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Search Results: 1 - 10 of 329 matches for " Venugopal Chandu "
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Kadomstev-Petviashvilli-Burgers (KPB) Equation in a Five Component Cometary Plasma with Kappa Described Electrons and Ions  [PDF]
Manesh Michael, Sreekala Gopinathan, Sijo Sebastian, Neethu T. Willington, Anu Varghese, Renuka Gangadharan, Chandu Venugopal
Journal of Applied Mathematics and Physics (JAMP) , 2015, DOI: 10.4236/jamp.2015.311171
Abstract: We investigate the existence of Ion-Acoustic solitary/shock waves in a five component cometary plasma consisting of positively and negatively charged oxygen ions, kappa described hydrogen ions, hot electrons and cold electrons. The KPB equation is derived for the system; its solution is plotted for different kappa values, as well as for the temperature ratios of ions. It is found that the amplitude of solitary structure increases with increasing kappa values and negatively charged oxygen ion densities. As the temperature of the positively charged oxygen ions increases, the amplitude of solitary wave also increases. We have also studied the dependence of coefficients of the KPB equation on physical parameters relevant to comet Halley.
Ion-Acoustic Instabilities in a Multi-Ion Plasma
Noble P. Abraham,Sijo Sebastian,G. Sreekala,R. Jayapal,C. P. Anilkumar,Venugopal Chandu
Journal of Astrophysics , 2013, DOI: 10.1155/2013/838534
Abstract: We have, in this paper, studied the stability of the ion-acoustic wave in a plasma composed of hydrogen, positively and negatively charged oxygen ions, and electrons, which approximates very well the plasma environment around a comet. Modelling each cometary component ( , , and ) by a ring distribution, we find that ion-acoustic waves can be generated at frequencies comparable to the hydrogen ion plasma frequency. The dispersion relation has been solved both analytically and numerically. We find that the ratio of the ring speed ( ) to the thermal spread ( ts) modifies the dispersion characteristics of the ion-acoustic wave. The contrasting behaviour of the phase velocity of the ion-acoustic wave in the presence of ions for ts (and vice versa) can be used to detect the presence of negatively charged oxygen ions and also their thermalization. 1. Introduction Low-frequency electrostatic or longitudinal ion density waves are one of the most fundamental of oscillations in a plasma [1, 2]. In the long-wavelength limit, the ions provide the inertia with the electrons as the source of the restoring force [1]. Ion-acoustic waves also exhibit strong nonlinear properties and are highly Landau damped unless , where and are, respectively, the ion and electron temperatures [3–5]. These waves have been observed in both space and laboratory plasmas; they have thus been extensively studied in many types of high-temperature laboratory plasmas [4, 6]. The waves have been invoked to explain wave characteristics observed in Earth’s ionosphere [7] and transport in the solar wind, corona, chromosphere [8], and comets [9]. In general a cometary environment contains new born hydrogen and heavier ions, with relative densities depending on the distance from the nucleus. Previous studies have concentrated on positively charged oxygen as the heavier ion species [10]. However, Giotto’s observations of the inner coma of comet Halley showed that a new component, namely, negatively charged cometary ions was present, in addition to the usual thermal electrons and ions, fast cometary pickup ions, and so forth, [11]. These negative ions were observed in three broad mass peaks at 7–19, 22–65, and 85–110 amu with being identified unambiguously [11]. A popular model of a cometary environment is the solar wind plasma environment permeated by dilute, drifting ring distribution of electrons and ions with finite thermal spreads [10]. Instabilities driven by an electron velocity ring distributions have been studied by many authors [12–14]. However, ion ring distributions are more important
Negatively Charged Oxygen Ions as a Plasma Diagnostic Tool: Application to Comets  [PDF]
Sreekala Gopinathan, Sijo Sebastian, Noble Abraham, Savithri Devi, Venugopal Chandu, Renuka Gangadharan
Open Access Library Journal (OALib Journal) , 2014, DOI: 10.4236/oalib.1100570
Abstract: We study the stability of the ion-acoustic (IA) wave in a collisional plasma composed of hydrogen, positively and negatively charged oxygen ions, electrons and neutral atoms. This composition approximates very well the plasma environment around a comet. A solution of the dispersion relation yields a frequency for the IA wave at around the hydrogen plasma frequency. The growth/ damping rate is sensitively dependent on the ring parameters u⊥s (the ring speed) and v ts (the thermal spread). The growth rate of the wave, which decreases with increasing collisional frequencies, is larger when u⊥s < v ts . In the presence of negatively charged oxygen ions, the phase and group velocities of the IA wave behave in a contrasting manner when u⊥s < v ts (and viceversa). We propose that this behaviour be exploited as a diagnostic tool for the detection of these ions and also their thermalization.
