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We present performance results and an analysis of an MPI/OpenACC implementation of an electromagnetic solver based on a spectral-element discontinuous Galerkin discretization of the time-dependent Maxwell equations. The OpenACC implementation covers all solution routines, including a highly tuned element-by-element operator evaluation and a GPUDirect(More)
As the number of processors increases to hundreds of thousands in parallel computer architectures, the failure probability rises correspondingly, making fault tolerance a highly important and challenging task. Application-level checkpointing is one of the most popular techniques to proactively deal with unexpected failures because of its portability and(More)
We describe Fourier pseudospectral time-domain simulations, carried out in order to study light interacting with a metallic nanoscale object. The difficulty of using Fourier methods to accurately predict the electromagnetic scattering in such problems arises from the discontinuity in the dielectric function along the surface of the metallic object. Standard(More)
We investigate efficient algorithms and a practical implementation of an explicittype high-order timestepping method based on Krylov subspace approximations, for possible application to large-scale engineering problems in electromagnetics. We consider a semi-discrete form of the Maxwell’s equations resulting from a high-order spectral-element discontinuous(More)
<i>Application-level checkpointing</i> has been one of the most popular techniques to proactively deal with unexpected failures in supercomputers with hundreds of thousands of cores. Unfortunately, this approach results in heavy I/O load and often causes I/O bottlenecks in production runs. In this paper, we examine a new thread-based application-level(More)
We present a spectral-element discontinuous Galerkin lattice Boltzmann method for solving single-phase incompressible flows. Decoupling the collision step from the streaming step offers numerical stability at high Reynolds numbers. In the streaming step, we employ high-order spectral-element discretizations using a tensor product basis of one-dimensional(More)
We developed a moving window algorithm for wakefield calculations for our SEDG time-domain electromagnetic code NekCEM. When the domain of interest is around a moving bunch within a certain distance, one does not need to carry out full domain simulations. The moving window approach is a natural choice for reducing the computational cost of the conventional(More)
We model the quantum dynamics of two, three, or four quantum dots in proximity to a plasmonic system such as a metal nanoparticle or an array of metal nanoparticles. For all systems, an initial state with only one quantum dot in its excited state evolves spontaneously into a state with entanglement between all pairs of QDs. The entanglement arises from the(More)