Showing papers by "Indian Institute of Technology Kharagpur published in 1979"
TL;DR: In this paper, the authors investigated the thermal instability in a layer of a ferromagnetic fluid rotating about a vertical axis and permeated by a vertical magnetic field, and found that overstability cannot occur if the Prandtl number P > 1.
91 citations
TL;DR: In this paper, the boundary layer equations in the inlet region and the Navier-Stokes equations with order-of-magnitude analysis in the filled region are solved using fourth-degree velocity profiles.
Abstract: The entrance region has been divided into two parts, the inlet region and the filled region. At the end of the inlet region, the boundary layers meet at the pipe axis but the velocity profiles are not yet similar. In the filled region, adjustment of the completely viscous profile takes place until the Poiseuille similar profile is attained at the end of it. The boundary-layer equations in the inlet region and the Navier-Stokes equations with order-of-magnitude analysis in the filled region are solved using fourth-degree velocity profiles. The total length of the entrance region so obtained is ξ = x/R Re = 0·150, whereas the boundary layers are observed to meet at approximately one-quarter of the entrance length, i.e. at ξ = 0·036. Experiments reported in the paper corroborate the analytical results.
80 citations
TL;DR: The economic of tractors in South Asia: An analytical review as mentioned in this paper, The economic of tractor in south Asia: an analytical review, An analysis review of the tractors of South Asia.
Abstract: The economic of tractors in South Asia: An analytical review , The economic of tractors in South Asia: An analytical review , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی
64 citations
TL;DR: In this paper, the crystal equilibrium condition was applied to an eight-parameter lattice dynamical model to calculate the elastic constants of K and Rb and the two results were found to be in fairly good agreement.
47 citations
TL;DR: In this paper, the authors combine the two techniques of Prasada Rao and Sivakumar, namely the iterative shift algorithm for identifying time-lag systems and the basic technique of system identification via Walsh functions.
Abstract: This note successfully combines the two techniques of Prasada Rao and Sivakumar, namely the iterative shift algorithm for identifying time-lag systems [5] and the basic technique of system identification via Walsh functions [1] and illustrates how Walsh functions may be employed to identify systems with unknown time lags.
43 citations
TL;DR: Stratiform quartz-sulphide lodes in Ingladhal occur in a typical Precambrian green-stone-belt environment comprising metabasalts, tuff, chert and cherty iron sulfide formation as discussed by the authors.
Abstract: Stratiform quartz-sulphide lodes in Ingladhal occur in a typical Precambrian green-stone-belt environment comprising metabasalts, tuff, chert and cherty iron-sulphide formation. Unusually high cobalt contents of metavolcanics and of sulphide minerals in orebodies suggest a consanguinity between ores and rocks. 90% of total nickel, 70% of total cobalt but only 30% of total copper in rocks occur in silicate phases and thus indicate an early separation of copper from cobalt and nickel. Unusually high non-sulphide copper in barren bedded cherts implies availability of Cu-rich solution prior to their lithification. Pyrite in sediments, in volcanics, and in orebodies is characterized by a distinctive pattern of Co-Ni distribution in each case. Partitioning of Co and Ni between coexisting sulphide pairs is complex, but gross equilibrium is indicated. Very high trace metal content of orebody pyrite sharply contrasts with very low such values in pyrite from adjacent sediments and points to a higher temperature of formation of orebodies.
42 citations
TL;DR: In this paper, the basic function in the circumferential direction satisfying the boundary conditions of the radial edges is substituted into the free vibration equation of the curved plate by a suitable transformation, an ordinary differential equation is obtained.
40 citations
TL;DR: A numerical method developed by the author has been used as a basis for determining natural frequencies of rectangular plates possessing different degrees of elastic restraints along the edges as discussed by the authors, and basic functions satisfying the boundary conditions along two opposite edges for such cases have been derived Comparison of results with others that are available indicates excellent accuracy Many new results have been presented
36 citations
TL;DR: In this article, an analysis of an end-launcher type, coaxial-to-rectangular waveguide transition, exciting dominant TE/sub 01/mode in X-band rectangular waveguide is presented.
