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International Conference on Cyberworlds

作者： Stanislav Klimenko Igor Nikitin Lialia Nikitina Kira Konich Kevin Reinartz Sergey Tyul'Bashev Institute of Computing for Physics and Technology Moscow Institute for Physics and Technology (State University) Protvino Russia Fraunhofer Institute for Algorithms and Scientific Computing Sankt Augustin Germany Bauhaus University Weimar Germany Fiziceskij institut imeni P N Lebedeva RAN Moskva Moskva RU

We extend our system for radio astronomical monitoring by a cross-validation filter, separating near Earth radio frequency interference (RFI) from deep space signals. The filter searches for similar signals in a nearby frequency band, coming from a different spatial direction than the tested signal. The filter passes the signals which do not have such duplicates. We apply this technique to a database of SETI institute (***), containing 1.5 millions of sky observations in a frequency range 0.5-11.2 GHz, where our primary selection identified 28 strong signals possessing extraterrestrial (ET) signature. Crossvalidation allows to filter out 24 of those signals as satellite RFI. We present parameters for the remaining 4 signals and discuss statistical significance of these findings.

关键词： Satellites Satellite broadcasting Telescopes Brain models Antennas Radio astronomy

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Sparse grids and applications : Munich 2012 /

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2014年

作者： SGA2012 (Conference)

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Preconditioning for Efficiently Applying Algebraic Multigrid in Fully Implicit Reservoir Simulations

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SPE JOURNAL 2014年第4期19卷 726-736页

作者： Gries, Sebastian Stueben, Klaus Brown, Geoffrey L. Chen, Dingjun Collins, David A. Fraunhofer Institute for Algorithms and Scientific Computing Computer Modelling Group Limited

Fully implicit black-oil simulations result in huge, often very-ill-conditioned, linear systems of equations for different unknowns (e.g., pressure and saturations). It is well-known that the underlying Jacobian matrices contain both hyperbolic and nearly elliptic subsystems (corresponding to saturations and pressure, respectively). Because a reservoir simulation is typically driven by the behavior of the pressure, constrained-pressure-residual (CPR)-type two-stage preconditioning methods to solve the coupled linear systems are a natural choice and still belong to the most popular approaches. After a suitable extraction and decoupling, the computationally most costly step in such two-stage methods consists in solving the elliptic subsystems accurately enough. Algebraic multigrid (AMG) provides a technique to solve elliptic linear equations very efficiently. Hence, in recent years, corresponding CPR-AMG approaches have been extensively used in practice. Unfortunately, if applied in a straightforward manner, CPR-AMG does not always work as expected. In this paper, we discuss the reasons for the lack of robustness observed in practice, and present remedies. More precisely, we will propose a preconditioning strategy (based on a suitable combination of left and right preconditioning of the Jacobian matrix) that aims at a compromise between the solvability of the pressure subproblem by AMG and the needs of the outer CPR process. The robustness of this new preconditioning strategy will be demonstrated for several industrial test cases, some of which are very ill-conditioned. Furthermore, we will demonstrate that CPR-AMG can be interpreted in a natural way as a special AMG process applied directly to the coupled Jacobian systems.

关键词： preconditioning decoupling dynamic rowsumming Constrained Pressure residual Algebraic Multigrid

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Radio Astronomical Monitoring in Virtual Environment

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Procedia Computer Science 2015年 66卷 592-601页

作者： Kira Konich Igor Nikitin Stanislav Klimenko Valery Malofeev Sergey Tyul’bashev Bauhaus University Weimar Germany Fraunhofer Institute for Algorithms and Scientific Computing Sankt Augustin Germany Institute of Computing for Physics and Technology Protvino Russia Pushchino Radio Astronomy Observatory Lebedev Physical Institute Pushchino Russia

We present StarWatch , our application for real-time analysis of radio astronomical data in Virtual Environment. Serving as an interface to radio astronomical databases or being applied to live data from the radio telescopes, the application supports various data filters measuring signal-to-noise ratio (SNR), Doppler's drift, degree of signal localization on celestial sphere and other useful tools for signal extraction and classification. Originally designed for the database of narrow band signals from SETI institute (***), the application has been recently extended for the detection of wide band periodic signals, necessary for the search of pulsars. We will also address the detection of week signals possessing arbitrary waveforms and present several data filters suitable for this purpose.

关键词： scientific visualization virtual environments Big Data radio astronomy

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StarWatch: Radio Astronomical Monitoring in Virtual Environment

StarWatch: Radio Astronomical Monitoring in Virtual Environm...

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International Conference on Cyberworlds

作者： Stanislav Klimenko Valery Malofeev Igor Nikitin Institute of Computing for Physics and Technology Protvino Russia Pushchino Radio Astronomy Observatory Pushchino Russia Fraunhofer Institute for Algorithms and Scientific Computing Sankt Augustin Germany

An application of Virtual Environment for real-time analysis of radio astronomical data is presented. Serving as an interface to radio astronomical databases or being applied to live data from the radio telescope, the application supports various data filters measuring signal-to-noise ratio (SNR), Doppler's drift, degree of signal localization on celestial sphere and other useful tools for signal extraction and classification. The application is created using Avango VE framework (***). The application has been used for analysis of radio astronomical data from SETI institute (***).

