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Search Results: 1 - 10 of 144457 matches for " B; Ponnusamy "
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An Effective Distributed Model for Power System Transient Stability Analysis
MUTHU, B. M.,VEILUMUTHU, R.,PONNUSAMY, L.
Advances in Electrical and Computer Engineering , 2011, DOI: 10.4316/aece.2011.03012
Abstract: The modern power systems consist of many interconnected synchronous generators having different inertia constants, connected with large transmission network and ever increasing demand for power exchange. The size of the power system grows exponentially due to increase in power demand. The data required for various power system applications have been stored in different formats in a heterogeneous environment. The power system applications themselves have been developed and deployed in different platforms and language paradigms. Interoperability between power system applications becomes a major issue because of the heterogeneous nature. The main aim of the paper is to develop a generalized distributed model for carrying out power system stability analysis. The more flexible and loosely coupled JAX-RPC model has been developed for representing transient stability analysis in large interconnected power systems. The proposed model includes Pre-Fault, During-Fault, Post-Fault and Swing Curve services which are accessible to the remote power system clients when the system is subjected to large disturbances. A generalized XML based model for data representation has also been proposed for exchanging data in order to enhance the interoperability between legacy power system applications. The performance measure, Round Trip Time (RTT) is estimated for different power systems using the proposed JAX-RPC model and compared with the results obtained using traditional client-server and Java RMI models.
Effect of Magnesium on the Mechanical and Bioactive Properties of Biphasic Calcium Phosphate  [PDF]
Ponnusamy Kanchana, Chinnathambi Sekar
Journal of Minerals and Materials Characterization and Engineering (JMMCE) , 2012, DOI: 10.4236/jmmce.2012.1110099
Abstract: Incorporation of trace elements into calcium phosphate structure is of great interest for the development of artificial bone implants. Biphasic calcium phosphate (BCP) composed of hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP) have been synthesized in the presence of magnesium (5 M% - 20 M%) by gel method under physiological conditions. Crystallization of Mg-BCP in the gel medium mimics the Mg intake in the human body. Powder X-ray dif- fraction and Fourier transform infrared analyses confirmed that the Mg doping leads to the enrichment of β-TCP phase and suppresses the HA content in BCP. Nanoindentation studies indicate a significant decrease in hardness and elastic modulus values of BCP due to Mg doping. In vitro bioactivity study has confirmed the formation of apatite layer on the Mg doped samples making it suitable for bone replacement. The results suggest that the optimum Mg doping promotes the bioactivity which is perquisite for biomedical applications.
On Some Problems of James Miller
Bhowmik,B; Ponnusamy,S; Wirths,K.-J;
Cubo (Temuco) , 2010, DOI: 10.4067/S0719-06462010000100003
Abstract: we consider the class of meromorphic univalent functions having a simple pole at and that map the unit disc onto the exterior of a domain which is starlike with respect to a point . we denote this class of functions by . in this paper, we find the exact region of variability for the second taylor coefficient for functions in . in view of this result we rectify some results of james miller.
On Some Problems of James Miller
B Bhowmik,S Ponnusamy,K.-J Wirths
Cubo : A Mathematical Journal , 2010,
Abstract: We consider the class of meromorphic univalent functions having a simple pole at and that map the unit disc onto the exterior of a domain which is starlike with respect to a point . We denote this class of functions by . In this paper, we find the exact region of variability for the second Taylor coefficient for functions in . In view of this result we rectify some results of James Miller. Consideramos la clase de funciones univalentes meromoforficos teniendo un polo simple en y la aplicación del disco unitario sobre el exterior de un dominio el cual es estrellado con respecto al punto . Denotamos esta clase de funciones por . En este artículo encontramos la región exacta de variabilidad del segundo coeficiente de Taylor para funciones in . En vista de estos resultados nosotros rectificamos algunos resultados de James Miller.
On the Fekete-Szeg? problem for concave univalent functions
B. Bhowmik,S. Ponnusamy,K-J. Wirths
Mathematics , 2010,
Abstract: We consider the Fekete-Szeg\"o problem with real parameter $\lambda$ for the class $Co(\alpha)$ of concave univalent functions.
Domains of variability of Laurent coefficients and the convex hull for the family of concave univalent functions
B. Bhowmik,S. Ponnusamy,K-J. Wirths
Mathematics , 2010,
Abstract: Let $\ID$ denote the open unit disc and let $p\in (0,1)$. We consider the family $Co(p)$ of functions $f:\ID\to \overline{\IC}$ that satisfy the following conditions: \bee \item[(i)] $f$ is meromorphic in $\ID$ and has a simple pole at the point $p$. \item[(ii)] $f(0)=f'(0)-1=0$. \item[(iii)] $f$ maps $\ID$ conformally onto a set whose complement with respect to $\overline{\IC}$ is convex. \eee We determine the exact domains of variability of some coefficients $a_n(f)$ of the Laurent expansion $$f(z)=\sum_{n=-1}^{\infty} a_n(f)(z-p)^n,\quad |z-p|<1-p, $$ for $f\in Co(p)$ and certain values of $p$. Knowledge on these Laurent coefficients is used to disprove a conjecture of the third author on the closed convex hull of $Co(p)$ for certain values of $p$.
