Moreover, the system was designed from the beginning to be maintained on an ongoing basis without the involvement of senior knowledge engineers. In the manufacture of paper, wood is first pulped to separate its fibers. One of the predominant pulp processes is done in a kraft pulp mill and consists of cooking wood chips at elevated temperature and pressure in the presence of certain chemicals (alkali and sulfide), washing the resultant brown pulp, bleaching to make the pulp white, and drying the pulp for shipment to a paper mill. Pitch, or wood resin, is the material in wood that is insoluble in water but soluble in organic solvents. It usually makes up 14 percent of the weight of wood after the bark is removed and is often a sticky material.

When building a controller for a physical process, traditional control theory requires a mathematical model to predict the behavior of the process so that appropriate control decisions can be made. Unfortunately, either many real-world processes are too complicated to accurately model, or insufficient information is available about the process environment. In addition, optimal control strategies can themselves exhibit undesirable complexity. However, a human controller can often acquire relatively simple strategies to effect near-optimal control from operational experience. This article reports on experiments performed using a black-box simulation of a spacecraft.