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JayTee1947
Joined: 22 Dec 2008 Posts: 8 Location: Inverclyde
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Posted: Fri Jul 03, 2020 1:08 pm Post subject: Mesh Analysis of RLC circuits: forming the meshes |
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I'm designing a program to analyse large-scale electrical circuit transients involving linear/nonlinear R, L & C elements and (ideal) switches. First challenge is forming the meshes. I want to select the meshes so that nonlinear & switched branches are in the co-tree: so preserving/maximising sparsity and ensuring independent meshes.
Any ideas on suitable tree-forming algorithms? Most mesh analysis texts assume you can choose the meshes "by eye" or "just write them down".
Seems to me there are two choices: (i) select the tree branches according their 'type' so that inductive/nonlinear/switched branches are in the co-tree; (ii) form the tree ignoring branch type(?) then sequentially swap tree and co-tree branches to the same end. But how to aim for sparsity?
All suggestions welcomed, and maybe even acknowledged. _________________ JayTee |
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John-Silver
Joined: 30 Jul 2013 Posts: 1520 Location: Aerospace Valley
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Posted: Fri Jul 03, 2020 3:52 pm Post subject: |
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Your subject is somewhat specialised and you're probably barking up the wrong tree on what is after all a forum dedicated to a specific fortran compiler, and not an electrician's workshop , however you could always try the usual method to start with _________________ ''Computers (HAL and MARVIN excepted) are incredibly rigid. They question nothing. Especially input data.Human beings are incredibly trusting of computers and don't check input data. Together cocking up even the simplest calculation ... " |
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JayTee1947
Joined: 22 Dec 2008 Posts: 8 Location: Inverclyde
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Posted: Fri Jul 03, 2020 4:22 pm Post subject: |
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Thanks, I've tried Google, Youtube and several Maths forums: on the first two all I see are various lecturers demonstrating elementary mesh analysis involving DC and R only. And they all draw meshes "by eye".
The maths forums dive straight into graph theory (further evidence that most math is "made up")
I'm sorry if you think this is somewhat specialised, but where else can I try? _________________ JayTee |
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PaulLaidler Site Admin
Joined: 21 Feb 2005 Posts: 7930 Location: Salford, UK
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Posted: Fri Jul 03, 2020 6:56 pm Post subject: |
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JayTee
You don't need to apologise. There is a reasonable chance that someone here might be able to help. |
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Kenneth_Smith
Joined: 18 May 2012 Posts: 697 Location: Hamilton, Lanarkshire, Scotland.
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Posted: Fri Jul 03, 2020 11:18 pm Post subject: |
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The chapter “Network geometry and network variables” in INTRODUCTORY CIRCUIT THEORY by Ernst A . Guillemin. John Wiley & Sons, Inc., 1953, gives a much more comprehensive discussion than that given in more recent text books.
There is a 1958 paper "Logic for Applying Topological Methods to Electric Networks", by Byerly, Long and King, published in the Transactions of the American Institute of Electrical Engineers, Part I: Communication and Electronics. This includes an algorithm for selecting links and tree branches. |
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LitusSaxonicum
Joined: 23 Aug 2005 Posts: 2388 Location: Yateley, Hants, UK
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Posted: Sat Jul 04, 2020 10:18 am Post subject: |
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Ken is the on-Forum expert because he does (I think) related things.
If it comes down to an issue of how to design and code the interactive bit then I might be able to help. I've sent you a private message - the exposition is likely to be far longer than the individual post limits in the forum.
Eddie |
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mecej4
Joined: 31 Oct 2006 Posts: 1888
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Posted: Sat Jul 04, 2020 10:48 am Post subject: |
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Liquid flow in a piping network is quite analogous, once you admit nonlinearity.
In particular, the topological issues are quite similar, although the terminology is slightly different. For example, what you call "mesh current" corresponds to "loop flow".
The problem of finding a minimal set of flow loops in a flow network has been studied extensively. Look up the "Hardy Cross Method". |
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JayTee1947
Joined: 22 Dec 2008 Posts: 8 Location: Inverclyde
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Posted: Sat Jul 04, 2020 2:30 pm Post subject: |
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That's a promising trio of responses: probably more than I deserve.
