Showing papers by "Indian Institute of Technology Kharagpur published in 1993"
TL;DR: In this article, the physical properties of pumpkin seeds and kernels were evaluated as functions of moisture content, and the results showed that the average length, width, thickness and unit mass of the seed were 16·91 mm, 8·67 mm, 3·00 mm and 0·203 g respectively.
343 citations
TL;DR: In this article, an intelligent structure composed of a laminated substrate of graphite/epox y composite coupled with distributed sensor and actuator layers of a biaxially polarized piezoelectric polymer, polyvinylidene fluoride (PVDF), is presented.
Abstract: Exact solutions for static analysis of simply supported rectangular plate-type intelligent structures are presented. The intelligent structure proposed here is composed of a laminated substrate of graphite/epox y composite coupled with distributed sensor and actuator layers of a biaxially polarized piezoelectric polymer, polyvinylidene fluoride (PVDF). The study aims at investigating the capability of the actuator and sensor layers to cause and sense the deformations, respectively, of the substrate of the intelligent structure. The results show that the effectiveness of the piezoelectric actuator layer to cause induced strain actuation in the structure significantly increases with the decrease in the length to thickness ratio of the substrate.
170 citations
TL;DR: This paper presents an application of fuzzy linear programming to the linear multiobjective solid transportation problem and gives efficient solutions as well as an optimal compromise.
159 citations
130 citations
TL;DR: In this paper, an exact static analysis of a simply supported intelligent structure under cylindrical bending is presented, where the performance of the actuator layer of the intelligent structure to cause induced axial and transverse stresses in the substrate layer is investigated.
121 citations
TL;DR: It has been shown through numerical computations of the resulting analytical expressions that the resistance to flow and the wall shear increase as the size of the stenosis increases.
121 citations
TL;DR: A novel scheme for utilizing the regular structure of three neighborhood additive cellular automata (CAs) for pseudoexhaustive test pattern generation is introduced.
Abstract: A novel scheme for utilizing the regular structure of three neighborhood additive cellular automata (CAs) for pseudoexhaustive test pattern generation is introduced. The vector space generated by a CA can be decomposed into several cyclic subspaces. A cycle corresponding to an m-dimensional cyclic subspace has been shown to pseudoexhaustively test an n-input circuit (n>or=m). Such a cycle is shown to supply a (m-1) bit exhaustive pattern including the all-zeros (m-1)-tuple. Schemes have been reported specifying how one or more subsets of (m-1) cell positions of an n-cell CA can be identified to generate exhaustive patterns in an m-dimensional cyclic subspace. >
96 citations
TL;DR: In this article, a simple expression of the Fermi potential (E F ) variation with the sheet carrier concentration ( n s ) in the two-dimensional electron gas at the heterojunction of a High Electron Mobility Transistor (HEMT) is presented.
Abstract: A simple expression of the Fermi potential ( E F ) variation with the sheet carrier concentration ( n s ) in the two-dimensional electron gas at the heterojunction of a High Electron Mobility Transistor (HEMT) is presented This particular approximation is shown to lead to an analytical expression for n s in termks of the applied gate voltage ( V G ) Comparisons with the exact solutions of n s vs E F and n s vs V G as well as with several previous approximations show that our results are more accurate for a wider range of values of n s at different temperatures This single analytical expression for n s as a function of V G , valid from subthreshold to high conduction, can be used for better analytical modelling of HEMTs
78 citations
TL;DR: In this paper, local heat transfer rates have been estimated from the outputs of three-wire differential thermocouple heat flux sensors, and the effective area for a nozzle has been defined when a non-dimensional heat transfer rate, H, has decreased from unity to e −1, Q = 0.54 is a good average value.
72 citations
TL;DR: An additive fuzzy programming model for the multiobjective transportation problem is presented that aggregates the membership functions of the objectives to construct the relevant decision function.
71 citations
TL;DR: A necessary and sufficient condition is developed for computing the upper bound in /sub 0/ of the parasitic parameter in in a singularly perturbed system, which ensures stability of such a system if 0 >.
Abstract: A necessary and sufficient condition is developed for computing the upper bound in /sub 0/ of the parasitic parameter in in a singularly perturbed system, which ensures stability of such a system if 0 >
TL;DR: In this paper, physicomechanical properties and electrical resistivity were studied on different blends of ethylene vinyl acetate (EVA) (28% VA content) and low density polyethylene (LDPE).
TL;DR: In this paper, the effects of such cryo-cooling relative to soluble oil and dry grinding have been investigated in respect of chip formation, grinding forces, specific energy, burning and surface characterisation.
TL;DR: The simulated annealing algorithm which has now become a very useful tool in solving a variety of combinatorial optimization problems is made use of here and solutions obtained using the proposed algorithm compare favourably with the best known results.
