Showing papers by "Indian Institute of Technology Kharagpur published in 1989"
TL;DR: In this paper, the spaces of convergent and bounded sequences of fuzzy numbers have been discussed, and the convergence and bounded spaces of fuzzy sequences have been studied in the context of fuzzy counting.
299 citations
TL;DR: In this paper, an exact analytical solution of the non-linear equation governing the self-similar flow is given, and the analysis of heat transfer in this flow reveals that when the wall and the ambient temperature are held constant, temperature at a point increases with increase in k1, for fixed Prandtl number σ.
Abstract: The paper discusses the flow of an incompressible second-order fluid due to stretching of a plane elastic surface in the approximation of boundary layer theory. An exact analytical solution of the non-linear equation governing the self-similar flow is given. The skin friction decreases with increase in the elastic parameter k1. The analysis of heat transfer in this flow reveals that when the wall and the ambient temperature are held constant, temperature at a point increases with increase in k1, for fixed Prandtl number σ.
217 citations
TL;DR: A composite method of segmentation is suggested which uses the variance criterion wherever the directional method fails, and is found to be effective and robust.
174 citations
TL;DR: In this paper, the nitrogen solubility, emulsification, and foaming properties of rice bran protein concentrates were measured over the pH range 2.0 to 10.5 and in three dispersion media including water, 0.1M NaCl (low salt), and 1.0M NaCL (high salt).
Abstract: Rice bran protein concentrates were prepared from full-fat and defatted raw rice bran. Selected functional properties, viz. nitrogen solubility, emulsification properties, and foaming properties were measured over the pH range 2.0 to 10.5 and in three dispersion media including water, 0.1M NaCl (low salt) and 1.0M NaCl (high salt). Below and above the isoelectric pH (4.5) the nitrogen solubility increased. Higher pH enhanced the nitrogen solubility and, thereby, considerably improved the functional properties. In higher salt concentration, nitrogen solubility was reduced which also altered the properties of emulsification and foaming. Multiple regression analysis showed that pH was the primary determinant of nitrogen solubility, emulsification and foaming properties. Multiple regression models including pH, salt concentration and nitrogen solubility as independent variables were found to be more accurate in predicting other functional properties.
173 citations
TL;DR: These parameterized algorithms are found to encompass a wide class of best first search algorithms and guarantee admissible solutions within specified memory limitations (above the minimum required).
134 citations
TL;DR: The concept of an integral of a fuzzy mapping is introduced that generalises the integral introduced by Matloka and also extends Riemann-Stieltjes integral over a closed interval to fuzzy mappings.
133 citations
TL;DR: In this article, the authors used a series of di-and mononuclear orthopalladated complexes of the type trans-Pd2L2X2 and trans-pdLL'Cl as catalysts in DMF medium.
119 citations
TL;DR: In this paper, a gomme et sa chimie are used to derive derives dans l'industrie des peinture, vernis, revetement, encre, adhesif, etc.
118 citations
TL;DR: In this paper, a second law analysis is carried out on convective heat transfer from a fluid flowing in a duct with constant heat flux, where the entropy generated is expressed as a function of the initial temperature difference and the frictional pressure drop.
Abstract: A second law analysis is carried out on convective heat transfer from a fluid flowing in a duct with constant heat flux. The entropy generated is expressed as a function of the initial temperature difference and the frictional pressure drop. Since the loss in available energy is directly proportional to the entropy generated, an optimum value of the initial temperature difference is found where the entropy generated is the minimum. A similar optimum is found for the ratio of heat transfer to pumping power. An optimum fluid velocity which corresponds to the minimum loss of available power is recommended.
82 citations
TL;DR: In this article, a semi-analytic finite difference method was extended to the vibration and stability analysis of stiffened plates, which essentially consists of substituting the displacement function satisfying boundary conditions along two opposite edges into the free vibration/stability equations of the stiffened plate and then, by using suitable transformation, they are reduced to ordinary differential equations with constant coefficients.
77 citations
TL;DR: A nonlinear model called the noncausal quadratic Volterra model is developed for the purpose of detecting small changes in shape nonlinear modeling, even though linear models may be sufficient to differentiate between shapes which differ widely.
