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11.
In this paper, we have investigated some tilted Bianchi Type I models with heat conduction filled with disordered radiation
of perfect fluid. To get a determinate solution, we have assumed a condition A =(BC)
n between metric potentials. Alternatively we have discussed the case A=(BC)
1/3 for which tilted nature of the model is preserved. The various and geometrical features with singularities in the models
are also discussed.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
12.
Rahul Nigam Bimal Kumar Bhattacharya Keshav R. Gunjal N. Padmanabhan N. K. Patel 《Journal of the Indian Society of Remote Sensing》2012,40(1):1-9
To study impact of climate change on vegetation time series vegetation index has a vital role to know the behaviour of vegetation
dynamics over a time period. INSAT 3A CCD (Charged Couple Device) is the only geostationary sensor to acquire regular coverage
of Asia continent at 1 km × 1 km spatial resolution with high temporal frequency (half-an-hour). A formulation of surface
reflectances in red, near infrared (NIR), short wave infrared (SWIR) and NDVI from INSAT 3A CCD has been defined and integrated
in the operational chain. The atmospheric correction of at-sensor reflectances using SMAC (Simple Model for Atmospheric Correction)
model improved the NDVI by 5–40% and also increased its dynamic range. The temporal dynamics of 16-day NDVI composite at 0500
GMT for a growing year (June 2008–March 2009) showed matching profiles with reference to global products (MODIS TERRA) over
known land targets. The root mean square deviation (RMSD) between the two was 0.14 with correlation coefficient (r) 0.84 from
200 paired datasets. This inter-sensor cross-correlation would help in NDVI calibration to add continuity in long term NDVI
database for climate change studies. 相似文献
13.
Other Index
List of forthcoming papers 相似文献14.
The focus of this study is a suite of garnet-bearing mantlexenoliths from Oahu, Hawaii. Clinopyroxene, olivine, and garnetconstitute the bulk of the xenoliths, and orthopyroxene is presentin small amounts. Clinopyroxene has exsolved orthopyroxene,spinel, and garnet. Many xenoliths also contain spinel-coredgarnets. Olivine, clinopyroxene, and garnet are in major elementchemical equilibrium with each other; large, discrete orthopyroxenedoes not appear to be in major-element chemical equilibriumwith the other minerals. Multiple compositions of orthopyroxeneoccur in individual xenoliths. The new data do not support theexisting hypothesis that all the xenoliths formed at 1 6–22GPa, and that the spinel-cored garnets formed as a consequenceof almost isobaric subsolidus cooling of a spinel-bearing assemblage.The lack of olivine or pyroxenes in the spinel–garnetreaction zones and the embayed outline of spinel grains insidegarnet suggest that the spinel-cored garnets grew in the presenceof a melt. The origin of these xenoliths is interpreted on thebasis of liquidus phase relations in the tholeiitic and slightlysilica-poor portion of the CaO–MgO–Al2O3–SiO2(CMAS) system at pressures from 30 to 50 GPa. The phase relationssuggest crystallization from slightly silica-poor melts (ortransitional basaltic melts) in the depth range 110–150km beneath Oahu. This depth estimate puts the formation of thesexenoliths in the asthenosphere. On the basis of this study itis proposed that the pyroxenite xenoliths are high-pressurecumulates related to polybaric magma fractionation in the asthenosphere,thus making Oahu the only locality among the oceanic regionswhere such deep magmatic fractional crystallization processeshave been recognized. KEY WORDS: xenolith; asthenosphere; basalt; CMAS; cumulate; oceanic lithosphere; experimental petrology; mantle; geothermobarometry; magma chamber 相似文献
15.
Tilted Bianchi Type I cosmological model for perfect fluid distribution in presence of magnetic field, is investigated. To
get a determinate solution, it has been assumed that the universe is filled with stiff perfect fluid distribution together
with A=(BC)
n where A,B,C are metric potentials and n is a constant. The behaviour of the model in presence and absence of magnetic field is discussed. The various physical and
geometrical aspects of the model, is also discussed. It has been shown that tilted nature of the Bianchi Type I model is preserved
due to magnetic field.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
16.
