GELDA: A software package for the solution of General Linear Differential Algebraic equations

We describe a new software package for the numerical solution of linear differential-algebraic equations with variable coefficients. The implementation is based on the new discretization scheme introduced in [19]. It can deal with systems of arbitrary index and with systems that do not have unique solutions or inconsistencies in the initial values or the inhomogeneity. The package includes a computation of all the local invariants of the system, a regularization procedure and an index reduction scheme and it can be combined with every solution method for standard index 1 systems. Nonuniqueness and inconsistencies are treated in a least square sense. We give explicit descriptions how to use the package and include a series of numerical examples as well as comparisons with results from other codes, as far as this is possible

Modelling of atmospheric chemistry-transport processes

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Diplom-Informatiker

ii In memory of my father Isaac To my mother Betti iii Modern Web Services applications encompass multiple distributed interacting components, possibly including millions of lines of code written in different programming languages. With this complexity, some bugs often remain undetected despite extensive testing procedures, and occasionally cause transient system failures. Incorrect failure handling in applications often leads to incomplete or to unintentional request executions. A family of recovery protocols called interaction contracts provides a generic solution to this problem by means of system-integrated data, process, and message recovery for multi-tier applications. It is able to mask failures, and allows programmers to concentrate on the application logic, thus speeding up the development process