Abstract: Time series modeling techniques are adapted to represent or describe two-dimensional closed contours. Both linear and nonlinear models are fitted. It is found that to detect small changes in shape nonlinear modeling is necessary, even though linear models may be sufficient to differentiate between shapes which differ widely. A nonlinear model called the noncausal quadratic Volterra model is developed for the purpose. Implementation is illustrated with shapes of aircraft. >
TL;DR: In this paper, a mixture of plasticized polyvinyl chloride and epoxidized natural rubber was used for the Brabender Plastic Order by the melt-mixing technique.
Abstract: Miscible blends from plasticized poly(vinyl chloride), and epoxidized natural rubber having 50 mol% epoxidation level were prepared in a Brabender Plasticorder by the melt-mixing technique. Changes in Brabender torque and temperature, density, dynamic mechanical properties, and differential scanning calorimetry of the samples were examined as a function of blend composition. The plasticized poly(vinyl chloride)/epoxidized natural rubber blends behaved as a compatible system at all composition ranges as evident from their single glass-rubber transition temperature (Tg) obtained from dynamic mechanical analysis as well as from differential scanning calorimetry. Profound changes in the nature of the glass-rubber transition were noted with respect to blend composition. The Tg-width values of blends lie between those of plasticized poly(vinyl chloride) and epoxidized natural rubber.
TL;DR: In this paper, the tensile properties such as the modulus, elongation at break, tensile strength, and hysteresis were studied by incorporating modified rubber and plastic phases with a view to make the heterogeneous phases compatible.
Abstract: Natural rubber–polyolefin (70/30) blends have been studied by incorporation of modified rubber and plastic phases with a view to make the heterogeneous phases compatible. The modified rubbers used were epoxidized natural rubber (ENR) and sulfonated ethylene–propylene diene rubber (S-EPDM) at a level of 20 parts. Other rubbers such as chlorinated polyethylene (CPE) and ethylene propylene diene rubbers (EPDM) were also used at a level of 20 parts in the natural rubber–polyethylene (NR/PE) systems. The plastic phase was chemically modified with maleic anhydride (MA) in presence of benzoyl peroxide (BPO) and used at a concentration of 10% of PE, i.e., PEm. The tensile properties such as the modulus, elongation at break, tensile strength, and hysteresis were studied. NR/ENR/PEm/PE shows the greatest improvement in tensile strength (45% over control NR/PE). NR/S-EPDM/PEm/PE also shows similar improvement, although the hysteresis loss decreases. The change in these properties could be related to the adhesive strength. This was found to be improved by the incorporation of modified rubber and modified plastic phases. The best adhesion values have been obtained with NR/ENR/PEm/PE and NR/S-EPDM/PEm/PE. Thus, a correlation between tensile and adhesive strength was obtained for all the systems. The increase in adhesive strength is due to chemical reactions between the various phases. Probable chemical reactions have been suggested. Morphological observations show that the phases are interpenetrating, and this is consistent with the increased tensile strength. The natural rubber–polypropylene (NR/PP) systems do not offer good strength properties with the modified PP and modified rubbers. The adhesive strength also decreases with the incorporation of the modified system. The hysteresis properties show some improvement.
TL;DR: In this article, the optical constants (the refractive index n and the absorption constant K) and absorption coefficients x are measured on CdTe thin films in the wavelength range 500 to 2000 nm.
Abstract: The optical constants (the refractive index n and the absorption constant K) and absorption coefficients x are measured on CdTe thin films in the wavelength range 500 to 2000 nm. Some parameters which affect these optical properties of thin films, such as the film thickness, substrate temperature, doping with impurities like In, BaF2, PbCI2 are also investigated. Effective crystallite size and strain are determined by the method of variance analysis of the X-ray diffraction line profiles on the same films. It is observed that there is an increase in optical band gap with decrease in crystallite size and increase in strain.
Die optischen Konstanten (der Brechungsindex n und die Absorptionskonstante K) und der Absorptionskoeffizient x werden in dunnen CdTe-Schichten im Wellenlangenbereich von 500 bis 2000 nm gemessen. Einige Parameter, die diese optischen Eigenschaften dunner Schichten beeinflussen, wie Schichtdieke, Substrattemperatur, Dotierung mit Storstellen wie In, BaF2, PbCI2 werden ebenfalls untersucht. Effective Kristallitgrose und Spannung werden mit der Metbode der Varianzanalyse der Rontgenbeugungslinienprofile an denselben Schichten bestimmt. Es wird beobachtet, das ein Anstieg der optischen Bandlueke mit sinkender Kristallgrose und Anwachsen der Spannung auftritt.