We present the first comprehensive major, trace element and Hf, Nd and Sr isotope investigation of clinopyroxene and garnet mineral separates from a set of garnet clinopyroxenite xenoliths from the Salt Lake Crater, Oahu, Hawaii. These xenoliths occur in the posterosional Honolulu Volcanics Series lavas and represent some of the deepest samples from the oceanic mantle lithosphere. Our study shows that the Salt Lake Crater pyroxenites represent high pressure (>20 kb) accumulates from melts similar (but not identical) to the erupted Honolulu Volcanics, and unlike MORB or E-MORB-type melts. All clinopyroxene-garnet mineral pairs in these xenoliths show, within error, zero-age Lu-Hf and Sm-Nd isotope systematics. These pyroxenites have relatively radiogenic Hf isotope compositions (for a given Nd) and define a distinct steep slope (3.3) in εHf-εNd isotope space, similar to the Honolulu Volcanics but unlike other ocean island basalts (OIB). These compositions require an end-member component that falls above the OIB array in Nd-Hf space. This component is different than present-day MORB-mantle and it is best explained by an old depleted oceanic lithosphere. We suggest that this depleted component most likely represents a recycled depleted lithosphere that is intrinsic to the Hawaiian plume. In this respect, the Hawaiian plume is sampling both the enriched portion of a subducted oceanic crust (basalt and sediments) as well as the depleted lithospheric portion of it. This suggests that, at least for Hawaii, the whole subducted oceanic slab package has retained its integrity during subduction and subsequent mixing and storage in the mantle, probably in the order of a billion years, and that the plume is sampling the full range of these compositions. 相似文献
17.
Bimal Kumar Bhattacharya Keshav R. Gunjal Sushma Panigrahy Jai Singh Parihar 《Journal of the Indian Society of Remote Sensing》2011,39(3):393-406
Albedo determines radiation balance of land (soil-canopy complex) surface and influence boundary layer structure of the atmosphere.
Accurate surface albedo determination is important for weather forecasting, climate projection and ecosystem modelling. Albedo-rainfall
feedback relationship has not been studied so far using observations on spatial scale over Indian monsoon region due to lack
of consistent, systematic and simultaneous long-term measurements of both. The present study used dekadal (ten-day) composite
of satellite (e.g. NOAA) based Pathfinder AVHRR Land (PAL) datasets between 1981 and 2000 over India (68–100°E, 5–40°N) at
8 km spatial resolution. Land surface albedo was computed using linear transformation of red and near infrared (NIR) surface
reflectances. The cloud effects were removed using a smoothening filter with harmonic analysis applied to time series data
in each year. The monthly, annual and long term means were computed from dekadal reconstructed albedo. The mean per year and
coefficient of variation (CV) of surface albedo over seventeen years, averaged over Indian land region, were found to show
a significantly decreasing (0.15 to 0.14 and 60 to 40%, respectively) trend between 1981 and 2000. Among all the land use
patterns, the inter-annual variation of albedo of Himalayan snow cover showed a significant and the steepest reducing trend
(0.42 – 0.35) followed by open shurbland, grassland and cropland. No significant change was noticed over different forest
types.. This could be due to increase in snow melting period and snow melt area. A strong inverse exponential relation (correlation
coefficient r = 0.95, n = 100) was found between annual rainfall and annual albedo over seven rainfall zones. The decreasing trend in snow-albedo
of accumulation period (September to March) follows the declining trend in measured south-west monsoon rainfall between 1988
(980 mm) to 1998 (880 mm) over India. This finding perhaps suggests the possible reversal of reported coupling of increased
snowfall followed by lower monsoon rainfall. 相似文献
18.
Theoretical and Applied Climatology - Ocean interactions are known to play a major role in the modulation of intraseasonal variability. The role of sea surface temperature (SST) and major oceanic... 相似文献
19.
Land-use and climatic changes are ofmajor concerns in the Himalayan region because oftheir potential impacts on a predominantlyagriculture-based economy and a regional hydrologydominated by the monsoons. Such concerns are notlimited to any particular basin but exist throughoutthe region including the downstream plains. As arepresentative basin of the Himalayas, the Kosi Basin(54,000 km2) located in the mountainous area ofthe central Himalayan region was selected as a studyarea. We used water balance and distributeddeterministic modeling approaches to analyze thehydrologic sensitivity of the basin to projectedland-use, and potential climate change scenarios.Runoff increase was higher than precipitation increasein all the potential precipitation change scenariosapplying contemporary temperature. The scenario ofcontemporary precipitation and a rise in temperatureof 4 °C caused a decrease in runoff bytwo to eight percent depending upon the areasconsidered and models used. In the absence of climaticchange, the results from a distributed water balancemodel applied in the humid south of the basinindicated a reduction in runoff by 1.3% in thescenario of maximum increase in forest areas below4,000 m. 相似文献
20.
The study reveals that 10.2% of the sampled households in Nepal suffer from chronic food insecurity,i.e.,neither are they able to produce sufficient food from their farms nor earn the food security threshold income for deficit months.With the highest and the lowest exponential value of coefficient obtained from binary logistic regression model,it is concluded that any program targeting occupational caste and small landholding farm category or landless will contribute significantly to reduce food-insecurity.... 相似文献