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Triangle counting serves as a key building block for a set of important graph algorithms in network science. In this paper, we address the IEEE HPEC Static Graph Challenge problem of triangle counting, focusing on obtaining the best parallel performance on a single multicore node. Our implementation uses a linear algebra-based approach to triangle counting that has grown out of work related to our...
The Interconnect topology is one of the key design choices of large-scale distributed computer architectures. It might also become one of the most power consuming design elements as traffic volumes and interconnect size continue to grow. High interconnect power consumption can be simply provoked by non-energy efficient components, or can in contrast be due to architectural misconception. In this paper,...
Input/output (I/O) operations can represent a significant proportion of the run-time when large scientific applications are run in parallel. Although there have been advances in the form of file-format libraries, file system design and I/O hardware, a growing divergence exists between the performance of parallel file systems and compute processing rates. In this paper we utilise RIOT, an input/output...
The divergence between processor and memory performance has been a well discussed aspect of computer architecture literature for some years. The recent use of multi-core processor designs has, however, brought new problems to the design of memory architectures - as more cores are added to each successive generation of processor, equivalent improvement in memory capacity and memory sub-systems must...
We have demonstrated an atom interferometer with completely separated beams using three 200 nm period transmission gratings. A stretched 10 cm long and 10 μm thick metal foil, was inserted in the interferometer so that separated portions of the atom wave went on opposite sides of the foil. A fringe amplitude of up to 900 cps was observed, which allows us to determine the phase to 15 milliradians in...
Manual analysis of body poses of bed-ridden patients requires staff to continuously track and record patient poses. Two limitations in the dissemination of pose-related therapies are scarce human resources and unreliable automated systems. This work addresses these issues by introducing a new method and a new system for robust automated classification of sleep poses in an Intensive Care Unit (ICU)...
A fundamental challenge for supercomputer architecture is that processors cannot be fed data from DRAM as fast as CPUs can consume it. Therefore, many applications are memory-bandwidth bound. As the number of cores per chip increases, and traditional DDR DRAM speeds stagnate, the problem is only getting worse. A variety of non-DDR 3D memory technologies (Wide I/O 2, HBM) offer higher bandwidth and...
Over the course of the last year, we have worked to adapt our multifluid PPM code to run well at scale on the Blue Waters machine at NCSA as well as on networks of Intel Xeon Phi coprocessors. The work on Blue Waters has been in collaboration with Cray and that with Intel's MIC co-processors in collaboration with Intel. Our starting point for this work was a version of the code that was developed...
The Finite Element Method (FEM) is a numerical technique widely used in finding approximate solutions for many scientific and engineering problems. The Data Assembly (DA) stage in FEM can take up to 50% of the total FEM execution time. Accelerating DA with Graphics Processing Units (GPUs) presents challenges due to DA's mixed compute-intensive and memory-intensive workloads. This paper uses a representative...
We report observation of electron self-injection and acceleration in a plasma accelerator driven by the Texas petawatt laser at 1017 cm−3 plasma density, an order of magnitude lower density than previous self-injected laser-plasma accelerators.
Modern supercomputers are growing in diversity and complexity - the arrival of technologies such as multi-core processors, general purpose-GPUs and specialised compute accelerators has increased the potential scientific delivery possible from such machines. This is not however without some cost, including significant increases in the sophistication and complexity of supporting operating systems and...
A Petawatt laser based on hybrid optical parametric chirped pulse amplification (OPCPA) and mixed Nd:glass has been demonstrated. This concept enables peak powers which can be scaled significantly beyond one petawatt. Higher power lasers enable access to unprecedented scientific research in the studies of high intensity physics. In this paper we discuss the laser, the potential of scaling to higher...
We report on the activation of the 1.1 Petawatt Laser (190 J, 170 fs) based on optical parametric chirped pulse amplification (OPCPA) and mixed Nd:glass amplification.
Broadcasting is a fundamental communication task in mobile ad hoc networks, and minimizing broadcasting time (or latency) is crucial to the performance ofmany applications. Extensive studies have been conducted on the minimization of broadcasting time in the context of radio networks, which are usually modeled as general graphs. In this paper, we consider how to achieve this goal with distributed...
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