A Parallel Genetic Algorithm for Three Dimensional Bin Packing with Heterogeneous Bins
Drona Pratap Chandu
Computer Science , 2014, DOI: 10.14445/22312803/IJCTT-V17P108
Abstract: This paper presents a parallel genetic algorithm for three dimensional bin packing with heterogeneous bins using Hadoop Map-Reduce framework. The most common three dimensional bin packing problem which packs given set of boxes into minimum number of equal sized bins is proven to be NP Hard. The variation of three dimensional bin packing problem that allows heterogeneous bin sizes and rotation of boxes is computationally more harder than common three dimensional bin packing problem. The proposed Map-Reduce implementation helps to run the genetic algorithm for three dimensional bin packing with heterogeneous bins on multiple machines parallely and computes the solution in relatively short time.
A Parallel Genetic Algorithm for Generalized Vertex Cover Problem
Drona Pratap Chandu
Computer Science , 2014,
Abstract: This paper presents a parallel genetic algorithm for generalised vertex cover problem (GVCP) using Hadoop Map-Reduce framework. The proposed Map-Reduce implementation helps to run the genetic algorithm for generalized vertex cover problem (GVCP) on multiple machines parallely and computes the solution in relatively short time.
Big Step Greedy Algorithm for Maximum Coverage Problem
Drona Pratap Chandu
Computer Science , 2015,
Abstract: This paper proposes a greedy heuristic named as Big step greedy heuristic and investigates the application of Big step greedy heuristic for maximum k-coverage problem. Greedy algorithms construct the solution in multiple steps, the classical greedy algorithm for maximum k-coverage problem, in each step selects one set that contains the greatest number of uncovered elements. The Big step greedy heuristic, in each step selects p (1 <= p <= k) sets such that the union of selected p sets contains the greatest number of uncovered elements by evaluating all possible p-combinations of given sets. When p=k Big step greedy algorithm behaves like exact algorithm that computes optimal solution by evaluating all possible k-combinations of given sets. When p=1 it behaves like the classical greedy algorithm.
Improved Greedy Algorithm for Set Covering Problem
Drona Pratap Chandu
Computer Science , 2015,
Abstract: This paper proposes a greedy algorithm named as Big step greedy set cover algorithm to compute approximate minimum set cover. The Big step greedy algorithm, in each step selects p sets such that the union of selected p sets contains greatest number of uncovered elements and adds the selected p sets to partial set cover. The process of adding p sets is repeated until all the elements are covered. When p=1 it behaves like the classical greedy algorithm.
In vitro susceptibility of dermatophytes to itraconazole
Venugopal Pankajalakshmi,Venugopal Taralakshmi
Indian Journal of Dermatology, Venereology and Leprology , 1992,
Abstract: The in vitro activity of itraconazole was investigated against 88 clinical isolates of dermatophytes. The isolates included Microsporum canis-50, M. audovinii-5, Trichophyton rubrum-6, T. mentagraphytes-5 T.violaceum-12, T.simii-5, T verrucosum-1, T.soundanense-1, T. erinacei-1 and Epidermophyton flooccosum-2 isolates. The results were compared with that of ketoconazole and griseofulvin. Itraconazole was more active, inhibiting 85 of the 88 isolates at a concentration of 0.5 μg/ml (MIC range 0.01-1 μg/ml). Ketoconazole (MIC range 0.1-10 μg/ml) required 2.5 μg/ml and 5 μg/ml of the drug respectively for inhibition of all the isolates except one of Microsporum species.
Tonic eye deviation due to nonketotic hyperglycaemia induced focal seizures: Case report
Venugopal N
Indian Journal of Ophthalmology , 2005,
Abstract: We report a case of intermittent tonic conjugate eye deviation due to nonketotic hyperglycaemia induced focal seizure.
Android Note Manager Application for People with Visual Impairment
Gayatri Venugopal
Computer Science , 2013, DOI: 10.5121/ijmnct.2013.3502
Abstract: With the outburst of smart-phones today, the market is exploding with various mobile applications. This paper proposes an application using which visually impaired people can type a note in Grade 1 Braille and save it in the external memory of their smart-phone. The application also shows intelligence by activating reminders and/or calling certain contacts based on the content in the notes.
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