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Solitons of K\"{A}hlerian Norden space-time manifolds
Praveena Manjappa Mundalamane,Bagewadi Channabasappa Shanthappa,Mallannara Siddalingappa Siddesha 대한수학회 2022 대한수학회논문집 Vol.37 No.3
We study solitons of K\"{a}hlerian Norden space-time manifolds and Bochner curvature tensor in almost pseudo symmetric K\"{a}hlerian space-time manifolds. It is shown that the steady, expanding or shrinking solitons depend on different relations of energy density/isotropic pressure, the cosmological constant, and gravitational constant.
Luminescence properties of Lu3Al5O12:Tb3+ nano-garnet
Praveena, R.,Shim, Jae Jeong,Cai, Peiqing,Seo, Hyo Jin,Chung, Wan-Young,Kwon, Tae Ha,Jayasankar, C. K.,Haritha, P.,Venkatramu, V. Korean Physical Society 2014 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.64 No.12
Trivalent terbium-doped lutetium-aluminate nano-garnet (Lu3Al5O12:Tb3+) powder was prepared by using the Pechini sol-gel process. The structure and crystallinity of the Lu3Al5O12:Tb3+ nano-garnet were characterized by using X-ray diffraction, transmission electron microscopy and Fourier transform infrared spectroscopy. The green emission of Tb3+ ions is observed at 545 nm corresponding to the D-5(4) -> F-7(5) transition under the 271-nm excitation. The temperature dependent luminescence properties of the Lu3Al5O12:Tb3+ nano-garnet are investigated. The results show that the present garnet exhibits better thermal stability than the other green emitting phosphors, hence, the Lu3Al5O12:Tb3+ phosphor is a promising candidate for light-emitting devices.
From the Eisenhart Problem to Ricci Solitons in Quaternion Space Forms
Praveena, Mundalamane Manjappa,Bagewadi, Channabasappa Shanthappa Department of Mathematics 2018 Kyungpook mathematical journal Vol.58 No.2
In this paper we obtain the condition for the existence of Ricci solitons in nonflat quaternion space form by using Eisenhart problem. Also it is proved that if (g, V, ${\lambda}$) is Ricci soliton then V is solenoidal if and only if it is shrinking, steady and expanding depending upon the sign of scalar curvature. Further it is shown that Ricci soliton in semi-symmetric quaternion space form depends on quaternion sectional curvature c if V is solenoidal.
Nalamani G. Praveena,Kandasamy Selvaraj,David Judson,Mahalingam Anandaraj 한국전자통신연구원 2023 ETRI Journal Vol.45 No.5
In mobile communication, the most exploratory technology of fifth generation is massive multiple input multiple output (MIMO). The minimum mean square error and zero forcing based linear detectors are used in multiuser detection for MIMO single-carrier frequency division multiple access (SCFDMA). When the received signal is detected and regularization sequence is joined in the equalization of spectral null amplification, these schemes experience an error performance and the signal detection assesses an inversion of a matrix computation that grows into complexity. Ordered successive interference cancelation (OSIC) detection is considered for MIMO SC-FDMA, which uses a posteriori information to eradicate these problems in a realistic environment. To cancel the interference, sorting is preferred based on signal-to-noise ratio and log-likelihood ratio. The distinctiveness of the methodology is to predict the symbol with the lowest error probability. The proposed work is compared with the existing methods, and simulation results prove that the defined algorithm outperforms conventional detection methods and accomplishes better performance with lower complication.
Degradation of 2,4-dichlorophenol in aqueous solution by sono-Fenton method
이창수,Praveena Juliya Dorathi. Ranjit,Kandasany Palanivelu 한국화학공학회 2008 Korean Journal of Chemical Engineering Vol.25 No.1
This study presents the results of the Sono-Fenton process for the degradation of 2,4-dichlorophenol (DCP). The influential parameters such as H2O2, Fe2+ and pH for the Sono-Fenton process were investigated. Sono-Fenton method was found to be the best one for degradation efficiency of DCP when compared with that of the Fenton process. The optimum concentrations for the degradation of DCP using conventional Fenton’s method were found to be 20 mg/ L of Fe2+ and 580 mg/L of H2O2 at pH 2.5. In the case of Sono-Fenton, the optimal concentrations were found to be 10 mg/L of Fe2+ and 400 mg/L of H2O2 at pH 2.5. Sono-Fenton method resulted in the reduction of required Fe2+ concentration (50%) and H2O2 concentration (31%). In addition, this method could be applicable even at pH 5.0 and a degradation efficiency of DCP was 77.6%. Kinetic studies for the degradation of DCP proved that the degradation of DCP tends to follow pseudo first order reaction and the rate constant was found to be 7×10−4 min−1.
Building Mobile Agents’ Applications Fault Tolerant
Preeti,Praveena Chaturvedi 보안공학연구지원센터 2015 International Journal of Hybrid Information Techno Vol.8 No.5
A mobile agent is self-governing software that has one or more goals and can migrate from one node to another in a network. Mobile agent has received pervasive interest in both research and academia in recent years because of its support for asynchronous and disconnected operation capability in distributed system Along with these affirmative sides, the full scale adoption of mobile agent has been delayed by several fault tolerance complexities in untrustworthy network environments such as Internet. This paper proposed a framework to provide fault tolerant execution to mobile agents. Key concepts used to accomplish this goal include the transaction manager concept, checkpointing, timeout mechanism. Agent saves partial results at home server. The framework can tolerate agent failure, server failure and communication delay. It has been implemented as an add-on to mobile agent platform called Aglets. Experiments have been conducted to test the feasibility and performance of the proposal.
Ramadevi N.,Praveena R.,Venkatramu V.,Basavapoornima Ch.,Lavín V.,Joshi B.D. 한국물리학회 2022 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.81 No.10
Lu3Sc2Ga3O12 garnet nanorods co-doped with Tm3+ and Yb3+ optically active ions have been synthesized by Pechini sol– gel method, and their structural, morphological and luminescence properties have been explored. X-ray difraction pattern confrmed that the synthesized Lu3Sc2Ga3O12 nanomaterials were crystallized in cubic garnet structure with an average crystallite size of 30 nm. Morphology of these powders confrmed the formation of rods with an average length of 8 μm and diameter of 90 nm. The difuse refectance spectra were used to obtain partial energy-level structure of Tm3+ and Yb3+ ions in Lu3Sc2Ga3O12 nanorods. Intense blue Stokes luminescence of Tm3+ ions at around 454 nm, under 360 nm ultraviolet excitation, as well as anti-Stokes luminescence at around 483 nm and co-operative luminescence at 490 nm, under near-infrared 980 nm excitation, have been measured. The intensity of these peaks increased with increasing of Yb3+ concentration up to 5 mol% and then decreased due to energy transfer between optically active ions. In addition, luminescence at ~ 545 and 565 nm has been observed in the anti-Stokes spectra which is due to the energy transfer from Ln3+ ions to the impurities such as Er3+ and Ho3+ ions. Laser pump power-dependent luminescence spectra confrmed that three photons were involved to populate the 1 G4 level in the upconversion mechanism. Luminescence decay curves have been measured for 1 D2 level and have been found to be non-exponential with an average lifetime of 20 μs. The non-exponential nature of decay curves is ascribed to energy transfer among Tm3+ ions through cross-relaxation processes. Colour co-ordinates of the samples excited at 980 nm lie in the blue–green region and also near to the white light region in the CIE diagram. All these results indicate that the present garnet nanorods could be a promising optically active material for the solid-state display devices.