@inproceedings {INPROC-2004-93, author = {Martin Buchholz and Dirk Pfl{\"u}ger and Josiah Poon}, title = {{Application of Machine Learning Techniques to the Re-ranking of Search Results}}, booktitle = {KI 2004: Advances in Artificial Intelligence}, editor = {Susanne Biundo and Thom Fr{\"u}hwirth and G{\"u}nther Palm}, publisher = {Springer-Verlag}, institution = {University of Stuttgart, Faculty of Computer Science, Electrical Engineering, and Information Technology, Germany}, series = {Lecture Notes in Computer Science}, volume = {3238}, pages = {67--81}, type = {Conference Paper}, month = {September}, year = {2004}, isbn = {3-540-23166-8}, language = {German}, cr-category = {I.6 Simulation and Modeling}, department = {University of Stuttgart, Institute of Parallel and Distributed Systems, Simulation of Large Systems}, abstract = {leer}, url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2004-93&engl=1} } @inproceedings {INPROC-2004-39, author = {Hans-Joachim Bungartz}, title = {{Some remarks on CSE education in Germany}}, booktitle = {Proceedings of the 2004 International Conference on Computational Science: ICCS 2004}, editor = {Marian Bubak and Geert D. van Albada and Peter M.A. Sloot and Jack J. Dongarra}, address = {Heidelberg}, publisher = {Springer}, institution = {University of Stuttgart, Faculty of Computer Science, Electrical Engineering, and Information Technology, Germany}, series = {Lecture Notes in Computer Science}, volume = {3039}, pages = {1180--1187}, type = {Conference Paper}, month = {May}, year = {2004}, isbn = {354022114X}, language = {English}, cr-category = {K.3 Computers and Education}, contact = {Hans-Joachim Bungartz bungartz@ipvs.uni-stuttgart.de}, department = {University of Stuttgart, Institute of Parallel and Distributed Systems, Simulation of Large Systems}, abstract = {no abstract available}, url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2004-39&engl=1} } @inproceedings {INPROC-2004-37, author = {Hans-Joachim Bungartz and Stefan Dirnstorfer}, title = {{Higher order quadrature on sparse grids}}, booktitle = {Proceedings of the 2004 International Conference on Computational Science: ICCS 2004}, editor = {Marian Bubak and Geert D. van Albada and Peter M.A. Sloot and Jack J. Dongarra}, address = {Heidelberg}, publisher = {Springer}, institution = {University of Stuttgart, Faculty of Computer Science, Electrical Engineering, and Information Technology, Germany}, series = {Lecture Notes in Computer Science}, volume = {3039}, pages = {394--401}, type = {Conference Paper}, month = {May}, year = {2004}, isbn = {354022114X}, language = {English}, cr-category = {G.1 Numerical Analysis}, contact = {Hans-Joachim Bungartz bungartz@ipvs.uni-stuttgart.de}, department = {University of Stuttgart, Institute of Parallel and Distributed Systems, Simulation of Large Systems}, abstract = {no abstract available}, url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2004-37&engl=1} } @inproceedings {INPROC-2004-36, author = {Andreas Niggl and Richard Romberg and Ernst Rank and Ralf-Peter Mundani and Hans-Joachim Bungartz}, title = {{A Framework for Concurrent Structure Analysis in Building Industry}}, booktitle = {Proceedings of the 5th European Conference on Product and Process Modelling in the Building and Construction Industry: ECPPM '04; Istanbul, Turkey, September 8-10, 2004}, editor = {A. Dikbas and R. Scherer}, publisher = {A.A. Balkema Publishers}, institution = {University of Stuttgart, Faculty of Computer Science, Electrical Engineering, and Information Technology, Germany}, type = {Conference Paper}, month = {September}, year = {2004}, isbn = {04-1535-938-4}, keywords = {octrees; volume-oriented geometric modelling; finite elements; RDBMS; network-based cooperative work}, language = {English}, cr-category = {E.1 Data Structures, E.4 Data Coding and Information Theory, G.1.8 Partial Differential Equations, H.2.4 Database Management Systems, J.2 Physical Sciences and Engineering, J.6 Computer-Aided Engineering}, department = {University of Stuttgart, Institute of Parallel and Distributed Systems, Simulation of Large Systems}, abstract = {In this paper, a software-framework, which helps to support the concurrent work of multiple planners in the construction industry, will be presented. Basis of this work is a strictly three dimensional building model. This model is stored in a central database, which supports the cooperative work of multiple planners by using an object based 'check in', 'checkout' and 'locking' mechanism. Furthermore a decomposition algorithm will be shown, which automatically derives a hexahedral mesh for a finite element computation from this central building model.