Assessment of Cartosat-1 DEM for Modeling Floods in Data Scarce Regions

Water Resources Management - Digital Elevation Model (DEM) plays an important role in modeling floods. In data scarce developing countries, unavailability of high resolution topography and river...     

Mass transfer from a carbon dioxide jet to tap water

When a jet of soluble gas is directed on to liquid surface, the kinetic energy of the jet is transferred to the liquid giving rise to circulation, which in turn enhances mass transfer. Consequently, the mass transfer coefficient is related to the characteristics of the jet.     

Emulsion polymerization of linseed and safflower acrylates and methacrylates

Acrylic and methacrylic esters of mixed fatty alcohols derived from linseed and safflower oils were homopolymerized, by emulsion polymerization technique, yielding polymers that gave hard, gloosy films with excellent flexibility and good water and chemical resistance.     

Simple delay-line p.c.m. coder

A simple p.c.m. coder, using a delay line as the coding network and having signal/noise ratio and other characteristics similar to conventional p.c.m. systems, has been developed. The coder can easily be extended to ternary and multilevel working, and the reconstructed message, available at the transmitter, may be used for purposes of monitoring and further reducing quantising noise.     

On the nature and structure of ‘niobic acid’ and its pyrolytic products: 1H NMR,I.R., conductivity and Ion exchange studies

Niobic acid of composition H₈Nb₆O₁₉ has been prepared by thorough drying of the hydrated oxide at 150°C. The mass was heated in stages up to 1200°C and the intermediate products were subjected to ¹H NMR measurements for determining their proton content. Infra red spectra indicate the presence of protons which are highly delocalised among different oxygen sites. The electrical conductivity of niobic acid has been interpreted as due to proton-hopping. The ion exchange capacity of the material has also been studied. The data have been used to formulate the structure of niobic acid and to obtain the correct procedure for the gravimetric determination of niobium as oxide.     

Mass transfer from an oxygen jet to liquid silver

A subsonic jet of pure oxygen discharging from a converging nozzle with a throat diameter of 2.5 mm was directed vertically on the surface of molten silver maintained at 1000°C. The effects of variation in lance height (5 to 25 cm), jet momentum (3000 to 56000 dyne), jet temperature (600° to 1000°C) and interfacial area (45 sq cm to 182 sq cm) were studied. In all cases the oxygen concentration in the silver was measured by lime stabilized zirconia probes. The mean liquid phase mass transfer coefficients calculated for transfer across the total surface area of the bath of 182 sq cm, ranged from 0.001 to 0.015 cmJs. The higher values were obtained with high jet momentums or with low values of the lance height. A decrease in the surface area of the bath to 45 sq cm only slightly reduced the rate of transfer and resulted in a threefold increase in the mass transfer coefficient based on the reduced area. The mass transfer coefficients were independent of the jet temperature providing the jet momentum was maintained constant and there were no thermal gradients in the liquid silver. A. CHATTERJEE, formerly Member of the John Percy Research Group in Process Metallurgy, Imperial College of Science and Technology, London, England. D. H. WAKELIN, formerly Member of the John Percy Research Group in Process Metallurgy, Imperial College of Science and Technology.     

The join calcium monoaluminate-calcium fluoride

The system CaO-Al₂O₃-CaF₂ is important in cement and slag technology and in metallurgy. A section of this system, the pseudo-binary join CaO·Al₂O₃-CaF₂, has been studied and the phase diagram established. This join is of particular interest since CaO·Al₂O₃ is one of the main constituents of high alumina cement.Quenching in sealed platinum capsules followed by microscopic and X-ray examination was the principal method used. The only compound on the join is 3CaO·3Al₂O₃·CaF₂ which melts congruently at 1507±1.5° C and forms one eutectic with CaO·Al₂O₃ at 11% CaF₂ and 1498±5° C and another with CaF₂ at 97.5% CaF₂ and 1405±10° C. There is a wide zone of liquid immiscibility. The m.p. of CaF₂ was determined to be 1422±1° C.Attempts to use high temperature microscopy to study this system are described.     

Study of electrochemical properties and formation of some phenolic block copolymers

Phenolic block copolymers have been prepared by condensation of p-cresol-formaldehyde and p-toluidine-formaldehyde homopolymer chains. The compositions of the copolymers have been determined by electrometric titrations in non-aqueous solvents. Efforts have been made to correlate structural features of the copolymers, such as intramolecular hydrogen bonding, and the probable number of phenolic and aromatic amine units in the respective blocks of the copolymer chain with their titration curves.     

The phase equilibrium diagram of the system CaO-Al2O3-CaF2

The phase equilibria of the system CaO-Al₂O₃-CaF₂ have been studied by quenching in sealed platinum capsules followed by microscopic and X-ray examination of quenched products. The established phase diagram contains five ternary eutectics, two ternary peritectics and two invariant points of four-phase monotectic transformations. The system Al₂O₃-CaF₂ has been established to be the stable diagonal of the reversible reciprocal system Al₂O₃ + 3CaF₂ = 3CaO + 2AlF₃. In the high-fluoride region a wide zone of liquid immiscibility has been found. The system also shows such rarely noticed but theoretically possible phenomena as the transformation of peritecticals into eutecticals and occurrence of three different primary fields under single continuous zone of liquid immiscibility.     

Analysis of surface preparation treatments for coating tungsten carbide substrates with diamond thin films

The effect of various substrate surface treatments on (i) the pre-growth topography and composition of the treated substrate, and (ii) the quality of diamond thin films produced by hot-filament chemical vapour deposition on tungsten carbide substrates, is reported. Two different substrate grain sizes were subjected to various surface treatments. They were then examined for surface material composition and topography using scanning electron microscopy and X-ray diffraction (XRD). Subsequently, diamond films were deposited on the samples and their quality analysed by Raman spectroscopy and XRD techniques. These analyses do not indicate a strong dependence between the substrate grain size and film quality. However, the surface-treatment method affects the resulting substrate surface topography and film quality. This revised version was published online in November 2006 with corrections to the Cover Date.