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Search Results: 1 - 10 of 45 matches for " Arjuna Balasuriya "
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Constructing a Distributed AUV Network for Underwater Plume-Tracking Operations
Stephanie Petillo,Henrik Schmidt,Arjuna Balasuriya
International Journal of Distributed Sensor Networks , 2012, DOI: 10.1155/2012/191235
Abstract: In recent years, there has been significant concern about the impacts of offshore oil spill plumes and harmful algal blooms on the coastal ocean environment and biology, as well as on the human populations adjacent to these coastal regions. Thus, it has become increasingly important to determine the 3D extent of these ocean features (“plumes”) and how they evolve over time. The ocean environment is largely inaccessible to sensing directly by humans, motivating the need for robots to intelligently sense the ocean for us. In this paper, we propose the use of an autonomous underwater vehicle (AUV) network to track and predict plume shape and motion, discussing solutions to the challenges of spatiotemporal data aliasing (coverage versus resolution), underwater communication, AUV autonomy, data fusion, and coordination of multiple AUVs. A plume simulation is also developed here as the first step toward implementing behaviors for autonomous, adaptive plume tracking with AUVs, modeling a plume as a sum of Fourier orders and examining the resulting errors. This is then extended to include plume forecasting based on time variations, and future improvements and implementation are discussed.
Autonomous Vehicles Navigation with Visual Target Tracking: Technical Approaches
Zhen Jia,Arjuna Balasuriya,Subhash Challa
Algorithms , 2008, DOI: 10.3390/a1020153
Abstract: This paper surveys the developments of last 10 years in the area of vision based target tracking for autonomous vehicles navigation. First, the motivations and applications of using vision based target tracking for autonomous vehicles navigation are presented in the introduction section. It can be concluded that it is very necessary to develop robust visual target tracking based navigation algorithms for the broad applications of autonomous vehicles. Then this paper reviews the recent techniques in three different categories: vision based target tracking for the applications of land, underwater and aerial vehicles navigation. Next, the increasing trends of using data fusion for visual target tracking based autonomous vehicles navigation are discussed. Through data fusion the tracking performance is improved and becomes more robust. Based on the review, the remaining research challenges are summarized and future research directions are investigated.
TCP-R with EPDN: Handling out of Order Packets in Error Prone Satellite Networks  [PDF]
Int'l J. of Communications, Network and System Sciences (IJCNS) , 2009, DOI: 10.4236/ijcns.2009.27078
Abstract: Studies have shown that packet reordering is common, especially in satellite networks where there are link level retransmissions and multipath routing. Moreover, traditional satellite networks exhibit high corruption rates causing packet losses. Reordering and corruption of packets decrease the TCP performance of a network, mainly because it leads to overestimation of the congestion in the network. We consider satellite networks and analyze the performance of such networks when reordering and corruption of packets occurs. We propose a solution that could significantly improve the performance of the network when reordering and corruption of packets occur in a satellite network. We report results of our simulation experiments, which support this claim.
Gradient evolution for potential vorticity flows
S. Balasuriya
Nonlinear Processes in Geophysics (NPG) , 2001,
Abstract: Two-dimensional unsteady incompressible flows in which the potential vorticity (PV) plays a key role are examined in this study, through the development of the evolution equation for the PV gradient. For the case where the PV is conserved, precise statements concerning topology-conservation are presented. While establishing some intuitively well-known results (the numbers of eddies and saddles is conserved), other less obvious consequences (PV patches cannot be generated, some types of Lagrangian and Eulerian entities are equivalent) are obtained. This approach enables an improvement on an integrability result for PV conserving flows (if there were no PV patches at time zero, the flow would be integrable). The evolution of the PV gradient is also determined for the nonconservative case, and a plausible experiment for estimating eddy diffusivity is suggested. The theory is applied to an analytical diffusive Rossby wave example.
