Showing papers by "Indian Institute of Technology Guwahati published in 2003"

Classification of ECG arrhythmias using multi-resolution analysis and neural networks

Abstract: Automatic detection and classification of cardiac arrhythmias is important for diagnosis of cardiac abnormalities. We propose a method to accurately classify ECG arrhythmias through a combination of wavelets and artificial neural networks (ANN). The ability of the wavelet transform to decompose signal at various resolutions allows accurate extraction/detection of features from non-stationary signals like ECG. A set of discrete wavelet transform (DWT) coefficients, which contain the maximum information about the arrhythmia, is selected from the wavelet decomposition. These coefficients are fed to the back-propagation neural network which classifies the arrhythmias. The proposed method is capable of distinguishing the normal sinus rhythm and 12 different arrhythmias and is robust against noise. The overall accuracy of classification of the proposed approach is 96.77%.

Peroxovanadium-catalyzed oxidative esterification of aldehydes

Abstract: The peroxovanadium species generated from V(2)O(5) and hydrogen peroxide, which is liberated from peroxy salts such as sodium perborate (SPB) or sodium percarbonate (SPC), transform aldehydes directly into esters in an alcoholic medium. Monoesters of diols have been achieved directly in one pot from aldehydes. High catalytic turnover number combined with inexpensive, easily available reagents and innocuous side products from the reaction make it a suitable alternative for the synthesis of esters from aldehydes.

Synthesis of a Self‐Assembled Molecular Capsule that Traps Pyridine Molecules by a Combination of Hydrogen Bonding and Copper(II) Coordination

Abstract: Molecule and molecular assemblies with cavities of different size and shape to encapsulate guest molecules have been synthesized in view of their potential use as selective hosts for anion sensing, catalysis, selective recognition, and separation of guest molecules.

Rolling element bearing design through genetic algorithms

Abstract: The design of rolling element bearings has been a challenging task in the field of mechanical engineering. While most of the real aspects of the design are never disclosed by bearing manufacturers, the common engineer is left with no other alternative than to refer to standard tables and charts containing the bearing performance characteristics. This paper presents a more viable method to solve this problem using genetic algorithms (GAs). Since the algorithm is basically a guided random search, it weakens the chances of getting trapped in local maxima or minima. The method used has yielded improved performance parameters than those catalogued in standard tables. *Indraneel Chakraborty is currently with Massachusetts Institute of Technology and can be reached at indranil@mit.edu †Vinay Kumar is currently with Mindtree Consulting, India and can be reached at vinayk@mindtree.com

A fuzzy neural network model for deriving the river stage-discharge relationship

Abstract: The measurement of discharge in major rivers is very important and serves as the base information for hydrological analysis. The rating curve is used to assess the discharge from the measured stage values in the gauging sites. The rating curve has important bearing on the correct assessment of discharge. The usefulness of the fuzzy neural network modelling approach in deriving the stage—discharge relationship is discussed. The performances of a neural network model, a modularized neural network model, a conventional curve-fitting approach and a fuzzy neural network model for deriving the rating curve are compared using a case study. Overall, the fuzzy neural network model gives the best results.

Script-based classification of hand-written text documents in a multilingual environment

Abstract: Script-based text document classification is an important field of research in the context of multilingual textual document processing But, all script identification techniques available in the literature so far do not consider handwritten documents Variations in the writing style, character size, inter-line and inter-word spacings, etc make the recognition process difficult and unreliable when these script identification algorithms, more specifically visual appearance based approaches, are applied directly on hand-written documents Therefore, in this paper, we propose to preprocess the input document images so as to compensate for the variations due to writing style and thereby making them suitable for analysis on the basis of their visual appearances Accordingly, we apply denoising, thinning, pruning, m-connectivity and text size normalization in sequence Multi-channel Gabor filtering is used to extract texture features that characterize the visual appearances of the document images Experimental result proves the potentiality of our proposed method of script identification for hand-written text document classification

Polyphenolic Compounds: an Overview

Abstract: A comprehensive review on the polyphenolic compounds is presented. The emphasis is placed on the structural and functional implications on the regiochemistry as well as on the stereochemistry of oligomeric polyphenols. A correlation between the natural polyphenolic compounds and the synthetic ones is highlighted by making a general classification of polyphenolic compounds. The uses and applications of polyphenolic compounds are discussed in detail.

An efficient hardware implementation of DWT and IDWT

Abstract: Real-time applications of discrete wavelet transform (DWT), like video and audio compression, necessitate fast computation of DWT. Full-custom VLSI devices have been used for fast, though expensive, implementations of DWT. Field-programmable gate array (FPGA) architectures offer economical but area-constrained implementation of DWT. The paper proposes an efficient FPGA architecture for DWT as well as inverse DWT (IDWT). Use of distributed arithmetic allows us to do without area-consuming multipliers in the present realization. The proposed architecture is modular and allows extension to any precision without much effect on the clock frequency. Simulation results have established that the proposed fast implementation scheme can produce high-quality reconstructed signals.

