Changes between Version 5 and Version 6 of EwEugPredatorSatiationAndHandlingTimeEffects


Ignore:
Timestamp:
2010-11-24 00:02:47 (9 years ago)
Author:
shermanl
Comment:

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  • EwEugPredatorSatiationAndHandlingTimeEffects

    v5 v6  
    1010''V'',,''ij'',, is calculated by solving the 'fast dynamics' equation 
    1111 
    12 ''dV'',,''ij'',,''/dt = v(Bi-V'',,''ij'',,'') - v'V'',,''ij'',,'' a'',,''ij'',,''PjV'',,''ij'',,'' / ''(''1 + hj Sia'',,''ij'',,'' V'',,''ij'',,'')''for V,,ij,,, 
     12''dV'',,''ij'',,''/dt = v(Bi-V'',,''ij'',,'') - v'V'',,''ij'',,'' - a'',,''ij'',,''PjV'',,''ij'',,'' / ''(''1 + hj Sia'',,''ij'',,'' V'',,''ij'',,'')''for V,,ij,,, 
    1313 
    1414while assuming the vulnerability-exploitation dynamics are fast enough to keep ''dV/dt'' near zero (vulnerability exchange rates ''v, v' '' large).  The solution for ''V'',,''ij'',,'over time involves a numerical procedure that can sometimes cause annoying 'chatter' in the Ecosim results when handling times are large (ratio of maximum/base consumption rate small). At each simulation time step the program updates an estimate of the ratio of predator search time to total time (this ratio is given by ''P'',,''sj'',,'' = 1 / ''(''1 + h'',,''j'',,'' S'',,''i'',,'' a'',,''ij'',,'' V'',,''ij'',,)  in the Holling formulation), using this update to provide an improved estimate of the'' V'',,''ij'',,.  We do this because providing an exact value for the ''V'',,''ij'',, (exact solution for the nonlinear equation solutions for all the'' V'',,''ij'',, at the condition ''dV'',,''ij'',,'' / dt''=0) at each simulation time step would require excessive computer time.