Renaming the NCDs
Aluwihare Arjuna
Bulletin of the World Health Organization , 2002,
Character sums with the aliquot divisors function
Sanka Balasuriya,Florian Luca
Uniform Distribution Theory , 2007,
Abstract: In this paper, we obtain nontrivial bounds for character sums involving the aliquot divisors function $s(n) = \sigma(n) - n$.
Analysing TCP for Bursty Traffic  [PDF]
Israfil Biswas, Arjuna Sathiaseelan, Raffaello Secchi, Gorry Fairhurst
Int'l J. of Communications, Network and System Sciences (IJCNS) , 2010, DOI: 10.4236/ijcns.2010.37078
Abstract: The Transmission Control Protocol has been designed to support interactive and bulk applications, with performance tuned to support bulk applications that desire to continuously send data. In contrast, this paper analyses TCP performance for a class of applications that do not wish to send continuous data, but instead generate bursts of data separated by application-limited periods in which little or no data is sent. In this context, the paper evaluates an experimental method, Congestion Window Validation (CWV), proposed to mitigate the network impact of bursty TCP applications. Simulation results show that TCP-CWV exhibits a conservative behaviour during application-limited periods. The results also show that TCP-CWV is able to use the available capacity after an idle period over a shared path and that this can have benefit, especially over long delay paths, when compared to slow-start restart specified by standard TCP. The paper recommends the development of CWV-like algorithms to improve the performance for bursty applications while also providing an incentive for application designers to use congestion control.
Diffusive draining and growth of eddies
S. Balasuriya,C. K. R. T. Jones
Nonlinear Processes in Geophysics (NPG) , 2001,
Abstract: The diffusive effect on barotropic models of mesoscale eddies is addressed, using the Melnikov method from dynamical systems. Simple geometric criteria are obtained, which identify whether a given eddy grows or drains out, under a diffusive (and forcing) perturbation on a potential vorticity conserving flow. Qualitatively, the following are shown to be features conducive to eddy growth (and, thereby, stability in a specific sense): (i) large radius of curvature of the eddy boundary, (ii) potential vorticity contours more tightly packed within the eddy than outside, (iii) acute eddy pinch-angle, (iv) small potential vorticity gradient across the eddy boundary, and (v) meridional wind forcing, which increases in the northward direction. The Melnikov approach also suggests how tendrils (filaments) could be formed through the breaking of the eddy boundary, as a diffusion-driven advective process.
Nonautonomous control of stable and unstable manifolds in two-dimensional flows
Sanjeeva Balasuriya,Kathrin Padberg-Gehle
Mathematics , 2013, DOI: 10.1016/j.physd.2014.03.003
Abstract: We outline a method for controlling the location of stable and unstable manifolds in the following sense. From a known location of the stable and unstable manifolds in a steady two-dimensional flow, the primary segments of the manifolds are to be moved to a user-specified time-varying location which is near the steady location. We determine the nonautonomous perturbation to the vector field required to achieve this control, and give a theoretical bound for the error in the manifolds resulting from applying this control. The efficacy of the control strategy is illustrated via a numerical example.
The Role of Location Based Technologies in Intelligent Transportation Systems
Nagendra R. Velaga,Arjuna Sathiaseelan
Asian Journal of Information Technology , 2012, DOI: 10.3923/ajit.2011.227.233
Abstract: Information Technology (IT) has played a significant role in enhancing the efficiency of modern day transportation systems. Recent advances in sensors, communication and information systems have enabled transportation systems to be more intelligent. Various location technologies and data integration methods (also known as map-matching algorithms) are used to support the navigation modules of such transport systems. This study provides a survey of location based technologies that encompass an Intelligent Transportation System (ITS) and provides an insight into the Required Navigation Performance (RNP) parameters that are required for decision-making in efficient delivery of transport systems. The reseachers also describe how various location sensors and map-matching algorithms are capable of supporting the navigation modules of ITS.
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