Showing papers by "Indian Institute of Technology Madras published in 1975"
TL;DR: In this paper, the effects of dilute solutions of linear, random-coiling macromolecules in turbulent pipe flow is reviewed. And the experimental evidence is emphasized in three sections concerned with the graphical display of established features of the phenomenon, data correlation and analysis, and the physical mechanism of drag reduction.
Abstract: Drag reduction by dilute solutions of linear, random-coiling macromolecules in turbulent pipe flow is reviewed. The experimental evidence is emphasized in three sections concerned with the graphical display of established features of the phenomenon, data correlation and analysis, and the physical mechanism of drag reduction. This work has application to increased pipelines capacity, the study of wall turbulence and molecular rheology.
1,010 citations
TL;DR: In this paper, the converses of recent fixed-point theorems due to Kannan and Chatterjea are obtained and an example is constructed to show that a metric space having the fixed point property for homeomorphisms need not be metrically topologically complete.
Abstract: In this note the converses of recent fixed-point theorems due toKannan andChatterjea are obtained. An example is constructed to show that a metric space having the fixed-point property for homeomorphisms need not be metrically topologically complete. An example ofConnell is formulated in a more general perspective.
124 citations
TL;DR: In this article, the authors report experiments on drag reduction by saline solutions of a partially hydrolysed polyacrylamide (PAMH) showing the effect of macromolecule conformation.
Abstract: I REPORT experiments on drag reduction by saline solutions of a partially hydrolysed polyacrylamide (PAMH) showing the effect of macromolecule conformation. The extreme collapsed and extended PAMH conformations also simulate the deportment of linear random-coiling macromolecules in solution, and of high aspect ratio fibres in suspension; and they indicate a possible relationship between the mechanisms of drag reduction produced by these additives.
56 citations
52 citations
TL;DR: In this paper, a modified form of Reynolds' equation was derived for steady finite width journal bearings, and the finite difference technique with successive over relaxation was used incorporating Reynolds' boundary conditions for pressure to obtain the pressure distribution and hence the attitude angle.
50 citations
TL;DR: In this paper, the authors investigated the characteristic decay and the radial-type decay regions of a three-dimensional isothermal turbulent wall jet in quiescent surroundings, and compared with the results of other workers.
Abstract: This paper reports experimental investigations on the characteristic decay and the radial-type decay regions of a three-dimensional isothermal turbulent wall jet in quiescent surroundings. The velocity and the length scale behaviour for both the longitudinal and the transverse directions are studied, and compared with the results of other workers. The estimated skin friction is discussed in relation to the available data from earlier investigations. Wall jet expansion rates and the behaviour of skin friction are also discussed. The rate of approach of turbulence components to a self-similar form is found to be influenced by the fact that the expansion rate of the wall jet in the longitudinal direction is different from that in the transverse.
48 citations
TL;DR: The left ventricle (l.v.) is represented as a shell of muscle whose performance is characterised in terms of the chamber pressure and stress/strain in the ventricular wall; the effective elastic modulus of the l.v. relates these peerformance variables, and hence represents the transfer function of the left ventricular physiological system.
Abstract: The left ventricle (l.v.) is represented as a shell of muscle whose performance is characterised in terms of the chamber pressure and stress/strain in the ventricular wall; the effective elastic modulus of the l.v. relates these peerformance variables, and hence represents the transfer function of the left ventricular physiological system. A method is presented for indirectly determining the effective modulusE for the left ventricle. The method employs a thick-walled mathematical model of the l.v. having a homogeneous isotropic medium. Instantaneous values ofE are determined for subjects with heart diseases of varied etiologies, in order to assess the responses of the l.v. to chronic overloads of pressure and volume. Resulting values forE are used diagnostically to characterise the physiological state of the l.v. Normal values ofE, at systole, indicate that the strength of contraction exercised by the l.v. is normal, and hence is an indication of the l.v. having adjusted to the heart disease.
47 citations
TL;DR: In this paper, a modified form of Reynolds' equation for journal bearings is derived for dynamically loaded finite width journal bearings, and the stability limit for such a bearing is obtained for different values of the nonlinear factor.
38 citations
37 citations
TL;DR: In this article, a mathematical model is developed to portray the vibroimpacts of a steel sphere which is trapped between two flat steel plates with clearance, while the plates are oscillated by an electromagnetic shaker.
