U
upshaw211
Hi, I'm working on a pretty simple queuing optimization proble
involving a non-linear mixed integer problem.
Before I describe the setup, basically whats happening is that th
solver isn't giving me the optimum solution. Depending on what I pu
into the cells which solver manipulates, solver will give me differen
objective function values. Only sometimes will it give me the tru
minimum which I'm seeking.
The objective function is (minimize): A*S+B*R+C*Q
-such that:-
S is an integer
S*R > Arrival Rate
S , R > 0
-where: -
S is the number of servers (integer) and A is the cost per server
R is the service rate (continuous) and B is the cost per "unit" o
service rate
Q is the average number of people in the system during steady state an
C is the cost per person in the system.
A, B, and C, along with the Arrival Rate are all input by the user.
Q is affected by S, R, and the Arrival Rate and involves a very lon
formula (i'll post if you want).
Solver changes S and R to find the objective's minimum.
When I run solver it will converge on some value for S, and then i
finds the value for R which gives the objective's minimum -for tha
particular S- . The problem is that it has a hard time converging o
the correct S which would result in it finding the absolute minimum.
Any help would be very nice. I'd be glad to give the exact formula
for this problem anyone wants.
PS: very sorry about the double-post earlier, Myrn
involving a non-linear mixed integer problem.
Before I describe the setup, basically whats happening is that th
solver isn't giving me the optimum solution. Depending on what I pu
into the cells which solver manipulates, solver will give me differen
objective function values. Only sometimes will it give me the tru
minimum which I'm seeking.
The objective function is (minimize): A*S+B*R+C*Q
-such that:-
S is an integer
S*R > Arrival Rate
S , R > 0
-where: -
S is the number of servers (integer) and A is the cost per server
R is the service rate (continuous) and B is the cost per "unit" o
service rate
Q is the average number of people in the system during steady state an
C is the cost per person in the system.
A, B, and C, along with the Arrival Rate are all input by the user.
Q is affected by S, R, and the Arrival Rate and involves a very lon
formula (i'll post if you want).
Solver changes S and R to find the objective's minimum.
When I run solver it will converge on some value for S, and then i
finds the value for R which gives the objective's minimum -for tha
particular S- . The problem is that it has a hard time converging o
the correct S which would result in it finding the absolute minimum.
Any help would be very nice. I'd be glad to give the exact formula
for this problem anyone wants.
PS: very sorry about the double-post earlier, Myrn