Showing papers by "Indian Institute of Technology Bombay published in 1974"
TL;DR: In this paper, an analytical solution for performance characteristics of a narrow journal bearing is obtained, taking account of the velocity slip at the surface of a porous medium by using Beavers-Joseph criterion.
Abstract: Analytical solution for performance characteristics of a narrow journal bearing is obtained. The analysis takes account of the velocity slip at the surface of a porous medium by using Beavers-Joseph criterion [1]. Results are presented for various bearing characteristics and compared with earlier results obtained by using no-slip condition. A comparison is also made with an earlier approximate analysis [8] which considers the slip effects but assumes the bearing wall thickness to be infinitesimally small.
62 citations
TL;DR: In this article, the thermal decomposition of ferrous oxalate dihydrate FeC2O4.2H2O has been investigated using thermogravimetric (TG), DTG, differential thermal analysis (DTA), X-ray diffraction and infra-red spectroscopic techniques.
Abstract: The thermal decomposition of ferrous oxalate dihydrate FeC2O4.2H2O, has been investigated using thermogravimetric (TG), differential thermogravimetric (DTG), differential thermal analysis (DTA), X-ray diffraction and infra-red spectroscopic techniques. The DTA data obtained in air consist of an endothermic dehydration peak at ∼ 190‡ C and two exothermic peaks at ∼ 245 and ∼ 360‡ C. The first exotherm corresponds to the primary oxidative decomposition while the second one seems to be due to a structural transformation from a disordered or non-crystalline to a crystalline state ofα-Fe2O3. Similar experiments carried out using a nitrogen atmosphere show an endothermic peak ∼ 190‡ C followed immediately by an exothermic peak at 240‡ C. The final product of this decomposition has been identified as Fe3O4. The oxalate dihydrate containing traces of moisture decomposes in air under the ambient of its own gaseous products at ∼ 300‡ C to giveγ-Fe2O3. This compound has been characterized by X-ray diffraction and magnetic hysteresis measurements.
58 citations
TL;DR: In this article, the characteristics of physical state of the bed with the variation of the variables which include flow of fluid, particle diameter, orifice diameter, bed height, are studied.
Abstract: Spoutfluidization is a new technique for solid-fluid contact which aims at incorporating the advantages of spouted bed and fluidized bed technique.
The characteristics of physical state of the bed with the variation of the variables which include flow of fluid, particle diameter, orifice diameter, bed height, are studied in this investigation. Experimental study of minimum spoutfluidizing velocity using glass beads with mean particle diameters from 0.254 to 0.600 mm has been carried out in a 90 mm glass column with three spouting inlet orifice sizes at different bed heights. Phase diagrams indicate that the minimum spout-fluid flow rate in a gas-solid system may be a point property for a given bed. A correlation is presented in which the standard deviation of experimental from calculated minimum spoutfluidizing velocity is within 5%.
La fluidisation avec giclage est une nouvelle technique pour mettre en contact des matieres solides et fluides; elle cherche a combiner les avantages des lits fluidises et des lits gicles (spouted).
On a etudie les caracteristiques de l'etat physique du lit en changeant les variables telles qu'ecoulement du fluide, diametre de l'orifice et hauteur du lit. On a fait une etude experimentale de la vitesse minimale de fluidisation avec giclage, en employant des perles de verre et un diametre moyen des particules compris entre 0.254 et 0.600 millimetres; l'experience s'est faite dans une colonne en verre de 90 millimetres et avec trois dimensions d'orifices d'entree de la giclee places a differentes hauteurs du lit. Les diagrammes des phases indiquent que le debit minimal du fluide a giclage dans un systeme de gaz et de solide peut ětre un point approprie au lit donne. On presente une correlation dans laquelle l'ecart normal entre la vitesse minimale de fluidisation avec giclage trouvee experimentalement et celle qu'on avait calculee n'excede pas 5%.
51 citations
01 Jan 1974
30 citations
TL;DR: In this paper, the exact distributions of products of independent generalized Snedecor's F-variables have been established in H-function, G-function and in computable form.
Abstract: In this paper the exact distributions of products of independent generalized Snedecor's F-variables have been established in H-function, G-function, and in computable form. The exact distributions of products of independent F-variables, folded Student-t variables, beta second kind and folded Cauchy variables have also been obtained as particular cases. One particular case is verified with the result available in the literature. Calculus of residues, properties of Meijer's G-function, Psi function, H-function and Zeta function are used in deriving the results. Percentage points can be computed directly from the representation given in this article.
