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Showing papers by "Indian Institute of Technology Bombay published in 1989"


Proceedings ArticleDOI
22 Nov 1989
TL;DR: In this experiment, certain issues encountered in natural language understanding are discussed and the NLQ presented cannot detect semantic contradictions, as it does not use any data restriction/dependency information to detect semantic errors in conversation.
Abstract: A description is given of the implementation of a natural language query (NLQ) processor based on the pattern matching paradigm (PMP) in standard Prolog on an IBM-PC/XT. In the light of this experiment, certain issues encountered in natural language understanding are discussed. PMP is a simplistic syntactic approach to natural language understanding and works well in limited applications. However, the NLQ presented cannot detect semantic contradictions, as it does not use any data restriction/dependency information to detect semantic errors in conversation. >

112 citations


Journal ArticleDOI
TL;DR: The authors examined the relationship between political behaviors, e.g., ingratiation, structure change, cooptation, and threat, and their outcomes such as interpersonal trust, alienation, and feeling about job performance.
Abstract: The study examines the relationship between political behaviors, e.g., ingratiation, structure change, cooptation, and threat, and their outcomes such as interpersonal trust, alienation, and feeling about job performance. A negative relationship between political behaviors and interpersonal trust andfeelings about performance, and a positive relationship between political behaviors and alienation is hypothesized. Results largely support the hypotheses. However, a relationship between political behaviors and feelings about job performance is marginal. Findings are discussed in the light of available research.

98 citations


Journal ArticleDOI
TL;DR: Three palladium (II) complexes of 2, 2′-bipyridine (bipy), 1, 10-phenanthroline (phen) and 1, 2-diaminocyclohexane (dach) with diethyldithiocarbamate (ddtc) have been synthesized and characterized.

85 citations


Journal ArticleDOI
01 Jan 1989-Biomass
TL;DR: In this paper, the performance of a downdraft, biomass gasifier-engine system is reported, where two types of diesel (direct injected and indirect injected) engines used in agricultural applications have been operated with the same gasifier system in the producer gas-cum-diesel, dual fuel mode.

51 citations


Journal ArticleDOI
TL;DR: In this article, the effect of substrate temperature and post-deposition annealing temperature on the structural properties of the SnO 2 films for gas sensor application was studied, and it was observed from X-ray diffraction (XRD) results that the films deposited at lower substrate temperatures are amorphous and become polycrystalline SnO at 350 °C.

46 citations


Book ChapterDOI
16 Oct 1989
TL;DR: This work has focused on the integration of computer vision and the generation of natural language expressions for the description of image sequences in the context of 3D image recognition.
Abstract: Although image understanding and natural language processing constitute two major areas of AI, they have mostly been studied independently of each other. Only a few attempts have been concerned with the integration of computer vision and the generation of natural language expressions for the description of image sequences.

42 citations


Journal ArticleDOI
TL;DR: In this paper, conditions for simultaneous oxidation of tungsten carbide and dissolution of cobalt have been investigated, using concentration of nitric acid, current density, temperature and time as the variables.

38 citations


Journal ArticleDOI
TL;DR: In this article, the first detailed photoelectrochemical study of n-type nickel phosphide (Ni2P) material (thin film as well as powder) was reported, which has a hexagonal structure with a band gap of 1.0 eV.

37 citations



Journal ArticleDOI
TL;DR: In this article, a technique to synthesize a four-bar adjustable function generator operating in two phases to produce two specified functions is presented and is based on five-bar linkage theory.

30 citations


Journal ArticleDOI
TL;DR: In this article, the corrosion behavior of porous type 316L stainless steel has been evaluated and compared to that of conventionally made wrought stainless steel, and it was shown that the corrosion behaviour of the porous type is different from that of the conventional type.
Abstract: In this study the corrosion behavior of porous type 316L stainless steel has been evaluated and compared to that of conventionally made wrought stainless steel The corrosion behavior of t

