Flotation of calcareous Mussorie phosphate ore     

D.Vaman Rao  M.K. Narayanan  U.B. Nayak  K. Ananthapadmanabhan  P. Somasundaran 《International Journal of Mineral Processing》1985,14(1):57-66

Separation of Mussorie rock phosphate (P₂O₅ = 20%) from Uttar Pradesh, India, containing pyrite, calcite and other carbonaceous impurities by flotation has been successfully attempted to upgrade the phosphate values. Based on Hallimond cell flotation results of single and synthetic mineral mixtures of calcite and apatite using oleic acid and potassium phosphate, conditions were obtained for the separation of calcite from apatite which is considered to be the most difficult step in the beneficiation of calcareous phosphates. Further studies using 250 g of the mineral (?60 +150 and ?150 mesh fractions, deslimed) in laboratory size Fagergren subaeration machine employed a stagewise flotation viz. carbonaceous materials using terpineol, pyrite using potassium-ethyl xanthate and calcite using oleic acid respectively. Separation was, however, found to be unsatisfactory in the absence of a depressant.Among starch, hydrofluosilicic acid and dipotassium hydrogen phosphate, which were tried as depressants for apatite in the final flotation stage, dipotassium hydrogen phosphate proved to be superior to others. However, the tests with the above fractions did not yield the required grade. This was possibly due to insufficient liberation of the phosphate mineral from the ore body and different experimental conditions due to scale up operations. Experiments conducted using ?200 mesh deslimed fractions has yielded an acceptable grade of 27.6% P₂O₅ with a recovery of about 60%. The results have been explained in terms of the specific adsorption characteristics of phosphate ions on apatite and the liberation size of the mineral.  相似文献   

Stratigraphic and structural development of the Precambrian Cuddapah basin,S.E. India   总被引：1，自引：0，他引：1  

A.M.J. Meijerink  D.P. Rao  J. Rupke 《Precambrian Research》1984,26(1):57-104

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A comparative study of different dielectric models—computation of representative dielectric profiles of black soils     

K. S. Rao  Girish Chandra  C. Suresh Raju 《Journal of the Indian Society of Remote Sensing》1987,15(2):53-63

The dielectric property of the soil is an important parameter for microwave remote sensing. Therefore an attempt is made to study and compare the models for the dielectric constant of moist soils by considering three soil types namely Haldi series (sandy loam), Hathiapathar series (silt loam) and Jambria series (clay) and at frequencies 1.4, 4.0 and 18.0 GHz. The semiempirical models of Wang et al. (1980) and Dobson et al (1985) predict more or les same results in the domain of their applicability. However, at lower frequencies below 1.0 GHz, the imaginary part of dielectric constant shows a decreasing trend with decreasing frequency for Wang et al (1980) model whereas it shows reverse trend for Dobson et al (1985) model. The soil texture and frequency dependence of dielectric constant have been investigated for Indian soils. Some of the representative dielectric profiles of black soils of Pune have been computed using semiempirical model of Dobson et al (1985) which are useful for the development of multifrequency models for the study of soil moisture.  相似文献   

Landsat mss data as base for mapping coastal soils     

B. R. M. Rao  D. C. Joshi  R. S. Dwivedi  Shyam Sunder 《Journal of the Indian Society of Remote Sensing》1986,14(1):55-60

A Soil map at 1:250,000 scale was prepared for a part of Prakasam District (Andhra Pradesh) along the east coast using Landsat MSS data through monoscopic visual interpretation in conjunctionwith collateral information and limited field check. In general, a fair amount of correlation among physiography, image elements and soils was found. Anomalies with respect to the above correlation wherever noticed are also discussed.  相似文献   

Georeference correction on landsat imagery     

T. Ch. Malleswara Rao  K. Narasimha Rao  K. V. K. Mohana Rao 《Journal of the Indian Society of Remote Sensing》1986,14(1):67-76

This paper discusses the geometric anomalies present in bulk images which are being generated on NRSA Data Processing System (DPS). A georeference correction algorithm has been presented to correct geometric scale anomalies in a systematic manner. An approach to generalize and integrate georeference correction algorithm with existing bulk correction program has been realised without crippling the speed of DPS film product generation Software. Limitations and accuracy of the algorithm are discussed.  相似文献   

