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Math Help - help needed

  1. #1
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    help needed



    please help i have no clue where to start and its doing my nut in!!!!
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  2. #2
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    so far i have an objective function

    obj = f*28 + a*f*32 + 0.4*a*f*45 - 0.1*a*f*190 + c*0.5*a*f*25 + d*0.5*a*f*35 + b*f*31 + 0.37*b*f*45 - 0.08*b*f*210 + c*0.55*b*f*25 + d*0.55*b*f*35 - 0.2*c*0.5*a*f*210 - 0.4*c*0.5*a*f*175 + 0.4*c*0.5*a*f*45 - 0.3*d*0.5*a*f*175 - 0.4*d*0.5*a*f*190 + 0.3*d*0.5*a*f*45 - 0.2*c*0.55*b*f*210 - 0.4*c*0.55*b*f*175 + 0.4*c*0.55*b*f*45 - 0.3*d*0.55*b*f*175 - 0.4*d*0.55*b*f*190 + 0.3*d*0.55*b*f*45

    where f = feedstock in tonnes
    a,b,c,d are all percentages

    the waste bit just seems to go round in circles so dont know how to put that into the objective function
    eg. process c produces 0.4 tonnes of waste which goes into process r which produces 0.4*0.3 tonnes of intermediary which goes back into either process c or d producing yet more waste
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  3. #3
    MHF Contributor

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    Since "waste product cannot be disposed of by the plant" it generates no profit and so has no place in the objective function which should be "total profit".
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  4. #4
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    it costs money to go through process r which all waste has to in order to be disposed so it does need to be in the objective function as i am trying to maximise profit which is revenue - costs
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