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569 results on '"Neogy, S."'

103. On generalizations of positive subdefinite matrices and the linear complementarity problem.

Author

Dubey, Dipti and Neogy, S. K.

Subjects
*MATRICES (Mathematics), *LINEAR complementarity problem, *VECTOR fields, *QUADRATIC programming, *LINEAR programming
Abstract

In this paper, we introduce the notion of generalized positive subdefinite matrices of level k by generalizing the definition of generalized positive subdefinite matrices introduced by Crouzeix and Komlósi in [Applied optimization. Vol. 59, Dordrecht: Kluwer Academic Publications; 2001. p. 45-63]. The main motivation behind this generalization is to identify new subclasses of row sufficient matrices [Cottle, Pang and Venkateswaran, Linear Algebra Appl. 1989;114/115:231-249] which are not a subclass of copositive matrices. We establish new sufficient conditions for a matrix to be a non-copositive matrix and a non-copositive row sufficient matrix using the notion of generalized positive subdefinite matrices of level k. We present a new termination result for Lemke’s algorithm which supplements Jones’ result [Math Program. 1986;35:239-242]. [ABSTRACT FROM AUTHOR]

Published
2018
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104. A viscoelastic Timoshenko shaft finite element for dynamic analysis of rotors.

Author

Ganguly, Smitadhi, Nandi, A., and Neogy, S.

Subjects
VISCOELASTICITY, ROTOR dynamics, SHEAR (Mechanics), FINITE element method, DEFORMATIONS (Mechanics), MECHANICAL loads
Abstract

A new shaft element is proposed for viscoelastic rotors in a spinning frame considering the shear deformation in addition to bending deformation. The Maxwell–Wiechert model is considered here to replicate linear viscoelastic behavior. This model considers additional internal damping displacement variables between elastic and viscous elements and the stress depends not only on the elastic strain and elastic strain rate, but also on additional strains and their rates corresponding to the damping variables. The present work assumes that these additional strains can be derived from continuous fictitious displacement variables, which in turn are interpolated from their nodal values using the Timoshenko beam shape functions. Therefore, in addition to the standard degrees of freedom for a three-dimensional shaft, extra degrees of freedom are defined at the nodes. The finite element matrices are assembled in state space. The time domain equations are then used for stability analysis and computation of response to a unit step load and an unbalance. [ABSTRACT FROM AUTHOR]

Published
2018
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105. Synthesis, characterisation and structural aspects of some symmetrical organotellurium halides based on <italic>Bis</italic>(2-(3,5-dimethyl-1H-pyrazol-1-yl)ethyl)telluride.

Author

Bhasin, K. K., Pundir, S., Neogy, S., Mehta, D., and Mehta, S. K.

Subjects
TELLURIDES, TELLURIUM, ORGANOTELLURIUM compounds, HALIDES, ELECTRON diffraction, X-ray fluorescence, AQUEOUS solutions, MASS spectrometry
Abstract

Bis(2-(3,5-dimethyl-1H-pyrazol-1-yl)ethyl)telluride (2) has been synthesised in good yield by reacting 1-(2-chloroethyl)-3,5-dimethylpyrazole with in situ prepared sodium telluride, Na2Te in an aqueous solution. A number of new organotellurium halides from bis(2-(3,5-dimethyl-1H-pyrazol-1-yl)ethyl)telluride have been synthesised by using different halogenating reagents. Reaction of 2 with bromine gave bis(2-(3,5-dimethyl-1H-pyrazol-1-yl)ethyl)telluride dibromide (5a) in addition to unexpected product bis(2-(4-bromo-3,5-dimethyl-1H-pyrazol-1-yl)ethyl)telluride dibromide (5b). All compounds were characterized by different spectroscopic techniques viz., 1H, 13C, 125Te NMR, Mass spectroscopy, IR and CHN analysis. EDXRF studies have also been employed to confirm the identity of 5a and 5b. Thermal gravimetric analysis of bis(2-(3,5-dimethyl-1H-pyrazol-1-yl)ethyl)telluride (IV) chloride (4) and bis(2-(3,5-dimethyl-1H-pyrazol-1-yl)ethyl)telluride (IV) iodide (5c) reveals the thermal stability of these molecules above 100°C. The X-ray studies of 5c shows trigonal bipyramidal geometry around tellurium atom and intermolecular secondary interaction viz., C-H π stacking between H23A and C22 showing a supramolecular packing between two molecules. [ABSTRACT FROM AUTHOR]

Published
2018
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106. Completely Mixed Strategies for Two Structured Classes of Semi-Markov Games, Principal Pivot Transform and Its Generalizations.

Author

Mondal, P., Neogy, S., Sinha, S., and Ghorui, D.

Subjects
*MARKOV processes, *GENERALIZATION, *LINEAR complementarity problem, *MATRICES (Mathematics), *ALGORITHMS
Abstract

In this article, we revisit the applications of principal pivot transform and its generalization for a rectangular matrix (in the context of vertical linear complementarity problem) to solve some structured classes of zero-sum two-person discounted semi-Markov games with finitely many states and actions. The single controller semi-Markov games have been formulated as a linear complementarity problem and solved using a stepwise principal pivoting algorithm. We provide a sufficient condition for such games to be completely mixed. The concept of switching controller semi-Markov games is introduced and we prove the ordered field property and the existence of stationary optimal strategies for such games. Moreover, such games are formulated as a vertical linear complementarity problem and have been solved using a stepwise generalized principal pivoting algorithm. Sufficient conditions are also given for such games to be completely mixed. For both these classes of games, some properties analogous to completely mixed matrix games, are established. [ABSTRACT FROM AUTHOR]

Published
2017
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110. Preface

Author

Neogy, S. K., primary, Parthasarathy, T., additional, and Das, A. K., additional

Published
2015
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118. Effect of cracks on the natural frequency of cantilevered plates - A Rayleigh-Ritz solution

Author

Ramamurti, V. and Neogy, S.

Subjects
Failure analysis, Mathematical models, Cantilevered plates, Rayleigh-Ritz methods, Crack propagation, Computer simulation, Turbomachine blades, Natural frequencies
Abstract

The possibility of cracks appearing in the blades of turbo machines cannot be ruled out. The failure of this critical component may occur due to the presence of cracks. The feasibility of natural frequency being considered as a criterion for damage detection has been investigated. As a first step toward this goal, the natural frequency being considered as a criterion for damage detection has been investigated. As a first step toward this goal, the natural frequency of the cracked blade is estimated by the generalized Rayleigh-Ritz method using simplifying assumptions. The paper concludes that natural frequency does not appear to be an appropriate criterion for integrity analysis as far as the simplified model is concerned, but recommends further in-depth study using completely numerical and experimental methods before reaching a firm conclusion.

Published
1998

124. Texture and Microstructure Development during Swaging and Annealing Process of Fabrication of Zircaloy-4 Rod Products

Author

Neogy, S., primary, Acharya, S., additional, Mani Krishna, Karri V., additional, Srivastava, Dinesh, additional, Dey, G.K., additional, Phani Babu, C., additional, Das, Gourahari, additional, Raut, B., additional, Chaube, R.K., additional, Jha, S.K., additional, Prahlad, B., additional, Saibaba, N., additional, Kumar, A., additional, and Samajdar, Indradev, additional

Published
2011
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