TL;DR: A semi-analytic method developed by the author for plates is extended to the vibration analysis of eccentric stiffened plates in this article, which results in three coupled partial differential equations, which have been solved by the semi analytic method.
TL;DR: In this paper, the authors developed correlations for the pressure drop and heat transfer coefficient for the tube and shell sides of a helical coil heat exchanger, where the laminar friction factor and Nusselt numbers were represented as functions of Re √ d/D, whereas in turbulent flow the results were correlated with Re ·( d / D ) 2.
Abstract: Experiments have been conducted, and correlations are developed for the pressure drop and heat transfer coefficient for the tube and shell sides of a helical coil heat exchanger. In the tube side, the laminar friction factor and Nusselt numbers are represented as functions of Re √ d / D , whereas in turbulent flow the results are correlated with Re ·( d / D ) 2 . The pressure drop and heat transfer values for the shell side are found to follow the classical Blasius and Dittus-Boelter type relations, while a strong dependence on the coil to tube diameter ratio is detected. The performance of the exchanger has been tested not only as simulated experimental exchanger but also as a waste heat recovery device for a 60 HP gas turbine. Excellent corroboration of the effectiveness-NTU relation has been observed between the simulation and in situ experiments.
TL;DR: It is observed that the slip velocity bears the potential to influence the velocity distribution of blood to a remarkable extent and to reduce considerably the pressure-gradient as well as the skin-friction.
TL;DR: In this article, a series of differential scanning calorimetry (d.s.c.), X-ray and dynamic mechanical studies were carried out on natural rubber polyethylene (PE) thermoplastic elastomeric blends of various levels of interactions.
TL;DR: An analytical method of defining and measuring various pertinent characteristics of both routine and non‐routine white‐collar jobs helps in the development of a more suitable productivity management methodology.
Abstract: Critical analysis of previously developed white‐collar productivity management techniques focuses on the existing shortcomings of several measurement and evaluation methodologies of white‐collar personnel and functions. An analytical method of defining and measuring various pertinent characteristics of both routine and non‐routine white‐collar jobs helps in the development of a more suitable productivity management methodology. A systematic procedure is described for the measurement and evaluation of white‐collar productivity for an individual, a group of individuals or a department. The recommended measures, viz, operations‐based productivity measures for routine and non‐routine jobs, explain in detail the relationship of different white‐collar job characteristics and individual and group productivity at the middle management level. A case example is cited which illustrates the proposed approach. The advantages, along with some limitations, of the methodology are also highlighted.
TL;DR: The Extended Safe Point Thinning Algorithm (ESPTA) is presented for thinning 3-D images and it is shown that ESPTA preserves the 18-connectivity of the image.
TL;DR: In this article, the effects of silane coupling agents on styrene-butadiene rubber (SBR)-mica composites have been studied with special reference to the technical properties and polymer-filler interaction.
Abstract: The effects of silane coupling agents on styrene-butadiene rubber (SBR)-mica composites have been studied with special reference to the technical properties and polymer-filler interaction. Silane-treated mica improves polymer-filler interaction, which subsequently enhances the tensile and other technically important mechanical properties. Failure surfaces of tensile, tear, and wear specimens have been examined under scanning electron microscope (SEM) and the fractographs have been correlated with the strength and failure mode of the composites.
TL;DR: In this paper, the dielectric constant (K), loss (tanδ), and hence conductivity (σ) of SrTiO3 single crystals have been measured in the frequency region 102-107 Hz and in the temperature range 30°-350° C.
Abstract: The dielectric constant (K), loss (tanδ), and hence conductivity (σ) of SrTiO3 single crystals have been measured in the frequency region 102–107 Hz and in the temperature range 30°–350° C. Quenching, subjecting the crystals to high electric fields (a.c. or d.c.) and X-ray orγ-ray irradiation, or a combination of these treatments, is found to bring about interesting changes in these properties. An attempt is made to understand the results.
