Showing papers by "Indian Institute of Technology Kharagpur published in 1999"
TL;DR: In this article, an attempt has been made to generate the complete stress-strain curve experimentally for steel-fiber reinforced concrete for compressive strength ranging from 30 to 50 MPa.
Abstract: Steel-fiber reinforced concrete is increasingly being used day by day as a structural material. The complete stress–strain curve of the material in compression is needed for the analysis and design of structures. In this experimental investigation, an attempt has been made to generate the complete stress–strain curve experimentally for steel-fiber reinforced concrete for compressive strength ranging from 30 to 50 MPa. Round crimped fibers with three volume fractions of 0.5%, 0.75% and 1.0% (39, 59, and 78 kg/m3) and for two aspect ratios of 55 and 82 are considered. The effect of fiber addition to concrete on some of the major parameters namely peak stress, strain at peak stress, the toughness of concrete and the nature of the stress–strain curve is studied. A simple analytical model is proposed to generate both the ascending and descending portions of the stress–strain curve. There exists a good correlation between the experimental results and those calculated based on the analytical model. Equations are also proposed to quantify the effect of fiber on compressive strength, strain at peak stress and the toughness of concrete in terms of fiber reinforcing parameter.
431 citations
01 Apr 1999
TL;DR: An alternate ANN structure called functional link ANN (FLANN) for nonlinear dynamic system identification using the popular backpropagation algorithm and performs as good as and in some cases even better than the MLP structure for the problem of nonlinear system identification.
Abstract: We have presented an alternate ANN structure called functional link ANN (FLANN) for nonlinear dynamic system identification using the popular backpropagation algorithm. In contrast to a feedforward ANN structure, i.e., a multilayer perceptron (MLP), the FLANN is basically a single layer structure in which nonlinearity is introduced by enhancing the input pattern with nonlinear functional expansion. With proper choice of functional expansion in a FLANN, this network performs as good as and in some cases even better than the MLP structure for the problem of nonlinear system identification.
382 citations
TL;DR: It is very difficult to diagnose early symptoms of arsenicosis because such nonspecific symptoms may also be present in many other diseases, and the correct diagnosis depends largely on awareness of the problem.
Abstract: The incidence of arsenic contamination of ground water used for both irrigation as well as for human consumption or industrial activities has taken the dimension of an epidemiological problem. It has been established that inorganic arsenic is extremely toxic, both acute and chronic. Initially, it enters into the human body through ingestion, inhalation, or skin absorption. After entering into the body it is distributed in a large number of organs, including the lungs, liver, kidney, and skin. The clinical manifestations of arsenic poisoning are myriad, and the correct diagnosis depends largely on awareness of the problem. It is very difficult to diagnose early symptoms of arsenicosis because such nonspecific symptoms may also be present in many other diseases. Medicine used for the remedy of arsenicosis has been found to be unsatisfactory by repeated application and experience. Melanosis may disappear but keratosis is not altered, although it can prevent further complication. Once the complication (malign...
380 citations
TL;DR: In this paper, the role of the physical layer in setting up lightpaths by employing appropriate models of multi-wavelength optical devices (XCSs and EDFAs) such that the received bit error rate (BER) at the destination node might become unacceptably high.
Abstract: In a wavelength-routed optical network, a transmitted signal remains in the optical domain over the entire route (lightpath) assigned to it between its source and destination nodes. The optical signal may have to traverse a number of crossconnect switches (XCSs), fiber segments, and optical amplifiers, e.g., erbium-doped fiber amplifiers (EDFAs). Thus, while propagating through the network, the signal may degrade in quality as it encounters crosstalk at the XCSs and also picks up amplified spontaneous emission (ASE) noise at the EDFAs. Since these impairments continue to degrade the signal quality as it progresses toward its destination, the received bit error rate (BER) at the destination node might become unacceptably high. Previous work on the lightpath routing and wavelength assignment (RWA) problem assumed an ideal physical layer and ignored these transmission impairments. The main contribution of our work is to incorporate the role of the physical layer in setting up lightpaths by employing appropriate models of multiwavelength optical devices (XCSs and EDFAs) such that the BER of a candidate lightpath can be computed, in advance, to determine if this lightpath should be used for the call. Features from existing RWA algorithms are integrated with our on-line BER calculation mechanism. Our simulation studies indicate that employing BER-based call-admission algorithms has a significant impact on the performance of realistic networks.
