Control systems theoretical background

In part 2 the problems arising during the real design of SRP/CS (Safety Related Part of a Control System) of machines are addressed on the background of relevant safety standards. Using the informative theoretical appendix A of ISO 13849-1 to determine the Performance Level required (PLr) may cause sometimes technically impracticable requirements, which are far beyond the state of the art in existing type C standards. For the sake of connection between theory and practice, the probabiUty of occurrence of a hazardous situation must be taken into account in order to appropriately consider the required risk reduction of a SRP/CS in the context of the three-step-method of ISO 12100. For this purpose two practical solutions are provided ... 

In this chapter we concentrate on nano-semiconductor systems, where it has become possible during the last 15 years to handle and control single excitons. More specifically we focus on excitons and exciton-polaritons in semiconductor QDs. This chapter presents first a theoretical background of the solid-state theory, the exciton and the coupling between the exdton and the photon (excitonic polariton). Optical properties of exciton polaritons in nanostructures and their photonic engineering are then discussed. 

Fault analysis and process control are areas in which expert systems can be used which propose results out of a limited number of possible solutions (see Section 4.1). Therefore, the development of these systems is relatively easy compared to design expert systems. The theoretical background including data validation is well understood. This explains why nearly 50% of all expert system applications in chemical engineering deal with fault analysis and control. 

---