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1
Content available remote A new baroreflex sensitivity index based on improved Hilbert–Huang transform for assessment of baroreflex in supine and standing postures
Singh A., Saini B. S., Singh D.
Biocybernetics and Biomedical Engineering
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2016
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Vol. 36, no. 2
355--365
EN
The aim of this study is to propose a new baroreflex sensitivity (BRS) index using improved Hilbert–Huang transform (HHT) using weighted coherence (CW) criterion and apply it to assess baroreflex in supine and standing postures. Improved HHT is obtained by addressing the mode mixing and end effect problems associated with empirical mode decomposition which is a required step in the computation of HHT and thus mitigating the unwanted low frequency component from the power spectrum. This study was first performed on synthetic signals generated using integral pulse frequency model and further extended to real RR interval and systolic blood pressure records of 50 healthy subjects, 20 post acute myocardial infarction patients undergoing postural stress from supine to standing position. Evaluation is also performed on standard EuroBaVar database, comprising of 21 subjects, under supine and standing positions. The results are (i) enhanced values of supine-to-standing low frequency BRS index (α-LF) equal to 1.78 and high frequency BRS index (α-HF) equal to 2.48 are obtained using improved HHT compared to standard HHT (α-LF = 1.54, α-HF = 2.36) and traditional power spectral density (α-LF = 1.55, α-HF = 2.34) for healthy subjects, (ii) there is an increased rate of change of LF/HF power ratios from supine to standing positions, and (iii) number of BRS responses obtained using CW criterion are greater than those obtained by using mean coherence criterion. In conclusion, the new BRS index takes into consid-eration the non-linear nature of interactions between heart rate variability and systolic blood pressure variability.
2
Content available Optimality conditions in multiobjective programming problems with interval valued objective functions
Ahmad I., Singh D., Dar B. A.
Control and Cybernetics
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2015
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Vol. 44, no. 1
19--45
EN
We devote this paper to study of multiobjective programming problems with interval valued objective functions. For this, we consider two order relations LU and LS on the set of all closed intervals and propose several concepts of Pareto optimal solutions and generalized convexity. Based on generalized convexity (viz. LU and LS-pseudoconvexity) and generalized differentiability (viz. gHdifferentiablity) of interval valued functions, the KKT optimality conditions for aforesaid problems are obtained. The theoretical development is illustrated by suitable examples.
3
Content available remote Thermomechanical interactions due to laser pulse in microstretch thermoelastic medium
Kumar R., Kumar A., Singh D.
Archives of Mechanics
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2015
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Vol. 67, nr 6
439--456
EN
The present investigation deals with deformation in microstretch generalized thermoelastic medium subjected to thermomechanical loading induced by thermal laser pulse. The Laplace and Fourier transform techniques are used to solve the problem, and concentrated normal force and thermal source describe the application of this approach. The closed form expressions of normal stress, tangential stress, couple stress, microstress and temperature distribution are obtained for the transferred domain. The numerical inversion technique of Laplace transform and Fourier transform has been applied to obtain the resulting quantities in the physical domain after developing a computer program. Normal stress, tangential stress, coupled stress and microstress temperature distribution are depicted graphically to show the microstretch effect. Some particular and special cases of interest are gathered and presented in the investigation.
4
Content available remote Rδ-supercontinuous functions
Kohli J. K., Tyagi B. K., Singh D., Aggarwal J.
Demonstratio Mathematica
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2014
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Vol. 47, nr 2
433--448
EN
A new class of functions called ‘Rδ-supercontinuous functions’ is introduced. Their basic properties are studied and their place in the hierarchy of strong variants of continuity which already exist in the literature is elaborated. The class of Rδ-supercontinuous functions (Math. Bohem., to appear) properly contains the class of Rz-supercontinuous functions which in its turn properly contains the class of Rcl-supercontinuous functions (Demonstratio Math. 46(1) (2013), 229–244) and so includes all cl-supercontinuous (=clopen continuous) functions (Applied Gen. Topol. 8(2) (2007), 293–300; Indian J. Pure Appl. Math. 14(6) (1983), 767–772) and is properly contained in the class of R-supercontinuous functions (Demonstratio Math. 43(3) (2010), 703–723).
5
Content available remote Small Signal Stability Analysis of Six-phase Synchronous Generator
Singh G. K., Singh D.
Przegląd Elektrotechniczny
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2013
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R. 89, nr 6
76--82
EN
In the present work, a higher order linearized model has been developed to assess the small signal excursion characteristics of an asymmetrical six-phase synchronous generator system connected to infinite bus using eigenvalue criterion. The stability of the system under small perturbation of different variables has been examined from the placement of eigenvalues. The work establishes an association between generator and loading parameters with pair of eigenvalues, thus the system stability. Further a participation factor analysis has also been carried out to identify the effect of dynamic state variable on a given mode or eigenvalue.
PL
W artykule zaprezentowano linearyzowany model wyższego rzędu umożliwiający analizę asymetrycznego sześciofazowego generatora asynchronicznego podłączonego do nieskończonej linii. Badano stabilność systemu przy małych zakłóceniach.
6
Content available remote Rcl-supercontinuous functions
Tyagi B. K., Kohli J. K., Singh D.
