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1.
R. Das B. Venkataraman R. M. Mineeva L. V. Bershov 《Physics and Chemistry of Minerals》1990,17(1):24-26
The electron spin-lattice relaxation time (T1e) of the paramagnetic radical-ion center SO 3 ? in a naturally occurring single crystal of barite was studied in the temperature range 10–300 K by the pulse saturation recovery technique. The changes in T1e from 30 K to 300 K are much smaller than those expected from usual Raman processes in solids. The results suggest a very weak connection between SO 3 ? center and lattice. 相似文献
2.
Application of statistical methods to study seasonal variation in the mine contaminants in soil and groundwater of Goa, India 总被引：1，自引：0，他引：1
Soil and groundwater samples were collected during two seasons, premonsoon (April 1990) and postmonsoon (December 1990),
and analyzed for major elements (Na, Mg, Al, Si, P, K, Ca, Ti, Mn and Fe), trace elements (Ni, Pb, Co, Cr and Zn) and water
parameters (pH, conductivity, acidity, alkalinity, hardness, Cl and SO4). All the data were subjected to linear discriminant analysis and partial correlation analysis in order to understand the
seasonal variation in the data. It was observed from the Mahalanobis generalized distance that in both soil and groundwater
samples there was a large difference in the concentration level of premonsoon and postmonsoon data. Linear discriminant functions
were calculated to distinguish between premonsoon and postmonsoon samples. From the partial correlation coefficient analysis
of soil samples, dominance of chemical weathering and precipitation of atmospheric fallout during monsoon were inferred. In
the case of the water samples, high conductivity and high hardness in the postmonsoon samples as well as atmospheric fallout
of Pb and Ni during the premonsoon period was suggested from partial correlation of water samples.
Received: 19 September 1995 · Accepted: 12 December 1995 相似文献
3.
Summary An evaluation of the combination approach of Penman [1] as modified by Kohler and Parmele [2] for estimating potential evaporation (PE) is made at Poona, India, vis-a-vis the evaporation from the Russian 20 m2 tank and associated meteorological data. The use of Penman's form of wind function and net radiation computed from solar radiation, air temperature, and pyrgeometric value of sky radiation at 20.30 hrs. Indian Standard Time is seen to be adequate for obtaining reliable values of potential evaporation. Further lines of work to evaluate the potential evaporation climate over India are indicated.
Abschätzung der potentiellen Verdunstung durch kombinierte Annäherung
Zusammenfassung Eine Abschätzung der potentiellen Verdunstung (PE) wurde unter Benützung der Formel von Penman [1] mit der Abänderung von Kohler und Parmele [2] in Poona (Indien) durchgeführt und mit der Verdunstung von einer russischen 20m2-Wanne und gleichzeitigen meteorologischen Bedingungen verglichen. Die Benützung der Penman-Formel der Windabhängigkeit und der Strahlungsbilanz, berechnet aus Globalstrahlung, langwelliger Himmelsstrahlung und Lufttemperatur um 20.30 Uhr (indischer Lokalzeit) erweist sich als geeignet zur Gewinnung zuverlässiger Werte der potentiellen Verdunstung. Auf weitere Gesichtspunkte zur Bestimmung des potentiellen Verdunstungsklimas über Indien wird hingewiesen.
L'estimation de l'évaporation potentielle par combinaison approchée
Résumé L'évaluation du rapprochement de combinaison de Penman [1] telle qúelle est modifée par Kohler et Parmele [2] pour evaluér l'évaporation potentielle (PE) a étè employée à Poona, l'Inde, en comparaison avec l'évaporation de la citerne russe de 20 m2 et des données météorologiques supplémentaires. L'emploi de la formule de Penman de l'effet du vent et de la radiation nette calculée de la radiation solaire, de la température de l'air et de la valeur pyrgéométrique de la radiation du ciel à 20 heures 30 (heure indienne) se trouve être suffisant pour obtenir les valeurs sûres de l'évaporation potentielle. De plus, des directives du travail pour évaluer l'évaporation potentielle au-dessus de l'Inde sont discutées.相似文献
4.