Abstract: A mathematical model is developed to portray the vibroimpacts of a steel sphere which is trapped between two flat steel plates with clearance, while the plates are oscillated by an electromagnetic shaker. Data from a long series of experimental observations are reported in Part 1 of this paper [53]. The aim is to determine a law of motion by which a computer simulation can satisfactorily reproduce the major characteristics of the observed movement. During each impact the motion of the ball is taken to be a brief half wave, due to the highly nonlinear forces of surface compliance and surface damping. Modelling is by analog simulation. It was found first that linearization of the surface stiffness does not reproduce the observed phenomena. The mathematical model formulated is that the motion of the ball during contact is governed by the equation mx + cx1.5 x + kx1.5 = 0, where x is the penetration, c is a damping constant, and kx1.5 is the Hertzian force of compliance. The results of experiments can be corroborated only on the basis of a variable damping coefficient cxn with n = 3/2.
31 citations
TL;DR: In this paper, free vibration analysis of skew orthotropic plates with point supports has been accomplished by using higher degree skew finite strips, where the displacement function for the strips is assumed as a series with polynomials in one direction and beam functions in the other direction.
TL;DR: In this paper, the authors discussed the theoretical models, experimental data and the range of applicability along with the correlations to predict the characteristics of the bed and discussed the correlations with respect to the theoretical model and experimental data.
TL;DR: In this paper, the formation, structures and properties of ternary oxides TlNbO 3, TlTaO 3 and BiVO 3+ x occurring in A 2 B 2 O 7-y defect pyrochlore structure are reported.
TL;DR: In this paper, the results of the Mossbauer spectra at room temperature have been taken for all and at liquid nitrogen temperature for some of them and the effect of thermal treatment is also investigated.
Abstract: Binary alloys of the FeSex system have been prepared with x possessing the values 1.00, 1.04, 1.08, 1.12, 1.16, 1.25, 1.50, 1.75, and 2.00. Mossbauer spectra at room temperature have been taken for all and at liquid nitrogen temperature for some of them. The effect of thermal treatment is also investigated. The spectra are mostly quadrupole split or single lines, except for the compositions FeSe1.08 to FeSe1.16, which show magnetic hyperfine splitting. The iron ion exists in the high spin 2+ state for the entire system, with varying degrees of covalency.
Es wurden binare Legierungen des Systems FeSex mit x-Werten von 1,00; 1,04; 1,08; 1,12; 1,16; 1,25; 1,50; 1,75 und 2,00 hergestellt und daran Mosbauerspektren bei Raumtemperatur und von einigen Zusammensetzungen auch bei 80 K aufgenommen. Untersucht wurde auch der Einflus von Warmebehandlungen. Die Spektren zeigen in den meisten Fallen eine Quadrupolaufspaltung oder nur eine einzige Linie, mit Ausnahme der Verbindungen von FeSe1,08 bis FeSe1,16, die eine Hyperfeinaufspaltung aufweisen. Das Eisen-Ion befindet sich im ganzen System im Zustand schneller Spindrehung 2+ mit verschiedenen Kovalenzgraden.
TL;DR: In this paper, a study of the thermal decomposition of intimate mixtures of different molar ratios of KClO4 and chromium(III) oxide was conducted employing thermogravimetry, differential thermal analysis, chemical analysis, infrared spectroscopy and X-ray diffraction analysis.
TL;DR: The Dynamic Relaxation (DR) method as discussed by the authors is a well-known structural analysis technique for bending of a beam, which was originally developed by Day during the course of his investigations of complex prestressed concrete pressure vessels for nuclear reactors.
TL;DR: In this paper, a repairable 2-unit warm-standby system with repair and preventive maintenance is discussed, and the mean time to system failure and the steady state availability are calculated.
Abstract: A repairable 2-unit warm-standby system with repair and preventive maintenance is discussed. Two models are presented. In each of the models the mean time to system failure and the steady state availability are calculated. Some numerical calculations illustrate the results.
TL;DR: In this paper, the influence of large amplitudes on free flexural vibrations of circular plates with linearly varying thickness is analyzed, using Berger's assumption to derive the basic governing equations.
TL;DR: In this paper, the cross-flow model was matched with the experimental data taken subsequently on the residence time distribution of solids in a multistage fluidised bed, and conditions for smooth fluidisation were suggested.
TL;DR: In this article, a two-loop configuration is proposed for controlling a physical process with predominant time delay, where a fast auxiliary loop consisting of a proportional controller and a simple lag element, and a main (process) loop provided with another proportional controller operating on the process.
