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Search Results: 1 - 10 of 83 matches for " Sezhian Annamalai "
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CaCo1-xRuxOy: Role of Ru/Co Ratio on Its Transport Properties  [PDF]
Sezhian Annamalai, Rudra P. Bhatta, Jugdersuren Battogtokh, Ian L. Pegg, Biprodas Dutta
New Journal of Glass and Ceramics (NJGC) , 2014, DOI: 10.4236/njgc.2014.41002
Abstract:

Calcium cobaltites, especially Ca3Co4O9 with a misfit layered structure, are promising thermoelectric materials due to their suitability for high temperature applications and low densities. The existence of low spin-state electronic configurations for both \"\" and \"\" species is one of the key parameter to explain the large thermopower values. Ruthenium oxide, with a layered structure, exhibits strong electron-electron correlation and the extended nature of their 4d electrons enhances orbital overlapping which is expected to influence the transport characteristics of CaCo1-xRuxOy (CCR) samples, by affecting the spin state of the 3d Co ions. The effect on thermopower and electrical resistivity due to partial substitution of Co by Ru ions, up to 0.33 moles, from 300 to 600 K was investigated. A sharp decline in resistivity and in thermopower was observed until a transition ion ratio (TIR), (Ru/(Ru + Co)), of 0.5 is reached, beyond which both the properties became less sensitive to TIR. These variations in the transport properties are explained by the presence of 4d Ru in close proximity to the Co, which could influence the spin and oxidation state of Co ions. The Co rich and Ru rich samples exhibit very distinct microstructures and phase assemblages.

Applications of exponential decay and geometric series in effective medicine dosage  [PDF]
Chinnaraji Annamalai
Advances in Bioscience and Biotechnology (ABB) , 2010, DOI: 10.4236/abb.2010.11008
Abstract: The problem facing by physicians is the fact that for most drugs there is a minimum concentration below which the drug is ineffective, and a maximum concentration above which the drug is dangerous. Thus, this paper discusses the effective medicine dosage and its concentration in bloodstream of a patient. For analysis of dose concentration and mathematical mo- delling of minimum and maximum concentration of a drug administered intravenously, the EDM (Exponential Decay Model) and GSF (Geometric Series and its Formula) are the powerful mathematical tools. In the present research study, these two mathematical tools were used to predict the dose concentration of a drug in bloodstream of a patient.
Contrast Enhanced Magnetic Resonance Angiography with Gadofosveset Used in Detection and Localization of Bleeding  [PDF]
D. Durant, G. Annamalai
Open Journal of Radiology (OJRad) , 2014, DOI: 10.4236/ojrad.2014.41004
Abstract:

It has been established that internal hemorrhage can be detected and localized with noninvasive and minimally invasive imaging methods such as CT angiography, conventional angiography and nuclear scintigraphy. The use of steady-state MRI with the relatively new intravascular contrast agent gadofosveset offers the possibility of accurate anatomic localization of bleeding without the use of ionizing radiation or iodinated contrast media. To illustrate this assertion, we describe two cases from our institution in which MR angiography was successfully performed specifically for this indication.

