Solitary sound pulses via electron-vortex distribution in partially ionized plasmas     

J. Srinivas  P. K. Shukla 《Astrophysics and Space Science》1994,219(1):143-147

It is shown that nonlinear propagation of sound waves in partially ionized collisional plasmas is governed by a modified Korteweg-de Vries (mKdV) equation when the electron distribution function deviates from the Boltzmann distribution. The mKdV equation admits a sharply localized solitary sound pulse, the profile and width of which are different from that which involves the Boltzmann electron number density response. Since the electron-vortex distribution induced solitary sound pulses are more pronounced, it can easily be identified in partially ionized plasmas.  相似文献   

Spherical harmonic synthesis and least squares computations in satellite gravity gradiometry     

Srinivas V. Bettadpur  Bob E. Schutz  John B. Lundberg 《Journal of Geodesy》1992,66(3):261-271

The computational requirements in the simulations of geopotential estimation from satellite gravity gradiometry are discussed. Fast algorithms for spherical harmonic synthesis and least squares accumulation on a vectorizing supercomputers are presented. Using these methods, in a test case estimation of 2595 coefficients of a degree and order 50 gravity field, sustained program execution speeds of 275 Mflops (87 % peak machine speed) on a single processor of a CRAY Y-MP were achieved, with spherical harmonics computation accounting for less than 1 % of total cost. From the results, it appears that brute-force estimation of a degree and order 180 field would require 537 Million Words of memory and 85 hours of CPU time, assuming mission duration of 1 month, and execution speed of 1 Gflops. Both memory size and execution speed requirements are within the capabilities of modern multi-processor supercomputers.  相似文献   

OBSERVATIONS ON ESTUARINE FLUID MUD ENTRAINMENT     

Srinivas  R.  Mehta  A. J. Graduate Research Assistant. Coastal  Oceanographic Engineering Department  University of Florida. Gainesville. FL . U. S. A.  Professor  Coastal  Deeanographic Engineering Department. University of Florida. Gainesville. FL U. S. A. 《国际泥沙研究》1990,(1)

I. INTRODUCTIONPrediction of mud bed erosion by forcing due to tidal currents usually requires a numerical solution of the advection--dispersion equation for sediment mass transport. Key role is of course played inthis by the bottom boundary conditions defining erosion and deposition fluxes. The issue of erosion isbriefly considered here. noting that it is customary to calculate the rate of erosion as a function of thebed shear stress in excess of the erosion shear strength of the bed (Me…  相似文献   

Physical Modeling Results on Modified Pseudodepth Sections in Exploration of Highly Resistive Targets     

A. Apparao  G. S. Srinivas  V. Subrahmanya Sarma 《Pure and Applied Geophysics》1997,150(2):341-352

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Carbonaceous aerosols over Pune and Hyderabad (India) and influence of meteorological factors     

Kaushar Ali  A. S. Panicker  G. Beig  R. Srinivas  P. Acharja 《Journal of Atmospheric Chemistry》2016,73(1):1-27

Sampling of particulate matter with aerodynamic diameter cut off at 2.5 μm (PM_2.5) has been carried out over a semi urban site of Pune and an urban site of Hyderabad. Analysis of elemental Carbon (EC) and Organic Carbon (OC) present in PM_2.5 was carried out using advanced Desert Research Institute’s (DRI) Thermal/Optical Carbon Analyzer operated on IMPROVE_ A (Interagency Monitoring of Protected Visual Environments_ A) protocol. It is found that average concentration of EC and OC both at Pune and Hyderabad was highest during winter season and lowest during monsoon season. Winter high is mainly controlled by inversion, whereas monsoon low is due to rain-out and wash-out process. OC/EC ratio showed higher variation over Pune compared to that over Hyderabad in different seasons, indicating divergent sources of emission of OC and EC at Pune. Formation of Secondary Organic Carbon (SOC) has also been identified as one of the reasons for wide variation in OC/EC ratio value in different seasons over both the sites.  相似文献   

Analysis of multi-channel seismic refection and magnetic data along 13° N latitude across the bay of bengal     

D. Gopala Rao  G. C. Bhattacharya  M. V. Ramana  V. Subrahmanyam  T. Ramprasad  K. S. Krishna  A. K. Chaubey  G. P. S. Murty  K. Srinivas  Maria Desa  S. I. Reddy  B. Ashalata  C. Subrahmanyam  G. S. Mital  R. K. Drolia  S. N. Rai  S. K. Ghosh  R. N. Singh  R. Majumdar 《Marine Geophysical Researches》1995,17(3):321-322

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Far infrared photometry of planets: Saturn and Venus: Volume 38, Number 3 (1979), in the article,by R. Courtin,P. Léna,M. De Muizon,D. Rouan,C. Nicollier,and J. Wijnbergen,pp. 411–419     