V. K. Anand G. Venkataraman S. Vishwanathan G. S. K. Rao 《Journal of the Indian Society of Remote Sensing》1987,15(1):49-54
This paper deals with the processes operating on the beaches of Goa, interpreted from imagery, followed by ground-truth collection and field checks. Studies on Landsat imagery bring out two distinct coastal geomorphological features, one north and the other south of Vasco-da-Gama. The beaches to the south indicate the prograding shoreline with deposition being the dominant phenomenon. The beaches to the north of Vasco-da-Gama reveal a retrograding shoreline where erosion is dominant. The presence of chimneys and stacks to the north of Vasco-da-Gama are characteristic of intensive erosional action while to the south a wide regular beach backed by a palaeo-strand line points to deposition. The pattern of the sediment load (in Band 4) is used as an index of longshore current movement. The action of erosion as against that of deposition in the two regions can be surmised from the diffused pattern vis-a-vis the uniformly wide even tone. Sand samples from the northern portion give a sorting coefficient of 1.100 while the southern portion shows a value of 0.712. It is hypothesised that the promontory on which Vasco-da-Gama lies is responsible for the formation of two different geomorphic zones. 相似文献
5.
D.W. Fuerstenau K.S. Venkataraman B.V. Velamakanni 《International Journal of Mineral Processing》1985,15(4):251-267
Recent papers on the role of grinding aids in wet ball mills indicate that certain polymeric aids favorably act by altering pulp rheology, leading to improved production rates at high pulp densities. Analysis of recent data indicates that there can be an improvement in terms of the production of fine particles per unit time, but on the other hand, the production per unit of expended energy remains the same. Our experiments indicate that there is a critical pulp viscosity above which the grinding media tend to centrifuge because the balls cannot be detached from the mill wall during the time of rotation. Under these conditions the mill power draft decreases and a smaller amount of fines is generated. The polymeric additives are able to reduce the pulp viscosity to a value less than the critical value so that the balls no longer centrifuge and the mill draws full power. From an analysis of the force field acting on a ball inside the mill, this critical viscosity can be estimated and the results are in agreement with experiment. 相似文献
6.
P. Srinivas V. Raghu Venkataraman I. Jayalakshmi 《Journal of the Indian Society of Remote Sensing》2012,40(3):497-506
Large scale aerial photographs were acquired for one entire district of Andhra Pradesh in the southern India encompassing approx. 10,000 sq.kms. The voluminous data was processed using digital photogrammetry techniques to generate seamless digital orthoimages as a base map for cadastral mapping applications. Historically the cadastral mapping was carried out with traditional surveying methods such as ETS, theodolites not at regular intervals. With the advent of modern surveying & remote sensing techniques, generation of Digital Cadastral Database for Land Information System (LIS) is possible. The trends of cadastral mapping started with individual plan of survey of parcels with local datum and arbitrary map projections. This study essentially required an accurate and standard spatial reference for seamless cadastral mapping over the entire Area of Interest (AOI) in single datum and projection. Towards this a spatial reference in World Geodetic System (WGS 84) datum with Universal Transverse Mercator (UTM) projection was established. The terrain in the study area is moderately undulating and the relief due to manmade features was not so significant. The aerial orthobase was found suitable for delineating and measuring the individual parcels information. A good GCP configuration, triangulation accuracy and reliable and consistent Digital Elevation Model (DEM) was ensured the generation of Digital aerial orthobases with an accuracy of better than 25cm over a distance of 1000m. The orthobase was used for identification, delineation of the cadastre parcels and most importantly to validate the aerial orthobase with the field measurements. 相似文献
7.
The environmental satellite (ENVISAT) advanced synthetic aperture radar (ASAR) offers the opportunity for monitoring snow parameters with dual polarization and multi-incidence angle. Snow wetness is an important index for indicating snow avalanche, snowmelt runoff modelling, water supply for irrigation and hydropower stations, weather forecasts and understanding climate change. We used a first-order scattering model that includes both volume and air/snow surface scattering based on a developed inversion model to estimate snow dielectric constant, which can be further related for estimating snow wetness. Comparison with field measurement showed that the correlation coefficient for snow permittivity estimated from ASAR data was observed to be 0.8 at 95% confidence interval and model bias was observed as 2.42% by volume at 95% confidence interval. The comparison of ASAR-derived snow permittivity with ground measurements shows the average absolute error 2.5%. The snow wetness range varies from 0 to 15% by volume. 相似文献
8.
