This work is concerned with the simulation of inviscid compressible flow in time dependent domains. We present an ALE (Arbitrary Lagrangian-Eulerian) formulation of the Euler equations describing compressible flow, discretize them in space by the discontinous Galerkin method and introduce a semi-implicit linearized time stepping for the numerical solution of the complete problem. Special attent...

The solution of time-dependent PDE-constrained optimization problems subject to unsteady flow equations presents a challenge to both algorithms and computers. In this paper we present an all-at-once approach where we solve for all time-steps of the discretized unsteady Stokes problem at once. The most desirable feature of this approach is that for all steps of an iterative scheme we only need a...

In this paper we consider the problem of finding a decomposed solution to a Markov model where the action rates may depend on the global state space. To do this we consider regular cycles in the underlying state space and show that a semi-product form solution exists when the functions describing the action rates have specific forms. The approach is illustrated with a simple queueing example al...

The orienteering problem (OP) is defined on a graph in which scores are assigned to the vertices and a travel time is assigned to each edge linking two vertices. The objective of the OP is to select a subset of vertices and determine the order in which they are visited so that the total collected score is maximized while the maximum total travel time is not exceeded. In addition, a feasible OP ...

We consider the numerical computation of stationary distributions for level dependent quasi-birth-and-death processes. An algorithm based on matrix continued fractions is presented and compared to standard solution techniques. Its computational efficiency and numerical stability is demonstrated by numerical examples.

Changes in the conformation of the polyelectrolytes when contacted with oppositely charged polyelectrolytes or when subjected to shifts in solution conditions (pH), have been studied in this work along with reversibility of the changes using fluorescence spectroscopy. While changes due to both of the above are marked, they are measurably different from each other. Thus, the extent of coiling of...

The paper deals with numerical simulation of a compressible flow in timedependent 2D domains with a special interest in medical applications to airflow in the human vocal tract. The mathematical model of this process is described by the compressible Navier-Stokes equations. For the treatment of the time-dependent domain, the arbitrary Lagrangian-Eulerian (ALE) method is used. The discontinuous ...

An adaptive numerical method for solution of the time-dependent Schrödinger equation is presented. By using an interpolating wavelet transform the number of used points can be reduced, constructing an adaptive sparse point representation. Two di erent discretisation approaches are studied in 1D ; one point-based and one based on equidistant blocks. Due to the nature of the wavelet transform a s...

The tau-leaping method is often effective for speeding up discrete stochasticsimulation of chemically reacting systems. However, when fast reactions areinvolved, the speed-up for this method can be quite limited. One way to ad-dress this is to apply a stochastic quasi-steady state assumption. However wemust to be careful when using this assumption. If the fast subsystem cann...

We present a non-perturbative solution of the Schrödinger equation iψt = −ψxx−(2−α sinωt)δ(x)ψ describing the ionization of a model atom by a parametric oscillating potential. This model has been studied extensively by many authors, including us. It has surprisingly many features in common with those observed in the ionization of real atoms and emission by solids, subjected to microwave or lase...