Andreas Greuer

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2 years, 33 days

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These are questions asked by Andreas Greuer

Hello,

I want to evaluate the change of temperature and energy loss during the flow through an expansion valve.

But the command fsolve this does not work with CoolProp.

The following command is just repeated, but gives no result.

fsolve({ThermophysicalData:-Property("D", "H2", "temperature" = TTT, "pressure" = ppp) = 31.13, ThermophysicalData:-Property("H", "H2", "temperature" = TTT, "pressure" = ppp) = 4.098640000*10^6}, {TTT, ppp})

Regards,

Andreas

How do I calculate the intersection curve between a plane and a drop?
The "drop" is defined in the following way:

R1 := 3.;R2 := 1.0;DR := 4;g := R2 + DR;

f1 := h -> sqrt(R1^2 - h^2);
f2 := h -> sqrt(g^2 - h^2);
f3 := h -> (1 - h/g)*f1(h*R1/g) + h*f2(h)/g;
f4 := h -> sqrt(1/2*g - 1/2*h);
f5 := h -> (1 - h/g)*f3(h) + h*f4(h)/g;
gg := h -> piecewise(h < 0, f1(h), 0 <= h, f5(h));#Radius depending on the z-position h
cir := (h, phi, R) -> <sin(phi)*R, cos(phi)*R, h>; # a circle at the hight h with radius R
#The plane is placed inside the drop.
n := (x, y, z) -> <x, y, z>/sqrt(x^2 + y^2 + z^2);

# the following lines show, how it looks like:
with(plots);
with(plottools);
dro1 := plot3d(cir(h, phi, gg(h)), h = -R1 .. g, phi = 0 .. 2*Pi, scaling = constrained, orientation = [-60, 72, 0]);
plotDropWithPlane := (x, y, z) -> display(dro1, arrow(Vector([0, 0, 0]), 2*R1*n(x, y, z), 0.2, 0.4, 0.1, cylindrical_arrow, fringe = blue, color = "Green"), implicitplot3d(x*x1 + y*y1 + z*z1 = 0, x1 = -R1 .. R1, y1 = -R1 .. R1, z1 = -R1 .. g, color = blue));
plotDropWithPlane(3, 1, 2);

#I'm searching a function like
fintersect:=theta-><"?,?,?>"

Any idea how to solve?

Best regards,

Andreas

In Maple 2019 it is not possible to change to "1-D Math Input".

But it is possible to convert (right mouse->convert to-> 1D Math Input)

In this mode I get the following results:


> 6/2*(1 + 2);
                               9
> 6/2(1 + 2);
                               3
I have the feeling the 2nd result is wrong.
If I change to "Maple input", I get the following result:
> 6/2(1 + 2);
                               9
 
In this editor, where I write this post, it is possible to insert Maple Math.
If I enter there "6/2(1 + 2)", in the preview is written "3".
and
If I enter there "6/2(1 + 2+9)", in the preview is written "3".
 
The parser gives no error message, but a wrong result.
 
If I enter nonsense, there is the following message "You have entered an invalid Maple expression". 
 
Are you aware of this?
 

How do I use characters in a file using the "read" statement?

Example: The following function code is written in a textfile test.mpl.

test:=proc()
print("hüstel");
end proc:

I read the file with

> read("test.mpl");
> test()

"h�stel"

The Letter "ü" appears like "�".

If the comand is input direct in the document mode it appears correct:

print("hüstel");

"hüstel"

 

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