TL;DR: In this article, a polycrystalline, 10μm size magnesium silicide was prepared by alloying 99.9% purity poly crystalstalline silicon obtained from rice husk ash and high-purity magnesium powder.
Abstract: Polycrystalline, 10μm size magnesium silicide was prepared by alloying 99.9% purity polycrystalline silicon obtained from rice husk ash and high-purity magnesium powder. The material in sintered pellet form was characterized for its structural, electrical, thermal, thermoelectric and other properties. A typical sintered pellet exhibited a room-temperature (30°C) thermoelectric power of 565 μV K−1 and an electrical resistivity of 35 Ω cm. On the other hand, the material was found to be thermally quite stable up to 650°C with a room-temperature thermal conductivity of 6.3×10−3cals−1cm−1K−1 (2.6 J s−1 m−1 K−1). These properties of the material indicate that the material can find potential applications as a thermoelectric generator and in other semiconductor devices. Furthermore, an indigenous technology for large-scale production of silanes (SiH4) can be developed using this Mg2Si which could be prepared in large quantities by a simple and low-cost process.
TL;DR: In this paper, an analysis of the thermodynamic cycles commonly used for the liquefaction of hydrogen in order to predict their performance under a given set of operating conditions and component efficiencies is presented.
TL;DR: In this article, the validity of maximum hardness and maximum molecular valency principles was evaluated using the 6-31G* basis set on a number of molecules and it was observed that the former is valid under a variety of bonding situations.
01 Jan 1993
TL;DR: The ideas of chemical hardness and chemical softness are reviewed in this article, with special emphasis on the research work done on these concepts at the University of North Carolina at Chapel Hill.
Abstract: The ideas of chemical hardness and chemical softness are reviewed, with special emphasis on the research work done on these concepts at the University of North Carolina at Chapel Hill.
TL;DR: In this paper, the resistivity and mechanical properties of nitrile-rubber based conductive composites filled with short carbon fibres (SCFs) and mixed filler system (SCF + carbon black) are studied as functions of the extensional strain and the strain rate.
Abstract: The resistivity and mechanical properties of nitrile-rubber based conductive composites filled with short carbon fibres (SCFs) and mixed filler system (SCF + carbon black) are studied as functions of the extensional strain and the strain rate It has been observed that both strain and strain rate have a strong influence on the resistivity of the composites The sensitivity of the change in resistivity against the strain and strain rate depends on the concentration as well as the type of conductive filler SCFs impart higher conductivity to the composite than a blend of SCFs and carbon black at the same level of loading parts per hundred of rubber (phr) Composites filled with a mixed filler system show high mechanical properties in contrast to those of SCF-filled composites The change in resistivity with the degree of strain is less pronounced in mixed-filler-filled composites than in only carbon-fibre-filled composites The mechanical properties of the composites are dependent on the polymer-filler interaction whereas change in resistivity is dependent on the transient arrangement of the conducting components in the polymer matrix A good correlation exists between mechanical and electrical response to the strain sensitivity
TL;DR: In this paper, the effect of the ethylene-methylacrylate copolymer as a chemical compatibilizer in the 50:50 blend of low-density polyethylene (LDPE) and polydimethylsiloxane rubber (PDMS) has been studied in detail.
Abstract: The effect of the ethylene–methylacrylate copolymer as a chemical compatibilizer in the 50:50 blend of low-density polyethylene (LDPE) and polydimethylsiloxane rubber (PDMS) has been studied in detail. Ethylene–methylacrylate (EMA) reacted with PDMS rubber during melt-mixing at 180°C to form EMA-grafted PDMS rubber (EMA-g-PDMS) in situ, which acted as a compatibilizer in the LDPE–PDMS rubber blend. An optimum proportion of the compatibilizer (EMA) was found to be 6 wt % based on results of dynamic mechanical analysis, adhesion studies, and phase morphology. Lap shear adhesion between the phases increased significantly on incorporation of 6 wt % of EMA. Dynamic mechanical analysis showed a single glass transition (Tg) peak at −119°C. This was further supported by X-ray diffraction studies, which exhibited a remarkable increase in the degree of crystallinity and phase morphology and showed a drastic reduction in the size of the dispersed phase at the optimum concentration of EMA. © 1993 John Wiley & Sons, Inc.
TL;DR: It is suggested that the magnetization reversal is mainly due to coherent rotation, and the maximum change in resistance that occurs at small field increases from 8.8% at σ=0 to 12.2% at τ=240 MPa; this occurs at 300 K but the change is much reduced with the decrease of temperature.