Abstract: The analysis of an end-launcher type, coaxial-to-rectangular waveguide transition, exciting dominant TE/sub 01/ mode in X-band rectangular waveguide is presented. Expressions for the real and imaginary parts of the input impedance seen by the coaxial line are derived for the general case of an offset launcher using self-reaction of an assumed current over the loop. The dimensions of the combined electric and magnetic loops having low input VSWR in the coaxial line are determined. There is satisfactory agreement between theoretical and experimental results.
34 citations
TL;DR: In this paper, an expression for the equivalent network of a long axial slot in the common narrow wall between two rectangular waveguides is detemined from self-reaction and discontinuity in modal current.
Abstract: An expression for the equivalent network of a long axial slot in the common narrow wall between two rectangular waveguides is detemined from self-reaction and discontinuity in modal current. The analysis is extended to the case of H-plane Tee junction coupled through a Iongitudinal slot in the narrow wall of primary guide. Variation of coupling, input VSWR, and impedance loading on the primary guide are determined from the equivalent network parameter. A comparison between theoretical and experimental results is presented.
30 citations
TL;DR: Vulcanization is a process which decreases the plastic properties of rubber while maintaining or improving the elastic properties as discussed by the authors, and it has been applied mainly to the reaction of rubber with sulfur, but now is generally used for the process which results in changes in properties, by sulfur or some other agent.
Abstract: Vulcanization is a process which decreases the plastic properties of rubber while maintaining or improving the elastic properties. The term vulcanization has been applied in the past mainly to the reaction of rubber with sulfur, but now is generally used for the process which results in changes in properties, by sulfur or some other agent. There are four principal changes brought about by vulcanization: (1) rubber is changed from essentially a plastic to a non-plastic material; (2) rubber is changed from a material soluble in a number of solvents to one which is insoluble; (3) rubber is changed to a material with greatly improved physical properties; (4) these properties of vulcanized rubber are maintained over a much wider range of temperature than those of unvulcanized rubber. What is meant by high vulcanizing temperature? There is no unique answer. About 160°C can be taken conveniently as the lower limit; this temperature has been suggested as the highest suitable for some normally compounded ...
TL;DR: In this article, the eigenvalue problem governing the perturbations is solved numerically using finite difference method and Wilkinson's iteration technique, and the cell pattern for positive temperature gradient is highly elongated when compared with that of negative temperature gradient.
Abstract: In this paper, we consider the convective instability of a heat conducting micropolar fluid layer between rigid boundaries. The eigenvalue problem governing the perturbations is solved, numerically, using finite difference method and Wilkinson's iteration technique. The heat induced by microrotation leads to the onset of instability not only due to adverse temperature gradient but also for positive temperature gradient. In the case of rigid boundaries, the critical Rayleigh number is seen to be higher than that of free boundaries. Here we notice that the cell pattern for positive temperature gradient are highly elongated when compared with that of negative temperature gradient.
TL;DR: In this article, the authors present a method of time-domain synthesis of dynamical systems treating the process signals as distributions or generalized functions, in the manner originally established by L. Schwartz.
Abstract: This paper presents a method of time-domain synthesis of dynamical systems treating the process signals as distributions or generalized functions, in the manner originally established by L. Schwartz. The technique of synthesizing the transfer function or the state-space model of a system employs exponentially weighted series of the generalized time derivatives of the impulse distribution, known also as the Poisson moment functional expansion. General algorithms are developed and their application is illustrated in typical eases.
TL;DR: In this article, a tire tread compound suitable for high-temperature vulcanization has been designed, which contains dithiodimorpholine (1 phr), CBS (2 phr), and sulfur (0.5 phr).
Abstract: A tire tread compound suitable for high-temperature vulcanization has been designed. Of the various mixes studied, the one containing dithiodimorpholine (1 phr), CBS (2 phr) and sulfur (0.5 phr) was found to be most suitable for high temperature vulcanization of natural rubber. The network structures of the vulcanizates have been determined, and the technical properties of the new tire tread compound have been compared with those of a conventional compound. It has been found that a DTDM-based compound is superior in technical properties, reversion resistance and ageing resistance. The polymer-filler attachment was found to be higher DTDM-based compounds than for conventional ones.