Unified Analysis of Two-Hop Cooperative Amplify-and-Forward Multi-Relay Networks
Oluwatobi Olabiyi,Annamalai Annamalai
International Journal of Computer Networks & Communications , 2012,
Abstract: This article develops an extremely simple and tight closed-form approximation for the momentgenerating function (MGF) of signal-to-noise ratio (SNR) for two-hop amplify-and-forward relayedpaths over generalized fading environments. The resulting expression facilitates efficient analysis of twohopcooperative amplify-and-forward (CAF) multi-relay networks over a myriad of stochastic channelmodels (including mixed-fading scenarios where fading statistics of distinct links in the relayed path maybe from different family of distributions). The efficacy of our proposed MGF expression for computingthe average symbol error rate (ASER), outage probability, and the ergodic capacity (with limitedchannel side-information among cooperating nodes) is also studied. Numerical results indicate that theproposed MGF expression tightly approximates the exact MGF formulas and outperforms the existingMGF of lower and upper bounds of the half-harmonic mean (HM) SNR, while overcoming the difficultiesassociated in deriving an accurate MGF formula for the end-to-end SNR over generalized fadingchannels. Further application of our new closed-form formula for the MGF of end-to-end SNR forevaluating the average bit and/or packet error rate with adaptive discrete-rate modulation in CAF relaynetworks is also discussed.
Extending the Capability of Energy Detector for Sensing of Heterogeneous Wideband Spectrum
Oluwatobi Olabiyi,Annamalai Annamalai
International Journal of Computer Networks & Communications , 2012,
Abstract: Reliable spectrum sensing is the very task upon which the entire operation of the cognitive radio rests. Energy detection is one of the solutions that have been proposed for enabling opportunistic spectrum access but its capability has limited sensitivity, no resolution and requires high sampling rate when employed in the detection of wideband heterogeneous spectrum. This article proposes a solution that can extend the capability of traditional energy detector to wideband sensing with improved performance. The solution involves the use of parallel detection circuitry with each tuned to different frequencies. The decision of each detection circuit can then be used to create a spectral map of the entire spectrum. This introduces some resolution component and improved sensitivity based on the number of parallel circuitsand bandwidth of each detection circuit. Since the bandwidth of the incumbent signal is generally not known a priori, there is possibility that it spans across multiple detectors. The detection of such wideband signal can be achieved by either data or decision fusion of the results of each narrowband detector. We show that the use of parallel multi-channel detection can greatly enhance the detection of wideband signal compared to averaging while improving the resolution and sensitivity of energy detection of wideband spectrum. Further performance improvement can be achieved through the use of diversity reception on each narrow band detectors. Numerical results have been shown for representative cases and careful review of previous works reveals that these have never been considered in literature.
Efficient Symbol Error Rate Analysis of Cooperative Non-Regenerative Relay Systems over Generalized Fading Channels
Oluwatobi Olabiyi,Annamalai Annamalai
International Journal of Wireless & Mobile Networks , 2012,
Abstract: In this article, we develop a unified approach to the asymptotic performance analysis of symbol error rates for two-hop cooperative non-regenerative multi-relay networks over a myriad of stochastic channel models. Our proposed moment generating function (MGF) based analytical framework is also sufficiently general to encapsulate all types of coherent, differentially-coherent and non-coherent digital modulation schemes. In addition to simplifying the computation complexity of average symbol error rate (ASER) forcooperative amplify-and-forward (CAF) diversity systems treated in the literature, we also provide an accurate approximation for the desired ASER in a number of fading environments that heretofore had resisted a simple solution. The accuracy of our approximations has been validated with the closed-formformulas that are available for specific fading environments (e.g., Rayleigh and Nakagami-m channels) and via computer (Monte Carlo) simulations. Our analytical approach may also be extended to other types of cooperative strategies and multi-hop networks, although it is beyond the scope of this article.
Invitation to Ezhil: A Tamil Programming Language for Early Computer-Science Education
Muthiah Annamalai
Computer Science , 2013,
Abstract: Ezhil is a Tamil programming language with support for imperative programming, with mixed use of Tamil and English identifiers and function-names. Ezhil programing system is targeted toward the K-12 (junior high-school) level Tamil speaking students, as an early introduction to thinking like a computer-scientist. We believe this 'numeracy' knowledge is easily transferred over from a native language (Tamil) to the pervasive English language programming systems, in Java, dot-Net, Ruby or Python. Ezhil is an effort to improve access to computing in the 21st Century.
Finding Perfect Matchings in Bipartite Hypergraphs
Chidambaram Annamalai
Computer Science , 2015,
Abstract: Haxell's condition is a natural hypergraph analog of Hall's condition, which is a well-known necessary and sufficient condition for a bipartite graph to admit a perfect matching. That is, when Haxell's condition holds it forces the existence of a perfect matching in the bipartite hypergraph. Unlike in graphs, however, there is no known polynomial time algorithm to find the hypergraph perfect matching that is guaranteed to exist when Haxell's condition is satisfied. We prove the existence of an efficient algorithm to find perfect matchings in bipartite hypergraphs whenever a stronger version of Haxell's condition holds. Our algorithm can be seen as a generalization of the classical Hungarian algorithm for finding perfect matchings in bipartite graphs. The techniques we use to achieve this result could be of use more generally in other combinatorial problems on hypergraphs where disjointness structure is crucial, e.g. Set Packing.
Ezhil: A Tamil Programming Language
Muthiah Annamalai
Computer Science , 2009,
Abstract: Ezhil is a Tamil language based interpreted procedural programming language. Tamil keywords and grammar are chosen to make the native Tamil speaker write programs in the Ezhil system. Ezhil allows easy representation of computer program closer to the Tamil language logical constructs equivalent to the conditional, branch and loop statements in modern English based programming languages. Ezhil is a compact programming language aimed towards Tamil speaking novice computer users. Grammar for Ezhil and a few example programs are reported here, from the initial proof-of-concept implementation using the Python programming language1. To the best of our knowledge, Ezhil language is the first freely available Tamil programming language.
On the Asymptotic Behavior of Second Order Quasilinear Difference Equations  [PDF]
Vadivel Sadhasivam, Pon Sundar, Annamalai Santhi
Applied Mathematics (AM) , 2016, DOI: 10.4236/am.2016.714139
Abstract: In this paper, we investigate the asymptotic behavior of the following quasilinear difference equations \"\" (E) where \"\", \"\". We classified the solutions into six types by means of their asymptotic behavior. We establish the necessary and/or sufficient conditions for such equations to possess a solution of each of these six types.
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