This paper discusses some of the interesting properties of stability analysis of a discretized wave equation. The solutions of the wave equation are wave functions, hence oscillating, so when testing stability the discretization scheme usually shows marginal stability. Marginal stability is a sufficient condition for a discrete scheme convergence and many authors don't bother with mathematical consistency. However, inadequatly chosen discretization method may lead to the additional unwanted oscillations. This paper illustrates this effect in a different approach. First, the wave equation is introduced together with a Perfectly matched layer (PML). Then the 1D wave equation is discretized by using Finite Differences Method (FDM) and Finite-differences Time-domain method (FDTD). It is shown that the latter method does not produce spurious oscillations in the solution. Eigenvalue analysis is done to explain this effect and discuss stability of the numerical scheme.

A local area network (LAN) was developed to connect the distributed parts of power plant process control systems. The following requirements had to be met: fast transfer of short messages (alarms); transfer of long messages with high throughput; reliable transfer of data in harsh environments; and access to shared resources for all participants in process control. Performance measurements were carried out. Results indicate that in the network configuration of four stations, for maximum throughput of SDN (send data with no acknowledge) services the channel efficiency is 60%, while for SDA (send data with acknowledge) services it is 35%.<<ETX>>