Showing papers by "Indian Institute of Technology Madras published in 1988"
TL;DR: Une propriete tres simple des graphes intervalle is utilisee dans la realisation d'algorithmes a temps lineaire, developpes pour la resolution de differents problemes de domination as mentioned in this paper.
130 citations
TL;DR: In this paper, face turning trials were carried out on glass fibre reinforced plastics (GFRP), carbon fibre reinforced plastic (CFRP) and kevlar fiber reinforced plastics cylindrical tubes to study their machined surfaces for possible application as friction surfaces.
108 citations
TL;DR: In this article, a flow pattern was visually observed for non-foaming and foaming Newtonian and non-Newtonian liquids under concurrent downflow with air in packed beds using different configurations of column geometry and packins.
Abstract: Flow pattern was visually observed for non-foaming and foaming Newtonian and non-Newtonian liquids under concurrent downflow with air in packed beds using different configurations of column geometry and packins. Flow maps delineating the different flow regions were presented based on the present study as well as that of earlier investigations. The total and dynamic liquid saturation were experimentally measured and correlations were presented in terms of (i) the Lockhart-Martinelli parameter, χ, and (ii) the flow variables.
On a observe de maniere visuelle les profils d'ecoulement pour des liquides newtoniens ou non newtoniens, moussants et non moussants, dans le cas d'un acoulement descendant de liquides et d'air dans un lit a garnissage. On a fait varier la gaomatrie de la colonne et le garnissage. Les diagrammes d'ecoulement delimitant les differentes regions d'ecoulement, presentes dans cette etude, s'appuient sur le travail actuel ainsi que sur des recherches anterieures. On a mesure de maniere experimentale la saturation du liquide dynamique et to tale, et les correlations sont presentes en fonction (i) du parametre Lockhart-Martinelli, χ, et (ii) des variables d'ecoulement.
58 citations
TL;DR: In this paper, a lumped parameter system for the tractor occupants' response to high-intensity vibrations in the 0.5-11-Hz range is presented, and the composite model is analyzed by computer simulation for vertical vibrational responses for a new type of seat suspension.
54 citations
TL;DR: In this paper, a ternary combination (Mg-Ni-Cu) for hydrogen storage purposes is proposed, and the kinetic parameters such as activation energies, reaction rates and orders of the reaction for the decomposition of the hydrides formed from Mg, Mg2Ni and Mg 2Cu alloys are evaluated from the DTA data.
53 citations
TL;DR: Improved techniques of collimation testing based on Talbot imaging and shearing interferometry are presented in this paper, which carry their own reference pattern to indicate collimation of the light beam.
Abstract: Improved techniques of collimation testing based on Talbot imaging and shearing interferometry are presented. The proposed techniques carry their own reference pattern to indicate collimation of the light beam. Detailed analysis is also given.
48 citations
TL;DR: In this article, the authors investigated the effect of bulk viscosity on the evolution of Friedmann models and found that the presence of a tiny time independent component, although it may not be discernible at the present epoch, will play a crucial role in driving the present day universe into a steady state.
48 citations
TL;DR: Les equations non lineaires sont calculees a partir de considerations energetiques and la force d'etirement non lineaire est formulee en termes de deplacement transversal seul as mentioned in this paper.
Abstract: Les equations non lineaires sont calculees a partir de considerations energetiques et la force d'etirement non lineaire est formulee en termes de deplacement transversal seul
47 citations
TL;DR: In this paper, the results of some experiments on the electromagnetic emission of heat-treated spring steel are reported and attributed to the abrupt deceleration of the accelerated energized dislocation during the creation of the new surfaces during the brittle fracture.
44 citations
TL;DR: The synthesis, characterization and electrical properties of representative members of the metal-rich ternary system of shandite-parkerite phases, A 2 M 3 Ch 2 and solid solutions at the A site were reported in this article.
Abstract: The synthesis, characterization and electrical properties are reported of representative members of the metal-rich ternary system of shandite-parkerite phases, A 2 M 3 Ch 2 and solid solutions at the A site. Typical metallic behaviour is exhibited by all the phases. Analysis of the Seebeck coefficients and resistivity data indicate that the rhodium and palladium containing compounds are broad band metals. Sn 2 Co 3 S 2 exhibits a phase transition below 150 K, possibly magnetic.
41 citations
TL;DR: In this paper, the electron-beam-induced crystallization of polycrystalline thin films was investigated and it was found that the films were amorphous, and that more than one orientation usually occurred in single crystal regions.