Srinivas N. Mohan 《Icarus》1979,40(2):317-330

The global distribution of existing lunar topography suffers from a lack of measurements of far-side radii because of the sparsity of data types in the nonequatorial regions. This paper presents determinations of far-side lunar radii based on the reduction of photogrammetric measurements derived from selected Apollo 16 trans-Earth phase photographs. The regions covered in this analysis lie west of Mare Moscoviense between longitudes 90 and 130°E and latitudes 10 and 60°N. The determinations are made using control points appearing on both NASA topographic orthophoto maps and the Apollo 16 photographs. The estimated lunar radii are referred to these control points and determined with a relative accuracy of 500 m. The new lunar radii are used to generate a topographic map covering the area investigated. The map shows that, with the given spatial density of surface festures measured, basin-sized features can be resolved. In particular, the far-side craters Fabry, Riemann, and Szilard comprise a topographically depressed region about 500 km in diameter centered at 120°E and 38.5°N. The floor of this basin is 2.4 to 3.4 km below the reference sphere of 1738.0 km and 4.8 to 5.8 km below the northern rim of the basin. A comparison of the depth of the unfilled basin with the depths of maria-filled front-side basins leads to the conclusion that basalt fill of the near-side maria may be 2 km deep. The topographic map shows good correlation with geologic provinces of young plains and cratered terra in the far-side highland region investigated. Lack of correlation between sampled values of the state-of-the-art 16th-order and 16th-degree harmonic gravity field model and corresponding topographical values leads to the conclusion that the far-side region investigated is isostatically compensated.  相似文献   

Lemniscate representation for inversion of gravity and magnetic data through nonlocal optimization     

P. S. Moharir  V. M. Maru  S. Srinivas 《Journal of Earth System Science》1999,108(4):223-231

A method of representing surfaces and volumes by a set of geometric points and a small set of auxiliary parameters, based on generalization of Bernoulli’s notion of lemniscates is introduced. It provides for easy generation and modification of surfaces and volumes, which could be connected, disjoint or even with very irregular boundaries. This allows solving geophysical inversion problems, without constraining the anomalous volumes to some ideal or simple forms. This is illustrated by the example of joint inversion of gravity and magnetic data sets attributable to two-dimensional anomalous bodies. A nonlocal optimization algorithm calledsegmented Hamming scan is used for inversion. Comparison with nonlinear least-squares algorithm shows the advantages of the chosen approach. The concepts ofdesideratal andprocedural detours are illustrated.  相似文献   

Evaluation of Ground Water Potential Zones Using Remote Sensing Data -A Case Study of Gaimukh Watershed, Bhandara District, Maharashtra     

G. P. OBI Reddy  K.Chandra Mouli  S. K. Srivastav  C. V. Srinivas  A. K. Maji 《Journal of the Indian Society of Remote Sensing》2000,28(1):19-32

In the present study efforts have been made to evaluate ground water potential zones for ground water targeting using IRS-IC LISS-II1 geo-coded data on 1:50,000 scale. The drainage, geology, geomorpholgoy and lineament information has been generated and integrated to evaluate hydro-geomorphological characteristics of the Gairnukh watershed, Bhandara district, Maharashtra for delineation of ground water potential zones. The analysis reveals that the deep valley fills with thick alluvium have excellent, shallow valley tills and deeply weathered pediplains with thin alluvium have very good and moderately weathered pediplains in the geological formations of Tirodi Gneiss and Sausar Groups have god ground water potential and these units are highly favourable for ground water exploration and development. Shallow weathered pediments in geological formations of Tirodi Gnesis and Sausar Groups are marked under moderate ground water potential zone. Shallow weathered pediplains in geological formations of Tiridi Gneiss and Sausor Groups are grouped under limited ground water potential category, except along the fractures/lineaments. Structural hills in geological formations of Tirodi Gneiss and Sausar Groups have poor ground water prospects. Inselbergs and Linear ridges in geological formations of Tirodi Gneiss are grouped under very poor ground water prospects zone. The good inter-relationship was found among the geological units, geomorphological units, lineament density, hydro-geomorphological zones and ground water yield data.  相似文献   

Study of forward–backward solute dispersion profiles in a semi-infinite groundwater system     

Mritunjay Kumar Singh  Srinivas Pasupuleti 《水文科学杂志》2020,65(8):1416-1429

ABSTRACT

Forward–backward solute dispersion with an intermediate point source in one-dimensional semi-infinite homogeneous porous media is studied in this paper. Solute transport under sorption conditions, first-order decay and zero-order production terms are included. The first type of boundary condition is taken as a constant point source at an intermediate point from where forward and backward solute dispersion is examined. The Laplace transform method is adopted to solve the governing equation analytically. All the analytical results are obtained in graphical form to investigate the forward–backward solute transport in porous media for various hydrological input data. The graphical nature of the analytical solution is compared with numerical data taken from existing literature and similar results are obtained. Also, numerical solution of the governing equation is obtained by the Crank-Nicolson finite difference scheme and validated with the analytical solution, which demonstrates good agreement between them. Accuracy of the solution is also observed by using RMSE.  相似文献