A Highly Dependable Computing Architecture for Safety-Critical Control Applications

. More and more technical systems are supervised, controlled and regulated by programmable electronic systems. The dependability of the entire system depends heavily on the safety of the embedded software. But the technological trend to entrust software with tasks of growing complexity and safety relevance conflicts with the lacking acceptance of rigorous proofs of software safety. Based on an international standard for higher level programming languages for programmable logic controllers (PLC, IEC 1131-3), a mathematically based method for validating the behavioral correctness and the functional safety of graphical designs of safe-critical control applications is introduced. The design elements taken from a domain specific module library are proven correct and safe only once. The functional correctness and satifaction of safety requirements of new application graphical programs can then be shown effectively by reference to the proven properties of the library components used. This app..

Stability analysis and limit cycles of high order sigma-delta modulators

In this chapter we present an unified approach for study the stability and validation of potential limit cycles of one bit high order Sigma-Delta modulators. The approach is general because it uses the general form of a Sigma-Delta modulator. It is based on a parallel decomposition of the modulator and a direct nonlinear systems analysis. In this representation, the general N-th order modulator is transformed into a decomposition of low order, generally complex modulators, which interact only through the quantizer function. The developed conditions for stability and for validation of potential limit cycles are very easy for implementation and this procedure is very fast

Synchronization of movement for a large-scale crowd

Real world models of large-scale crowd movement lead to computationally intractable problems implied by various classes of non-linear stochastic differential equations. Recently, cellular automata (CA) have been successfully applied to model the dynamics of vehicular traffic, ants and pedestrians’ crowd movement and evacuation without taking into account mental properties. In this paper we study a large-scale crowd movement based on a CA approach and evaluated by the following three criteria: the minimization of evacuation time, maximization of instantaneous flow of pedestrians, and maximization of mentality-based synchronization of a crowd. Our computational experiments show that there exist interdependencies between the three criteria