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Search Results: 1 - 10 of 396 matches for " Valli Shanmugam "
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A Relearning Virtual Machine for Hot Method Prediction
Sandra Johnson,Valli Shanmugam
International Journal of Soft Computing , 2012, DOI: 10.3923/ijscomp.2010.206.210
Abstract: Predicting hot methods of a program code using machine learning algorithms in compiler optimization eliminates the overhead incurred during runtime identification. Since learning is a continuous process, the system should be able to relearn and update itself. In this study we implement this idea in a virtual machine which learns and relearns as to how hot methods can be effectively predicted in a program. This is the first attempt to make a compilation system relearn about hot method prediction after each execution. By applying relearning we are able to develop models for the prediction of the frequently called and the long running hot methods that can obtain 19 and 37% accuracies showing an improvement of 10 and 21%, respectively over the corresponding models without relearning. This is due to the ability of the model to learn from every program that enters execution and reconstruct itself.
Performance Comparison of Routing Attacks in Manet and WSN
Shyamala Ramachandran,Valli Shanmugam
International Journal of Ad Hoc, Sensor & Ubiquitous Computing , 2012,
Abstract: Routing is a basic step for data exchange. In wireless ad-hoc networks each node acts as a router and executes a routing protocol. Wireless ad-hoc networks are highly resource constrained in terms of network topology, memory and computation power. The reliable data transfer is a difficult task in wireless ad-hoc networks because of resource constraints. A mobile ad-hoc network (MANET) is a kind of wireless ad-hoc network, and is a self-configuring network of mobile routers connected by wireless links. A wireless sensor network (WSN) is a highly constrained wireless ad-hoc network. In these network, multicast is the efficient routing service for data broadcasting. Denial of service (DOS) attack, sinkhole, wormhole, sybil, black hole and rushing attacks are some routing attacks. So, it is necessary to study the impact of routing attacks on existing multicast routing protocols to suggest a suitable secure multicast routing protocol. The objective of this paper is to study the effects of black hole and rushing attack on MANET and WSN. The NS-2 based simulation is used in analyzing the black hole and rushing attacks. From performance metrics such as packet delivery ratio (PDR), packet drop ratio (PDrR), network throughput (NTh) and energy consumption it is observed that the routing attacks have severe impact on MANET than WSN.
Modeling and Analysis of Bandwidth Allocation in IEEE 802.16 MAC: A Stochastic Reward Net Approach  [PDF]
Shanmugam Geetha, Raman Jayaparvathy
Int'l J. of Communications, Network and System Sciences (IJCNS) , 2010, DOI: 10.4236/ijcns.2010.37085
Abstract: In this paper, we present a stochastic reward net (SRN) approach to analyse the performance of IEEE 802.16 MAC with multiple traffic classes. The SRN model captures the quality of service requirements of the traffic classes. The model also takes into account pre-emption, priority and timeout characteristics associated with the traffic classes under consideration. The performance of the system is evaluated in terms of mean delay and normalized throughput considering the on-off traffic model. Our analytical model is validated by simulations.
Ab Initio and Density Functional Theory (DFT) Study on Clonazepam  [PDF]
Bachu Sylaja, Shanmugam Srinivasan
Open Journal of Biophysics (OJBIPHY) , 2012, DOI: 10.4236/ojbiphy.2012.23011
Abstract: Quantum chemical calculations have been carried out to investigate the vibrational frequencies of clonazepam. The FTIR spectrum of clonazepam was recorded in the region 4000 to 400 cm–1 in the solid phase. The optimized geometry, wave number and intensity of the vibrational bands of clonazepam were obtained by ab initio Restricted Hartree Fock (RHF) and Density Functional Theory (DFT) methods with complete relaxation in the potential energy surface using the 6-31G (d,p) basis set. A complete vibrational assignment aided by the theoretical harmonic frequency analysis is proposed. The observed and the calculated wavenumbers are found to be in good agreement. The experimental spectra also coincide satisfactorily with those of theoretical spectra. Theoretical spectrograms for the IR spectrum were also constructed in RHF and B3LYP levels. In addition to this the RHF and DFT based NMR calculation procedure was used to assign the 1H NMR chemical shift of clonazepam. Theoretical values are compared with the experimental data.
