Showing papers by "Indian Institute of Technology Bombay published in 1988"
TL;DR: In this article, the authors discuss the state of the art of delamination behavior and its effect on structural performance, analytical and experimental techniques to predict its behavior and some preventive measures to delay the delamination so as to make the structure more damage tolerant.
334 citations
TL;DR: In this paper, the effect of delamination on the natural vibration characteristics of laminated beam type structures is studied and an analytical model is presented for beams with through-width delaminations parallel to the beam surface located arbitrarily in both the spanwise and thicknesswise directions.
267 citations
TL;DR: Schiff bases derived from salicylaldehyde and 2-substituted anilines have been synthesized and characterized by their elemental analysis, TGA, IR and electronic spectral studies, molar conductance and magnetic susceptibility measurements as mentioned in this paper.
219 citations
TL;DR: In this article, a finite element formulation for flexure of a symmetrically laminated plate based on a higher-order displacement model and a three-dimensional state of stress and strain is presented.
Abstract: A finite element formulation for flexure of a symmetrically laminated plate based on a higher-order displacement model and a three-dimensional state of stress and strain is presented here. The present higher-order theory incorporates linear variation of transverse normal strains and parabolic variation of transverse shear strains through the plate thickness, and as a result it does not require shear correction coefficients. A nine-noded Lagrangian parabolic isoparametric plate bending element is described. The applications of the element to bending of laminated plates with various loading, boundary conditions, and lamination types are discussed. The numerical evaluations also include the convergence study of the element used. The present solutions for deflections and stresses are compared with those obtained using the three-dimensional elasticity theory, closed-form solutions with another high-order shear deformation theory, and the Mindlin's theory. In addition, numerical results for a number of new problems, not available in the literature, are presented for future reference.
113 citations
TL;DR: The estimation of optical flow fields is discussed, exhibiting a common foundation for feature-based and differential approaches, and the desire to describe the spatio-temporal development recorded by an image sequence not only at the level of geometry, but also at higher conceptual levels.
Abstract: Many investigations of image sequences can be understood on the basis of a few concepts for which computational approaches become increasingly available. The estimation of optical flow fields is discussed, exhibiting a common foundation for feature-based and differential approaches. The interpretation of optical flow fields is mostly concerned so far with approaches which infer the 3-D structure of a rigid point configuration in 3-D space and its relative motion with respect to the image sensor from an image sequence. The combination of stereo and motion provides additional incentives to evaluate image sequences, especially for the control of robots and autonomous vehicles. Advances in all these areas lead to the desire to describe the spatio-temporal development recorded by an image sequence not only at the level of geometry, but also at higher conceptual levels, for example by natural language descriptions.
98 citations
TL;DR: In this article, a higher-order shear-deformable beam model is proposed, which is based on a higher order displacement model and incorporates linear and quadratic variation of transverse normal strain and transverse shearing strain through the beam thickness.
78 citations
TL;DR: A new approach to the use of bi-directional dependencies using the concept of edge placement is developed, shown to yield higher profitabilities of optimisation and an efficient solution method is developed.
Abstract: Code optimisation algorithms using bi-directional data flow dependencies have become increasingly important in recent years. The use of these algorithms faces two difficulties in practice: (a) Low profitabilities, and (b) high solution costs. This paper develops a new approach to the use of bi-directional dependencies using the concept of edge placement. This is shown to yield higher profitabilities of optimisation. An efficient solution method for such algorithms is also developed. The complexity of this method is shown to be bounded by O(e) operations, where e is the number of edges in the program flow graph. Ths is comparable to the complexity of uni-directional flow algorithms commonly used in optimisation.
56 citations
TL;DR: In this article, the photoelectrochemical behavior of n-snS was studied in Fe3+/Fe2+, Ce4+/Ce3+ and I2/I− redox couples.
50 citations
TL;DR: In this paper, the effects of the additives MgO and Nb2O5 and the effect of furnace atmosphere on the sinterability of ThO2 have been investigated and the interdependence of additive and atmosphere has been brought out.
43 citations
TL;DR: In this article, the mechanical properties of steel wire-reinforced aluminium matrix composites were investigated and it was found that their tensile strength was somewhat lower than that predicted by the rule-of-mixtures; failure occurred predominantly by fibre pull-out.
42 citations
TL;DR: A generalised mathematical formulation for any melting and solidification problem is provided in this article, with a review of recent progress in all the numerical methods of numerical methods and recent progress of numerical aspects of all the methods are discussed.
Abstract: A generalised mathematical formulation is provided for any melting and solidification problem. Non-dimensional parameters governing this problem are identified. Depending on the problem, ways of simplifying the generalised mathematical statement are discussed. Different methods of formulation of melting and solidification problems, namely, variable and fixed domain methods, are discussed highlighting their merits and demerits. Methods to solve the momentum equation in the molten region and model alloy solidification problems are presented. Recent progress in all the numerical methods is reviewed. Critical numerical aspects of all the methods are discussed. Guidelines are provided to select the correct numerical method. Areas needing emphasis in future research are highlighted.
