2,060 research outputs found
Linux Cluster in Theory and Practice: A Novel Approach in Teaching Cluster Computing Based on the Intel Atom Platform
AbstractCurrent trends and studies on future architectures show, that the complexity of parallel computer systems is increasing steadily. Hence, the industry requires skilled employees, who have in addition to the theoretical fundamentals, practical experiences in the design and administration of such systems. However, investigations have shown, that practical approaches are still missing in current curricula, especially in these areas. For this reason, the chair of Computer Architecture at the faculty of Computer Science at the Technische Universiẗat Dresden, developed and introduced the course “Linux Cluster in Theory and Practice” (LCTP). The main objectives of this course are to provide background knowledge about the design and administration of large-scale parallel computer systems and the practical implementation on the available hardware. In addition, students learn how to solve problems in a structured approach and as part of a team. This paper analyzes the current variety of courses in the area of parallel computing systems, describes the structure and implementation of LCTP and provides first conclusions and an outlook on possible further developments
Unimagined Imaginary Parts in Heavy Quark Effective Field Theory
We argue that the imaginary parts of the anomalous dimensions in the
multiparticle sectors of heavy quark effective field theory may be removed by a
suitable redefinition of the multiparticle states. The connection between the
imaginary parts of the anomalous dimensions and the interquark potential is
pointed outComment: 14 Pages, LaTeX, HUTP-93/A009, IKDA 93/
Performance and quality of service of data and video movement over a 100 Gbps testbed
AbstractDigital instruments and simulations are creating an ever-increasing amount of data. The need for institutions to acquire these data and transfer them for analysis, visualization, and archiving is growing as well. In parallel, networking technology is evolving, but at a much slower rate than our ability to create and store data. Single fiber 100 Gbps networking solutions have recently been deployed as national infrastructure. This article describes our experiences with data movement and video conferencing across a networking testbed, using the first commercially available single fiber 100 Gbps technology. The testbed is unique in its ability to be configured for a total length of 60, 200, or 400 km, allowing for tests with varying network latency. We performed low-level TCP tests and were able to use more than 99.9% of the theoretical available bandwidth with minimal tuning efforts. We used the Lustre file system to simulate how end users would interact with a remote file system over such a high performance link. We were able to use 94.4% of the theoretical available bandwidth with a standard file system benchmark, essentially saturating the wide area network. Finally, we performed tests with H.323 video conferencing hardware and quality of service (QoS) settings, showing that the link can reliably carry a full high-definition stream. Overall, we demonstrated the practicality of 100 Gbps networking and Lustre as excellent tools for data management
Diffractive Guiding of Waves by a Periodic Array of Slits
We show that in order to guide waves, it is sufficient to periodically
truncate their edges. The modes supported by this type of wave guide propagate
freely between the slits, and the propagation pattern repeats itself. We
experimentally demonstrate this general wave phenomenon for two types of waves:
(i) plasmonic waves propagating on a metal-air interface that are periodically
blocked by nanometric metallic walls, and (ii) surface gravity water waves
whose evolution is recorded, the packet is truncated, and generated again to
show repeated patterns. This guiding concept is applicable for a wide variety
of waves.Comment: 5 pages, 4 figure
Safety assessment of electrically cycled cells at high temperatures under mechanical crush loads
Static and dynamic pile testing of reinforced concrete pileswith structure integrated fibre optic strain sensors
Polarization and relaxation of radon
Investigations of the polarization and relaxation of Rn by spin
exchange with laser optically pumped rubidium are reported. On the order of one
million atoms per shot were collected in coated and uncoated glass cells.
Gamma-ray anisotropies were measured as a signal of the alignment (second order
moment of the polarization) resulting from the combination of polarization and
quadrupole relaxation at the cell walls. The temperature dependence over the
range 130C to 220C shows the anisotropies increasing with
increasing temperature as the ratio of the spin exchange polarization rate to
the wall relaxation rate increases faster than the rubidium polarization
decreases. Polarization relaxation rates for coated and uncoated cells are
presented. In addition, improved limits on the multipole mixing ratios of some
of the main gamma-ray transitions have been extracted. These results are
promising for electric dipole moment measurements of octupole-deformed
Rn and other isotopes, provided sufficient quantities of the rare
isotopes can be produced.Comment: 4 pages, 4 figure
MSSM Higgs bosons associated with high-pT jets at hadron colliders
The cross section for the production of the lightest neutral Higgs boson in
association with a high-pT hadronic jet, calculated in the framework of the
minimal supersymmetric standard model (MSSM), is presented. The expectations
for the hadronic cross section at the Large Hadron Collider are discussed using
reasonable kinematical cuts. In particular the contributions from superpartner
loops to the cross section and their dependence on the parameters of the MSSM
are investigated and found to be significant. Comparisons show that the
production rate for h0 + jet in the MSSM can differ widely from the
corresponding standard-model prediction.Comment: 20 page
QCD Corrected Contributions to B\bbar--Mixixng
We calculate the QCD corrected effective Hamiltonian for B\bbar--Mixing in
heavy quark effective theory including corrections of the order . The matrix elements of the subleading operators are estimated using the
vacuum insertion assumption. We show that the major part of the subleading
corrections may be absorbed into the heavy meson decay constant ; the
remaining corrections are only due to QCD effects and give an enhancement of
of 5\%.Comment: 16 Pages, LaTeX, 3 figures in separate uuencoded Postscript file,
Darmstadt report IKDA 92 / 3
LEGaTO: first steps towards energy-efficient toolset for heterogeneous computing
LEGaTO is a three-year EU H2020 project which started in December 2017. The LEGaTO project will leverage task-based programming models to provide a software ecosystem for Made-in-Europe heterogeneous hardware composed of CPUs, GPUs, FPGAs and dataflow engines. The aim is to attain one order of magnitude energy savings from the edge to the converged cloud/HPC.Peer ReviewedPostprint (author's final draft
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