Abstract: Thin films of ${\mathrm{Se}}_{80}$${\mathrm{Te}}_{20}$ were prepared by vacuum evaporation of the polycrystalline bulk alloy at a fast rate onto replicating tape pieces held at room temperature in a vacuum of 5\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}5}$ Torr. The alloy films were separated from the tape by dissolving the latter in acetone and were examined in an electron microscope at low electron-beam currents (8 \ensuremath{\mu}A). The films were found to be amorphous. On increasing the electron-beam current (to a maximum of 60 \ensuremath{\mu}A), the films were found to crystallize very quickly into either polycrystalline or more than one single-crystalline orientation, as observed by the disappearance of the diffuse rings and the appearance of systematic spot patterns and sharp ring patterns. The analysis of the spot patterns revealed that more than one orientation usually occurred in single-crystalline regions. Thus, it is found that ${\mathrm{Se}}_{80}$${\mathrm{Te}}_{20}$ amorphous thin films crystallize in the electron microscope due to electron-beam interaction and lead to more than one single-crystalline orientation of the phase-transformed films. The very fast rate of crystallization, the crystallization of the entire film by irradiation of only one spot, and the observed dendritic growth features confirm that the electron-beam-induced crystallization is ``explosive.''
TL;DR: In this paper, the authors extended the Semiloof shell finite element formulation to thermal stress analysis of laminated plates and shells and verified the accuracy of the formulation using sample problems available in the literature.
TL;DR: An anomalous change in $c$ in a narrow temperature range around ${T}_{c}$.
Abstract: Using a powder diffractometer with a continuous flow arrangement, the lattice parameters of a sample of $\mathrm{Y}{\mathrm{Ba}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{7\ensuremath{-}\ensuremath{\delta}}$ (with $\ensuremath{\delta}$ estimated to be between 0.10 and 0.15) were determined from 300 K down to 80 K with a temperature regulation of 0.1 K. The diffractogram showed a single phase with the orthorhombic structure. Measurements from 100-80 K were performed at close temperature intervals and showed an anomalous change in $c$ in a narrow temperature range around ${T}_{c}$. This anomaly correlates with the anomaly in the nuclear quadrupole resonance frequency, positron annihilation lifetimes, and sound velocity observed by some workers. A smaller decrease in $c$ was observed around 240 K as the sample was cooled, which again correlates with anomalies observed in sound velocity and attenuation and differential scanning calorimetry. The present observations differ from the recently published results of Horn et al.
TL;DR: Revision de l'algorithme propose par Keil pour l'ensemble dominant total de cardinalite minima dans les graphes d'intervalles.
TL;DR: In this paper, a new approach to the stress analysis of spur gear teeth using finite element method and cyclic symmetry is presented, where each tooth is considered as an identical substructure of the gear wheel.
TL;DR: In this paper, the performance of geothermal power plants using binary-fluid Rankine cycles is studied using the thermal cycle efficiency (first law), cycle effectiveness and the second law cycle efficiency.
TL;DR: The present experimental and theoretical results are in good agreement, but disagree somewhat with earlier Hartree-Fock (HF) calculations, as the HF values are found to be significantly higher in the near-threshold region.
Abstract: The angular distribution for Ar 2p photoionization has been measured from just above threshold to 400 eV photon energy, and calculated in the same energy range using the relativistic random-phase approximation. The present experimental and theoretical results are in good agreement, but disagree somewhat with earlier Hartree-Fock (HF) calculations. The HF values are found to be significantly higher in the near-threshold region. Possible reasons for this discrepancy are discussed with relevance to the general understanding of inner-shell photoionization phenomena.
TL;DR: In this article, the authors measured the drop size distribution in a pulsed plate column for the kerosene-water system under binary conditions and under solute transfer from dispersed to continuous and continuous to dispersed phases.
Abstract: Dispersed phase holdup was measured in a pulsed plate column for the kerosene-water system under binary conditions and under solute transfer from dispersed to continuous and continuous to dispersed phases. The experimental data were satisfactorily modelled through a recirculation regime model.
The drop size distribution, measured by a photographic technique, exhibited a multinodal character at low agitation rates and high dispersed phase flow rate. Sauter mean drop diameter was found to depend on the agitation rate, the dispersed phase flow rate, the mass transfer direction and the plate free area. Correlations for d32 and the interfacial area were presented using Kolmogoroff's isotropic turbulence model.
On a mesure la retention en phase dispersee dans une colonne a plateaux en regime puise pour le systeme eau-kerosene sous des conditions binaires et avec transfert de solute de la phase dispersee a la phase continue et de la phase continue a la phase dispersee. Les donnees experimentales ont pu etre modelisees de maniere satisfaisante par l'intermediaire d'un modele de regime en recirculation.