TL;DR: In this article, it was shown that for any positive integer k, the existence of k cospectral digraphs of each of the above types, with given automorphism group, is known.
01 Feb 1975
TL;DR: In this article, the development and evaluation of a mathematical model for a 4-stroke, single-cylinder, spark ignition engine is described, where the assumptions that were made in the model are also described.
Abstract: This paper deals with the development and evaluation of a mathematical model for a 4-stroke, single-cylinder, spark ignition engine. The first part describes the development of the mathematical model and the computer program. The assumptions that were made in the model are also described. The instruments that were developed for the evaluation of the model are included in the second part, which also contains the evaluation of the results obtained from the model. /GMRL/
TL;DR: Data acquisition for developing the model, analysis of the left ventricular model to yield ready-for-use nomograms givingE for prescribed heart sound frequency and the procedure for clinical use of the nomograms and clinical application of the model are presented.
Abstract: A quantitative estimate of the left ventricular muscle'sin vivo elasticity, as given by the Young's modulusE of the left ventricular muscle medium characterises resistance to left ventricular filling during diastole, contractile effort of the left ventricle, at the instant of opening of the aortic valve and myocardial diseases, such as myocardiopathy. This paper aims to provide the pertinent analysis (and in particular its, results in the form of nomograms) that can be employed, in conjunction with closed-chested data-acquisition methods, to obtainin vivo values of the effective modulus of left ventricular muscle medium. A vibrational analysis of the left-ventricle chamber model is developed to obtain the values of the primary freqeencies of vibration in terms of the dimensions of the model and the modulusE. On obtaining the values of the model dimensions (by matching the model volume and mass with the left-ventricle dimensions obtained from cineangiocardiography), and of the frequency associated with the maximum energy content of the pertinent heart sound, we can employ the analysis to determine the instantaneous value of the modulusE of the left ventricle. Our paper hence presents data acquisition for developing the model, analysis of the left ventricular model to yield ready-for-use nomograms givingE for prescribed heart sound frequency and the procedure for clinical use of the nomograms and clinical application of the model.
TL;DR: In this paper, it was shown that freshly formed metal accelerates the rate of reduction of ferric oxide in the presence of water vapour, and this effect was explained on the basis of the spillover of hydrogen from the metal sites to the oxide phase through "portholes" of water.
Abstract: Freshly formed metal accelerates the rate of reduction of ferric oxide in the presence of water vapour. This effect is explained on the basis of the spillover of hydrogen from the metal sites to the oxide phase through “portholes” of water.
TL;DR: In this paper, a method of analysis of prismatic shells having different internal ribbing for their torsional vibrations was proposed. And the results for some wellknown boundary conditions with the results obtained by classical methods were compared.
TL;DR: In this paper, the Schapery's method of inversion for Laplace transform is used in the analysis of transient flow towards a well of zero discharge with different initial heads, and the solution is obtained for a well penetrating two aquifers with a constant discharge and identical initial heads.
TL;DR: The mass spectra of trichloromethyl radical from the molecular ion is the abundant fragment in the mass spectrum of most of the thirteen substituted triciacetanilides studied in this paper.
Abstract: Elimination of trichloromethyl radical from the molecular ion is the abundant fragment in the mass spectra of most of the thirteen substituted trichloracetanilides studied. Unusual ortho effects of —OCH 3 , —NO 2 and —COOH groups are noticed only after the initial ejection of trichloromethyl radical from the molecular ion.
TL;DR: In this paper, the authors derived the fields radiated by a feed structure consisting of a dielectric sphere placed in front of, but displaced from, the open end of a corrugated pipe with quarter-wave teeth, carrying the HE 11 mode.
Abstract: The fields radiated by a feed structure consisting of a dielectric sphere placed in front of, but displaced from, the open end of a corrugated pipe with quarter-wave teeth, carrying the HE 11 mode, are derived. It is shown that this feed system has near-circular far-field characteristics with increased on-axis gain. The feed also has a reduced input VSWR due to the aperture-sphere separation. Theoretical expressions are derived for the radiated far-field components, by treating the off-set sphere as a microwave lens. Experimental results obtained from a test feed confirm the theoretical calculations made.
TL;DR: In this article, a stochastic model based on Markov chains is proposed for the residence time and contact time distributions of the fluid phase in a packed bed and the analysis considers stagnancy in the pores and adsorption on the packing surface separately by postulating a zero velocity state and an adsorbed state.