}, url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2004-36&engl=1} } @inproceedings {INPROC-2004-35, author = {Ralf-Peter Mundani and Hans-Joachim Bungartz}, title = {{Octrees for Cooperative Work in a Network-Based Environment}}, booktitle = {Proceedings of the 10th International Conference on Computing in Civil and Building Engineering: ICCCBE '04; Weimar, Germany, June 2-4, 2004}, editor = {K. Beucke and Firmenich B. and D. Donath and R. Fruchter and K. Roddis}, publisher = {VDG Weimar}, institution = {University of Stuttgart, Faculty of Computer Science, Electrical Engineering, and Information Technology, Germany}, type = {Conference Paper}, month = {June}, year = {2004}, keywords = {octrees; volume-oriented geometric modelling; convex hull decomposition; RDBMS; network-based cooperative work}, language = {English}, cr-category = {E.1 Data Structures, E.4 Data Coding and Information Theory, H.2.4 Database Management Systems, I.3.5 Computational Geometry and Object Modeling, J.2 Physical Sciences and Engineering, J.6 Computer-Aided Engineering}, contact = {Ralf-Peter Mundani Ralf.Mundani@ipvs.uni-stuttgart.de}, department = {University of Stuttgart, Institute of Parallel and Distributed Systems, Simulation of Large Systems}, abstract = {While surface-oriented models became more and more popular because of their flexibility concerning manipulation, especially within CAD applications, they are only conditionally suited for simulation or controlling tasks, a field still dominated by volume-oriented models. Due to their spatial decomposition of the underlying geometry, volume-oriented models provide an easy access to simulation tasks relevant in civil engineering like air conditioning of rooms, statics analysis of buildings, or managing and controlling design processes. Here, hierarchical recursive data structures like octrees seem to be perfectly suited to efficiently bridge the gap between classical CAD applications on the one side and volume-oriented tasks as mentioned above on the other side. Within our research, a global geometric model represented by an octree is the starting point of a network-based cooperative working environment, allowing us a fast and efficient control of collision detection and model revision as well as the integration of different simulation tasks or disciplines like architecture and civil engineering, for instance. For a fast derivation - even on-the-fly - of a volume-oriented model from a surface-oriented one, the octrees are generated by intersecting half-spaces that come from single flat surface patches of the original CAD model, provided in the (Eurostep) IFC format. As only convex objects can obviously be processed by this method, non-convex objects have to be decomposed into convex parts in advance. For a convex decomposition, such an object's convex hull is recursively calculated, marking all faces lying on the convex hull and processing the rest in the same way until all faces are labelled. With respect to these labels, an expression consisting of the three Boolean operators union, difference, and intersection is formed, describing a unique order to process the corresponding half-spaces. Hence, the result is an (volume-oriented) octree representation of the original surface-oriented geometry. A linearisation and binary encoding of these octrees result in bit streams to which different operators like collision detection, for instance, can be applied. Any inconsistencies can be easily detected to be removed by the respective expert. Thus, the consistency of the global geometric model is ensured. For a cooperative work, the global geometric model is stored in a Relational Database Management System (RDBMS), accessed by a second control octree storing the primary keys to the RDBMS's tables, such that neighbouring elements or collisions between revised elements can be detected in a fast and efficient way. The cooperative work is further supported by several check-in/check-out methods, providing different levels of granularity concerning notifications being sent to all participating experts based on their actual processed elements as well as typical read-only, read-write, and exclusive-write permissions for each element. The usage of octrees as integral element in a network-based cooperative working environment not only simplifies the control and combination of different tasks, it can also work as common interface between several disciplines - e.g. architecture and civil engineering - to bring us one step closer to the long-term objective of completely embedded simulation processes.