Dare to question the obvious!

摘要

A FEW YEARS AGO,I WAS IN A PULP and paper mill where I was doing a combination of training and control troubleshooting services.My student and I had spent a good deal of the week hooking up to control loops and troubleshooting them.We discovered the usual assortment of faulty valves,transmitter damping,and improper tuning.However,the very last task of that week has always stuck in my mind.