rquirt

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12 years, 315 days

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These are questions asked by rquirt

I have attached a MapleFlow file that shows a result I don't quite understand.  For some reason the FinalValue result that I get using the DynamicSystems:-StepProperties is different than the steady state value from a DynamicSystems:-ResponsePlot to a unit step using a DifferentialEquation object.

You will notice that I played around a bit, including transforming the DiffEquation object to a TransferFunction object, to see if I could make sense of it.  All of the results are the same as the StepProperties result, it appears that only the ResponsePlot for the DifferentialEquation object is different.

Am I doing something wrong?  Does anyone have any ideas?

Dynamic_Systems_Final_Value.flow

I'm doing some experimenting with the Optimization:-Maximize and Minimize functions, and I'm having difficulties getting them to find the actual extrema within a set of bounds.  I have found that the extrema they identify depend on the bounds, even when the same extrema lie within those bounds. I've also tried the initialpoint option to start the solution near the extrema and I've found three things: sometimes it works to get the correct solution, sometimes it doesn't and sometimes I get a message saying the initial point was ignored by the solver.

The problems I'm using are all taken from the Maple help or tutorials.

I haven't included a bunch of test cases but I've attached the Maple Flow file.  I have a suspicion it has to do with the second derivatives of the functions near the boundaries, but I'm not sure.

Can anyone point me to more information, or am I doing something wrong?

Thanks for your help.

Optimization_Local_Max_and_Min.flow

I have a problem where there is a true deadtime due to a transport delay.  The delay is in the order of 8 minutes as a fluid flows very slowly down a tube.

I've fit an expression to some measured data and have found the following expression

I'd like to work with this using the Dynamic Systems Package, so I'm trying to build a system from the time-domain expression.  When I try to use the inttrans:-laplace function to convert to the s-domain, I get an overflow.  If I manually express this as a Laplace transform and try to make a system and do a step response, I get this, with an error that "transfer function(s) are not rational-polynomial(s) in s"

Is a delay supported in the Dynamic Systems Package?  If so, could you provide guidance on how?

I tried this combination of transfer functions, and it appears that the PhasePlot isn't correct.  Does anyone have any suggestions on what might be causing the issue? 

What_do_I_have_wrong_Phase_Plot.zip

I'm experiencing weird behaviour when dragging a plot generated from a DynamicSystems function.  If I hide the command, the plot stretches vertically rather than moving when I drag it.  If I don't hide the command, it drags normally.

Is anyone else observing this behaviour, or does it have to do with my setup?

I've attached a simple example flow file.Odd_Plot_Drag_Behaviour.zip

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