}, url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2004-35&engl=1} } @inproceedings {INPROC-2004-34, author = {Ralf-Peter Mundani and Hans-Joachim Bungartz}, title = {{An Octree-Based Framework for Process Integration in Structural Engineering}}, booktitle = {Proceedings of the 8th World Multi-Conference on Systemics, Cybernetics and Informatics - Volume II: SCI '04; Orlando, Florida, USA, July 18-21, 2004}, editor = {N. Callaos and W. Lesso and B. Sanchez}, publisher = {International Institute of Informatics and Systemics}, institution = {University of Stuttgart, Faculty of Computer Science, Electrical Engineering, and Information Technology, Germany}, pages = {197--202}, type = {Conference Paper}, month = {July}, year = {2004}, isbn = {980-6560-13-2}, keywords = {octrees; hierarchical data structures; octree-based framework; process integration; cooperative work; collision detection}, language = {English}, cr-category = {E.1 Data Structures, E.4 Data Coding and Information Theory, I.3.5 Computational Geometry and Object Modeling, I.3.7 Three-Dimensional Graphics and Realism, J.2 Physical Sciences and Engineering, J.6 Computer-Aided Engineering}, contact = {Ralf-Peter Mundani Ralf.Mundani@ipvs.uni-stuttgart.de}, department = {University of Stuttgart, Institute of Parallel and Distributed Systems, Simulation of Large Systems}, abstract = {Octrees - hierarchical data structures based on recursive substructuring - have turned out to be a powerful representative of the hierarchical paradigm, advantageous in a large variety of applications such as visualisation, computer graphics, databases resp. data mining, mesh generation, numerical simulation, or Geographic Information Systems (GIS). In this paper, octrees are used to build up a framework for the integration of CAD, simulation, and visualisation tasks from the field of structural engineering in a network-based cooperative working environment. It will be shown that, by providing octree-based tools, the coupling of these tasks and the control of the entire design process can be improved and simplified. Starting from a CAD model, due to a new method based on the intersection of half-spaces, an octree representation can be efficiently derived, if necessary also in real time more details). A linearisation followed by a binary encoding of such trees results in streams that can be assigned to Boolean operators or more sophisticated tools for further processing - even on-the-fly. As such streams can be described by a Chomsky-II-grammar, their integrity - e.g. after transmission over a network - can easily be checked by a corresponding finite state automaton. Based on octree encoded streams, tools for various purposes like providing interfaces between different applications (e.g. CAD and numerical simulation tasks such as computational fluid dynamics) or collision detection between single parts of a geometric model, for instance, are possible. Furthermore, to ensure global consistency of shared data processed by several experts in a network-based cooperative working environment, for instance, a geometric model is stored in a Relational Database Managment System (RDBMS) which can only be accessed by an octree and corresponding check-in/check-out functions. Thus, any modified parts intended to be written to the RDBMS and conflicting with the rest of the data can easily be detected. As octrees - because of their inherent hierarchy - also allow access to the data on different resolutions levels (e.g. walls, rooms, or floors), even conflicts among various processes can be detected and, hence, entire design processes can be coordinated and improved. Another application scenario - visualisation and virtual reality - is also covered by this framework. Here, the former discussed model can be augmented by any arbitrary data (e.g. room informations), and a graph for shortest-path algorithms can automatically be derived and manipulated, meant for viewing both as VRML application within a web browser and as immersive stereo projection on more sophisticated devices like a power wall or a CAVE. Summarising, the usage of an octree-based framework for the integration of processes from the field of structural engineering not only bridges the gap between the different applications like CAD, simulation, and visualisation, it also simplifies and improves the control abilities of these processes as a fundamental in a network-based cooperative working environment.