TL;DR: The proposed constructive method for the inference of Even Linear Grammars from positive samples is employed and it is shown that the method can be used in a hierarchical manner to infer grammars for more complex pictures.
TL;DR: In this article, a new approach for the representation of a point support in the analysis of plates is presented, based on the use of a flexibility function, representing the distribution of a fictitious elastic restraint over the boundary, which is such that it has a zero value at the point support location but assumes large values resulting in negligible restraint over free boundary.
TL;DR: A new clerodane diterpenoid has been isolated from the stems of Tinospora cordifolia by as mentioned in this paper, which was established by spectroscopic means and by comparison with closely related related clericsodane derivatives.
TL;DR: In this paper, the effects of finite values and distributions of the elastic edge restraint on the natural frequencies of rectangular plates are examined and guidelines are provided in terms of their ranges and limits for their use in representing classical edge conditions.
TL;DR: Etude du frittage de ThO 2 a 1150°C dans l'air avec addition de Nb 2 O 5, on obtient une densite de 94 a 98% de la densite theorique as mentioned in this paper.
Abstract: Etude du frittage de ThO 2 a 1150°C dans l'air avec addition de Nb 2 O 5 . On obtient une densite de 94 a 98% de la densite theorique
TL;DR: In this paper, the properties of polyurethane systems were investigated using TMA and thermogravimetry, and the experiments were designed to understand various factors such as length of chain extender moiety, flexibility of extender units by substitution of ether link in the diol chain, nature of bonds (unsaturation) in the extender unit, and nature of diisocyanates.
Abstract: Thermal properties like glass transition temperature (Tg), initial decomposition temperature (idt), integral procedural decomposition temperature (ipdt), and temperature at various % weight loss of a number of polyurethane systems are reported in this paper. Glass transition temperature was determined on TMA, and other thermal properties were determined by thermogravimetry. The experiments were designed to understand various factors such as length of chain extender moiety, flexibility of chain extender units by substitution of ether link in the diol chain, nature of bonds (unsaturation) in the extender unit, and nature of diisocyanates.
TL;DR: In this article, the hygrothermal effect on the fracture behavior of T300/934 graphite/epoxy laminates has been investigated and the effect of moisture on fracture toughness has been shown.
TL;DR: A series of fluorenyl fatty acids with varying fatty acid chain lengths are reported, i.e., (2-fluorenyl)acetic acid, -butyric Acid, -hexanoic acid, and -octanoic Acid, in order to obtain information at different depths in the membrane hydrophobic core.
Abstract: Fluorescent fatty acids have proved very useful in studying the membrane hydrophobic core. They readily partition into membranes or can be converted to phospholipids, which form integral components of membranes. By attaching the fluorescent chromophore to different positions along the alkyl chain of fatty acids, e.g., an anthroyloxy group attached via an ester linkage to n-hydroxystearic acid, membranes have been probed at different depths. While this is an interesting approach and has been extensively used, relatively little attention has been paid to the molecular design of these probes in order to have minimal membrane perturbation. In the present study we have looked into the general problem of design of such depth-dependent membrane probes. We report here a series of fluorenyl fatty acids with varying fatty acid chain lengths, i.e., (2-fluorenyl)acetic acid, -butyric acid, -hexanoic acid, and -octanoic acid, in order to obtain information at different depths in the membrane hydrophobic core. To see the effect of attachment of a hydrophobic tail on the orientation of such fatty acids in membranes, an n-butyl group was linked to the C-7 position of fluorene in (2-fluorenyl)butyric acid to get 4-(7-n-butylfluoren-2-yl)butyric acid. Further, to assess their ability to act as depth-dependent fluorescent probes, these fatty acids were incorporated in vesicles prepared from egg phosphatidylcholine, and their fluorescence quenching was studied with potassium iodide, Cu(II), 9,10-dibromostearic acid, and 12-bromostearic acid.(ABSTRACT TRUNCATED AT 250 WORDS)
TL;DR: In this paper, a theoretical study has been made to see the influence of microwave frequency, soil moisture, soil texture and soil temperature on penetration depth in the context of microwave remote sensing.
Abstract: A theoretical study has been made to see the influence of microwave frequency, soil moisture, soil texture and soil temperature on penetration depth in the context of microwave remote sensing. The results are presented in the form of figures and also coefficients of least square fitting. The study reveals that there is a definite dependence of penetration depth on the above parameters. The range of penetration depth has been found to be 0 to 10 cms and varies as a function of several parameters. These results are in agreement with experimental observations.
TL;DR: In this article, the design and implementation of a computer-assisted process planning system for turned components used in the batch manufacture of portable electric tools is described, which incorporates modules for component geometry representation, automatic selection and sequencing of machining operations, process parameter selection, machine and tool selection, time and cost calculation and report generation.
