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In the book 'Realtime Programming in Java' there is an example which I need help with:

To avoid explosion, there is a deadline for the pump to be switched off once the methane level exceeds a critical threshold. The deadline (D) is related to:

  • (T) methane sampling period
  • (R) rate at which methane can accumulate
  • (M) margin of safety between the level of methane regarded as critical and the level at which it explodes.
  • R(D+T) < M

It is assumed that presence of methane pockets may cause levels to raise rapidly, and therefore a deadline requirement of 200ms is assumed. This can be met by setting the rate for the methane sensor at 80ms, with a deadline of 30ms. Now the displacement between 2 readings is at least 50ms.

Can someone explain me this, please?

Ryan Gates
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Radna
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    Is this verbatim? If so then the text is badly written, probably by someone who didn't understand the subject. – Beta Sep 06 '11 at 03:09
  • Having spent a little time trying to work out the explanation, I have to agree with @Beta; the question as quoted is badly written. If that is verbatim, ignore the exercise (example) as 'incomprehensible'. – Jonathan Leffler Sep 06 '11 at 03:14
  • Redo: There are two plausible books, neither with exactly the quoted title...[Concurrent and Real-Time Programming in Java](http://www.amazon.com/Concurrent-Real-Time-Programming-Andrew-Wellings/dp/047084437X) and [Real-Time Java Programming: With Java RTS](http://amazon.com/Real-Time-Java-Programming-RTS/dp/0137142986). Was your book either of these? – Jonathan Leffler Sep 06 '11 at 03:17
  • Sorry for wrong title, here is the link with the example [link](http://books.google.com/books?id=tJ03VlKJacMC&pg=PA363&lpg=PA363&dq=%22low+water+level+detector%22+%22water+flow+sensor&source=bl&ots=TL4XYaDqQq&sig=iMtuUP9uqLDj6YJahAKv01zh9Dw&hl=en&ei=jDlXTuL2JO3KiAKX3cmYCQ&sa=X&oi=book_result&ct=result&resnum=3&sqi=2&ved=0CHIQ6AEwAg#v=onepage&q=%22low%20water%20level%20detector%22%20%22water%20flow%20sensor&f=false) – Radna Sep 06 '11 at 04:10

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You're aware that java can suddenly decide without warning to temporarily abandon your program and spend time collecting garbage instead?

EDIT: I'm just now reading about java RTS. My information appears to be out of date. My apologies.

user732933
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