关键词： Signal to noise ratio Extraterrestrial measurements Radon Virtual environments Electronic mail Databases Telescopes

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Disease systems modeling for discovery of mechanistic biomarkers

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New Horizons in Translational Medicine 2015年第2期2卷 61-61页

作者： Erfan Younesi Fraunhofer Institute for Algorithms and Scientific Computing SCAI Sankt Augustin Germany

The use of biomarkers is becoming increasingly integral to to the contemporary practice of medicine and continues to play a central role in preventive, predictive and personalized medicine. However, the limited number of FDA-approved, in use biomarkers, on one hand, and an increasing number of published potential biomarkers, on the other hand, calls for an accelerated approach to translating biomarker research to clinical application. In this talk, I introduce novel concept of "Biomarker-guided Mechanism Discovery" through an integrative disease modeling approach and present the successful application of this methodology to deciphering the network model of genomic hormone interactions underlying dementia and its translational validation through serendipitous off-target effect. Moreover, the current challenges in biomarker discovery is discussed and results of our proposed Biomarker Ontology in collaboration with pharma industry will be presented.

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Erratum to “On DFT Molecular Simulation for Non-Adaptive Kernel Approximation” [Advances in Materials Physics and Chemistry Vol. 4 No. 6 (June 2014) 105-115]

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Advances in Materials Physics and Chemistry 2015年第3期5卷 95-95页

作者： Maharavo Randrianarivony Virtual Material Design Fraunhofer Institute for Algorithms and Scientific Computing SCAI Schloss Birlinghoven Sankt Augustin Germany

The original online version of this article (Randrianarivony, M. (June 2014) On DFT Molecular Simulation for Non-Adaptive Kernel Approximation. Advances in Materials Physics and Chemistry, Vol. 4 No. 6, 105-115. http://***/10.4236/ampc.2014.46013) did not contain any acknowledgment. The author wishes to add the following acknowledgements: Acknowledgements: This work was partially supported by Eurostars Project E!6935 funded by German Federal Ministry of Education and Research.

关键词： DFT Energy Stochastic Covariance Hyperparameter

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Erratum to “Multilevel B-Spline Repulsive Energy in Nanomodeling of Graphenes” [Journal of Surface Engineered Materials and Advanced Technology Vol. 4 No. 2 (April 2014) 75-86]

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Journal of Surface Engineered Materials and Advanced Technology 2015年第2期5卷 84-84页

作者： Maharavo Randrianarivony Virtual Material Design Fraunhofer Institute for Algorithms and Scientific Computing SCAI Schloss Birlinghoven Sankt Augustin Germany

Quantum energies which are used in applications are usually composed of repulsive and attractive terms. The objective of this study is to use an accurate and efficient fitting of the repulsive energy instead of using standard parametrizations. The investigation is based on Density Functional Theory and Tight Binding simulations. Our objective is not only to capture the values of the repulsive terms but also to efficiently reproduce the elastic properties and the forces. The elasticity values determine the rigidity of a material when some traction or load is applied on it. The pair-potential is based on an exponential term corrected by B-spline terms. In order to accelerate the computations, one uses a hierarchical optimization for the B-splines on different levels. Carbon graphenes constitute the configurations used in the simulations. We report on some results to show the efficiency of the B-splines on different levels.

关键词： Repulsive potential B-spline Force Elastic stress Hierarchy

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Fast discrete fourier transform on generalized sparse grids 1

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2nd Workshop on Sparse Grids and Applications, SGA 2012

作者： Griebel, Michael Hamaekers, Jan Institute for Numerical Simulation University of Bonn Wegelerstr. 6 Bonn53115 Germany Fraunhofer Institute for Algorithms and Scientific Computing SCAI Schloss Birlinghoven Sankt Augustin53754 Germany

ISBN: (数字)9783319045375

ISBN: (纸本)9783319045368

In this paper, we present an algorithm for trigonometric interpolation of multivariate functions on generalized sparse grids and study its application for the approximation of functions in periodic Sobolev spaces of dominating mixed smoothness. In particular, we derive estimates for the error and the cost. We construct interpolants with a computational cost complexity which is substantially lower than for the standard full grid case. The associated generalized sparse grid interpolants have the same approximation order as the standard full grid interpolants, provided that certain additional regularity assumptions on the considered functions are fulfilled. Numerical results validate our theoretical findings. © Springer International Publishing Switzerland 2014.

关键词： Sobolev spaces

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Robust optimization for long running computer simulations with a focus on robustness measures 1

Robust optimization for long running computer simulations wi...

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1st International Conference on Engineering and Applied Sciences Optimization, OPT-i 2014

作者： Rhein, Beate Clees, Tanja Ruschitzka, Margot Cologne University of Applied Sciences Betzdorfer Str. 2 Koeln50679 Germany Fraunhofer Institute for Algorithms and Scientific Computing SCAI Schloss Birlinghoven Sankt Augustin53754 Germany

ISBN: (纸本)9789609999465

Robust optimization determines how the input variables dispersion is propagated on the output variables. This is of great practical relevance: For example, the quality of a product is influenced decisively by production tolerances. In industrial applications it is important to characterize the range of variation with appropriate measures. The industry is particularly interested in accurate limits of the output distribution or its centered part. In this article the mathematical characterization of robustness is discussed under the viewpoint of its practical applicability. It is shown, that the usually used robustness measures mean for central tendency and standard deviation for dispersion produce inaccurate limits. Instead several measures based on quantiles are proposed. The median is used as measure of central tendency while different quantile ranges are used as measure of dispersion. They are compared for the robust optimization of mathematical functions and industrial applications. The advantages of the quantile measures are pointed out. The computation of quantiles is expensive, because it needs many function evaluations. Due to their long runtime only a few simulations can be executed in practice. A methodology tailored to this situation is proposed. It is based on the use of metamodels. Starting with a few real simulations a metamodel for the system is build. Further ones for median and dispersion of the output variables are derived from it. This enables the user to perform a full multicriteria robust optimization on the whole parameter range. The methodology takes the tolerances of the metamodels into account. A new measure for the tolerance of metamodels which are derived from metamodels is presented. It is used to estimate the accuracy of the quantile models. The tolerance can easily be integrated in the robust optimization process.

关键词： Functions

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