Provided is a continuous method and apparatus of purifying carbon nanotubes. Function f=ax2+bx+c are used to describe the destination data within 0 and 1. The article may include a post attached to a base plate and the article may include part of a plastics barrier or fence system. The finite state automaton is then transformed into a hidden Markov model such that a sequence of observation symbols produced from an observation alphabet by the hidden Markov model is equal to the sequence of output symbols.