Sensible Sensor Speed-Part 2

Greg McMillan and Stan Weiner Continue Their Conversation on Sensor Speeds

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9. Your DCS historian is humming right along.

8. Every model you generate is different than the one before, even when you don’t change anything.

7. Your statistic for gauging model effectiveness is no more reliable than an intestinal emission in a wind storm.

6. QA values for six consecutive batches are identical.

5. Your team lead says, “All we need to do now is generate models.”

4. Although your presentation to the project team about collecting and aligning the data includes the analogies of herding cats, pushing rope and peeing in the wind, there are still no questions.

3. The director of the Colorado State Correctional Facilities just called to let you know the QA data for batch #4567723 is scratched on the wall in cell block D. You’re elated!

2. Your four-year-old stays up at night comforting you when you wake in a cold sweat screaming “The data! The data! We must get THE DATA!!”

1. Your data utility indicates a successful extraction by crashing. 

I just need to make sure I don't lose the signal. If I'd lost most of my hearing at Grateful Dead concerts, I'd have an excuse. I feel I'm becoming more like my older friends, who are no longer listening. Stan, if I ever get to this point, just yell in my ear, "Be here now!" especially if you're talking about your pool in Naples.

Stan: One thing I don't do is drive slower. Zipping around big ol' Buicks in my Miata is my way of having fun while minimizing transportation delays.

Greg: Talking about transportation delays, the time it takes a sample to get through and be processed by a sample system and an at-line analyzer, which is often like a little chemical plant, creates problems that go well beyond the horrendous dead time. The lack of intermediate values creates a stepped response that creates havoc with PID response, which is expecting a continuous measurement. The wireless PID algorithm discussed in "Unlocking the Secret Profiles of Batch Reactors" (July '08) and "Is Wireless Process Control Ready for Prime Time" (May '09) shows promise for dealing with the stepped response. However, you still have the whole reliability, maintenance and expertise issue of at-line analyzers. Strangely enough, the compositions and QA data from labs and raw material delivery sheets still mostly reside in spreadsheets and lab systems. Maybe 30 years after the appearance of the DCS, we can finally get process compositions and QA data into the data historian when the lab sample was taken. Just think what we could do with data analytics and statistical models to diagnose problems and predict compositions. Now for a timely contribution from our favorite and only source of insightful top 10 lists, Randy Reiss.

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