Snow cover mapping is important for snow and glacier-related research. The spatial and temporal distribution of snow cover area is a fundamental input to the atmospheric models, snowmelt runoff models and climate models, as well as other applications. Daily snow cover maps from Moderate Resolution Imaging Spectroradiometer (MODIS) Terra satellite were retrieved for the period between 2004 and 2007, and pixels in these images were classified as cloud, snow or snow-free. These images have then been compared with ground snow depth (SD) measurements from the four observatories located at different parts of Himalayas. Comparison of snow maps with in situ data showed good agreement with overall accuracies in between 78.15 and 95.60%. When snow cover was less, MODIS data were found to be less accurate in mapping snow cover region. As the SD increases, the accuracy of MODIS snow cover maps also increases. 相似文献
9.
Hydraulic fracturing involves the initiation and propagation of fractures in rock formations by the injection of pressurized fluid. The largest use of hydraulic fracturing is in enhancing oil and gas production. Tiltmeters are sometimes used in the process to monitor the generated fracture geometry by measuring the fracture‐induced deformations. Fracture growth parameters obtained from tiltmeter mapping can be used to study the effectiveness of such stimulations. In this work, we present a novel scheme that uses the ensemble Kalman Filter (EnKF) to assimilate tiltmeter data using a simple process model to describe the evolution of fracture growth parameters, and an observation model that maps the fracture geometry with the observed tilt. The forward observation model is based on the analytical solution for computing the displacements and tilts due to a point source displacement discontinuity in an elastic half‐space developed by Okada 1 . The displacement and tilts for any given fracture geometry are then obtained by numerical integration of this solution, by considering multiple point sources to be located at the quadrature points. The proposed method is validated using synthetic data sets generated from polygon and elliptical shaped fracture geometries. Finally, real data from a field site, where asymmetry was measured from the intersections of the hydraulic fracture with offset boreholes, have been analyzed. Preliminary results show that, in addition to extracting the fracture dip, orientation, and volume, the procedure is able to satisfactorily predict fracture growth parameters when the fracture is relatively close to the tiltmeter array and provides some insight into the development of asymmetry when the measurements are relatively far from the fracture plane. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
10.
Sagar S. Salunkhe S. S. Rao I. Prabu V. Raghu Venkataraman Y. V. N. Krishna Murthy Chintamani Sadolikar Supriya Deshpande 《Journal of the Indian Society of Remote Sensing》2018,46(6):915-925
In many flood prone river basins, water inundates vast areas of land causing loss of life and heavy damage to the dwellings in flood plains. It also impacts agricultural productivity and cause severe economic losses. One of the reasons for flooding in plains of Brahmaputra valley in north east India is embankment breaching. In this study, an attempt was made for probabilistic flood hazard modelling of July 2008 embankment breaching scenario of Brahmaputra river at Matmara village, Lakhimpur district in Assam, based on various numerical simulations with the help of Center for Computational Hydro science and Engineering hydro-dynamic model. The methodology was applied over 2146 km2 flood prone area. Data inputs in the study include: Advanced Spaceborne Thermal Emission and Reflection Radiometer Digital Elevation Model, Pre-flood and Post flood satellite images of Landsat Enhanced Thematic Mapper Plus (ETM+) and other ancillary data. The simulation was carried out for various discharge levels based on flood frequency analysis. The result of the model includes spatial variations of inundated water depth and water velocity. The results were validated by comparing it with the post-flood ETM+ data and flood situation status report of National Informatics Centre. Flood hazard maps were prepared by carrying out a spatial analysis of simulated inundation depth and velocity. It was seen that the majority of flooded area fell into the very high and high categories. This information can be used to plan appropriate cost effective flood mitigation schemes. 相似文献