Journal ArticleDOI
TL;DR: Growth kinetics of binary intermetallic compounds in the fibre/matrix interface has been studied in stainless steel fibre reinforced aluminium matrix composites fabricated by the P/M hot pressing, squeeze casting, and infiltration techniques as mentioned in this paper.
Abstract: Growth kinetics of binary intermetallic compounds in the fibre/matrix interface has been studied in stainless steel fibre reinforced aluminium matrix composites fabricated by the P/M hot pressing, squeeze casting, and infiltration techniques. As expected in most binary diffusion couples, more than one intermetallic compound of the type FexAly forms at the interface. However, not all the iron-aluminide intermetallic compounds possible as dictated by the binary phase diagram are present. This is primarily the result of the non-equilibrium conditions at the interphase boundaries as the activation-controlled and diffusion-controlled interfacial reactions progress between the fibre and the matrix. Two equations have been established for the growth kinetics of the interface; one relates to hot pressing, the other to squeeze casting and infiltration. Parabolic rate constants have been determined. A rate constant of about 0.7 × 10−16 m2 sec−1 for hot-pressed composites produces an optimum thickness of the interface of about 3 μm and results in the maximum strength of the composites. In addition to the FeAl and Fe2Al5 that form at the interface, the presence of NiAl3 intermetallic compound is also predicted. Further investigation is suggested for the determination of the rate constants in squeeze-cast and infiltrated composites.

Journal ArticleDOI
01 Jun 1989-Fuel
TL;DR: The surface and bulk properties of six coal-derived fly ash samples taken from air fall, air hopper collectors, magnetic precipitators, electrostatic precipitator, bottom ash, river sediment, and original coal were examined by various spectroscopic and microscopic techniques as mentioned in this paper.

Journal ArticleDOI
TL;DR: In this article, the authors measured and semi-empirically evaluated the friction and Nusselt number data for twisted tape generated helical flow in annuli and reported an increase in pressure drop and heat transfer rates.
Abstract: Friction and Nusselt number data have been measured and semi-empirically evaluated for twisted tape generated helical flow in annuli. Results have been obtained for radius ratios of 0.41 and 0.61 and twist ratios of {infinity}, 5.302, 5.038, and 2.659. The increase in pressure drop and heat transfer rates obtained are comparable to those reported for twisted tape generated swirl flow in tubes. Also, for the same heat transfer rates the pumping power requirements compare favorably with those for empty annuli. The analytical predictions based on the principle of superposition of pressure drops and analogy between heat and momentum transfer have yielded excellent predictions for y = {infinity} and 5.302 but somewhat poor agreement at y = 2.659.

Journal ArticleDOI
TL;DR: In this paper, PZT powders were processed to sintered ceramics by conventional cold pressing and sintering at various temperatures and periods between 1000 to 1250°C for 0.5 to 12h.
Abstract: PZT powders of the composition Pb0.94Sr0.06 (Zr0.53Ti0.47)O3, prepared by spray drying and calcining techniques, were processed to sintered ceramics by conventional cold pressing and sintering at various temperatures and periods between 1000 to 1250°C for 0.5 to 12h. Sintered ceramics were evaluated for their microstructure and electromechanical properties. Highly dense ceramics having bulk density of the order of 97% of the theoretical value could be obtained after sintering at a considerably lower temperature of 1000°C in comparison to the 1300°C generally required for powders prepared by conventional ceramic processing. However, the increase in sintering temperature of reactive spray-dried powders causes the entrapment of closed pores as a result of exaggerated grain growth and subsequent pore coarsening thereby leading to a decrease in the bulk density of the ceramics. It has been observed that minor variations in the sintering parameters influence the porosity, grain size and electromechanical properties. Values of the dielectric constant, piezoelectric strain coefficient and electromechanic coupling factor increase with the increase in grain size and decrease with the increase in porosity of the sintered ceramic whereas the dielectric dissipation factor decreases with the increase in sintering temperature.

Journal ArticleDOI
TL;DR: It is proposed that Hindu temples may be viewed as threedimensional fractal models and that the use of fractal geometry procedures has a special symbolic meaning in the generation of the forms of Hindu temples.
Abstract: Hindu philosophy views the cosmos to be holonomic and self-similar in nature. According to ancient architectural tradition, Hindu temples are symbols of models of the cosmos and their form represents the cosmos symbolically. The procedures and methods used in the construction of Hindu temples bear a striking resemblance to the procedures of computer graphics, including discretization, fractalization and extensive use of recursive procedures, including self-similar iteration. The instructions given in ancient Vastu shastras (texts on architecture) work like general programmes to generate various types of temples. The paper is an attempt to draw attention to the similarities between the procedures and resulting forms in computer graphics and Hindu temple architecture and to explain the relationship that exists between the form of the temple and the concepts of Hindu philosophy. It is proposed that Hindu temples may be viewed as threedimensional fractal models and that the use of fractal geometry procedures has a special symbolic meaning in the generation of the forms of Hindu temples.

