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11.
12.
Ali?AhmadalipourEmail author Arun?Rana Hamid?Moradkhani Ashish?Sharma 《Theoretical and Applied Climatology》2017,128(1-2):71-87
Climate change is expected to have severe impacts on global hydrological cycle along with food-water-energy nexus. Currently, there are many climate models used in predicting important climatic variables. Though there have been advances in the field, there are still many problems to be resolved related to reliability, uncertainty, and computing needs, among many others. In the present work, we have analyzed performance of 20 different global climate models (GCMs) from Climate Model Intercomparison Project Phase 5 (CMIP5) dataset over the Columbia River Basin (CRB) in the Pacific Northwest USA. We demonstrate a statistical multicriteria approach, using univariate and multivariate techniques, for selecting suitable GCMs to be used for climate change impact analysis in the region. Univariate methods includes mean, standard deviation, coefficient of variation, relative change (variability), Mann-Kendall test, and Kolmogorov-Smirnov test (KS-test); whereas multivariate methods used were principal component analysis (PCA), singular value decomposition (SVD), canonical correlation analysis (CCA), and cluster analysis. The analysis is performed on raw GCM data, i.e., before bias correction, for precipitation and temperature climatic variables for all the 20 models to capture the reliability and nature of the particular model at regional scale. The analysis is based on spatially averaged datasets of GCMs and observation for the period of 1970 to 2000. Ranking is provided to each of the GCMs based on the performance evaluated against gridded observational data on various temporal scales (daily, monthly, and seasonal). Results have provided insight into each of the methods and various statistical properties addressed by them employed in ranking GCMs. Further; evaluation was also performed for raw GCM simulations against different sets of gridded observational dataset in the area. 相似文献
13.
In view of the recognition of the importance of the interdependent behavior of strength and stiffness of walltype structural elements,the seismic demand of plan-asymmetric systems is revisited.Useful strength distribution strategies,i.e.,’Center of Strength-Center of Mass(CV-CM) coinciding’ and ’Balanced Center of Strength-Center of Resistance(CVCR)’ are adopted.Design charts for the seismic demand of classical uni-directionally and bi-directionally asymmetric systems are developed in a simple unified format.A conceptual framework is also outlined to conveniently apply the design charts.Illustrations are included to explain the use of the current recommendations in practical design.The study also highlights the relative performance of ’CV-CM coinciding’ and ’Balanced CV-CR’ criteria. 相似文献
14.
N. C. Rana 《Astrophysics and Space Science》1990,164(1):172-177
List of forthcoming papers 相似文献
15.
We have tried to determine the rate of chemical evolution of high redshift galaxies from the observed redshift distribution
of the heavy element absorption systems in the spectra of QSOs, taking into account the evolution in the intensity of the
metagalactic UV ionizing radiation background, the radius and/or the co-moving number density of, and the fraction of mass
in the form of gas in, the absorbers. The data for both the Lyman limit systems and the C IV systems have been fitted simultaneously.
It seems that the abundance of carbon has possibly increased by about a factor of 5 to 20 from the cosmic time corresponding
to the redshift ≃ 4 to 2. The data also suggest that either the radius or the co-moving number density of the galaxies increased
with redshift up to z = 2.0 and decreased slowly thereafter. The total mass of the halo gas was higher in the past, almost
equal to the entire mass of the galaxy at z = 4. The hydrogen column density distribution for Lyman limit systems predicted
by the model is in agreement with the observed distribution. 相似文献
16.
The study intended to describe the alpine vegetation of a protected area of the northwestern Himalaya and identify the important
environmental variables responsible for species distribution. We placed random plots covering different habitats and altitude
to record species composition and environmental variables. Vegetation was classified using hierarchical cluster analysis and
vegetation-environment relationships were evaluated with Canonical Correspondence Analysis. Four communities, each in alpine
shrub and meadows were delineated and well justified in the ordination plots. Indicator species for the different communities
were identified. Maximum species richness and diversity were found in community IV among shrub communities and community II
among the meadows. Studied environmental variables explained 61.5% variation in shrub vegetation and 59.8% variation in meadows.
