Showing papers by "Indian Institute of Technology Bombay published in 1986"
TL;DR: In this article, the authors present a simple ternary isothermal section for the Mo-V-W and Cd-Sn-Pb systems, which can be expressed as follows:
Abstract: The thermodynamic route of establishing phase diagrams is a relatively recent activity, considering that till about the fifties most phase diagrams were determined by the measurement of certain physical property or quantitative microscopy using light optics or x-ray diffraction. The thermodynamic formalism used by Kaufman and Bernstein is explained and illustrated with examples of the development of hypothetical binary phase diagrams. The calculation of ternary phase diagrams can begin with the binary phase diagram data as a first approximation. However, to calculate a reasonably accurate ternary phase diagram a certain amount of ternary solution data is necessary. Various empirical equations have been proposed in the literature to express ternary thermodynamic data. Calculation of simple ternary isothermal sections is illustrated with the examples of Mo-V-W and Cd-Sn-Pb systems. The numerical techniques which involve the differentiation of thermodynamic parameters with respect to composition get more involved with the number of components becoming 3 or more. A simpler approach has been applied recently to find the minimum position on the Gibbs free energy surface.
263 citations
185 citations
TL;DR: In this paper, the experimental investigations on reducing burr formation while drilling through-holes in metals were conducted based on response surface methodology (RSM) technique, where mathematical models correlating response parameters (burr sizes) to the process parameters, e.g. feed, hole size and workpiece hardness have been obtained.
66 citations
TL;DR: In this paper, a survey of the literature is made for the phosphides of those metals which are cheap and chemically stable in acid and/or alkali, including cobalt, iron, moybdenum, nickel, vanadium and tungsten, and the preparation and characterization for the band gap, empirical formula, band diagram and photoresponse of these semiconducting materials are discussed.
Abstract: The principle of a solar chargeable battery and the necessity for development of new materials for such a battery are discussed in this paper. A survey of the literature is made for the phosphides of those metals which are cheap and chemically stable in acid and/or alkali. For the first time the phosphides of cobalt, iron, moybdenum, nickel, vanadium and tungsten are considered as suitable materials for use as photoelectrodes in such cells. The preparation and characterization for the band gap, empirical formula, band diagram and photoresponse of these semiconducting materials are discussed in this paper.
55 citations
TL;DR: In this paper, a modified SIMPLE procedure is used for this purpose and it is shown that this procedure yields faster convergence for L / D i = 0.8 and 0.15.
52 citations
TL;DR: In this paper, the coefficient de frottement and de transfert de chaleur for des ecoulements turbulents d'un melange 50-50 d'eau and de glycerol dans des tubes a cannelures en spirales for different configurations and des valeurs du nombre de Reynolds de 5000 a 80000.
Abstract: Etude experimentale du coefficient de frottement et de transfert de chaleur pour des ecoulements turbulents d'un melange 50-50 d'eau et de glycerol dans des tubes a cannelures en spirales pour differentes configurations et des valeurs du nombre de Reynolds de 5000 a 80000. Comparaison avec des tubes lisses. Etablissement de correlations
43 citations
TL;DR: In this article, the thermal conductivity of flake graphite cast irons has been investigated for thermal fatigue applications, where the temperature of the component usually reaches a maximum of 700° C. Thermal conductivity values are determined up to the temperature range 40 to 500° C and values up to 40 to 700°C are presented by extrapolation.
Abstract: Thermal conductivity is one of the most important properties of flake graphite cast iron, that decides the transient temperature and thermal stress distribution in the components which are subjected to elevated temperature applications. Such applications include cylinder heads, brake-drums, exhaust manifolds, ingot moulds, hot mill rolls and dies. Thermal conductivity values are experimentally measured in 23 flake graphite cast irons having an identical base iron composition. The irons selected can be classified into two groups: one with high carbon (3.93%) content and another with medium carbon (3.00%) content. The irons are alloyed with commonly used alloying elements such as molybdenum, chromium, vanadium, nickel, tin, antimony, copper and aluminium. Thermal conductivity values are determined up to the temperature range 40 to 500° C and values up to 40 to 700° C are presented by extrapolation. The present work has provided information regarding thermal conductivitiy of flake graphite cast irons which are used for thermal fatigue applications (where the temperature of the component usually reaches a maximum of 700° C). It is concluded that an increased amount of graphite carbon, an increased amount of type A graphite and an increased fineness of graphite increase thermal conductivity. Further, molybdenum increases thermal conductivity appreciably while nickel and copper increase it moderately. Aluminium and silicon considerably reduce thermal conductivity while chromium, vanadium, tin and antimony reduce it moderately.
40 citations
TL;DR: In this paper, the structure property relationship of four different diisocyanates is studied in detail and the isocyanate selected are TDI, MDI Crude, HDI, and IPDI.
Abstract: Structure property relationship of four different diisocyanates is studied in detail. The isocyanates selected are TDI, MDI Crude, HDI, and IPDI. Physical properties such as mechanical, dynamic mechanical, electrical, and thermal are studied. Dynamic mechanical analyses are based on the compound resonance principle. Among all, IPDI-based polymer showed mediocre trend and TDI-based polymer showed best properties.
