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Effects of a static electric field on nonsequential double ionization

Physical Review A 2007年第3期76卷 033405-033405页

作者： Hongyun Li Bingbing Wang Jing Chen Hongbing Jiang Xiaofeng Li Jie Liu Qihuang Gong Zong-Chao Yan Panming Fu Laboratory of Optical Physics Institute of Physics Chinese Academy of Sciences Beijing 100080 China Department of Physics State Key Laboratory for Artificial Microstructures and Mesoscopic Physics Peking University Beijing 100871 China Center for Nonlinear Studies Institute of Applied Physics and Computational Mathematics Beijing 100088 China Department of Physics University of New Brunswick P.O. Box 4400 Fredericton New Brunswick Canada E3B 5A3 Research Academy of Science and Technology Harbin Institute of Technology Harbin 150001 China

Using a three-dimensional semiclassical method, we perform a systematic analysis of the effects of an additional static electric field on nonsequential double ionization (NSDI) of a helium atom in an intense, linearly polarized laser field. It is found that the static electric field influences not only the ionization rate, but also the kinetic energy of the ionized electron returning to the parent ion, in such a way that, if the rate is increased, then the kinetic energy of the first returning electron is decreased, and vice versa. These two effects compete in NSDI. Since the effect of the static electric field on the ionization of the first electron plays a more crucial role in the competition, the symmetric double-peak structure of the He2+ momentum distribution parallel to the polarization of the laser field is destroyed. Furthermore, the contribution of the trajectories with multiple recollisions to the NSDI is also changed dramatically by the static electric field. As the static electric field increases, the trajectories with two recollisions, which start at the time when the laser and the static electric field are in the same direction, become increasingly important for the NSDI.

关键词： HIGH-HARMONIC-GENERATION RAY-ATOM SCATTERING HELIUM DEPENDENCE PLATEAU IONS

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A Framework for Intensional and Extensional Integration of Geographic Ontologies

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Transactions in GIS 2007年第6期11卷

作者： Eleni Tomai Poulicos Prastacos Marinos Kavouras Institute of Applied and Computational Mathematics Foundation of Research and Technology Heraklion Crete Greece Cartography Laboratory School of Rural and Surveying Engineering National Technical University of Athens

This paper presents ongoing research in the field of extensional mappings between ontologies. Hitherto, the task of generating mappings between ontologies has focused on the intensional level of ontologies. The term intensional level herein, refers to the set of concepts that are included in an ontology. However, an ontology that has been created for a specific task or application needs to be populated with instances. These comprise the extensional level of an ontology. This particular level is generally neglected during the ontologies’ integration procedure. Thus, although methodologies of geographic ontologies integration, ranging from alignment to true integration, have, in the course of years, presented a solid ground for information exchange, little has been done in exploring the relationships between the data. In this context, this research strives to set a framework for extensional mappings between ontologies using Information Flow Theory by presenting a case study of interoperability between the thematic content of maps.

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A framework for intensional and extensional integration of geographic ontologies

A framework for intensional and extensional integration of g...

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9th AGILE International Conference on Geographic Information Science: "Shaping the Future of Geographic Information Science in Europe", AGILE 2006

作者： Tomai, Eleni Prastacos, Poulicos Institute of Applied and Computational Mathematics Foundation of Research and Technology P.O BOX 1529 7110 Heraklion Crete Greece

This paper presents ongoing research in the field of extensional mappings between ontologies. Hitherto, the task of generating mappings between ontologies has focused on the intensional level of ontologies. The term intensional level refers to the set of concepts that are included in an ontology. However, an ontology that has been created for a specific task or application needs to be populated with instances. These comprise the extensional level of an ontology. This particular level is being generally neglected during the ontologies' integration procedure. Thus, although methodologies of geographic ontologies integration, ranging from alignment to true integration, have, in the course of years, presented a solid ground for information exchange, little has been done in exploring the relationships between the data. In this context, this research strives to set a framework for extensional mappings between ontologies using Information Flow.

关键词： Ontology

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Comparing rainfall estimates derived from rain gages and satellite images at the eastern Mediterranean region

Comparing rainfall estimates derived from rain gages and sat...