377 citations
TL;DR: In this paper, growing small particles of silver have been observed to be more efficient catalysts than stable colloidal particles, and these growing particles catalyze the borohydride reduction of several organic dy...
Abstract: Growing small particles of silver have been observed to be more efficient catalysts than stable colloidal particles. These growing particles catalyze the borohydride reduction of several organic dy...
353 citations
TL;DR: In this paper, a series of dual-phase (DP) steels containing finely dispersed martensite with different volume fractions of martensites (Vm) were produced by intermediate quenching of a boron- and vanadium-containing microalloyed steel.
Abstract: A series of dual-phase (DP) steels containing finely dispersed martensite with different volume fractions of martensite (Vm) were produced by intermediate quenching of a boron- and vanadium-containing microalloyed steel The volume fraction of martensite was varied from 03 to 08 by changing the intercritical annealing temperature The tensile and impact properties of these steels were studied and compared to those of step-quenched steels, which showed banded microstructures The experimental results show that DP steels with finely dispersed microstructures have excellent mechanical properties, including high impact toughness values, with an optimum in properties obtained at ∼055 Vm A further increase in Vm was found to decrease the yield and tensile strengths as well as the impact properties It was shown that models developed on the basis of a rule of mixtures are inadequate in capturing the tensile properties of DP steels with Vm>055 Jaoul-Crussard analyses of the work-hardening behavior of the high-martensite volume fraction DP steels show three distinct stages of plastic deformation
344 citations
01 Nov 1999
TL;DR: In this article, a simple and efficient method for solving radial distribution networks is presented, which involves only the evaluation of a simple algebraic expression of receiving-end voltages, which is very efficient.
Abstract: A simple and efficient method for solving radial distribution networks is presented. The proposed method involves only the evaluation of a simple algebraic expression of receiving-end voltages. Computationally, the proposed method is very efficient. The effectiveness of the proposed method is demonstrated through three examples.
327 citations
TL;DR: In this article, each of the nine subwatersheds of the major part of Nayagram Block in the Midnapore District, West Bengal have been studied in terms of the morphometric parameters - stream length, bifurcation ratio, drainage density stream frequency, texture ratio, form factor, circularity ratio and elongation ratio.
Abstract: Remote Sensing and Geographic Information System (GIS) techniques are being effectively used in recent times as tools in determining the quantitative description of basin geometry i.e., morphometric analysis. In the present study, each of the nine subwatersheds of the major part of Nayagram Block in the Midnapore District, West Bengal have been studied in terms of the morphometric parameters - stream length, bifurcation ratio, drainage density stream frequency, texture ratio, form factor, circularity ratio and elongation ratio and prioritised all the subwatersheds under study. The results suggest that the ratio between cumulative stream length and stream order is constant throughout the successive orders of a basin. The morphometric parametersbifurcation ratio and drainage density, confirm that the area is under dense vegetation cover and virtually the drainage has not been affected by structural disturbances. The form factor values indicate that the basin has moderately high and short duration peak flows. It was observed from the prioritisation of subwatersheds, the subwatershed 8 has got the highest priority because of high erosion intensity considering the above mentioned morphometric parameters. The subwatersheds have been analysed through Sediment Yield Index (SYI) model also and the results tally in most of the cases with the present approach. The subwatershed 8 is coming under priority—I by SYI model also, which indicates that the morphometric analysis could be used for prioritisation of subwatersheds even without the availability of reliable soil maps of the area under study.