38 citations
TL;DR: In this paper, a new diterpenoid furnolactone having molecular formula C20H22O6 has been isolated from the stems of Tinospora cordifolia.
34 citations
TL;DR: In this paper, a specially fabricated magnetic hysteresis unit has been used to study the magnetic properties of ferromagnetic specimens which have undergone various stages of fatiguing, and the variations in magnetic properties are found to be related to the fatigue stress and life experienced by the specimens.
Abstract: A specially fabricated magnetic hysteresis unit has been used to study the magnetic properties ( B , H c , B r ) of ferromagnetic specimens which have undergone various stages of fatiguing. The variations in magnetic properties are found to be related to the fatigue stress and life experienced by the specimens. The possibility of exploiting this technique for the study of the fatigue process is discussed.
33 citations
TL;DR: In this article, the optical properties of undoped and fluorine-doped tin oxide films were investigated in the UV region (225-350 nm) and it was observed that the absorption edge lies at 3.71 eV and 4.03 eV, respectively.
TL;DR: The hydrogen bonding is, however, the most probable mode of bonding involved in stabilizing the DNA-amino acid complexes.
TL;DR: In this article, the transformation characteristics of a Cu-27Ni-2Cr alloy were studied on ageing in the temperature range of 773 to 1073 K, by means of X-ray diffraction and transmission electron microscopy.
Abstract: Transformation characteristics of a Cu-27Ni-2Cr alloy were studied on ageing in the temperature range of 773 to 1073 K, by means of X-ray diffraction and transmission electron microscopy. It was concluded from morphological features that the alloy undergoes spinodal decomposition and the coherent spinodal was estimated to be 946 K. Yield stress increment on ageing was found to follow monotonically the strain amplitude and to be independent of the wavelength of composition modulation.
TL;DR: In this paper, the effect of implantation at two doses, i.e., 1×1017 ions cm−2 (specimen-1) and 1 ×1018 ions cm −2 (Specimen-2) of N2+ ions implanted on 304 stainless steel foils, was investigated using X-ray photoelectron spectroscopy.
01 Jun 1986-Graphical Models \/graphical Models and Image Processing \/computer Vision, Graphics, and Image Processing
TL;DR: Techniques to improve the object description by incorporation of surface concavities and surface markings are described.
Abstract: L. Dreschler and H.-H. Nagel [Comput. Graphics Image Process. 20, 1982, 199–228] describe a system which derives convex polyhedral object descriptions of moving rigid objects from monocular image sequences. Here, we describe techniques to improve the object description by incorporation of surface concavities and surface markings. Results from three street scenes are presented.
TL;DR: In this paper, a simple expression for nuclear densities was proposed, which brings out the following important nuclear properties: (i) shell effects in proton and neutron central densities, (ii) approximate global constancy of neutron central density, and (iii) approximate constancy for RpZ−1/3 whereR is the nuclear half-density radius andRp is the rms radius of the proton density.
Abstract: We propose a simple expression for nuclear densities, which brings out the following important nuclear properties: (i) shell effects in proton and neutron central densities, (ii) approximate global constancy of neutron central densities, (iii) approximate constancy ofRN−1/3 and RpZ−1/3 whereR is the nuclear half-density radius andRp is the rms radius of the proton density, (iv) larger surface thickness and rms radius for neutron density as compared to those for proton density.
TL;DR: In-situ spectral reflectance of soils was measured at various test sites of India in four spectral bands within the visible and near-infrared wavelength comparable to Landsat Multispectral Scanner (MSS) as mentioned in this paper.
Abstract: In-situ spectral reflectance of soils was measured at various test sites of India in four spectral bands within the visible and near-infrared wavelength comparable to Landsat Multispectral Scanner (MSS). Reflectance behaviour of soils under different field conditions was analysed and the spectral reflectance curves for different soil types were obtained. Soil samples pertaining to each test site were analysed for mechanical composition, physioco-chemical properties to identify their relationship with soil reflectance. These spectral reflectance curves were further examined as to their usefulness in discriminating various soil types. Five distinct soil types namely, Black cotton soils (Typic Pellusterts), Marine Soils (Typic Halaquepts), Lateritic Soils (Plinthic Tropohumults), Alluvial Soils (Typic Ustochrepts), Coastal Sandy Soils (Typic Psammaquents), were discriminated on the basis of significant relationships between the spectral reflectance data and soil properties.
TL;DR: It is found that exchange energies and corrections to polarization energies are of comparable magnitude to that of the direct term and must be included in the analysis of these states of a Rydberg atom.
Abstract: Analytic expressions are obtained for direct and exchange penetration energies, corrections to polarization energies, and nonadiabatic corrections in high-angular-momentum Rydberg states. It is found that exchange energies and corrections to polarization energies are of comparable magnitude to that of the direct term and must be included in the analysis of these states.