Application of remote sensing for vegetation mapping — A case study along the northern coastal districts of andhra pradesh     

S. Sudnakar  P. H. V. Vasudeva Rao  Y. V. N. Krishna Murthy  R. V. Rama Rao 《Journal of the Indian Society of Remote Sensing》1986,14(2):1-8

The study deals with the application of Remote Sensing for delineating various vegetation types along the three coastal districts of Andhra Pradesh. The satellite imagery of the region is divided into three types depending upon tone and texture. Each type is correlated with the ground truth. The species composition has been given and discussed.  相似文献   

Seasonal and solar cycle variations of night-time anomalous enhancements in total electron content     

N. Balan  P. B. Rao  K. N. Iyer 《Journal of Earth System Science》1986,95(3):409-416

Seasonal and solar cycle variations of the various characteristics of night-time anomalous enhancements in total electron content (TEC) of the ionosphere are presented for a low latitude station, Hawaii by considering TEC data for a full solar cycle. All the characteristics of the TEC enhancements have seasonal and solar cycle dependence. TEC enhancement characteristics such as frequency of occurrence, amplitude and duration are positively correlated with solar activity. The possible source mechanisms for the observed enhancements are also discussed.  相似文献   

Gravity anomalies of a trapezoidal model with quadratic density function     

D Bhaskara Rao 《Journal of Earth System Science》1986,95(2):275-284

The decrease of density contrast with depth in sedimentary strata is approximated by a quadratic function. The anomaly equation of a trapezoidal model with the quadratic density function is derived. Nonlinear optimization technique using the Marquardt algorithm has been developed and used to interpret a synthetic anomaly profile of the trapezoidal model. The exact values of the coefficients of the quadratic density function are assumed to be known. The convergence of the method is shown by plotting the values of the objective function λ and the various parameters with respect to iteration number. θ and half-width of the trapezoidal model are found to be correlated. The method is also applied to interpret the gravity anomalies over San Jacinto graben, California. Finally, the use of modelling with quadratic density function is discussed.  相似文献   

Intra-field variability of scalar flux densities across a transition between a desert and an irrigated potato field     

Dennis D. Baldocchi  K. Shankar Rao 《Boundary-Layer Meteorology》1995,76(1-2):109-136

This paper reports on measurements of sensible and latent heat and CO₂ fluxes made over an irrigated potato field, growing next to a patch of desert. The study was conducted using two eddy correlation systems. One measurement system was located within the equilibrium boundary layer 800 m downwind from the edge of the potato field. The other measurement system was mobile and was placed at various downwind positions to probe the horizontal transition of vertical scalar fluxes. Latent (LE) and sensible (H) heat fluxes, measured at 4 m above the surface, exhibited marked variations with downwind distance over the field. Only after the fetch to height ratio exceeded 75 to 1 didLE andH become invariant with downwind distance. When latent and sensible heat fluxes were measured upwind of this threshold, significant advection of humidity-deficit occurred, causing a vertical flux divergence ofH andLE.The measured fluxes of momentum, heat, and moisture were compared with predictions from a second-order closure two-dimensional atmospheric boundary layer model. There is good agreement between measurements and model predictions. A soil-plant-atmosphere model was used to examine nonlinear feedbacks between humidity-deficits, stomatal conductance and evaporation. Data interpretation with this model revealed that the advection of hot dry air did not enhance surface evaporation rates near the upwind edge of the potato field, because of negative feedbacks among stomatal conductance, humidity-deficits, andLE. This finding is consistent with results from several recent studies.  相似文献   

Analysis of objective functions used in urban runoff models   总被引：1，自引：0，他引：1  

A. Ramachandra Rao 《Advances in water resources》1987,10(4)

The objective functions used in parameter estimation in urban runoff models are compared by using a method proposed by Diskin and Simon¹ and the urban runoff model ILLUDAS. Two sets of objective functions, the first one used by Diskin and Simon in their study and a second one which includes other objective functions are used. Rainfall-runoff data from urban watersheds in the US are used in the study. The results indicate that the least squares criterion is the best among those studied.  相似文献