TL;DR: A series of bridged encapsulation compounds of iron(II) of the type FeL 3 (BX) 2 (L = 2,4-pentanedione dioximate ion or 1,2-diphenylethane-1, 2-dione-dioxime ion and X = OH, OCH 3, OC 2 H 5, O,i,C 3 H 7 or O-n-C 4 H 9 ) have been synthesized by adopting an in situ procedure using iron (II) chloride, pentane-2,
TL;DR: In a laboratory experiment median seedling emergence forces of cowpea, maize, cotton and paddy at 25°C and of wheat at 20°C were worked out to be 1431, 1029, 803, 686 and 931.5 millibars respectively.
Abstract: In a laboratory experiment median seedling emergence forces of cowpea, maize, cotton and paddy at 25°C and of wheat at 20°C were worked out to be 1431, 1029, 803, 686 and 931.5 millibars respectively. Changes in temperature brought about variation in the median emergence forces.
TL;DR: In this article, the dispersion of a solute in an electrically conducting fluid flowing between two parallel plates in the presence of a uniform transverse magnetic field was analyzed using a generalized dispersion model.
Abstract: The paper presents an exact analysis of the dispersion of a solute in an electrically conducting fluid flowing between two parallel plates in the presence of a uniform transverse magnetic field. Using a generalized dispersion model, which is valid for all time after the injection of the solute in the flow we evaluate the longitudinal dispersion coefficients as functions of time. For small values of the Hartmann number M , the values of the dispersion coefficients show rapid fluctuations which decay with increase in M , and for moderate and large values of M , these coefficients monotonically decrease with increase in M . In a non-conducting fluid, such rapid fluctuations are absent and the dispersion coefficients for a pipe flow are less than the corresponding values for a channel flow.
TL;DR: In this article, a technique to select Airy's stress function suitable to solve laminated rectangular beam is suggested, and the results show that the deflection of three-layered beam with weak mid-layer given by elasticity solution is about 35% larger than that given by elementary strength of materials theory.
Abstract: A technique to select Airy’s stress function suitable to solve laminated rectangular beam is suggested. Analysis of laminated beam under uniformly distributed load is presented. The results show that the deflection of three-layered beam with weak mid-layer given by elasticity solution is about 35% larger than that given by elementary strength of materials theory.
TL;DR: In this article, a simple and convenient preparative method for hitherto unknown compounds with these new structural features was reported, and the resultant complex was treated with aq. sodium acetate solution till pH5-6 was reached.
TL;DR: In this paper, the authors deal with the study of flow and heat transfer in a viscous fluid from a disk performing small rotating oscillations about a constant mean, and find that near the disk the oscillating components of radial and tangential velocities lag behind the disk oscillations.
Abstract: The paper deals with the study of flow and heat transfer in a viscous fluid from a disk performing small rotating oscillations about a constant mean. Separate solutions for low and high frequency ranges are developed. In the low frequency range the solution is obtained by Karman-Pohlhausen method. It is found that near the disk the oscillating components of radial and tangential velocities lag behind the disk oscillations. This tendency to phase lag is more than compensated as we move away from the disk. The oscillating components of the radial stress and the rate of heat transfer at the disk always lag behind, while the tangential stress has a phase lead. For very high frequencies the velocity field is of “shear-wave” type, predicting a phase lead of 45° in the tangential stress at the disk.
TL;DR: In this article, an analytical solution for one-phase diffusion controlled dissolution of uniformly sized and equispaced stacked plates in an infinite or finite matrix has been worked out in a manner analogous to the momentum integral method in fluid mechanics.
TL;DR: Bioturbation structures in the form of worm burrows are reported for the first time from the Middle Proterozoic Narji Formation belonging to the Kurnool Group in Andhra Pradesh, India.
TL;DR: In this paper, a numerical solution for the dissolution of planar second phase particles is given by the iso-concentration contour migration (ICCM) technique, which transforms the field equations such that concentration C and time and t become independent variables, and the space variable X depends on C and t.
