Greg Harrington
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 Mar 8 revised 2d or 1d conduction in this scenario? deleted 33 characters in body Mar 8 asked 2d or 1d conduction in this scenario? Mar 3 accepted How to find the value of the parameter $a$ in this transfer function? Mar 1 comment How to find the value of the parameter $a$ in this transfer function? I am taking a Systems, Dynamics, and Controls course at the undergraduate level right now. I hope you are good at this stuff so I got the right answer! Mar 1 asked How to find the value of the parameter a in this transfer function? Mar 1 comment How to find the value of the parameter $a$ in this transfer function? Well i gave the question and then gave my solution and asked if it was right. Maybe it didn't look like a question to the common reader. Oops. Do you have any knowledge about this question though? Mar 1 comment How to find the value of the parameter $a$ in this transfer function? Yes it's a homework question. I am given a transfer function and then asked to find the value of $a$ that would make $\zeta=.7$ Mar 1 comment How to find the value of the parameter $a$ in this transfer function? It wouldn't be 2.86 because $\omega_{n}=\sqrt{a}$. I got $a=8.163$. But thank you for letting me know that I did it right. I didnt think that I could equate it like that Mar 1 asked How to find the value of the parameter $a$ in this transfer function? Feb 27 comment In what situations do I use the characteristic length of a fin to find the surface area? So just answer these few questions with yes or no answers (if possible): 1. Was it fine that I used the equation $R_{f}=\frac{1}{hA_{f}\eta{f}}$ with the corrected area even though you just said that you would permanently get rid of it you were a teacher. 2. Was it wrong of my professor to not be consistent with his formulas? I.e. He used the corrected length for the efficiency but not for the area. Feb 26 comment In what situations do I use the characteristic length of a fin to find the surface area? Ok nevermind. I was thinking of some other equation by accident. So in the case with the exam I took, I was asked to find the efficiency and resistance of a fin. I used the equation $$R_{f}=\frac{1}{hA_{f}\eta_{f}}$$ but I used the efficiency and area equation using the corrected length and the professor used the efficiency equation with the corrected length and the area equation with the regular length. Who would be right in this case? Would I be able to argue for full credit? Feb 26 comment In what situations do I use the characteristic length of a fin to find the surface area? He didnt use that rigorous one. I looked at the solution and he used $$\eta_{f}=\frac{tanh(mL_{c})}{mL_{c}}$$ and $$A_{f}=2(w+t)L+wt$$ Essentially, he is using the corrected length for one equation but not for the other which, like you said, is inconsistent. But what if he used the area equation without the corrected length but use the other equation for the efficiency by using the temperature distribution. Would that theoretically yield the same result or would it be different? Pretty much does it matter which method you use as long as you stay consistent with which 'type' of length you use? Feb 26 asked At what point can we assume the tip of a fin is adiabatic? Feb 25 comment In what situations do I use the characteristic length of a fin to find the surface area? Here's why I ask. I just had an exam the other day where there was a rectangular fin attached to the wall the protruded a distance L=8mm and exposed ta fluid. It's width was 10mm and it's thickness was 1mm. We had to determine the resistance and efficiency of the fin. He said $$A_{f}=PL+A_{c}=2(w+t)L+wt=186mm^{2}$$ whereas I said $$A_{f}=2wL_{c}=2w(L+\frac{t}{2})=170mm^{2}$$ Now there is a $16mm^{2}$ difference between the two areas. So which way is correct? Feb 25 accepted In what situations do I use the characteristic length of a fin to find the surface area? Feb 25 asked In what situations do I use the characteristic length of a fin to find the surface area? Feb 20 comment What's the temperature distribution of a plane wall insulated on one side with no internal heat gen.? So my intuition is wrong, but is my derivation correct in this case? Would the temperature of the wall be a constant temperature that is equal to the temperature of the flowing hot/cold liquid? And yes this problem was assuming that it is not insulated on the top or bottom. There is only insulation on one side and the other side is exposed to the fluid. I guess you could say it is an infinitely long/high wall Feb 20 accepted What's the temperature distribution of a plane wall insulated on one side with no internal heat gen.? Feb 20 asked What's the temperature distribution of a plane wall insulated on one side with no internal heat gen.? Feb 16 revised Is the $mL_c$ value for triangular and rectangular fins the same value? added 34 characters in body