Dans cet article, la distribution exacte du produit de variables independantes distribuees selon des fonctions F de Snedecor generalisees a ete etablie en fonction H, en fonction G et en frome calculable. Les distributions exactes de produits de variables independantes distribuees selon des fonctions F, des fonctions t de student ‘repliees’ des fonctions Beta de deuxieeme genre et des fonctions de cauchy ‘repliees’, ont aussi ete obtenues comme cas particuliers. Des pourcentages peuvnet etre directement calcules a partir de l’exposee donne dans cet article.
14 citations
TL;DR: In this paper, the X-ray fine structure of cobalt-zinc ferrites of composition, ZnxCo1-xFe2O4 (x = 0,0.25, 0.50 and 0.75) have been recorded employing a 40cm curved crystal spectrograph of transmission type.
13 citations
13 citations
TL;DR: In this article, solid solutions of tetragonal MgMn2O4 and cubic MgAl 2O4 have been synthesized and characterized using the x-ray diffraction technique and electrical conductivity and magnetic susceptibility have been measured over the temperature ranges 25-1000 °C and - 195-60 °C respectively.
Abstract: Solid solutions of tetragonal MgMn2O4 and cubic MgAl2O4 have been synthesized and characterized using the x-ray diffraction technique. Electrical conductivity (σ) and magnetic susceptibility (χ) have been measured over the temperature ranges 25-1000 °C and - 195-60 °C respectively. All the compounds were found to be monophasic and crystallize, with either tetragonal (c/a> 1) or cubic symmetry. The critical concentration of MgAl2O4, required to stabilize the cubic structure, was found to be only 12·5%. This may be explained as due to migration of a considerable amount of Mn3+ to A sites. The values of energy of activation and free energy of activation obtained from ln σ-1/T and ln (σT)-1/T plots were found to be almost identical. All the samples exhibited paramagnetism at T> - 195 °C and indications of antiferromagnetic ordering at lower temperatures. Further, an increase in χ values with increasing concentration of MgAl2O4 was observed. An explanation is offered for this behaviour.
13 citations
TL;DR: In this article, the elastic analysis of cylindrical pressure vessels with hemispherical, torispherical and ellipsoidal heads, involving partial differential equations for the classical theory of thin shells of revolution axisymmetric in character, is attempted using a step-by-step integration procedure and a segmentation technique.
12 citations
TL;DR: In this article, the influence of thermomechanical treatments (TMT) has been studied in a low carbon CrNi-Mo steel with equal amounts of total deformation of austenite, LTMT, i.e. low temperature (550°C) TMT and HTMT, produced nearly equal martensite lath size.
10 citations
TL;DR: Thiothenoyltrifluoroacetone in carbon tetrachloride-butanol (1:1) is used for extraction and spectrophotometric determination of vanadium (IV) at pH 4.5-5.5 and conforms to Beer's law over the range 2-11 mug/ml of extract.
TL;DR: In this paper, the rotor rectifier cascade feeding a resistance whose effective value is controlled by controlling the ON to OFF time ratio of a thyristor chopper connected in parallel with it is shown that the use of this scheme permits the realization of a theoretically expected performance.
Abstract: The optimum dc dynamic braking control here implies that, at all the speeds, the motor is operated at peak torque point. This can be achieved by controlling the rotor resistance of an induction motor such that the peak torque occurs at the speed at which the motor is running. The optimum control permits the stopping of a load in a minimum time with minimum heating of the motor and therefore is useful where very frequent and quick stops are needed. The present paper is concerned with the optimum dc dynamic braking control using rotor rectifier cascade feeding a resistance whose effective value is controlled by controlling the ON to OFF time ratio Of a thyristor chopper connected in parallel with it. It is shown that the use of this scheme permits the realization of a theoretically expected performance.
TL;DR: The orange-red complex formed between zirconium(IV) and 4-(2-pyridylazo)-resorcinol (1∶1) at pH 2.5, in presence of ascorbic acid and phthalate buffer, is used for spectrophotometric determination of ZIRCONIUM, the absorbance being measured at 540 nm.
