Topic
• Latest Post - ‏2013-07-31T17:14:56Z by aravindnambiar
taylor318
1 Post

# Pinned topic how to maximize the model using multiperiod location problem?

‏2013-07-26T07:18:04Z | cplex opl

Hello.

I have been studying  OPL for about two weeks, but I am not sure how to formulate a code for multi-period location problem.

I have formulated a code for the basic location problem, which works!  and by fixing some of the code, i have to make it as a multi-period (t = 1,2,3) problem.

so the problem that I am having is that

when I use the data from the excel, my data's density should increase by 10 percent each year. (i am only doing for 3 periods)

1)  First year's data = D

Second year's data = D*1.1

Third year's data = D*1.2

I tried to do it but I get the correct answer till the second year but in third year I get the value of D*1.32 which is D*1.1*1.2.

range Time = 0..2;

execute Density{
for (var i in PatientData){
for (var t in Time){

Patient[i].x = Patient[i].x*(1.0+0.1*t);
Patient[i].y = Patient[i].y*(1.0+0.1*t);

}
writeln(Patient[i]);  }
}

what should i change to fix it?

2) for the objective and constraint function, i need to maximize the number of patients for each period using limited number of ambulance in that specific period. So for period 1= 2, period 2 =3, period 3 =1.

What is the formulation of the iteration be like for this?

Also, for the objective function, I need to maximize the number of patients for each period, which requires double summation for each period.

how should i change from the code below?

maximize

sum (i in PatientNum) Y[i];

subject to{
forall(i in PatientNum){
sum(j in AmbulanceNum)
W[i][j]*X[j] >= Y[i];
}

sum(j in AmbulanceNum)
X[j] <= P;
}
• aravindnambiar
6 Posts

#### Re: how to maximize the model using multiperiod location problem?

‏2013-07-31T17:14:56Z

You will need to add an indice to your X & Y.

X[j][t] and Y[i][t]

Your objective function can be denoted as:

maximize

sum(i in PatienyNum, t in Time)Y[i][t];

similarly for the constraints..