Soil variables explained higher variability (∼35%) than spatial variables (∼21%) in both shrubs and meadows. Altitude, among
the spatial variables and carbon/nitrogen ratio and nitrogen among the soil variables explained maximum variation. About 40%
variations left unexplained. Latitude and species diversity among the other variables had significant correlation with ordination
axes. Study showed that altitude and C/N ratio played a significant role in species composition. Extensive sampling efforts
and inclusion of other non-studied variables are also suggested for better understanding. 相似文献
17.
This paper deals with detailed analysis of the fiasco created by the Tehri High Dam in Uttarakhand, India, particularly in terms of resettlement and rehabilitation of the local inhabitants. Aspects pertaining to the environmental issues are also discussed. Currently, the river valleys in Uttarakhand state of India are the targets of increasing hydroelectric projects. Virtually all rivers are being exploited for generating environmental friendly power. Having being learned the hard lesson from Tehri Dam, it has been decided to opt for such schemes in which comparatively little submergence and tempering with the fragile eco-systems is involved.However, our observations suggest that even in such schemes if due care is not taken they may turn out to be a failure. 相似文献
18.
The bearing capacity of interfering footings located near the slope face suffers from reduced bearing capacity due to the formation of the curtailed passive zone. Depending upon the position of the footing, their spacing and steepness of the slope, different extents of bearing capacity reduction can be exhibited. A series of finite element investigation has been done with the aid of Plaxis 3D vAE.01 to elucidate the influence of various geotechnical and geometrical parameters on the ultimate bearing capacity of interfering surface strip footings located at the crest of the natural soil slope. Based on the large database obtained from the numerical simulation, a 6-8-1 Artificial Neural Network architecture has been considered for the assessment of the ultimate bearing capacity of interfering strip footings placed on the crest of natural soil slope. Sensitivity analyses have been conducted to establish the relative significance of the contributory parameters, which exhibited that for the stated problem, apart from shear strength parameters, the setback ratio and spacing of footing are the prime contributory parameters. 相似文献
19.
Y. H. Jonathan Tan Jacqueline K. Q. Tham Aayush Paul Umair Rana Hui Ping Ang Nhung T. H. Nguyen Alex T. K. Yee Bryan P. I. Leong Simon Drummond Karenne P. P. Tun 《Singapore journal of tropical geography》2023,44(1):130-148
Rapid urbanization has resulted in the loss of coastal and marine habitats in cities worldwide. The effective conservation of urban coastal ecosystems requires detailed knowledge of their spatial distribution, necessitating high-resolution mapping. Our study produces a high-resolution coastal and marine habitat map and shoreline map for the tropical city-state of Singapore created through pixel-based supervised classification of satellite imagery, bathymetry data and expert ground knowledge. These maps can be used as a base reference for multiple applications including ecological research, conservation and urban planning. They also help identifiy trends in the extent of key coastal habitats, providing insight into their differing levels of vulnerability to loss and potential for restoration to ensure long-term resilience. The method used for mapping shoreline typologies and resulting insights gained, can guide other rapidly urbanizing coastal cities on strategies to assemble useful spatial knowledge for effective conservation of their urban coastal ecosystems. 相似文献
20.
S Ghosh K K Sen U Rana K S Rao K G Saxena 《Journal of the Indian Society of Remote Sensing》1996,24(3):193-202
Integration of remote sensing data with other spatial/non-spatial data was carried out using ARC/INFO software package. A simple classification technique was adopted for land cover/land-use change analyses in relation to elevation, slope, aspect and bio-climatic classes. Suitability assessment of land where agricultural extension occurred between 1963 and 1993 was made using GIS software package. Expansion of agriculture and was found to be maximum in 2200-2400 m elevation zone and 20–30° slope classes. When topographic aspects were considered expansion was maximum on south east and west facing slopes. The loss of vegetal cover is estimated to be 15 per cent between 1963–1993. However regeneration of forest was found to be maximum in elevation ranges of 1600–2000 metre and mostly having 20–30° average slope, Land deterioration over the two mapping periods was identified and strategies were suggested to mitigate the problem. 相似文献