Abstract: This paper reports the design and implementation of a computer-assisted process planning system for turned components used in the batch manufacture of portable electric tools The software incorporates modules for component geometry representation, automatic selection and sequencing of machining operations, process parameter selection, machine and tool selection, time and cost calculation and report generation The user-friendly package has been developed on an IBM PC XT compatible system and has been extensively tested for a large group of turned components It provides a quick and efficient method of generating consistent process plans
TL;DR: In this article, the Gabay-Toulouse phase diagram transitions occur not for individual spins but for groups of correlated spins whose effective spin's transverse and longitudinal components successively freeze.
Abstract: Mossbauer effect, d. c. magnetisation and a. c. susceptibility measurements in disordered spinel ferrite Ga0.8Fe0.2NiCrO4 (0.3≦T≦300 K, −12≦H (external field) ≦12 kOe) show it to be a cluster spin glass where Gabay-Toulouse phase diagram transitions occur not for individual spins but for groups of correlated spins (clusters) whose effective spin's transverse and longitudinal components successively freeze.
02 Oct 1988
TL;DR: The application of personal computers as a design tool for microprocessor-based transmission-line fault locators is presented and five fault-locating algorithms are simulated and their performances are analyzed.
Abstract: The application of personal computers as a design tool for microprocessor-based transmission line fault locators is presented. Five fault-locating algorithms are simulated, and their performances are analyzed. Simulation results using a 400 kV transmission line model are presented. Simulation studies based on the data obtained from a laboratory model of a 400 kV, 510 km transmission line are also discussed. It is noted that the methods outlined are useful for relay design engineers for testing various fault locator designs and analyzing their performances. >
TL;DR: In this article, it was shown that binary Barker sequences, which are polarity reversed coded rectangular pulses of N bits with an autocorrelation function of peak value N and side lobe level unity or less, do not exist for N greater than 13.
Abstract: It is shown that binary Barker sequences, which are polarity reversed coded rectangular pulses of N bits with an autocorrelation function of peak value N and side lobe level unity or less, do not exist for N greater than 13.
TL;DR: In this paper, the authors present the theoretical work done for stability analysis, which can be extended to any mechanism in general and gives the speed ranges, in which response is unbounded, and presents the study of the response at various speeds for undamped system.
TL;DR: Zirconium reacts with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol in the pH range 3.8-5.8 to form a red chelate that is soluble in methanol-water mixtures and obeys Beer's law over the zIRconium concentration range.
TL;DR: In this paper, a quasi-steady state model based on two parallel modes of diffusion and a polycondensation reaction at the inside surface of a microcapsule is formulated to compute the time of this microencapsulation process.
Abstract: A quasi-steady state model, based on two parallel modes of diffusion and a polycondensation reaction at the inside surface of a microcapsule, is formulated to compute the time of this microencapsulation process. The predicted times of encapsulation are in agreement with observed values reported in patents. It is also shown that, for small shell thickness, the process is reaction-controlled.
Un modale en ragime quasi stationnaire basa sur deux modes de diffusion parallales et une raaction de polycondensation a la surface interne d'une microcapsule, a ata mis au point pour calculer par ordinateur le temps nacessaire au procada de microencapsulation. Les temps d'encapsulation pradits concordent avec les valeurs expakimentdes donnaes dans les descriptions de brevets. On montre agalement que le procada est contrǒla par la raaction pour des petites apaisseurs d'enveloppe.
TL;DR: It is found that as the cone angle increases, the apparent viscosity increases and is being reported first time in cone-plate viscometer.
TL;DR: The metal concentrations at certain stations were relatively higher than those of uncontaminated sediments, possibly due to industrial activity in the former area.
Abstract: Sediments affect the water quality substantially. The metal concentrations in sediments often reflect the degree of pollution of the aquatic environment. The sediments of Thane Creek near Bombay were analyzed for nine metals Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn on twenty stations. The average metal concentrations in the sediments were 2.29, 37.25, 39.89, 103.38, 69825.0, 860.15, 105.08, 54.08, and 169.60 μg g-1 dwt respectively. The metal concentrations at certain stations were relatively higher than those of uncontaminated sediments, possibly due to industrial activity in the former area.
TL;DR: In this paper, the effect of Mo and Si on the icorr of commercial metallic glasses in 1 N Na2SO4 of varying pH and in 0.5 N H 2SO4 has been investigated.
Abstract: Potentiodynamic polarization studies on Vitrovac 0040 (Fe40Ni40B20), Metglas 2826 MB (Fe40Ni38Mo4B18) and Vitrovac 4040 (Fe39Ni39Mo4Si6 B12) commercial metallic glasses in 1 N Na2SO4 of varying pH and in 0.5 N H2SO4 have been performed. It is found that in alkaline and neutral sulfate solution, Mo and Si have a subtle effect in reducing icorr. Mo imparts passivation in neutral sulfate and fails to passivate the glass in H2SO4 solution. No perceptible change in icorr is found with the addition of Mo to the glass in H2SO4 solution. While Si increases the corrosion rate of the glass, it also promotes passivation in H2SO4. However, in the presence of chloride ions, the Si-containing glass is susceptible to pitting. Devitrification of Vitrovac 4040 leads to active dissolution irrespective of the crystalline products present, while the corrosion rate and electrochemical parameters depend on the nature of crystalline phases formed during the devitrification.