Demonstratio Mathematica
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2013
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Vol. 46, nr 1
229--244
EN
A new class of functions called ‘Rcl-supercontinuous functions’ is introduced. Their basic properties are studied and their place in the hierarchy of strong variants of continuity that already exist in the literature is elaborated. The class of Rcl-supercontinuous functions properly contains the class of cl-supercontinuous (≡ clopen continuous) functions (Applied Gen. Topology 8(2) (2007), 293–300; Indian J. Pure Appl. Math. 14(6) (1983), 767–772) and is strictly contained in the class of Rδ-supercontinuous functions which in its turn, is properly contained in the class of R-supercontinuous functions (Demonstratio Math. 43(3) (2010), 703–723).
7
Content available remote Between local connectedness and sum connectedness
Kohli J. K., Singh D., Tyagi B. K.
Commentationes Mathematicae
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2013
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Vol 53, No. 1
3--16
EN
A new generalization of local connectedness called Z-local connectedness is introduced. Basic properties of Z-locally connected spaces are studied and their place in the hierarchy of variants of local connectedness, which already exist in the literature, is elaborated. The class of Z-locally connected spaces lies strictly between the classes of pseudo locally connected spaces (Commentations Math. 50(2)(2010),183-199) and sum connected spaces ( weakly locally connected spaces) (Math. Nachrichten 82(1978), 121-129; Ann. Acad. Sci. Fenn. AI Math. 3(1977), 185- 205) and so contains all quasi locally connected spaces which in their turn contain all almost locally connected spaces introduced by Mancuso (J. Austral. Math. Soc. 31(1981), 421-428). Formulations of product and subspace theorems for Z-locally connected spaces are suggested. Their preservation under mappings and their interplay with mappings are discussed. Change of topology of a Z-locally connected space is considered so that it is simply a locally connected space in the coarser topology. It turns out that the full subcategory of Z-locally connected spaces provides another example of a mono-coreflective subcategory of TOP which properly contains all almost locally connected spaces.
8
Content available remote R-supercontinuous functions
Kohli J. K., Singh D., Aggarwal J.
Demonstratio Mathematica
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2010
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Vol. 43, nr 3
703-723
EN
A new strong variant of continuity called 'R-supercontinuity' is introduced. Basic properties of R-supercontinuous functions are studied and their place in the hierarchy of strong variants of continuity that already exist in the literature is elaborated. It is shown that R-supercontinuity is preserved under the restriction, shrinking and expansion of range, composition of functions, products and the passage to graph function. The class of R-supercontinuous functions properly contains each of the classes of (i) strongly (...)-continuous functions introduced by Noiri and also studied by Long and Herrington; (ii) D-supercontinuous functions; and (iii) F-supercontinuous functions; and so include all z-supercontinuous functions and hence all clopen maps ((...) cl-supercontinuous functions) introduced by Reilly and Vamnamurthy, perfectly continuous functions defined by Noiri and strongly continuous functions due to Levine. Moreover, the notion of r-quotient topology is introduced and its interrelations with the usual quotient topology and other variants of quotient topology in the literature are discussed. Retopologization of the domain of a function satisfying a strong variant of continuity is considered and interrelations among various coarser topologies so obtained are observed.
9
Content available remote Quasi Locally Connected Spaces and Pseudo Locally Connected Spaces
Kohli J. K., Singh D., Tyagi B. K.
Commentationes Mathematicae
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2010
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Vol. 50, [Z] 2
183-199
EN
Two new generalizations of locally connected spaces called "quasi locally connected spaces" and "pseudo locally connected spaces" are introduced and their basic properties are studied. The class of quasi locally connected spaces properly contains the class of almost locally connected spaces (J. Austral. Math. Soc. 31(1981), 421–428) and is strictly contained in the class of pseudo locally connected spaces which in its turn is properly contained in the class of sum connected spaces (Math.Nachrichten 82(1978), 121-129; Ann. Acad. Sci. Fenn. A I Math. 3(1977), 185–205). Product and subspace theorems for quasi (pseudo) locally connected spaces are discussed. Their preservation under mappings and their interplay with mappings are outlined. Function spaces of quasi (pseudo) locally connected spaces are considered. Change of topology of a quasi (pseudo) locally connected space is considered so that it is simply a locally connected space in the coarser topology. In contradistinction with almost locally connected spaces, quasi (pseudo) locally connected spaces constitute a coreflective subcategory of TOP.
10
Content available remote Perfectly continuous functions
Kohli J., Singh D.
Demonstratio Mathematica
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2009
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Vol. 42, nr 1
221-231
EN
A new class of functions called [...]perfectly continuous functions is introduced and their basic properties are studied. Their place in the hierarchy of other variants of continuity that already exist in the literature is elaborated. Further, it is shown that if X is sum connected (e.g. connected or locally connected) and Y is Hausdorff, then the function space PA (X, Y] of all (...]-perfectly continuous functions from X into Y is closed in Yx in the topology of pointwise convergence.
11
Content available remote On a sum form functional equation related to entropies and some moments of a discrete random variable
Nath P., Singh D.
Demonstratio Mathematica
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2009
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Vol. 42, nr 1
83-96
EN
The general solutions of a sum form functional equation have been obtained. The importance of its solutions in relation to the entropies and some moments of a discrete random variable has been discussed.
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