An Algorithm for Classification of Algal Blooms Using MODIS-Aqua Data in Oceanic Waters around India  [PDF]
Arthi Simon, Palanisamy Shanmugam
Advances in Remote Sensing (ARS) , 2012, DOI: 10.4236/ars.2012.12004
Abstract: Increasing incidences and severity of algal blooms are of major concern in coastal waters around India. In this work an automatic algorithm has been developed and applied to a series of MODIS-Aqua ocean color data to classify and monitor four major algal blooms in these waters (i.e., Trichodesmium erythareum, Noctiluca scintillans/miliaris (green/brown), and Cochlodinium polykrikoides (red)). The algorithm is based on unique spectral signatures of these blooms previously reported by various field sampling programs. An examination of the algorithm results revealed that classified blooms agree very well with in-situ data in most oceanic waters around India. Accuracy assessment based on overall, user’s and producer’s accuracy and Kappa accuracy further revealed that the producer’s/user’s accuracy of the four algal blooms were 100% / 100%, 79.16% / 79.16%, 100% / 80%, 100% / 86.95%, respectively. The Kappa coefficient was 1.01. These results suggest that the new algorithm has the potential to classify and monitor these major algal blooms and such information is highly desired by fishermen, fish farmers and public health officials in this region. It should be noted that coefficients with the new algorithm may be finetuned based on more in-situ data sets and the optical properties of these algal blooms in oceanic waters around India.
Finding Optimal Allocation of Constrained Cloud Capacity Using Hyperbolic Voronoi Diagrams on the Sphere  [PDF]
Shanthi Shanmugam, Caroline Shouraboura
Intelligent Information Management (IIM) , 2012, DOI: 10.4236/iim.2012.425035
Abstract: We consider a network of computer data centers on the earth surface delivering computing as a service to a big number of users. The problem is to assign users to data centers to minimize the total communication distance between compu-ting resources and their users in the face of capacity constrained datacenters. In this paper, we extend the classical pla-nar Voronoi Diagram to a hyperbolic Voronoi Diagram on the sphere. We show that a solution to the distance minimi-zation problem under capacity constraints is given by a hyperbolic spherical Voronoi Diagram of data centers. We also present numerical algorithms, computer implementation and results of simulations illustrating our solution. We note applicability of our solution to other important assignment problems, including the assignment of population to regional trauma centers, location of airbases, the distribution of the telecommunication centers for mobile telephones in global telephone companies, and others.
Spectral Models for Improving Atmospheric Correction Results in Complex Oceanic Waters around India  [PDF]
Palanisamy Shanmugam, Muniyandi Tholkapiyan
Advances in Remote Sensing (ARS) , 2013, DOI: 10.4236/ars.2013.22007

Atmospheric correction over turbid and productive waters continues to be problematic and often results in excessive errors in retrieved water-leaving radiance and bio-geo-physical products. This may be likely due to overestimation of La + Lra (atmospheric signal due to aerosol and Rayleigh scattering) in the visible and thus reduction in Lw which appears as an elevated pigment concentration. Spectral models for reconstructing the atmospherically distorted data are developed and their results are thoroughly validated with in-situ data from a wide range of waters. Good agreement was found between the retrieved products and in-situ data. Our results indicate that the new spectral models have the potential to improve the accuracy of ocean colour retrievals in optically complex waters, and can become an important part of the processing of data from ocean colour sensors (e.g., Ocean colour monitor OCM2) with only two near-infrared bands (i.e., 765 and 865 nm).

In memoriam: Angus Maddison's Mission to Understand the World and its History through Numbers
Valli, Vittorio
The European Journal of Comparative Economics , 2010,
Abstract: Angus Maddison's contribution to the analysis of long-run developments in the world economy has been monumental. His continuous cumulative work on an ever expanding data-set of national accounts and his in-depth analysis of changes in the main trends in the world's economic history has given us fundamental tools for a better understanding of past secular trends and future scenarios. His tentative estimates of total and per capita income in remote times must be considered important preliminary building stones in the process of cumulative learning. His main contributions to our knowledge of world economic changes, briefly surveyed in this paper, will be treasured by generations of scholars of comparative growth and development and of economic historians
Book Review of: "Contours of the World Economy, 1-2030 AD. Essays on Macro-Economic History", Angus Maddison
Vittorio Valli
The European Journal of Comparative Economics , 2008,
Book Review of: "Global Sustainability: Social and Environmental Conditions", Simone Borghesi and Alessandro Vercelli
Valli, Vittorio
The European Journal of Comparative Economics , 2009,
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