30 Sep 1986
TL;DR: Eine Methode zur Auswertung of TV-Bildfolgen des Verkehrsgeschehens vorgeschlagen, with der diese Informationen zu einem grosen Teil gewonnen werden konnen, ist eine Ubersicht uber Methoden der Bildfolgenverarbeitung siehe.
Abstract: Bei der automatischen Uberwachung und Analyse des Strasenverkehrs werden Informationen benotigt, z B die Anzahl der Fahrzeuge, deren Geschwindigkeit, die Besetzungsdichte der Fahrspuren, die mittlere Geschwindigkeit auf den Spuren, die Haufigkeit von Spurwechseln, die Anzahl der PKW und LKW Diese Informationen konnen von den bekannten Mesmethoden wie Induktionsschleifen und Lichtschranken z T nur mit grosem Aufwand erhalten werden Im vorliegenden Beitrag wird deshalb eine Methode zur Auswertung von TV-Bildfolgen des Verkehrsgeschehens vorgeschlagen, mit der diese Informationen zu einem grosen Teil gewonnen werden konnen Fur eine Ubersicht uber Methoden der Bildfolgenverarbeitung siehe /1/
TL;DR: Uranium(VI) reacts with 1-(2′-thiazolylazo)-2-naphthol to form a red-coloured chelate in the pH range 5.3-7.2, maintained by 0.04 M acetate buffer as discussed by the authors.
Abstract: Uranium(VI) reacts with 1-(2′-thiazolylazo)-2-naphthol to form a red-coloured chelate in the pH range 5.3–7.2, maintained by 0.04 M acetate buffer. Absorbance of the sparingly soluble complex, solubilized and stabilized by Triton X-100, is measured after 30 min and it is stable for at least 16 hours. The complex exhibits maximum absorbance at 575 and 625–630 nm, but absorbance at longer wavelengths is not stable. The 1∶2 complex obeys Beer's law over the concentration range 0.4–6.4 μg of uranium(VI) per cm3, has molar absorptivity 3.36·104 dm3·mol−1·cm−1, Sandell sensitivity 7.0 ng·cm−2, formation constant (log K) 9.32 and coefficient of variation ±0.77%. Effect of 60 ions has been studied and selectivity improved considerably in presence of CDTA. The method has been applied for determination of uranium content in a rock sample.
01 Jan 1986
TL;DR: In this article, the effects of surface roughness, saturation pressure and polymer concentration on boiling heat transfer were studied and the results were compared with Rohsenow's correlation, and the authors concluded that the results showed that the effect of the additive on smooth and rough aluminium surfaces having effective cavity size within the range as predicted by Hsu model.
TL;DR: In this article, a simple C°-continuous beam/plate flexure element based on a shear-deformable theory is proposed to solve the locking problem in the thin limit.
TL;DR: In this article, a plausible qualitative model, in which a linear or planar defect pins the Fermi level across the space-charge layer, is built to explain the low shunt resistance accompanied by premature localized avalanche breakdowns.
Abstract: In situ measurements of the derivatives of conductance with reverse bias, conducted at two temperatures, have been used to show that spatially-localized avalanche breakdown occurs in silicon diffused-junction solar cells even at voltages an order of magnitude below the bulk breakdown voltage. These breakdowns occur at a few sites forming microplasmas that emit light. These light emissions have been used to selectively etch mesas, measurements on which show that low shunt resistance (as obtained from dark forward IV measurements), localized avalanche breakdowns and soft reverse characteristics are concomitant. A plausible qualitative model, in which a linear or planar defect pins the Fermi level across the space-charge layer, is built to explain the low shunt resistance accompanied by premature localized avalanche breakdowns.
TL;DR: Ru-Pt/SiO2 bimetallic catalysts with varying Ru:Pt ratio have been prepared and studied with the aim to establish if they contain coclusters or isolated ruthenium and platinum particles as mentioned in this paper.
TL;DR: In this article, the band gap of semiconductor is determined by photovoltage spectrum using the Mott-Schottky plot, which gives the position of Fermi level, approximate position of band edges, donor density in the semiconductor and space charge layer thickness.
Abstract: The band gap of semiconductor is determined by photovoltage spectrum. The photovoltage sign shows the semiconductor to be ofn-type conductivity. Mott-Schottky plot gives the position of Fermi level, the approximate position of band edges, donor density in the semiconductor and space charge layer thickness. The results agree with other reported values.
TL;DR: In this article, a method based on piecewise cubic interpolatory polynomials for the numerical solution of singular integral equations of Cauchy type is considered, and the class of interpolatory functions under consideration is the class X-splines.
Abstract: A method based on piecewise cubic interpolatory polynomials for the numerical solution of singular integral equations of Cauchy type is considered. The class of interpolatory functions under consideration is the class of X-splines. Of particular interest is the size of the matrix of linear algebraic equations. It is shown that one can get matrices of order N × N , where N is the number of node points on the interval of integration. The analysis becomes considerably simpler for the case when the node points are equally spaced. Numerical results from the X-spline method are compared with those obtained using other methods.