Alexander Bell

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hpGEM, a novel framework for the implementation of discontinuous Galerkin finite element methods (FEMs), is described. We present data structures and methods that are common for many (discontinuous) FEMs and show how we have implemented the components as an object-oriented framework. This framework facilitates and accelerates the implementation of finite(More)
In this paper we present algorithms for model checking CTL over systems specified as Petri nets. We present sequential as well as distributed model checking algorithms. The algorithms rely on an explicit representation of the system state space, but do not require the transition relation to be explicitly available; it is recomputed whenever required. This(More)
In this paper we present data structures and distributed algorithms for CSL model checking-based performance and dependability evaluation. We show that all the necessary computations are composed of series or sums of matrix-vector products. We discuss sparse storage structures for the required matrices and present efficient sequential and distributed(More)
In this paper we present eecient techniques for the generation of very large continuous-time Markov chains (CTMCs) speciied as stochastic Petri nets (SPNs). In particular, we investigate how the storage eeciency of the reachability graph generation can be improved by using clever state coding techniques and by using hashing tables instead of tree-based data(More)
This paper discusses four topics, using the publicly released AFRL X-band backhoe " datadome " , as well as our own UHF backhoe datadome. First we show that wide-angle SAR apertures, ideally spanning 360 • in azimuth with dense elevation coverage, combined with volumetric backprojection imaging, yield imagery that bears a strong literal resemblance to the(More)