Abstract: The orange-red complex formed between zirconium(IV) and 4-(2-pyridylazo)-resorcinol (1∶1) at pH 2.5, in presence of ascorbic acid and phthalate buffer, is used for spectrophotometric determination of zirconium, the absorbance being measured at 540 nm. Beer's law is obeyed for zirconium concentration of 0.5,μg to 5.0μg per ml. Molar absorptivity is 6.75×103. Apparent formation constant (log K) of the complex is 5.664±0.2. The method has sensitivity of 0.013μg of zirconium per cm2 and relative standard deviation ±1.30%.
TL;DR: The electronic structure of the NO3 radical is discussed in this paper, where three anisotropic lines of equal intensity are attributed to identical radicals, situated at three nonequivalent sites in the crystal.
TL;DR: The ferromagnetic resonance linewidth in polycrystalline insulators contains contributions which arise from intrinsic and extrinsic properties of the material and also from the electromagnetic perturbations of the resonant cavity.
TL;DR: In this paper, chemical shifts of the L3-absorption edges and that of the main absorption peaks for some platinum compounds are reported, and an attempt has been made to interpret the chemical shifts on the basis of the molecular orbital description.
TL;DR: In this article, the binding energy per nucleon for 16 O was found to be about 7 MeV when the spectrum for higher intermediate states is chosen to join smoothly to the self-consistent results.
TL;DR: In this article, the authors used the method of biorthogonal functions developed by Johnson and Little [8] for the flexure of semi-infinite orthotropic plates whose long edges are clamped and upon whose short edge (a) deflection and slope, or (b)deflection and moment or (c) moment and shear force are prescribed.
TL;DR: In this paper, the rotor rectifier cascade feeding a resistance whose effective value is controlled by controlling the ON to OFF time ratio of a thyristor chopper connected in parallel with it is shown that the use of this scheme permits the realization of a theoretically expected performance.
Abstract: The optimum dc dynamic braking control here implies that, at all the speeds, the motor is operated at peak torque point. This can be achieved by controlling the rotor resistance of an induction motor such that the peak torque occurs at the speed at which the motor is running. The optimum control permits the stopping of a load in a minimum time with minimum heating of the motor and therefore is useful where very frequent and quick stops are needed. The present paper is concerned with the optimum dc dynamic braking control using rotor rectifier cascade feeding a resistance whose effective value is controlled by controlling the ON to OFF time ratio of a thyristor chopper connected in parallel with it. It is shown that the use of this scheme permits the realization of a theoretically expected performance.
TL;DR: In this article, vanadium was extracted as a deep violet complex with 5 ml of 0.1 N -m -Tolyl-O -methoxybenzohydroxamic acid (N - m -T- o -MBHA) in chloroform.
01 Sep 1974
TL;DR: In this paper, the effects of self-gravitating force are of third order and the pressure, density and velocity distributions are calculated upto third approximation and shown graphically.
Abstract: The propagation of variable energy blast wave through self-gravitating gas spheres has been studied. Similarity method has been used to obtain the solution in the form of a power series in non-dimensional shock radius. The analysis shows that the effects of self-gravitating force are of third order Therefore, the pressure, density and velocity distributions are calculated upto third approximation and shown graphically.
TL;DR: In this article, an analysis of a two dimensional oscillatory flow past an infinite porous plate with contant suction is carried out on taking into account the couple stresses, where the free stream velocity oscillates about a nonzero constant mean.
Abstract: An analysis of a two dimensional oscillatory flow past an infinite porous plate with contant suction is carried out on taking into account the couple stresses. Here the free stream velocity oscillates about a nonzero constant mean. Approximate solutions are derived to coupled linear equations, and the expressions for the mean velocity, the transient velocity, the mean skinfriction, the amplitude and the phase of skin-friction are obtained. The solutions are followed by discussion. the effects of variations of α(νr/ν), β(Iν/γ) and λ, the frequency are graphically represented and physically interpreted. It is observed that the reverse type of flow does not occur in the presence of the couple stresses.
01 Feb 1974
Abstract: The aim of the present paper is to study the propagation of a variable energy blast wave (cylindrical) through a gas having solid-body rotation. The modified similarity method has been used to obtain the first, second and third approximation solutions. The analysis shows that the effects of solid-body rotation on the flow are of third order. Variation of pressure, density and radial velocity distributions with initial angular velocity has been discussed.
TL;DR: In this paper, a new computer aided design has been proposed to search out the optimal solution for aerostatic slideways with groove type of sources, which can further reduce the air consumption in such bearings.