264 citations
TL;DR: In this article, a theoretical framework for the classification of border collision bifurcations is presented, which can help in explaining bifurbation in all systems, which are represented by two-dimensional piecewise smooth maps.
Abstract: Recent investigations on the bifurcations in switching circuits have shown that many atypical bifurcations can occur in piecewise smooth maps that cannot be classified among the generic cases like saddle-node, pitchfork, or Hopf bifurcations occurring in smooth maps. In this paper we first present experimental results to establish the need for the development of a theoretical framework and classification of the bifurcations resulting from border collision. We then present a systematic analysis of such bifurcations by deriving a normal form - the piecewise linear approximation in the neighborhood of the border. We show that there can be eleven qualitatively different types of border collision bifurcations depending on the parameters of the normal form, and these are classified under six cases. We present a partitioning of the parameter space of the normal form showing the regions where different types of bifurcations occur. This theoretical framework will help in explaining bifurcations in all systems, which can be represented by two-dimensional piecewise smooth maps.
255 citations
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13 Jun 1999
TL;DR: It is shown that if the Delaunay triangulation has the ratio property introduced in [15] then there is an assignment of weights so the weighted Delauny triangulations contains no slivers.
Abstract: A sliver is a tetrahedron whose four vertices lie close to a plane and whose projection to that plane is a convex quadrilateral with no short edge. Slivers are notoriously common in 3-dimensional Delaunay triangulations even for well-spaced point sets. We show that if the Delaunay triangulation has the ratio property introduced in [15] then there is an assignment of weights so the weighted Delaunay triangulation contains no slivers. We also give an algorithm to compute such a weight assignment.
221 citations
TL;DR: In this article, the capacity factors computed from the Weibull statistical model using cubic mean of wind speed data fairly match the actual capacity factors obtained from Kappadagudda wind power station.
Abstract: Site matching of wind turbine generators is investigated based on the appropriate selection of statistical models and means of wind speed data. The wind speed means are computed using arithmetic mean, root mean square and cubic mean cuberoot. Wind speed frequency distributions are modelled using Weibull and Rayleigh probability density functions. Wind speed data of an existing wind power station, located at Kappadagudda, Karnataka, India, is used for computational purposes. The analytically obtained capacity factors are validated by comparing with the actual capacity factors obtained at Kappadagudda. It is observed that the capacity factors computed from the Weibull statistical model using cubic mean of wind speed data fairly match the actual capacity factors obtained from Kappadagudda wind power station. Various commercially available wind turbine generators are used for site matching studies. The model described in the paper is useful for planning of wind power stations as it can be applied for the accurate assessment of wind power potential at a site.
TL;DR: Ranking alternatives (both qualitative as well as quantitative) in a multicriterion environment, employing experts opinion (preference structure) using fuzzy numbers and linguistic variables, are presented in this paper.
01 Apr 1999
TL;DR: Application of artificial neural networks (ANN's) to adaptive channel equalization in a digital communication system with 4-QAM signal constellation is reported and a novel computationally efficient single layer functional link ANN (FLANN) is proposed for this purpose.
Abstract: Application of artificial neural networks (ANN's) to adaptive channel equalization in a digital communication system with 4-QAM signal constellation is reported in this paper. A novel computationally efficient single layer functional link ANN (FLANN) is proposed for this purpose. This network has a simple structure in which the nonlinearity is introduced by functional expansion of the input pattern by trigonometric polynomials. Because of input pattern enhancement, the FLANN is capable of forming arbitrarily nonlinear decision boundaries and can perform complex pattern classification tasks. Considering channel equalization as a nonlinear classification problem, the FLANN has been utilized for nonlinear channel equalization. The performance of the FLANN is compared with two other ANN structures [a multilayer perceptron (MLP) and a polynomial perceptron network (PPN)] along with a conventional linear LMS-based equalizer for different linear and nonlinear channel models. The effect of eigenvalue ratio (EVR) of input correlation matrix on the equalizer performance has been studied. The comparison of computational complexity involved for the three ANN structures is also provided.