}, url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2004-34&engl=1} } @article {ART-2004-09, author = {Hans-Joachim Bungartz and Michael Griebel}, title = {{Sparse Grids}}, journal = {Acta Numerica}, publisher = {Cambridge University Press}, volume = {13}, pages = {147--269}, type = {Article in Journal}, month = {May}, year = {2004}, language = {English}, cr-category = {G.1 Numerical Analysis}, contact = {Hans-Joachim Bungartz bungartz@ipvs.uni-stuttgart.de}, department = {University of Stuttgart, Institute of Parallel and Distributed Systems, Simulation of Large Systems}, abstract = {We present a survey of the fundamentals and the applications of sparse grids, with a focus on the solution of partial differential equations (PDEs). The sparse grid approach, introduced in Zenger (1991), is based on a higher-dimensional multiscale basis, which is derived from a one-dimensional multi-scale basis by a tensor product construction. Discretizations on sparse grids involve \$O(N $\backslash$cdot ($\backslash$log N)^{d-1})\$ degrees of freedom only, where \$d\$ denotes the underlying problem's dimensionality and where \$N\$ is the number of grid points in one coordinate direction at the boundary. The accuracy obtained with piecewise linear basis functions, for example, is \$O(N^{-2} $\backslash$cdot ($\backslash$log N)^{d-1})\$ with respect to the \$L\_{2^-}\$ and \$L\_{$\backslash$infty}\$-norm, if the solution has bounded second mixed derivatives. This way, the curse of dimensionality, i.e., the exponential dependence \$O(N^d)\$ of conventional approaches, is overcome to some extent. For the energy norm, only \$O(N)\$ degrees of freedom are needed to give an accuracy of \$O(N^{-1})\$. That is why sparse grids are especially well-suited for problems of very high dimensionality. The sparse grid approach can be extended to nonsmooth solutions by adaptive refinement methods. Furthermore, it can be generalized from piecewise linear to higher-order polynomials. Also, more sophisticated basis functions like interpolets, prewavelets, or wavelets can be used in a straightforward way. We describe the basic features of sparse grids and report the results of various numerical experiments for the solution of elliptic PDEs as well as for other selected problems such as numerical quadrature and data mining.}, url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=ART-2004-09&engl=1} } @article {ART-2004-08, author = {M. Kuehn and M. Mehl and M. Hausner and H.J. Bungartz and S. Wuertz}, title = {{Time-resolved study of biofilm architecture and transport processes using experimental and simulation techniques: the role of EPS}}, journal = {Water Science and Technology}, publisher = {IWA Publishing}, volume = {43}, number = {6}, pages = {143--150}, type = {Article in Journal}, month = {January}, year = {2004}, language = {English}, cr-category = {I.6 Simulation and Modeling, J.3 Life and Medical Sciences}, contact = {Hans-Joachim Bungartz bungartz@ipvs.uni-stuttgart.de}, department = {University of Stuttgart, Institute of Parallel and Distributed Systems, Simulation of Large Systems}, abstract = {Cellular material and extracellular polymeric substances are the basic structural elements in biofilm systems. The structure and role of EPS for biofilm development and metabolic processes have not been precisely determined and, therefore, have not yet been included as a necessary element in modelling and simulation studies. This is due to the difficulty of experimentally detecting the extracellular polymeric substances in situ and differentiating them from cellular material on the one hand, and to the subsequent uncertainty about appropriate models--e.g. rigid hindrances, porous microstructure or visco-elastic structure--on the other hand. In this work, we report on the use of confocal laser scanning microscopy to monitor the development of a monoculture biofilm of Sphingomonas sp. grown in a flow cell. The bacterial strain was genetically labelled resulting in strong constitutive expression of the green fluorescent protein. The development of extracellular polymeric substances was followed by binding of the lectin concavalin A to cell exopolysaccharides. The growth of the resulting strain was digitally recorded by automated confocal laser scanning microscopy. In addition, local velocity profiles of fluorescent carboxylate-modified microspheres were observed on pathlines throughout the biofilm. The CLSM image stacks were used as direct input for the explicit modelling and three-dimensional numerical simulation of flow fields and solute transport processes based on the conservation laws of continuum mechanics. At present, a strongly simplifying EPS-model is applied for numerical simulations. The EPSs are preliminarily assumed to behave like a rigid and dense hindrance with diffusive-reactive solute transport.}, url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=ART-2004-08&engl=1} } @inbook {INBOOK-2004-20, author = {Frank G{\"u}nther and Andreas Krahnke and Markus Langlotz and Miriam Mehl and Markus P{\"o}gl and Christoph Zenger}, title = {{Recent Advances in Parallel Virtual Machine and Message Passing Interface. 