献
80.
P. V. Bhaskar Evonne Cardozo Asha Giriyan Anita Garg Narayan B. Bhosle 《Estuaries and Coasts》2000,23(5):722-734
Data on hydrography, nutrients, suspended particles, and sedimented particles were collected at weekly intervals from November to May during 1995 to 1997 at a station in the coastal waters of Dona Paula Bay, India. Suspended and sedimented particles were analyzed for total suspended matter (SPM), total sedimented particulate matter (TPM), particulate organic carbon (POC), particulate organic nitrogen (PON), chlorophylla (chla), and diatom abundance. Variations in hydrography and nutrients influenced the quantity and composition of sedimented particles. The TPM, POC, PON, and chla fluxes showed small-scale seasonal variations and were higher in the summer (February to May) than in the winter (November to January). Resuspension of carbon accounted for approximately 25% of the gross POC and was highest in April 1997 (45%). The mean net POC flux was 197±90 mg C m−2 d−1 and accounts for 4.6% of the TPM. The average C∶N (w∶w) ratio of the sedimented material was 13.2±6.6. The POC:chla ratio was relatively higher in the sedimented material as compared to the suspended material. The particulate carbon reaching the bottom sediment was 39% of the primary production. The low organic carbon concentration (approximately 0.1% of dry sediment) in the sediments implies that about 98% of the sedimented carbon was either consumed at the sedimentwater interface or resuspended/advected before it was finally buried into the sediments. 相似文献