Research Article

Two-Echelon Location-Routing Problem with Time Windows and Transportation Resource Sharing

Algorithm 2

EMOPSO.
Input:
(1)max_Iter: the maximum iteration
(2)nP: the particle size
(3)nR: the size of external repository
(4): the lth particle inertia weight
(5)c1l: the lth particle personal learning coefficient
(6)c2l: the lth particle global learning coefficient
(7)nG: the count of grids per dimension
Output: the optimal solutions
(1)Initialize particles in the swarm (position and velocity)
(2)Evaluate each particle by calculating the corresponding objective function
(3)Initialize the external repository using nondominated solution maintaining
(4)Iter = 0
(5)For Iter = 1 : max_Iter
(6) For each particle
(7)  Update each particle’s position and velocity
(8)  Evaluate the newly generated particle
(9)  Update the pbest,l
(10) End for
(11) Update the external repository and control the repository size
(12) Select from the external repository by adaptive grids
(13) Adjust the parameters by self-adaptive flight parameter mechanism
(14)Iter = Iter + 1
(15)End for
(16)Report the optimal results