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9th AGILE International Conference on Geographic Information Science: "Shaping the Future of Geographic Information Science in Europe", AGILE 2006

作者： Kamarianakis, Yiannis Chrysoulakis, Nektarios Feidas, Haralambos Kokolatos, Georgios Department of Economics University of Crete Rethymnon Greece Regional Analysis Division Institute of Applied and Computational Mathematics Foundation for Research and Technology-Hellas Vasilika Vouton P.O. Box 1527 GR-711 10 Heraklion-Crete Greece Department of Geography University of the Aegean Building of Geography University Hill Mytilene GR 811 00 Greece

This article aims to test a satellite infrared (IR) technique for estimating rainfall over Mediterranean. On that purpose, we use 6hr, 12hr and 24hr cumulative rainfall measurements, obtained from a large set of gages located at the eastern Mediterranean region, during October 2004. Two kinds of comparisons are undertaken. First, rainfall estimates derived from satellite images are projected to the locations of the rain gages and then compared to the actual gage measurements. Results in this case coincide with those reported in Barret (1988): IR satellite observations tend to overestimate precipitation. To obviate this, we seek optimal transformations for the IR satellite data via using statistical tools, namely the Box-Cox method and Linear Mixed models. Next, we perform spatial interpolation to the rain gage measurements and compare the derived surfaces to the ones obtained from satellite images for regions having high spatial density in gages. In both cases the estimation error is positively correlated to the rainfall level;we quantify this dependence using appropriate statistical tools.

关键词： Satellites

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Spin-polarized surface states close to adatoms on Cu(111)

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Physical Review B 2006年第4期73卷 045430-045430页

作者： B. Lazarovits L. Szunyogh P. Weinberger Center for Computational Materials Science Technical University Vienna A-1060 Gumpendorferstrasse 1.a. Vienna Austria Research Institute for Solid State Physics and Optics Hungarian Academy of Sciences Konkoly-Thege M. út 29-33 H-1121 Budapest Hungary Department of Theoretical Physics and Center for Applied Mathematics and Computational Physics Budapest University of Technology and Economics Budafoki út 8. H-1521 Budapest Hungary

We present a theoretical study of surface states close to 3d transition-metal adatoms (Cr, Mn, Fe, Co, Ni, and Cu) on a Cu(111) surface in terms of an embedding technique using the fully relativistic Korringa-Kohn-Rostoker method. For each of the adatoms we found resonances in the s-like states to be attributed to a localization of the surface states in the presence of an impurity. We studied the change of the s-like densities of states in the vicinity of the surface-state band edge due to scattering effects mediated via the adatom’s d orbitals. The results obtained clearly show that a magnetic impurity causes spin polarization of the surface states. In particular, the long-range oscillations of the spin-polarized s-like density of states around an Fe adatom are demonstrated.

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Ejected particle cluster detection algorithm and its application

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Jisuan Wuli/Chinese Journal of computational Physics 2006年第4期23卷 441-446页

作者： Zhang, Ying Chen, Qi-Feng Cao, Xiao-Lin Cai, Ling-Cang Chen, Dong-Quan Lu, Tie-Cheng Key Laboratory of Radiation Physics and Technology Department of Physics Sichuan University Chengdu 610064 China Laboratory for Shock Wave and Detonation Physics Research Institute of Fluid Physics Mianyang 621900 China State Key Laboratory of Computational Physics High Performance Computing Center Institute of Applied Physics and Computational Mathematics Beijing 100088 China

Based on the cluster multiple labeling technique, a novel cluster detection algorithm is presented as an analysis subroutine in two-and three-dimensional molecular dynamic simulations of ejecta that take place as a planar shock wave encounters a free metal surface. The algorithm is described, tested, and used to detect cluster distribution of ejecta from copper and aluminum under a shock loading. The information obtained about the size, distribution, evolution of the cluster is helpful in the understanding of ejection.

关键词： Molecular dynamics

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Parallel PDE-based simulations using the common component architecture

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Lecture Notes in computational Science and Engineering 2006年 51卷 327-381页

作者： McInnes, Lois Curfman Allan, Benjamin A. Armstrong, Robert Benson, Steven J. Bernholdt, David E. Dahlgren, Tamara L. Diachin, Lori Freitag Krishnan, Manojkumar Kohl, James A. Walter Larson, J. Lefantzi, Sophia Nieplocha, Jarek Norris, Boyana Parker, Steven G. Ray, Jaideep Zhou, Shujia Mathematics and Computer Science Division Argonne National Laboratory Argonne IL United States Livermore CA United States Computer Science and Mathematics Division Oak Ridge National Laboratory Oak Ridge TN United States Center for Applied Scientific Computing Lawrence Livermore National Laboratory Livermore CA United States Computational Sciences and Mathematics Pacific Northwest National Laboratory Richland WA United States Reacting Flow Research SNL Livermore CA United States Scientific Computing and Imaging Institute University of Utah Salt Lake City UT United States Advanced Software R and D SNL Livermore CA United States Northrop Grumman Corporation Information Technology Sector Chantilly VA United States

ISBN: (纸本)9783540290766

The complexity of parallel PDE-based simulations continues to increase as multimodel, multiphysics, and multi-institutional projects become widespread. A goal of component - based software engineering in such large-scale simulations is to help manage this complexity by enabling better interoperability among various codes that have been independently developed by different groups. The Common Component Architecture (CCA) Forum is defining a component architecture specification to address the challenges of high-performance scientific computing. In addition, several execution frameworks, supporting infrastructure, and general-purpose components are being developed. Furthermore, this group is collaborating with others in the high-performance computing community to design suites of domain-specific component interface specifications and underlying implementations. © Springer-Verlag Berlin Heidelberg 2006.