01 May 1989
TL;DR: In this article, the heat transfer characteristics of the three-dimensional flow of an incompressible viscous fluid caused by stretching of an elastic sheet with uniform tension in two horizontal directions are studied subject to the following conditions; (a) the sheet is held at constant temperature; (b) a sheet is exposed to a uniform heat flux; and (c) the similarity solutions for temperature exist for both the cases.
Abstract: The heat transfer characteristics of the three-dimensional flow of an incompressible viscous fluid caused by stretching of an elastic sheet with uniform tension in two horizontal directions are studied subject to the following conditions; (a) the sheet is held at constant temperature; (b) the sheet is exposed to a uniform heat flux. The similarity solutions for temperature exist for both the cases. It is shown that for fixedPr, the temperature at a point decreases with increase in α in Case (a) and the sheet temperature also decreases with increasing α for Case (b).
TL;DR: In this article, a pneumatic rice puffing machine was developed for increasing the production capacity of puffed rice for which a knowledge of the heat transfer process during puffing was required.
Abstract: A pneumatic rice puffing machine was developed for increasing the production capacity of puffed rice for which a knowledge of the heat transfer process during puffing was required. the physical properties of the rice grains and other fluidization parameters, necessary for this study was experimentally determined. the surface heat transfer coefficient in case of hot air fluidized bed puffing was found to be 155.39 W/m2K. the calculated grain surface temperature for puffing was about 170°C and this did not vary significantly for experimental puffing air temperatures ranging from 200°C to 270°C. the air temperature ranging from 240°C to 270°C with corresponding exposure time of 9.7 s to 7s was found to be optimum for higher expansion ratio (8.5 to 10) and better color of the product. the temperature differentials between surface and center temperatures and between surface and average temperatures of the grains at the time of puffing were found to vary linearly with various puffing air temperatures and their ratios remained almost constant at 2.056.
TL;DR: In this article, the authors describe the detail design and performance of a prototype, low cost and simple solar dryer coupled with a vertical flat plate collector chimney for drying 20 kg of field harvest high moisture paddy.
TL;DR: In this paper, precipitated products of hydrolysis of manganese sulphate with sodium hydroxide were obtained by adding a mixture of Mn3O4 and γ-Mn2O3.
01 Jan 1989
TL;DR: The linear stability of two-dimensional flow of a viscous electrically conducting fluid permeated by a uniform transverse magnetic field over a flat porous deformable sheet is investigated in this article.
Abstract: The linear stability of two-dimensional flow of a viscous electrically conducting fluid permeated by a uniform transverse magnetic field over a flat porous deformable sheet is investigated when the sheet is stretched in its own plane with an outward velocity proportional to the distance from a point on it. Since the flow has curved streamlines as in a stagnation point flow, its stability is examined with respect to three-dimensional disturbances in the form of Taylor-Gortler vortices. Using a numerical method, the differential equations governing stability are integrated for various values of the suction(R) and magnetic(M) parameter. It is shown that the flow is stable for all values of R, M and non-zero values of the dimensionless wave number \(\overline\alpha \) Further for fixed \(\overline\alpha \) and R, the decay rate of the disturbances increases with M. This study is likely to be relevant to certain metallurgical processes where a magnetic field is used to control the rate of cooling of a stretching sheet by drawing it through a coolant.
TL;DR: In this paper, a rational procedure is developed for ranking the multiobjectives of a vector maximum problem, thereby leading to proper assignment of weights to the objectives, and the range of each decision variable from the constraints set and transform them into the unit interval.
Abstract: A rational procedure is developed for ranking the multiobjectives of a vector maximum problem, thereby leading to proper assignment of weights to the objectives. To achieve this, we determine the range of each decision variable from the constraints set and transform them into the unit interval. After scaling the decision variables, we scale down the objectives also into the unit interval. Following Yager (1981), an ordering function of the objectives is determined. This ordering function value is nothing but the strength of preference inherent in the objectives. Accepting the strength of preference, we obtain the weights for the respective objectives. A numerical example is given to illustrate the procedure.
TL;DR: Etude des verres suivants: KH 2 PO 4, PbO-P 2 O 5, Al 2 O 3 -P 2 OD 5 et K 2 O-Al 2 O3 -P O 5 as mentioned in this paper.
Abstract: Etude des verres suivants: KH 2 PO 4 , PbO-P 2 O 5 , Al 2 O 3 -P 2 O 5 et K 2 O-Al 2 O 3 -P 2 O 5