553 results
Search Results
Now showing 1 - 10 of 553
- ItemStatistical methods for the qualitative assessment of dynamic models with time delay (R package qualV)(Los Angeles, CA : Foundation for Open Access Statistics, 2007) Jachner, S.; Van Den Boogaart, K.G.; Petzoldt, T.Results of ecological models differ, to some extent, more from measured data than from empirical knowledge. Existing techniques for validation based on quantitative assessments sometimes cause an underestimation of the performance of models due to time shifts, accelerations and delays or systematic differences between measurement and simulation. However, for the application of such models it is often more important to reproduce essential patterns instead of seemingly exact numerical values. This paper presents techniques to identify patterns and numerical methods to measure the consistency of patterns between observations and model results. An orthogonal set of deviance measures for absolute, relative and ordinal scale was compiled to provide informations about the type of difference. Furthermore, two different approaches accounting for time shifts were presented. The first one transforms the time to take time delays and speed differences into account. The second one describes known qualitative criteria dividing time series into interval units in accordance to their main features. The methods differ in their basic concepts and in the form of the resulting criteria. Both approaches and the deviance measures discussed are implemented in an R package. All methods are demonstrated by means of water quality measurements and simulation data. The proposed quality criteria allow to recognize systematic differences and time shifts between time series and to conclude about the quantitative and qualitative similarity of patterns.
- ItemAdaptive smoothing of digital images: The R package adimpro(Los Angeles, Calif. : UCLA, Dept. of Statistics, 2007) Polzehl, J.; Tabelow, K.Digital imaging has become omnipresent in the past years with a bulk of applications ranging from medical imaging to photography. When pushing the limits of resolution and sensitivity noise has ever been a major issue. However, commonly used non-adaptive filters can do noise reduction at the cost of a reduced effective spatial resolution only. Here we present a new package adimpro for R, which implements the propagationseparation approach by (Polzehl arid Spokoiriy 2006) for smoothing digital images. This method naturally adapts to different structures of different size in the image and thus avoids oversmoothing edges and fine structures. We extend the method for imaging data with spatial correlation. Furthermore we show how the estimation of the dependence between variance and mean value can be included. We illustrate the use of the package through some examples.
- ItemFunktionentheorie(Oberwolfach-Walke : Mathematisches Forschungsinstitut Oberwolfach, 2001) Bergweiler, Walter; Kühnau, Reiner[no abstract available]
- ItemMini-Workshop: Geometry of Quantum Entanglement(Zürich : EMS Publ. House, 2009) Szarek, Stanislaw; Werner, Elisabeth; Zyczkowski, KarolThe workshop aimed at developing interactions between researchers from quantum information theory and from asymptotic geometric analysis. A central notion discussed was the phenomenon of quantum entanglement, which naturally leads to geometric considerations in high-dimensional vector spaces. In these spaces, phenomena such as concentration of measure become prominent and may invalidate our low-dimensional intuition.
- ItemCombinatorics, Convexity and Algebraic Geometry(Oberwolfach-Walke : Mathematisches Forschungsinstitut Oberwolfach, 2003) McMullen, Peter; Sturmfels, Bernd; Teissier, Bernard[no abstract available]
- ItemMini-Workshop: Product Systems and Independence in Quantum Dynamics(Zürich : EMS Publ. House, 2009) Franz, Uwe; Skeide, MichaelQuantum dynamics, both reversible (i.e., closed quantum systems) and irreversible (i.e., open quantum systems), gives rise to product systems of Hilbert spaces or, more generally, of Hilbert modules. When we consider reversible dynamics that dilates an irreversible dynamics, then the product system of the latter is equal to the product system of the former (or is contained in a unique way). Whenever the dynamics is on a proper subalgebra of the algebra of all bounded operators on a Hilbert space, in particular, when the open system is classical (commutative) it is indispensable that we use Hilbert modules. The product system of a reversible dynamics is intimately related to a filtration of subalgebras that are independent in a state or conditionally independent in a conditional expectation of the reversible system. This has been illustrated in many concrete dilations that have been obtained with the help of quantum stochastic calculus. Here the underlying Fock space or module determines the sort of quantum independence underlying the reversible system. The mini-workshop brought together experts from quantum dynamics, product systems and quantum independence who have contributed to the general theory or who have studied intriguing examples. As the implications of the tight relationship between product systems and independence had so far been largely neglected, we expect from our mini-workshop a strong innovative impulse to this field.
- ItemNumerical Techniques for Optimization Problems with PDE Constraints(Oberwolfach-Walke : Mathematisches Forschungsinstitut Oberwolfach, 2003) Hoppe, Ronald H.W.; Schulz, Volker[no abstract available]
- ItemNichtkommutative Geometrie(Oberwolfach-Walke : Mathematisches Forschungsinstitut Oberwolfach, 2000) Cuntz, Joachim; Rieffel, Marc A.[no abstract available]
- ItemRepresentation Theory and Complex Analysis(Oberwolfach-Walke : Mathematisches Forschungsinstitut Oberwolfach, 2000) Huckleberry, Alan T.; Neeb, Karl-Hermann[no abstract available]
- Item4-dimensional Manifolds(Oberwolfach-Walke : Mathematisches Forschungsinstitut Oberwolfach, 2001) Kronheimer, Peter B.; Stern, Ronald J.[no abstract available]