Abstract: A numerical solution for the dissolution of planar second phase particles is given by the iso-concentration contour migration (ICCM) technique. The model transforms the field equations such that concentration C and time and t become independent variables, and the space variable X depends on C and t. The formulation can easily deal with mobile interfaces and concentration dependent diffusion parameters. Predictions of the model agree well with the available experimental data. The method is also compared with the model proposed by Tanzilli and Heckel.
Mit Hilfe der Iso-Konzentrationskontur-Wanderung (ICCM) wird die numerische Losung fur die Homogenisierung der Partikel der zweiten Phase berechnet. Das Modell transformiert die Feldgleichung so, das die Konzentration C und die Zeit t unabhangige Variable sind, jedoch die Raumvariable X von C und t abhangt. Die Formulierung kann leicht auf die beweglichen Zwischenphasen und konzentrationsabhangige Diffusionsparameter angewendet werden. Die Voraussagen des Modells stimmen gut mit zuganglichen experimentellen Daten uberein. Dieses Verfahren wird mit dem Modell von Tanzilli und Heckel verglichen.
TL;DR: In this article, a perturbation theory for small vibrations is used to solve an incompressible, finite journal bearing with a time-dependent term, and load capacity, attitude angle, friction parameter, stiffness and damping coefficients are evaluated for a capillary-compensated bearing.
Abstract: A theoretical analysis of the steady-state and dynamic characteristics of multi-recess hybrid oil journal bearings is presented. A perturbation theory for small vibrations is used to solve an incompressible, finite journal bearing with a time-dependent term. Load capacity, attitude angle, friction parameter, stiffness and damping coefficients are evaluated for a capillary-compensated bearing.
TL;DR: In this article, the strength properties of polyvinyl chloride-copper composites were investigated and the strength was found to be proportional to dm−½ where dm is the mean free path between the filler particles.
Abstract: The presence of additives influences the state of segregation of filler particles in the polymer matrix which in turn controls the electrical and mechanical properties of poly(vinyl chloride)-copper composites. The liquid plasticizer seems to form a coating on the filler surface which introduces quasirandomness in the segregated network. In accordance with the mathematical model proposed earlier, the strength properties were found to be proportional to dm−½ where dm is the mean free path between the filler particles. Calculations of dm were based on two different models, one for segregated network (unplasticized and low plasticized composites) and the other for quasi-random distribution of filler particles (plasticized composites). Extruded samples in general show more randomness in the filler distribution than the compression molded samples.
01 Jan 1979
TL;DR: Molecular sieves have potential uses as catalysts for vinyl polymerization reactions They have been widely used as cationic catalysts, and in a limited number of instances in anionic polymerisation reactions Molecular sieves also find uses as polymer modifiers bringing in definite improvements in their properties as discussed by the authors.
Abstract: Molecular sieves have potential uses as catalysts for vinyl polymerization reactions They have been widely used as cationic catalysts, and in a limited number of instances in anionic polymerization reactions Molecular sieves also find uses as polymer modifiers bringing in definite improvements in their properties
TL;DR: In this paper, a semianalytical method has been proposed to analyze the stability of ship plating and allied plated structures, which can be used to study the buckling of plates having any boundary and loading conditions, as well as for isotropic, orthotropic and variable thickness plates.
Abstract: The character of the ship structure and the loadings encountered in the design of ships poses a special problem of plate instability. A semianalytical method has been proposed in the paper to analyze the stability of ship plating and allied plated structures. The method is general and can be used to study the buckling of plates having any boundary and loading conditions, as well as for isotropic, orthotropic and variable thickness plates. It is simple and economic. Rectangular plates having different end conditions and loadings have been analyzed. Excellent accuracy has been obtained.
TL;DR: In this article, the effect of rigid inclusion on the crack extension in an infinite body was investigated and the result was derived from the Irwin's criterion, and some particular cases have also been considered.
Abstract: Dislocation layers have been utilized to study the effect of rigid inclusion on the crack extension in an infinite body and thereby to derive the crack extension condition from Irwin's criterion. Some particular cases have also been considered.