La distribution de la taille des gouttes, mesuree a l'aide d'une technique photographique, montre un comportement multinodal a de faibles vitesses d'agitation et a un debit de phase dispersee eleve. Le diametre moyen des gouttes de Sauter depend de la vitesse d'agitation, du debit de la phase dispersee, de la direction du transfert de matiere et de la surface libre du plateau. On presente des correlations pour di2 et la surface interfaciale grâce au modele de turbulence isotrope de Kolmogoroff.
TL;DR: In this paper, the interference effects of a rigid circular cyclinder on the transverse vibrations of a spring-mounted circular cylinder (test cylinder) exposed to a uniform flow were investigated at a single value of the reduced velocity, viz., 7·0.
TL;DR: In this paper, the authors have shown that the magnetic susceptibility of the heated polymer decreases with increasing temperature, which is explained by the presence of both localized and delocalized spins in the polymer network.
TL;DR: In this article, the effect of fillers such as glass, ferrite, and carbon on the dielectric properties of epoxide resin along with conductivity has been studied as a function of frequency (1-100 kHz) and temperature (30-200°C).
Abstract: The effect of fillers such as glass, ferrite, and carbon on the dielectric properties of epoxide resin along with conductivity has been studied as a function of frequency (1–100 kHz) and temperature (30–200°C). The glass transition temperature is not much affected by the presence of the fillers. The observed higher values of dielectric permittivity and loss in the case of filled polymers are attributed to Maxwell–Wagner–Sillars polarization.
TL;DR: In this paper, the authors consider solutions to the telegraph equation describing persistent diffusion on a line under various initial conditions and evaluate the first passage time distribution in closed-form, and derive a direct derivation from the stochastic equation for the displacement is presented in an appendix.
Abstract: We consider solutions to the telegraph equation describing persistent diffusion on a line under various initial conditions. The first passage time distribution is evaluated in closed form. Biased persistent diffusion is also considered. A direct derivation of the telegraph equation from the stochastic equation for the displacement is presented in an appendix.
TL;DR: In this paper, a one-pot synthesis of 4-chlorochromenes and chroman-4-ones was achieved from γ-chloropropargyl aryl ethers proceeding through Claisen rearrangement, depending upon the solvent of choice.
TL;DR: A new hydride phase apart from Mg2NiH4 has been identified in the MgNiH2 system by pressure-composition-temperature relationships, thermal analyses and X-ray diffraction measurements.
TL;DR: In this article, the alkylation of bicyclo(2.2)oct-5-en-2-one (1) and intramolecular radical cyclisation towards the synthesis of functionalised tricyclic carbocycles is reported.
TL;DR: In this paper, various finite element formulations of large amplitude free vibrations of beams with immovably supported ends are discussed and numerical results of the analytical approach are seen to be in good agreement with some of these formulations.
TL;DR: Morel et al. as discussed by the authors have elaborated a method to obtain the shape of contraction which gives small adverse pressure gradients and low non-uniformity in the velocity distribution at the exit.
Abstract: Based on a numerical study of the potential flow through contractions of chosen geometry, Morel (1975) has elaborated a method to obtain the shape of contraction which gives small adverse pressure gradients and low nonuniformity in the velocity distribution at the exit. Two contractions with area ratios of 12 and 3.464 designed using this method are investigated experimentally. It is found that there is no separation of flow, the thickness of the boundary layer at the exit is small and the nonuniformity in velocity at the exit is smaller than the predicted value.
TL;DR: Mesure de la vitesse moyenne et des fluctuations turbulentes longitudinales, les profils de vitez du sillage dans les conduites courbes sont asymetriques as discussed by the authors.
Abstract: Mesure de la vitesse moyenne et des fluctuations turbulentes longitudinales. Les profils de vitesse du sillage dans les conduites courbes sont asymetriques. L'epaisseur de la couche cisaillee est plus grande sur la paroi interne que sur la paroi externe
TL;DR: In this paper, electrical and optical properties of indium tin oxide films coated on soda-lime glass substrates have been investigated as a function of substrate temperature (Ts=250-450 °C).
Abstract: Electrical and optical properties of indium tin oxide films coated on soda-lime glass substrates have been investigated as a function of substrate temperature (Ts=250–450 °C). Highly conducting (ϱ≈8 x 10−4 Ω cm) and transparent (T≈90%) films have been obtained at a substrate temperature of 350°C and above. An increase in carrier concentration accompanied by a widening in optical band gap (the Burstein-Moss shift) have been observed with increasing substrate temperature. Enhancement of carrier concentration at higher substrate temperatures may be attributed to the presence of higher valency states of tin (Sn4+) occupying the indium sublattice of indium oxide.
TL;DR: In this article, the longshore transport rate at Visakhapatnam beach is computed and the values are compared with earlier studies, based on the inference that the Shore Protection Manual equation yields a better estimate for this region.