关键词： Multiphysics

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Spatial time-series modeling: A review of the proposed methodologies

Spatial time-series modeling: A review of the proposed metho...

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8th AGILE International Conference on Geographic Information Science, AGILE 2005

作者： Kamarianakis, Yiannis Prastacos, Poulicos Department of Economics University of Crete Rethymnon Greece Regional Analysis Division Institute of Applied and Computational Mathematics Foundation for Research and Technology-Hellas Vasilika Vouton P.O. Box 1527 GR-711 10 Heraklion-Crete Greece

This paper discusses three modelling techniques, which apply to multiple time series data that correspond to different spatial locations (spatial time series). The first two methods, namely the Space-Time ARIMA (STARIMA) and the Bayesian Vector Autoregressive (BVAR) model with spatial priors apply when interest lies on the spatio-temporal evolution of a single variable. The former is better suited for applications of large spatial and temporal dimension whereas the latter can be realistically performed when the number of locations of the study is rather small. Next, we consider models that aim to describe relationships between variables with a spatio-temporal reference and discuss the general class of dynamic space-time models in the framework presented by Elhorst (2001). Each model class is introduced through a motivating application.

关键词： Time series

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Treatment of an elastic bottom in the parabolic approximation

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The Journal of the Acoustical Society of America 2005年第S1期86卷 S65-S65页

作者： John S. Papadakis Michael I. Taroudakis Betty Mayfield Foundation for Research and Technology—Hellas Institute of Applied and Computational Mathematics P.O. Box 1527 711 10 Iraklion Crete Greece Hood College Frederick MD 21701

The use of impedance boundary conditions in the solution of the parabolic equation in underwater acoustics enables the treatment of bottoms of various types provided that appropriate boundary conditions can be expressed. The conditions are incorporated in an implicit finite difference (IFD) scheme for the parabolic equation. The integrals appearing in the computing scheme are evaluated either analytically, if possible, or numerically. For a sea bottom considered as an elastic homogeneous half‐space, an impedance boundary condition can be evaluated relating the acoustic field in the sea at the water‐bottom interface with that of the elastic bottom. The condition is inserted in the IFD scheme and the pertinent integrals are evaluated numerically by means of a fast Fourier transform algorithm. Results demonstrating the satisfactory behavior of the scheme are presented for range‐independent environments. However, the method is also directly applicable to range‐dependent environments.

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GIS web services and satellite imaging as a framework for environmental monitoring: The design and implementation of a vegetation indices calculation test case 20

GIS web services and satellite imaging as a framework for en...

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20th ISPRS Congress on Technical Commission VII

作者： Kotzinos, D. Chrysoulakis, N. Computer Science Department University of Crete P.O. Box 2208 Heraklio71110 Greece Institute of Applied and Computational Mathematics Foundation for Research and Technology - Hellas P.O. Box 1527 Heraklio71110 Greece

GIS web services bring to the Geographic information arena the promise to deliver algorithmic implementations and data services to the broader community, following a simple yet powerful paradigm. Under this paradigm, a solution to a problem is sought by providing individual services that can be used either in combination or standalone, as part of a greater application to solve the bigger problem. The main advantage is that the service can be used remotely without the user’s actual knowledge and intervention and by multiple users at the same time, eliminating the need for constant updates to locally installed software. Moreover it minimizes the network traffic, since data do not need to be transferred to the client in every step of the operation. This overall framework is currently being developed and tested and the one major test application presented is the development as a web service of an algorithm that calculates vegetation indices using low spatial resolution satellite images. To achieve the overall result two separate web services are developed: a) One handling the acquisition and manipulation of the satellite images being used. A low-resolution satellite ground receiving station is used to provide real time satellite data. b) A second one implementing a vegetation index calculation algorithm, using results form the first web service. It’s worth noting here that the system has the potential to be expanded by more algorithms (e.g. for surface temperature estimation, for aerosol spatial distribution monitoring, for perceptible water calculation) that will still use one or both of the already developed web services, leading to a services-chaining effect. Web services can by nature be used by both web-based and desktop applications alike so, as part of this work, two small client applications are developed – one web-based and one desktop, in order to showcase the applicability and availability of the framework. End users will use the two already mentioned clients

关键词： Geographic information systems

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