Journal ArticleDOI
TL;DR: Uranium(VI) was quantitatively extracted from 6 to 8M hydrochloric acid with 0.02M DC-18-crown-6 in chloroform as discussed by the authors.
Abstract: Uranium(VI) was quantitatively extracted from 6 to 8M hydrochloric acid with 0.02M DC-18-crown-6 in chloroform. It was stripped from the organic phase with 0.5M hydrochloric acid and determined as its Arsenazo-III complex at 665 nm. Uranium(VI) was separated from several elements such as thorium, zirconium, scandium, yttrium, thallium and tin in complex mixtures. The method was extended for analysis of uranium in monazite and rock sample.

Journal ArticleDOI
TL;DR: The paper reports the design and implementation of a computer-assisted process planning system (PC-CAPP) for prismatic components used in the batch production of portable electric tools.
Abstract: The paper reports the design and implementation of a computer-assisted process planning system (PC-CAPP) for prismatic components used in the batch production of portable electric tools. The software incorporates various modules for component feature representation; automatic machine, toolings and process parameter selection; set-up planning; production time calculation and finally the report generation. The user-friendly software package has been developed on an IBM PC/XT compatible system. It provides a quick and efficient method for generating consistent process plans.

Journal ArticleDOI
TL;DR: In this paper, a modified embedded approach was used to solve the problem incorporating the appropriate constraints based upon the real system and on the optimisation requirements for the Blue Lake aquifer, and it was estimated that HBMWD could have an annual saving of $20,000 by implementing the annual optimal pumping policy.

Journal ArticleDOI
TL;DR: Heterogeneous cation-and anion-exchange membranes were synthesized by radiation grafting of styrene on polyethylene films followed by introduction of ionogenic groups.

Journal ArticleDOI
TL;DR: In this paper, the effect of free-stream turbulence on the heat transfer coefficient distribution around gas turbine rotor blades and nozzle guide vanes was investigated under a uniform heat flux boundary condition.
Abstract: This paper describes the results of systematic investigations undertaken to study the effect of free-stream turbulence on the heat transfer coefficient distribution around gas turbine rotor blades and nozzle guide vanes. The heat transfer coefficient distribution around the blade surface was obtained under a uniform heat flux boundary condition. Experiments were conducted in the Reynolds number range 2.0-8.1 x 10 to the 5th (exit Mach number range 0.182 to 0.600) with the free-stream turbulence level in the range 1.0-21.3 percent. A new type of active turbulence generator was used for generating high turbulence levels. Correlations were obtained for the effect of free-stream turbulence on the local heat transfer coefficient in the laminar, transitional, and turbulent boundary layer regions.

Proceedings ArticleDOI
22 Nov 1989
TL;DR: In this article, the authors developed an AC-DC load flow program based on the fast decoupled algorithm, which is independent of a particular control mode of the DC link and the flow chart of the algorithm and the results of a sample run obtained using a MicroVAX-II computer are included.
Abstract: The development of an AC-DC load flow program based on the fast decoupled algorithm is dealt with. Variables of the DC link which have been chosen for the problem formulation are the converter terminal DC voltages, converter transformer tap ratios, firing angle of the rectifier, extinction angle of the inverter, and current in the DC link. Equations relating these seven variables and their solution strategy are discussed. The model developed is independent of a particular control mode of the DC link. The flow chart of the algorithm and the results of a sample run obtained using a MicroVAX-II computer are included. Use of multiple DC links in a large AC system is also described. >

Journal ArticleDOI
TL;DR: In this article, four general Miller equivalent circuits, one for each of the four possible connections of two two-port networks, are derived based on these, and a generalized Miller theorem is stated.
Abstract: Four general Miller equivalent circuits, one for each of the four possible connections of two two-port networks, are derived. Based on these, a generalized Miller theorem is stated. A number of illustrative examples are included to demonstrate the power of the Miller theorem as an analytical tool in the analysis and synthesis of networks. It is pointed out that many known results such as capacitance multiplication, high input impedance of the emitter follower and the Darlington pair, and synthesis of driving point and transfer functions by some network configurations can be understood through the Miller theorem. >

Journal ArticleDOI
01 Jul 1989-Fuel
TL;DR: The results of a study on eight organometallic additives tested for their efficacy in soot suppression are presented in this paper, where the parameters examined were air/fuel weight ratio and additive dosage in the fuel oil.