Abstract: Magnetoresistance and magnetization of an amorphous ferromagnetic wire having nominal composition ${\mathrm{Co}}_{68.1}$${\mathrm{Fe}}_{4.4}$${\mathrm{Si}}_{12.5}$${\mathrm{B}}_{15}$ are measured from 77 to 300 K and in the presence of tensile stress \ensuremath{\sigma} (0\ensuremath{\le}\ensuremath{\sigma}\ensuremath{\le}240 MPa). A large negative magnetoresistance is observed with accompanying hysteresis. The maximum change in resistance that occurs at small field increases from 8.8% at \ensuremath{\sigma}=0 to 12.2% at \ensuremath{\sigma}=240 MPa; this occurs at 300 K but the change is much reduced with the decrease of temperature. The results are discussed in terms of the scattering of carriers by a domain wall and it is suggested that the magnetization reversal is mainly due to coherent rotation.
TL;DR: In this article, a mixture of EMA and poly(dimethylsiloxane) rubber (PDMS) is demonstrated to be miscible, which results in a single and composition-dependent glass transition temperature.
Abstract: Blends of ethylene methyl acrylate (EMA) and poly(dimethylsiloxane) rubber (PDMS) are demonstrated to be miscible. The miscibility results in a single and composition-dependent glass transition temperature. IR spectra of the blends provide direct evidence of chemical reaction between EMA and PDMS rubber.
TL;DR: In this article, a fuzzy goal programming model for locating multiple new facilities on a plane bounded by a convex polygon under the criteria: (1) minimize the sum of all the transportation costs and (2) minimise the maximum distances from the facilities to the demand points.
TL;DR: In this paper, the effect of a superficially applied, cerium-oxide coating on the nonisothermal oxidation behavior of AISI 304 stainless steel in dry air has been investigated.
Abstract: The effect of a superficially-applied, cerium-oxide coating on the non-isothermal oxidation behavior of AISI 304 stainless steel in dry air has been investigated. The heating rate employed was 3 K/min up to a final temperature of 1423 K. The reactive oxide coating not only reduced the reaction rate but also facilitated scale adhesion to the alloy substrate. Post-oxidation analyses of the alloy/scale combination using optical microscopy, SEM, EDAX, and XRD provide evidence for a changeover in the mechanism of oxide growth from the scale/gas interface to the alloy/scale interface for the coated steel.
TL;DR: In this article, a thermogravimetric and derivative analysis of blends of polydimethylsiloxane and ethylenemethyl acrylate copolymer has been carried out, showing that degradation takes place in two stages with peak maxima at T 1max and T 2max, both proportional to the components in the blends.
TL;DR: The effect of tolerance in FLP is investigated and the presence of singular points is investigated for the FLFP.
01 Oct 1993
TL;DR: It has been proved that the algorithm proposed by Loizou et al. to test lossless join property for classical relations is applicable to examine losslessjoin of fuzzy relations in the presence of the fuzzy functional dependencies.
Abstract: To answer user's queries in a fuzzy relational database, it often becomes necessary to decompose a relation scheme into components and subsequently to perform the join operation of two or more component fuzzy relations. For maintaining database integrity, it is essential that the join operation of the components yield the original relation. Such a decomposition is termed a lossless join decomposition. However, the join may not always recover the original relation. In this paper, we study the decomposition problem of fuzzy relation schemes. The associated question of lossless join is also investigated. It has been proved that the algorithm proposed by Loizou et al. [8] to test lossless join property for classical relations is applicable to examine lossless join of fuzzy relations in the presence of the fuzzy functional dependencies.
TL;DR: In this paper, an empirical relation between contact angle and contact-angle hysteresis and the oxygen-carbon ratio of the functionalized polymer surfaces has been attempted, and it was found that the higher the oxygen carbon ratio, the lower the contact angle value for polyethylene.
Abstract: Low-density polyethylene (LDPE) has been functionalized in the bulk through dicumyl peroxide (DCP)-initiated grafting of dibutyl maleate (DBM) and vinyltrimethoxysilane (VTMO) in the temperature range from 140 to 200°C. The functionalized surfaces have been characterized through contact angle and contact-angle hysteresis measurements as well as through ESCA studies. The degree of grafting has been determined by infrared spectrophotometry. From the ESCA patterns of the modified polymers, the atomic ratios of oxygen to carbon and silicon to carbon have been calculated. Determination of an empirical relation between contact-angle hysteresis and the oxygen-carbon ratio of the functionalized polymer surfaces has been attempted. It is found that the higher the oxygen-carbon ratio, the lower the contact-angle value for polyethylene. Contact angle-hysteresis increases with increase of the degree of grafting. The total surface energy increases with grafting. The surface energy of the silane-grafted polyethylene (PEgS) is found to be the lower than that of dibutyl maleate-grafted polyethylene (PEgDBM). © 1993 John Wiley & Sons, Inc.
TL;DR: In this paper, a finite element analysis of the large deflection behavior of stiffened plates using the isoparametric quadratic stiffened plate bending element is presented, based on Mindlin's hypothesis.