% this file provides a model fit for the temperature data
% the file assumes that bulbdata.m has already been run
% and thus the vector bulbtemp1 already exists in memory
% along with the time vector t
% data taken for temperature of glass envelope of my desk lamp at home
% 75W light bulb
% temperature in degrees Centigrade, measured with thermocouple
% data taken at 5 sec intervals (yeah, that's a lot of points)
% bulb turned on at t=0
% bulb turned off at t= 655 sec
% I bumped the test lead at about 1130 sec; bump in data results
% D L Trumper 8/24/2004
tau =160; % time constant in sec for model fit
tempfinal = 120; % the final value of the temperature rise above ambient
figure(2)
clf
model1 = tempfinal*(1-exp(-t/tau));
model2 = tempfinal*(exp(-(t-665)/tau));
% ambient temperature is 29 C
% subtract from bulb temp in plot
% overlay model data plots on experimental data
plot(t,(bulbtemp1-29),'*',t,model1,t,model2)
axis([0 1600 0 120])
xlabel(['Time (sec); Model time constant = ',num2str(tau), ' sec']);
ylabel('Temperature rise above ambient [C]')
title('Model fit to light bulb dynamics')