Characterization and the pre-Schwarzian norm estimate for concave univalent functions
B. Bhowmik,S. Ponnusamy,K-J. Wirths
Mathematics , 2010,
Abstract: Let $Co(\alpha)$ denote the class of concave univalent functions in the unit disk $\ID$. Each function $f\in Co(\alpha)$ maps the unit disk $\ID$ onto the complement of an unbounded convex set. In this paper we find the exact disk of variability for the functional $(1-|z|^2)\left ( f''(z)/f'(z)\right)$, $f\in Co(\alpha)$. In particular, this gives sharp upper and lower estimates for the pre-Schwarzian norm of concave univalent functions. Next we obtain the set of variability of the functional $(1-|z|^2)\left(f''(z)/f'(z)\right)$, $f\in Co(\alpha)$ whenever $f''(0)$ is fixed. We also give a characterization for concave functions in terms of Hadamard convolution. In addition to sharp coefficient inequalities, we prove that functions in $Co(\alpha)$ belong to the $H^p$ space for $p<1/\alpha$.
On some problems of James Miller
B. Bhowmik,S. Ponnusamy,K-J. Wirths
Mathematics , 2010,
Abstract: We consider the class of meromorphic univalent functions having a simple pole at $p\in(0,1)$ and that map the unit disc onto the exterior of a domain which is starlike with respect to a point $w_0 \neq 0,\, \infty$. We denote this class of functions by $\Sigma^*(p,w_0)$. In this paper, we find the exact region of variability for the second Taylor coefficient for functions in $\Sigma^*(p,w_0)$. In view of this result we rectify some results of James Miller.
Three-dimensional dispersion analysis of homogeneous transversely isotropic thermo elastic solid bar of polygonal cross-sections immersed in fluid
P Ponnusamy
International Journal of Engineering, Science and Technology , 2011,
Abstract: The problem of wave propagation in an infinite, homogeneous, transversely isotropic thermo elastic polygonal cross-sectional bar immersed in fluid is studied using Fourier expansion collocation method, with in the framework of linearized, three dimensional theory of thermoelasticity. Three displacement potential functions are introduced, to uncouple the equations of motion and the heat conduction. The frequency equations are obtained for longitudinal and flexural (symmetric and antisymmetric) modes of vibration and are studied numerically for triangular, square, pentagonal and hexagonal cross- sectional Zinc bar. The computed non-dimensional wave numbers are presented in the form of dispersion curves.
Bacteria Stimulate Hatching of Yellow Fever Mosquito Eggs
Loganathan Ponnusamy, Katalin B?r?czky, Dawn M. Wesson, Coby Schal, Charles S. Apperson
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0024409
Abstract: Background Aedes aegypti Linnaeus is a peridomestic mosquito that lays desiccation-resistant eggs in water-filled human-made containers. Previous investigations connected egg hatching with declining dissolved oxygen (DO) that is associated with bacterial growth. However, past studies failed to uncouple DO from other potential stimulatory factors and they contained little quantitative information about the microbial community; consequently, a direct role for bacteria or compounds associated with bacteria in stimulating egg hatching cannot be dismissed. Methodology/Principal Findings Environmental factors stimulating hatch of Ae. aegypti eggs were investigated using non-sterile and sterile white oak leaf (WOL) infusions and a bacterial culture composed of a mix of 14 species originally isolated from bamboo leaf infusion. In WOL infusion with active microbes, 92.4% of eggs hatched in 2-h at an average DO concentration of 2.4 ppm. A 24-h old bacterial culture with a DO concentration of 0.73 ppm also stimulated 95.2% of eggs hatch within 1-h. In contrast, only 4.0% of eggs hatched in sterile infusion, whose DO averaged 7.4 ppm. Effects of bacteria were uncoupled from DO by exposing eggs to bacterial cells suspended in NaCl solution. Over a 4-h exposure period, 93.8% of eggs hatched while DO concentration changed minimally from 7.62 to 7.50 ppm. Removal of bacteria by ultra-filtration and cell-free filtrate resulted in only 52.0% of eggs hatching after 4-h at an average DO concentration of 5.5 ppm. Conclusions/Significance Collectively, the results provide compelling evidence that bacteria or water-soluble compounds secreted by bacteria, not just low DO concentration, stimulate hatching of Ae. aegypti eggs. However, the specific cues involved remain to be identified. These research findings contribute new insight into an important aspect of the oviposition biology of Ae. aegypti, a virus vector of global importance, providing the basis for a new paradigm of environmental factors involved in egg hatching.
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