11th European PVM/MPI Users Group Meeting Budapest, Hungary, September 19 - 22, 2004. Proceedings}}, series = {On the Parallelization of a Cache-Optimal Iterative Solver for PDEs Based on Hierarchical Data Structures and Space-Filling Curves}, address = {Berlin, Heidelberg,}, publisher = {Springer}, series = {LNCS}, volume = {3241}, pages = {425--429}, type = {Article in Book}, month = {January}, year = {2004}, language = {German}, cr-category = {I.6 Simulation and Modeling}, department = {University of Stuttgart, Institute of Parallel and Distributed Systems, Simulation of Large Systems}, abstract = {leer}, url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INBOOK-2004-20&engl=1} } @inbook {INBOOK-2004-12, author = {Hans-Joachim Bungartz and Anne T{\"o}pfer}, title = {{Die modulare Strukturierung und Aufbereitung der Lerninhalte in ITO}}, series = {Information Technology Online: Online-gest{\"u}tztes Lehren und Lernen in informationstechnischen Studieng{\"a}ngen}, publisher = {Waxmann}, pages = {35--43}, type = {Article in Book}, month = {June}, year = {2004}, isbn = {3830913583}, language = {German}, cr-category = {K.3 Computers and Education}, contact = {Hans-Joachim Bungartz bungartz@ipvs.uni-stuttgart.de}, department = {University of Stuttgart, Institute of Parallel and Distributed Systems, Simulation of Large Systems}, abstract = {no abstract available}, url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INBOOK-2004-12&engl=1} } @inbook {INBOOK-2004-11, author = {Hans-Joachim Bungartz and Thorsten Strobel}, title = {{Austausch von Lerninhalten und l{\"a}nder{\"u}bergreifende Kooperation}}, series = {Information Technology Online: Online-gest{\"u}tztes Lehren und Lernen in informationstechnischen Studieng{\"a}ngen}, publisher = {Waxmann}, pages = {31--34}, type = {Article in Book}, month = {June}, year = {2004}, isbn = {3830913583}, language = {German}, cr-category = {K.3 Computers and Education}, contact = {Hans-Joachim Bungartz bungartz@ipvs.uni-stuttgart.de}, department = {University of Stuttgart, Institute of Parallel and Distributed Systems, Simulation of Large Systems}, abstract = {no abstract available}, url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INBOOK-2004-11&engl=1} } @inbook {INBOOK-2004-10, author = {Hans-Joachim Bungartz and Stefan Zimmer}, title = {{Besondere Strukturen und Erfordernisse in Lehr-/Lernkontexten technisch-naturwissenschaftlicher Studieng{\"a}nge}}, series = {Information Technology Online: Online-gest{\"u}tztes Lehren und Lernen in informationstechnischen Studieng{\"a}ngen}, publisher = {Waxmann}, pages = {21--30}, type = {Article in Book}, month = {June}, year = {2004}, isbn = {3830913583}, language = {German}, cr-category = {K.3 Computers and Education}, contact = {Hans-Joachim Bungartz bungartz@ipvs.uni-stuttgart.de}, department = {University of Stuttgart, Institute of Parallel and Distributed Systems, Simulation of Large Systems}, abstract = {no abstract available}, url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INBOOK-2004-10&engl=1} } @book {BOOK-2004-02, author = {Hans-Joachim Bungartz and Michael Griebel and Christoph Zenger}, title = {{Introduction to Computer Graphics, Second Edition}}, publisher = {Charles River Media}, pages = {262}, type = {Book}, month = {February}, year = {2004}, isbn = {1-58450-332-7}, language = {English}, cr-category = {I.3 Computer Graphics, I.4 Image Processing and Computer Vision}, contact = {Hans-Joachim Bungartz bungartz@ipvs.uni-stuttgart.de}, department = {University of Stuttgart, Institute of Parallel and Distributed Systems, Simulation of Large Systems}, abstract = {In this essential guide to programming computer graphics, the authors begin with the basics of generating images on a computer screen, taking the first chapter to discuss coordinate systems and transformations, rudimentary shapes, and the representation of grays and colors. Later, the book moves into ways to model and represent three-dimensional objects, introducing geometric models, the vef graph, Euler operations, Bezier curves, three-dimensional clipping, lighting effects/shading, ray tracing, radiosity, and visualization. The final chapter addresses specific applications of mapping techniques and image processing, explaining how they are used to represent natural objects. This book can be used as a reference by engineers, architects, and professionals in the computer graphics field or as a textbook for students of computer graphics programming.}, url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=BOOK-2004-02&engl=1} }