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Ausgeweitete Radstreifen bei lichtsignalgesteuerten Knoten
(1994)Die Anordnung von ausgeweiteten Radstreifen in Knotenzufahrten zur Verbesserung der Sicherheit und des Komfortes der Zweiradfahrer erscheint aufgrund der vorliegenden Untersuchung in Ausnahmefällen sinnvoll.Report -
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Circuits in Power Electronics
(1994)SAM Research ReportThe dynamics of circuits in power electronics may often be modelled by means of systems of linear differential equations with piecewise constant coefficients and sinusoidal inhomogeneities. The Static Var (Volt-Ampere reactive) Compensator (SVC, a device for power network control) is a representative example. Initial value problems of this type may be handled by means of the matrix exponential, whereas the construction of periodic solutions ...Report -
A numerical method for unsteady flows
(1994)SAM Research ReportA high resolution finite volume method for the computation of unsteady solutions of the Euler equations in two space dimensions is presented and validated. The scheme is of Godunov-type. The first order part of the flux function uses the approximate Riemann problem solver of Pandolfi and here a new derivation of this solver is presented. This construction paves the way to understand the conditions under which the scheme satisfies an entropy ...Report -
Parallel Implementation of ADVISE on the Intel Paragon
(1994)SAM Research ReportEnvironmental models, such as the Pasture Model, require large computing resources to give results within reasonable time frames. This report focuses on the design and implementation of a parallel version of an ADVISE server running the Pasture Model on the Intel Paragon. In order to make the most efficient use of this computing resource, it is first necessary to perform a thorough analysis of the message passing, file I/O and computation ...Report -
A parallel implementation of a deflation algorithm for systems of linear equations
(1994)SAM Research ReportA general deflation technique for solving arbitrary systems of linear equations was described in Burrage et al. (1994a). This technique can be used with any iterative scheme. As the iterations proceed information is obtained about the eigenvalues of the iteration matrix which either cause slow convergence or divergence. These eigenvalues (and associated eigenvectors) are then deflated into a stiff subspace. This then leads to a coupled ...Report -
Knot removal with radial function interpolation
(1994)SAM Research ReportIn this note we study interpolants to $n$-variate, real valued functions from radial function spaces, \ie spaces that are spanned by radially symmetric functions $\varphi(\|\cdot - x_{j} \|_2)$ defined on $\R^n$. Here $\| \cdot \|_2$ denotes the Euclidean norm, $\varphi : \R_+ \to \R$ is a given "radial (basis) function" which we take here to be $\varphi (r) = ( r^2 + c^2)^{\beta /2}$, $-n \leq \beta < 0$, and the $\{x_j \} \subset \R^n$ ...Report -
Pre-Wavelets on Scattered Knots and from Radial Function Spaces: A Review
(1994)SAM Research ReportWe review recent work on univariate prewavelets that are either spline prewavelets on non-equally spaced knots or prewavelets from spaces spanned by translates of radial basis functions with non-equally spaced centres. Some of the results on radial basis functions we present apply to more than one dimension as well, so long as the centres are again confined to a grid.Report -
Hyperbolic Conservation Laws with Source Terms: Errors of the Shock Location
(1994)SAM Research ReportWe investigate the error of the shock location which occurs in numerical solutions of hyperbolic conservation laws with source terms. For our theoretical analysis we consider a scalar Riemann problem. We compute its solution using a splitting method. This means that in each time step the homogeneous conservation law and an ODE (modeling the source term) are solved separately. We show that the local error of the shock location can be ...Report -
ADVISE, Agricultural Developmental Visualisation Interactive Software Environment
(1994)SAM Research ReportThe quantum increase in computing power provided by contemporary parallel architectures offers the opportunity to confront problems of ever increasing complexity and size. With these developments new problems arise in techniques for the manipulation, transmission and display of large data sets as they occur for example in environmental modelling. The hardware and software of modern graphical display devices has the potential to enable ...Report