Help with Operation Research/Optimization

[lottio]

Hi tutflixer,
for the past two weeks i have been depressed and sick because of my thesis. My thesis is about VRP with time windows, i solved it with Lingo.
I have tried various ways ranging from changing the mathematical model, moving to gurobi, clustering. But all those ideas seems doesn't work. My nodes are just like at max 17 nodes (after clustering) and still not get the solution. I have been running it for like 10 hours. I find it suspicious as when i comment that time windows constraint, the solution comes under 1 minutes. Does anyone can help me how to get the optimal solution? Thanks for the time and have a nice day

 

[lottio]

Hi tutflixer,
for the past two weeks i have been depressed and sick because of my thesis. My thesis is about VRP with time windows, i solved it with Lingo.
I have tried various ways ranging from changing the mathematical model, moving to gurobi, clustering. But all those ideas seems doesn't work. My nodes are just like at max 17 nodes (after clustering) and still not get the solution. I have been running it for like 10 hours. I find it suspicious as when i comment that time windows constraint, the solution comes under 1 minutes. Does anyone can help me how to get the optimal solution? Thanks for the time and have a nice day

it's funny when i tried using simple dummy datas, with 10 nodes, the solver can get the solution under 1 mins, but when i change to real datas, with the same quantity for the nodes. Even for 3 hours, it still keep running. I think it have to do with capacity and time windows constraint. Can somebody please save me ?