Simplifying Additive Exponential Terms

AI Thread Summary
The discussion focuses on simplifying an equation for pollutant concentration expressed in terms of exponential functions. The user has successfully canceled the peak concentration variable, reducing the equation to a sum of exponential terms equating to 0.01. They seek advice on further simplifying these exponential terms to isolate wp as a function of x. A key insight shared is that while logarithms are typically useful, they are not effective for sums of exponentials. The common factor in the exponential terms may offer a pathway for simplification.
edge333
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Homework Statement



I have developed an equations for calculating some pollutant concentration as a function of x and y. I'm trying to simplify the problem so that I can write the equation for wp as a function of x. All variables except x and wp are known.


Homework Equations



c(x,y=w_{p})=0.01 \cdot c_{peak} = c_{peak} \cdot \left[ exp \left( -\frac{ u \left( w_{p} \right)^{2}}{ 4 E_{y}x}\right) + exp \left( -\frac{ u \left( w_{p} - y_{1} \right)^{2}}{ 4 E_{y}x} \right) + exp \left( -\frac{ u \left( w_{p} - y_{2} \right)^{2}}{ 4 E_{y}x} \right) + exp \left( -\frac{ u \left( w_{p} - y_{3} \right)^{2}}{ 4 E_{y}x} \right) + exp \left( -\frac{ u \left( w_{p} - y_{4} \right)^{2}}{ 4 E_{y}x}\right) \right]

The Attempt at a Solution



Basically, all I've gotten to simplify is that cpeak cancels such that:

0.01 = \left[ exp \left( -\frac{ u \left( w_{p} \right)^{2}}{ 4 E_{y}x}\right) + exp \left( -\frac{ u \left( w_{p} - y_{1} \right)^{2}}{ 4 E_{y}x} \right) + exp \left( -\frac{ u \left( w_{p} - y_{2} \right)^{2}}{ 4 E_{y}x} \right) + exp \left( -\frac{ u \left( w_{p} - y_{3} \right)^{2}}{ 4 E_{y}x} \right) + exp \left( -\frac{ u \left( w_{p} - y_{4} \right)^{2}}{ 4 E_{y}x}\right) \right]

Is there a way of simplifying the exponential terms so that I can take the natural log of the right side of the equation and solve for wp as a function of x?
 
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edge333 said:

Homework Statement



I have developed an equations for calculating some pollutant concentration as a function of x and y. I'm trying to simplify the problem so that I can write the equation for wp as a function of x. All variables except x and wp are known.


Homework Equations



c(x,y=w_{p})=0.01 \cdot c_{peak} = c_{peak} \cdot \left[ exp \left( -\frac{ u \left( w_{p} \right)^{2}}{ 4 E_{y}x}\right) + exp \left( -\frac{ u \left( w_{p} - y_{1} \right)^{2}}{ 4 E_{y}x} \right) + exp \left( -\frac{ u \left( w_{p} - y_{2} \right)^{2}}{ 4 E_{y}x} \right) + exp \left( -\frac{ u \left( w_{p} - y_{3} \right)^{2}}{ 4 E_{y}x} \right) + exp \left( -\frac{ u \left( w_{p} - y_{4} \right)^{2}}{ 4 E_{y}x}\right) \right]

The Attempt at a Solution



Basically, all I've gotten to simplify is that cpeak cancels such that:

0.01 = \left[ exp \left( -\frac{ u \left( w_{p} \right)^{2}}{ 4 E_{y}x}\right) + exp \left( -\frac{ u \left( w_{p} - y_{1} \right)^{2}}{ 4 E_{y}x} \right) + exp \left( -\frac{ u \left( w_{p} - y_{2} \right)^{2}}{ 4 E_{y}x} \right) + exp \left( -\frac{ u \left( w_{p} - y_{3} \right)^{2}}{ 4 E_{y}x} \right) + exp \left( -\frac{ u \left( w_{p} - y_{4} \right)^{2}}{ 4 E_{y}x}\right) \right]

Is there a way of simplifying the exponential terms so that I can take the natural log of the right side of the equation and solve for wp as a function of x?
WOW!

Logs aren't of much help in working with sums.

The only slight help I can see is that all the terms on the right have a common factor of \displaystyle\ \exp\left(\frac{-u(w_p)^2}{4E_y\,x}\right)\ .
 
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