A neural network based methodology for the prediction of roll force and roll torque in fuzzy form for cold flat rolling process

Abstract: Neural network models can be effectively used to predict any type of functional relationship. In this paper, a neural network model is used to predict roll force and roll torque in a cold flat rolling process, as a function of various process parameters. A strategy is developed to obtain a prescribed accuracy of prediction with a minimum number of data for training and testing. The effect of increasing the size of training and testing data set is also examined. After the prediction of most likely value, upper and lower bound estimates are also found with the help of the neural network. With these estimates, the predicted value can be represented as a fuzzy number for use in fuzzy-logic based systems.

Nonlinear Dynamics of a Cantilever Beam Carrying an Attached Mass with 1:3:9 Internal Resonances

Abstract: In this paper the nonlinear response of a base-excited slender beam carrying an attached mass is investigated with 1:3:9 internal resonances for principal and combinationparametric resonances. Here the method of normal forms is used to reduce the second order nonlinear temporal differential equation of motion of the system to a set offirst order nonlinear differential equations which are used to find the fixed-point, periodic, quasi-periodic and chaotic responses of the system.Stability and bifurcation analysis of the responses are carried out and bifurcation sets are plotted. Many chaotic phenomena are reported in this paper.

Simultaneous combination and 1:3:5 internal resonances in a parametrically excited beam–mass system

Abstract: The nonlinear dynamics of a base-excited slender beam carrying a lumped mass subjected to simultaneous combination parametric resonance of sum and difference type along with 1:3:5 internal resonances is investigated. Method of normal form is applied to the governing nonlinear temporal differential equation of motion to obtain a set of first-order differential equations which are used to obtain the steady-state, periodic, quasi-periodic and chaotic responses for different control parameters viz., amplitude and frequency of external excitation and damping. Frequency response, phase portraits, time spectra and bifurcation diagram are plotted to visualize the system behaviour with variation in the control parameters. Here, two distinct zones of trivial instability, blue sky catastrophe phenomena, jump down phenomena, simultaneous occurrence of periodic and chaotic orbits, period doubling of the mixed-mode periodic orbits leading to chaos, attractor merging crisis, boundary crisis, type II and on–off intermittencies are observed. Bifurcation diagram is plotted to facilitate the designer to choose a safe operating zone.

Adducts of 2-Hydroxyethylphthalimide with 1,3-Dihydroxybenene and 1,3,5-Trihydroxybenzene

Abstract: A new class of adducts from 2-hydroxyethylphthalimide with 1,3-dihydroxybenzene and 1,3,5-trihydroxybenzene as a basis for interesting supramolecular-layered architectures through donor acceptor interactions and linkers is discussed.

Vector median filter for removal of impulse noise from color images

Abstract: This paper presents a vector median filter that incorporates mechanism for the detection of impulses from color images. The vector pixels in a specified window is ranked on the basis of sum of the distances to other vector pixels in the window. The center vector pixel is declared as corrupted if its rank is bigger than a predefined rank and its distance from a nearby healthy vector pixel is bigger than a pre-defined threshold. The corrupted vector pixel is replaced by the vector median. The experimental results show the better performance of the proposed method than a number of existing schemes for color images corrupted by high percentage of fixed-valued and random-valued impulse noises.

Strange permutation representations of free groups

Abstract: Certain permutation representations of free groups are constructed by finite approximation. The first is a construction of a cofinitary group with special properties, answering a question of Tim Wall published by Cameron. The second yields, via a method of Kepert and Willis, a totally disconnected locally compact group which is compactly generated and uniscalar but has no compact open normal subgroup. Finally, an oligomorphic group of automorphisms of the random graph is built, all of whose non-trivial subgroups have just finitely many orbits.

Fabrication of submicron scale patterned plastic thin film fluidic devices with controllable thickness

Abstract: We present a soft-lithography based method to fabricate plastic thin film fluidic devices on glass and plastic substrates. Principles of soft-lithography and spin casting were used to generate the films. The thickness of these films is controllable and the patterns we have generated have submicron scale dimensions. By using commercially available compact disc (CD) components as molds, we have been able to generate parallel line and cross patterns on these thin films. These patterned films could be lifted from the substrates and further folded into rolls.

A new watershed algorithm based on hillclimbing technique for image segmentation

Abstract: The present paper proposes a fast watershed transform based on hillclimbing technique. The complexity of the algorithm has been reduced by doing away with multiplication normally required to form a lower complete image in an intermediate step of the overall segmentation process. Its moderate complexity makes it amenable to dedicated hardware implementation. The results of running both the proposed and the conventional algorithm on different test images clearly establish the superiority of the proposed algorithm. A prototype FPGA-based architecture for the proposed algorithm has also been developed. The FPGA implementation results show acceptable performance of the proposed architecture.