TL;DR: In this paper, a nonlinear geometric analysis of trapezoidal corrugated sheet is reported for the first time, and an equivalent orthotropic model is proposed that includes both extensional and bending rigidities.
TL;DR: In this paper, the authors proposed a model to estimate the electrostatic forces acting on the metal surface and the stress distribution inside the metal due to this electrostatic force, and then the variation of the yield strength with depth inside a metal has also been found out.
Abstract: In Electro Discharge Machining (EDM), melting is the main process for metal removal. However, for short pulses (discharge duration 100 μs), this electrostatic force becomes very small and does not play a significant role in the removal of metal. In the model proposed, the electrostatic force acting on the metal surface and the stress distribution inside the metal due to this electrostatic force have been estimated. The variation of the yield strength with depth inside the metal has also been found out and finally the 'crater depth' due to this electrostatic force has been calculated.
21 Feb 1999
TL;DR: This study evaluates the relative merits of three approaches (transparency, opacity, and translucency) for establishing calls in a wavelength-routed optical network.
Abstract: This study evaluates the relative merits of three approaches (transparency, opacity, and translucency) for establishing calls in a wavelength-routed optical network. Call-admission algorithms employ online bit-error-rate computation and include the effects of transmission impairments.
TL;DR: This paper focuses on the solution procedure of the multiobjective transportation problem (MOTP) where the cost coefficients of the objective functions, and the source and destination parameters have been expressed as interval values by the decision maker.
TL;DR: A systematic evaluation procedure for ML is discussed, which will lead to better evaluation of studies, and consequently to improved research and practice in the area of ML in engineering applications.
Proceedings Article•
01 Jan 1999TL;DR: An algorithm is presented that provably reconstructs a curve in the framework introduced by Amenta, Bern and Eppstein and requires a sampling density better than previously known and can be adapted for curve reconstruction in higher dimensions straightforwardly.
Abstract: We present an algorithm that provably reconstructs a curve in the framework introduced by Amenta, Bern and Eppstein. The highlights of the algorithm are: (i) it is simple, (ii) it requires a sampling density better than previously known, (iii) it can be adapted for curve reconstruction in higher dimensions straightforwardly.
TL;DR: This paper presents a new method for incorporating imperfect FC (fault coverage) into a combinatorial model, SEA, which applies to any system for which the FC probabilities are constant and state-independent; the hazard rates are state- independent; and an FC failure leads to immediate system failure.
Abstract: This paper presents a new method for incorporating imperfect FC (fault coverage) into a combinatorial model. Imperfect FC, the probability that a single malicious fault can thwart automatic recovery mechanisms, is important to accurate reliability assessment of fault-tolerant computer systems. Until recently, it was thought that the consideration of this probability necessitated a Markov model rather than the simpler (and usually faster) combinatorial model. SEA, the new approach, separates the modeling of FC failures into two terms that are multiplied to compute the system reliability. The first term, a simple product, represents the probability that no uncovered fault occurs. The second term comes from a combinatorial model which includes the covered faults that can lead to system failure. This second term can be computed from any common approach (e.g. fault tree, block diagram, digraph) which ignores the FC concept by slightly altering the component-failure probabilities. The result of this work is that reliability engineers can use their favorite software package (which ignores the FC concept) for computing reliability, and then adjust the input and output of that program slightly to produce a result which includes FC. This method applies to any system for which: the FC probabilities are constant and state-independent; the hazard rates are state-independent; and an FC failure leads to immediate system failure.
TL;DR: In this article, Finite Element analysis of a rotor system for flexural vibrations has been considered by including a shaft with two open cracks and the influence of one crack over the other for eigenfrequencies, mode shapes and for threshold speed limits has been observed.
TL;DR: In this article, a three-stage procedure is adopted combining multi objective optimisation, cluster analysis and multicriterion decision-making (MCDM) methods to select the best compromise irrigation plan in the multi objective context.
