CCFE perform Monte-Carlo transport simulations on large and complex tokamak models such as ITER. Such simulations are challenging since streaming and deep penetration effects are equally important. In order to make su...
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ISBN:
(纸本)9781627486439
CCFE perform Monte-Carlo transport simulations on large and complex tokamak models such as ITER. Such simulations are challenging since streaming and deep penetration effects are equally important. In order to make such simulations tractable, both variance reduction (VR) techniques and parallel computing are used. It has been found that the application of VR techniques in such models significantly reduces the efficiency of parallel computation due to 'long histories'. VR in MCNP can be accomplished using energy-dependent weight windows. The weight window represents an 'average behaviour' of particles, and large deviations in the arriving weight of a particle give rise to extreme amounts of splitting being performed and a long history. When running on parallel clusters, a long history can have a detrimental effect on the parallel efficiency - if one process is computing the long history, the other CPUs complete their batch of histories and wait idle. Furthermore some long histories have been found to be effectively intractable. To combat this effect, CCFE has developed an adaptation of MCNP which dynamically adjusts the WW where a large weight deviation is encountered. The method effectively 'de-optimises' the WW, reducing the VR performance but this is offset by a significant increase in parallel efficiency. Testing with a simple geometry has shown the method does not bias the result. This 'long history method' has enabled CCFE to significantly improve the performance of MCNP calculations for ITER on parallel clusters, and will be beneficial for any geometry combining streaming and deep penetration effects.
Multidisciplinary design optimization (MDO) is an intelligent optimization design method that can handle coupling relationships between disciplines in complex engineering systems. This paper presented a detailed intro...
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The tension between expressive power and computational tractability poses an acute problem for theories of underspecified semantic representation. In previous work we have presented an account of underspecified scope ...
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ISBN:
(纸本)9057761467
The tension between expressive power and computational tractability poses an acute problem for theories of underspecified semantic representation. In previous work we have presented an account of underspecified scope representations within Property Theory with Curry Typing (PTCT), an intensional first-order theory for natural language semantics. Here we show how filters applied to the underspecified-scope terms of PTCT permit both expressive completeness and the reduction of computational complexity in a significant class of non-worst case scenarios.
We present an efficient workflow that combines multiscale (MS) forward simulation and stochastic gradient computation - MS-StoSAG - for the optimization of well controls applied to waterflooding under geological uncer...
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In this study, we embarked on the journey to optimize the computational efficiency of feature selection techniques for machine learning models, with a focused case study on crime detection using criminal data. Through...
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In this study, efficient computational algorithm for three dimensional Euler equations is developed based on the multi-resolution analysis. A proper thresholding technique is applied to preserve the order of the accur...
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This paper considers the computational efficiency of the recently developed generalised function parameterisations predictive control algorithms using active set methods. Alternative parameterisations have been shown ...
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Privacy-enhancing attribute-based credential (Privacy-ABC) technologies use different cryptographic methods to enhance the privacy of the users. This results in important practical differences between these technologi...
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This paper provides a comprehensive review of time-series forecasting models for forecasting the performance of Indian mutual funds. Specifically, we evaluate the effectiveness of three popular approaches: ARIMA, deep...
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Transmission switching is widely used in the electric power industry for both preventive and corrective purposes. Optimal transmission switching (OTS) problems are usually formulated based on optimal power flow (OPF) ...
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