Browsing by Subject "Load Balancing"
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Item Open Access Efficient solution of the combined-field integral equation with the parallel multilevel fast multipole algorithm(IEEE, 2007-08) Gürel, Levent; Ergül, ÖzgürWe present fast and accurate solutions of large-scale scattering problems formulated with the combined-field integral equation. Using the multilevel fast multipole algorithm (MLFMA) parallelized on a cluster of computers, we easily solve scattering problems that are discretized with tens of millions of unknowns. For the efficient parallelization of MLFMA, we propose a hierarchical partitioning scheme based on distributing the multilevel tree among the processors with an improved load-balancing. The accuracy of the solutions is demonstrated on scattering problems involving spheres of various radii from 80λ to 110λ. In addition to canonical problems, we also present the solution of real-life problems involving complicated targets with large dimensions. © 2007 IEEE.Item Open Access Load balancing enhancements to the routing protocol for low power and lossy networks in the internet of things(Bilkent University, 2018-11) Noor, HiraThe internet today is shifting from the Internet of people to the Internet of Things (IoT). Particularly, in IoTs, wireless sensors connect edge devices to the Internet via a gateway that provides connectivity between wireless sensor networks (WSNs) and the Internet. IoT includes a variety of heterogeneous network applications ranging from smart grid automated metering infrastructures (AMIs), industrial and environmental monitoring networks to building automation. In WSNs, congestion causes a plenty of impairments such as increased packet losses, lower throughput, and energy wastage thus decreasing the lifetime and performance of wireless sensor applications. IPv6 over Low Power Wireless Personal Area Networks (6LoWPAN) is envisioned to be used in the majority of IoT applications. Recently, the Internet Engineering Task Force (IETF) Routing over Low power and Lossy Networks (ROLL) working group has proposed a Routing Protocol for Low power and Lossy networks called RPL. RPL is often studied in a multipoint-to-point sink node (MP2P) scenarios. We investigate the load balancing and congestion problem of RPL. RPL su ers from congestion and unbalanced load distribution due to the use of a single path for multipoint-to-point traffic. In particular, we propose queue utilization-based multipath RPL (QU-MRPL). In QU-MRPL, multiple parents are selected based on their queue size information. We demonstrate that QU-MRPL achieves load balance in the network and thus increases the packet delivery ratio.Item Open Access Parallel hardware and software implementations for electromagnetic computations(Bilkent University, 2005) Bozbulut, Ali RızaMultilevel fast multipole algorithm (MLFMA) is an accurate frequencydomain electromagnetics solver that reduces the computational complexity and memory requirement significantly. Despite the advantages of the MLFMA, the maximum size of an electromagnetic problem that can be solved on a single processor computer is still limited by the hardware resources of the system, i.e., memory and processor speed. In order to go beyond the hardware limitations of single processor systems, parallelization of the MLFMA, which is not a trivial task, is suggested. This process requires the parallel implementations of both hardware and software. For this purpose, we constructed our own parallel computer clusters and parallelized our MLFMA program by using message-passing paradigm to solve electromagnetics problems. In order to balance the work load and memory requirement over the processors of multiprocessors systems, efficient load balancing techniques and algorithms are included in this parallel code. As a result, we can solve large-scale electromagnetics problems accurately and rapidly with parallel MLFMA solver on parallel clusters.