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 NL-PSO fitting help due to strange K2 values
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yoyohami

Germany
2 Posts

Posted - 03/25/2024 :  11:00:25 AM  Show Profile  Edit Topic  Reply with Quote  View user's IP address  Delete Topic
Hello everyone. I am recently working on NL PSO fitting of my data.

NLPSO is the user-defined equation: qt = qe^2*k2*t/1+qt*k2*t

I'm quite new to the adsorption study, therefore, I only use the equation wiz initial parameters of qe=1 and k2 =1, the boundary of qe>0 and k2>0.

i know my experimental data look poor, cuz I have only three time intervals of 2, 24 and 168 hours.

Time (min) 0,0,120,120,1440,1440,10080, 10080
qe (mg/g) 0,0, 6.376 6.556 6.558 6.519 6.544 6.250
well, R2 is 0,99 and everything looks fantastic, except for the results of K2.

K2 is 4.15E33 with SE of 6,16E44.

I don't think it is right...but Idk how and where to debug.

I do appreciate it if someone could help me even slightly! I am working master thesis

No question is the biggest question. No news may be a good news

YimingChen

1594 Posts

Posted - 03/26/2024 :  08:47:12 AM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
A large error of the fitted parameter suggests strong linear collinearity between parameters.

Regarding the fitting function, it appears to be qt = qe^2*k2*t/(1-k2), and qe and k2 are the fitting parameters, is that right? However, it is unclear whether qe is parameter or y values as you provided the values of qe?

Thank you
James
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