TL;DR: In this article, the Pople 6-311G* basis set was used to measure the hardness and polarizability of a molecule around its equilibrium geometry, and it was shown that any nontotally symmetric distortion in bond length or bond angle along the vibrational symmetry coordinates decreases the equilibrium hardness value.
Abstract: Molecular vibrations in ammonia (NH3) and hydrogen sulfide (H2S), and internal rotations in hydrogen peroxide (HOOH), hydrogen thioperoxide (HSOH), hydrogen persulfide (HSSH), and ethylene (C2H4) are studied using ab initio SCF methods at the Hartree−Fock level using a standard Pople 6-311G** basis set. Polarizability values are calculated using both Pople's and Sadlej's basis sets. Any nontotally symmetric distortion in bond length or bond angle along the vibrational symmetry coordinates of a molecule around its equilibrium geometry decreases the equilibrium hardness value and increases the equilibrium polarizability value. During rotational isomerization the minimum energy conformation corresponds to the maximum hardness and minimum polarizability values and the maximum energy conformation corresponds to the minimum hardness and maximum polarizability values. Density functional calculations confirm these observed trends. In general we have found that the conditions of maximum hardness and minimum polari...
TL;DR: In this article, the redox catalytic properties of still growing and final particles of palladium were investigated using methylene blue (MB) and fluorescein (F) as redox probes.
Abstract: The redox catalytic property of still-growing and final particles of palladium has been investigated using methylene blue (MB) and fluorescein (F) as redox probes. Reductions of MB by N2H4 and of F...
TL;DR: Graft copolymers of sodium alginate with polyacrylamide were synthesized using a ceric ion initiated solution polymerization technique at 27±1°C as mentioned in this paper.
TL;DR: In this article, a bioreactor with a perforated float for carrying solid substrate and induced inoculum was used for the synthesis of tannase vis-a-vis gallic acid.
Abstract: Bioconversion of tannin to gallic acid from powder of teri pod (Caesalpinia digyna) cover was achieved by the locally isolated fungus, Rhizopus oryzae, in a bioreactor with a perforated float for carrying solid substrate and induced inoculum. Modified Czapek-Dox medium, put beneath the perforated float, with 2% tannic acid at pH 4.5, temperature 32°C, 93% relative humidity, incubated for 3 days with 3-day-old inoculum was optimum for the synthesis of tannase vis-a-vis gallic acid production. Conversion of tannin to gallic acid was 90.9%. Diethyl ether was used as the solvent for extraction of gallic acid from the fermented biomass.
TL;DR: In this paper, the variation in impact resistance of steel fiber-reinforced concrete and plain concrete as determined from a drop weight test is reported, and the observed coefficients of variation are about 57 and 46% for first-crack resistance and the ultimate resistance in the case of fiber concrete and the corresponding values for plain concrete are 54 and 51%, respectively.
TL;DR: Comparative evaluation of MCDM methods revealed that Compromise Programming is best suited for the present case study and the same preference strategy is reached by all the methods.
TL;DR: The method uses ANN based bus load prediction for the prediction step in the DSE using rectangular coordinate formulation for measurement equations and a second order dynamic state estimator which incorporates the full nonlinearities of the measurement function for the filtering step.
Abstract: This paper presents an algorithm for dynamic state estimation of a power systems. The method uses ANN based bus load prediction for the prediction step in the DSE. The proposed DSE uses rectangular coordinate formulation for measurement equations. A second order dynamic state estimator which incorporates the full nonlinearities of the measurement function is used for the filtering step. The inclusion of nonlinearities makes the proposed state estimator perform better in case of sudden large changes in load/generation.
TL;DR: In this paper, a novel copolyester was synthesized by solution polycondensation of terephthaloyl chloride with 4-[(4-hydroxy-2-pentadecenylphenyl)diazenyl] phenol (HPPDP) and 1,4-butane diol.