Virtual Network On Demand: Dedicating Network Resources to Distributed Scientific Workflows

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End-to-end network QoS via scheduling of flexible resource reservation requests

Modern data-intensive applications move vast amounts of data between multiple locations around the world. To enable predictable and reliable data transfer, next generation networks allow such applications to reserve network resources for exclusive use. In this paper, we solve an important problem (called SMR3) to accommodate multiple and concurrent network reservation requests between a pair of end-sites. Given the varying availability of bandwidth within the network, our goal is to accommodate as many reservation requests as possible while minimizing the total time needed to complete the data transfers. We first prove that SMR3 is an NP-hard problem. Then we solve it by developing a polynomial-time heuristic, called RRA. The RRA algorithm hinges on an efficient mechanism to accommodate large number of requests by minimizing the bandwidth wastage. Finally, via numerical results, we show that RRA constructs schedules that accommodate significantly larger number of requests compared to other, seemingly efficient, heuristics

Design and implementation of an intelligent end-to-end network QoS system

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Effects of the Tip Clearance Flow Field on the Secondary Losses

In this paper an extension of our secondary flow calculation method is presented in order to estimate the influence of the tip clearance on the secondary flow field. The impact of the tip clearance vortex is embodied in the method so that the secondary vorticity field, based on the complete form of the meridional vorticity transport equation is properly modified. In this way the changes of the secondary flow field quantities are predicted along with the resulting additional losses imposed by the existence of the tip clearance. The estimated tip clearance losses, based on the flow field structure, are compared to results obtained from various semi-empirical loss correlations found in the literature. Several cases encountered in axial flow compressor configurations are investigated and the calculated results are favourably compared to experimental data and results of previous calculations. Additionally, in order to clarify the influence of the tip clearance structure upon the secondary flow field, cases with and without tip clearance are also examined.</jats:p

Spatial and temporal characterization of polarization entanglement

We describe the full temporal and spatial characterization of polarization-entangled photons produced by Spontaneous Parametric Down Conversions using an intensified high-speed optical camera, Tpx3Cam. This novel technique allows for precise determination of Bell inequality parameters and for new characterization methods for the spatial distribution of entangled quantum information. We also discuss a technique to synchronize multiple cameras separated by vast distances, which will be required for a distributed quantum network

A Meta-scheduling Service for Co-allocating Arbitrary Types of Resources

The Grid paradigm implies the sharing of a variety of resources across multiple administrative domains. In order to execute a work-flow using these distributed resources an instrument is needed to co-allocate resources by reaching agreements with the different local scheduling systems involved. Apart from compute resources to execute the work-flow the co-ordinated usage of other resource types must be also guaranteed, as there are for example a network connectivity with dedicated QoS parameters or a visualisation device. We present a Web Service-based MetaScheduling Service which allows to negotiate a common time slot with local resource management systems to enable the execution of a distributed work-flow. The successful negotiation process results in a formal agreement based on the WS-Agreement recommendation that is currently specified by the GRAAP working group of the Global Grid Forum. As a use case we demonstrate the integration of this MetaScheduling Service into the UNICORE middleware