@Mercej4. I looked up the Hardy-Cross method. It looks analogous to the power flow problem in electrical power networks, with Kirchhoff's 1st and 2nd laws (on loop voltage and node current) being replaced by loop potential and nodal flow laws (no surprise: same topological rules apply). Interesting, and serendipitous, but doesn't tell me how to select independent meshes with the requisite properties.
@ken: ordered Guillemin's book form IET library. No joy yet on Trans AIEE paper
@Eddie (are your the count of the Saxon shore?). I'll reply by email to your kind message.
@John: just goes to show, some trees bear surprising fruit. I did try your suggestion (and I appreciate your candour), but the usual method got me back square one.
Genuine tnx to all _________________ JayTee |
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Kenneth_Smith
Joined: 18 May 2012 Posts: 697 Location: Hamilton, Lanarkshire, Scotland.
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John-Silver
Joined: 30 Jul 2013 Posts: 1520 Location: Aerospace Valley
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Posted: Mon Jul 06, 2020 2:29 am Post subject: |
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... so many sparky's in one forum ! , I know where to come the next time I'm unsure about doing some wiring LOL _________________ ''Computers (HAL and MARVIN excepted) are incredibly rigid. They question nothing. Especially input data.Human beings are incredibly trusting of computers and don't check input data. Together cocking up even the simplest calculation ... " |
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Kenneth_Smith
Joined: 18 May 2012 Posts: 697 Location: Hamilton, Lanarkshire, Scotland.
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Posted: Mon Jul 06, 2020 12:04 pm Post subject: |
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Quote: | .. so many sparky's in one forum ! |
It’s Electrical Engineers developing algorithms in Fortran and using programs written in Fortran that’s been keeping the lights on and your computers running for the last 60 years. |
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John-Silver
Joined: 30 Jul 2013 Posts: 1520 Location: Aerospace Valley
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Posted: Mon Jul 06, 2020 6:09 pm Post subject: |
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... An Electrical Engineer walking through the utilities substation was told to follow electrical discharge safety measures and stay outside the ESD-safe area. He replies "Don't worry, I've been told I have no potential".
... A group of NASA engineers were brainstorming how they might overcome the thermal challenges involved in sending a manned probe to the sun. An electrical engineer overheard their discussion and suggested "why don't you just go at night?".
m'lord I rest my case _________________ ''Computers (HAL and MARVIN excepted) are incredibly rigid. They question nothing. Especially input data.Human beings are incredibly trusting of computers and don't check input data. Together cocking up even the simplest calculation ... " |
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LitusSaxonicum
Joined: 23 Aug 2005 Posts: 2388 Location: Yateley, Hants, UK
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Posted: Mon Jul 06, 2020 6:28 pm Post subject: |
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Ken, JS has forgotten to add the [irony] tag!
I just watched Frozen II. After the dam has been destroyed, Arendelle's toilets don't flush, and there's no water. Civil Engineers who use Fortran in water resources engineering are appalled. Cases of cholera start to appear in the town, and diarrhoea is rife.
Even with the water supply, when the sea is frozen there is a nasty spreading stain under the ice, as Arendelle doesn't have a sewage works. I have seen such in ice-locked ships in the Gulf of Bothnia, but Disney doesn't show it.
Eddie |
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John-Silver
Joined: 30 Jul 2013 Posts: 1520 Location: Aerospace Valley
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Posted: Tue Jul 07, 2020 12:25 am Post subject: |
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Quote: | Arendelle's toilets don't flush, |
undoubtedly due to a case of bad wiring #I-Ronnie _________________ ''Computers (HAL and MARVIN excepted) are incredibly rigid. They question nothing. Especially input data.Human beings are incredibly trusting of computers and don't check input data. Together cocking up even the simplest calculation ... " |
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Robert
Joined: 29 Nov 2006 Posts: 445 Location: Manchester
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Posted: Tue Jul 07, 2020 2:41 pm Post subject: |
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Blimey you are a tough crowd, give the guy a break. |
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