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The ever-increasing power of high-performance computers and advances in numerical techniques make possible the realistic study of two-phase flow problems in three spatial dimensions. Unfortunately, today, there is often still a gap between the design of numerical algorithms and the characteristics of the hardware on which the algorithms are executed. For the solution of a particular sub problem of...
In this paper, we present performance analysis of two NASA applications using performance tools like Tuning and Analysis Utilities (TAU) and SGI MP Inside. MITgcmUV and OVERFLOW are two production-quality applications used extensively by scientists and engineers at NASA. MITgcmUV is a global ocean simulation model, developed by the Estimating the Circulation and Climate of the Ocean (ECCO) Consortium,...
GPUs (Graphics Processing Units) have become one of the main co-processors that contributed to desktops towards high performance computing. Together with multi-core CPUs, a powerful heterogeneous execution platform is built for massive calculations. To improve application performance and explore this heterogeneity, a distribution of workload in a balanced way over the PUs (Processing Units) plays...
This paper examines the initial parallel implementation of SCATTER, a computationally intensive inelastic neutron scattering routine with polycrystalline averaging capability, for the General Utility Lattice Program (GULP). Of particular importance to structural investigation on the atomic scale, this work identifies the computational features of SCATTER relevant to a parallel implementation and presents...
Large-scale simulation of the thermal convection in the Earth's outer core is studied. Starting from a legacy parallel code using Aztec and MPI, two optimized codes have been developed based on the PETSc software package. The first version gains several times acceleration with the help of the block-Jacobi preconditioners and the well-optimized libraries provided in PETSc. The second version, aiming...
Since the generation of detailed traffic statistics does not scale well with link speed, increasingly passive traffic measurement employs sampling at the packet or flow level. Sampling has become an attractive and scalable means to measure flow data on high-speed links. However, knowing the length distributions of traffic flows passing through a network link is useful for some applications such as...
This paper investigates the energy cost of control packets in contention-based medium access control protocols in wireless sensor networks. Control packets are useful to avoid collision and overhearing, but cost a significant amount of energy. Therefore, whether or not to apply control packets is a trade-off. It will be shown that this trade-off mainly depends on the packet arrival rate at individual...
Cognitive radio network (CRN) users are inherently expected to experience widely varied delays and jitters due to the uncertainty in channel availability. Supporting delay sensitive real-time services through CRNs thus remains a challenging task. This paper presents a novel technique to provision QoS guarantee in CRNs by modeling the resultant channel of multiple primary networks and finding the optimum...
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