Journal ArticleDOI
TL;DR: It is shown that both time- and frequency-domain approximation methods for multivariable systems lead to partial Pade approximation, and that full Pade exists only in the case of scalar systems.
Abstract: A unification of the time- and frequency-domain Pade approximation method for multivariable systems is presented. It is shown that both time- and frequency-domain approximation methods for multivariable systems lead to partial Pade approximation, and that full Pade exists only in the case of scalar systems. >

Journal ArticleDOI
TL;DR: In this article, a model of partial internal wetting of catalyst particles is extended to allow for pore-size distribution, multicomponent diffusion, and nonlinear kinetics for spherical particles exposed to condensible vapor undergoing an exothermic reaction.
Abstract: The recent model of partial internal wetting of catalyst particles (Bhatia, 1988) is extended to allow for pore-size distribution, multicomponent diffusion, and nonlinear kinetics for spherical particles exposed to condensible vapor undergoing an exothermic reaction. Profiles of liqid filling of the pores are computed, and the influence on mass transfer and effectiveness factor is determined. Under certain circumstances, the effectiveness factor has a maximum with respect to the mole fraction of condensible component suggesting an optimum vapor-phase composition. As the bulk vapor approaches saturation the effectiveness factor and particle temperature can drop sharply because of precipitious increase in liquid filling. However, a significant fraction of the pore space is still dry in contradiction to prior models assuming complete internal wetting of catalyst particles. The new model is more realistic than earlier attempts and lays the framework for proper representation of the physical phenomena involved.

Journal ArticleDOI
TL;DR: In this article, the mean and fluctuating pressures on various geometries of vertical-lift gates have been measured and analyzed and the influence of various hydraulic parameters and the magnitude of the gate opening on mean and r.m.s. pressure fluctuations and their spatial correlations has been investigated.
Abstract: Mean and fluctuating pressures on various geometries of vertical-lift gates have been measured and analysed. The influence of various hydraulic parameters and the magnitude of the gate opening on mean and r.m.s. pressure fluctuations and their spatial correlations has been investigated. The variations in the distribution pattern, spatial correlations and intensity of pressure fluctuations have been studied when the gate is forced to vibrate with a single degree-of-freedom in the vertical direction at specified frequencies and amplitude. Total intensity of fluctuating pressures on vibrating gates has been obtained by integrating the r.m.s. pressure fluctuations over the gate thickness. The distinct peak in the total intensity of fluctuating pressure on the gate indicates the presence of a dominant frequency which is considered to be the critical condition for the design of hydraulic control gates.

Journal ArticleDOI
TL;DR: In this article, various pyrometallurgical processes developed for the separation of hafnium from zirconium were reviewed and the criteria for the selection of the process to be adopted for the preparation of nuclear grade ZIRconium in the country were discussed.
Abstract: The paper reviews the various pyrometallurgical processes developed for the separation of hafnium from zirconium and also discusses the criteria for the selection of the process to be adopted for the preparation of nuclear grade zirconium in the country.


Journal ArticleDOI
TL;DR: In this article, improved solubility data predictions by the Peng-Robinson equation-of-state (PR-EOS) for supercritical fluid-solid systems are obtained for asymmetric systems by employing the covolume dependency in the mixing rule for the attraction parameter, a, along with the corresponding states approach for both like and unlike pair parameters of the EOS.
Abstract: Improved solubility data predictions by the Peng-Robinson equation-of-state (PR-EOS) for supercritical fluid-solid systems are obtained for asymmetric systems by employing the covolume dependency in the mixing rule for the attraction parameter, a , along with the corresponding states approach for both like and unlike pair parameters of the EOS. This method reduces the sensitivity of solubility predictions to variations in the value of the interaction parameter and allows the binary interaction parameter to be correlated in terms of the pure component properties with small sacrifice in accuracy. The solubility data predictions using the developed correlation for supercritical carbon dioxide and hydrocarbon solvents compare well with the experimental results.