Regional Location Routing Problem for Waste Collection Using Hybrid Genetic Algorithm-Simulated Annealing

Municipal waste management has become a challenging issue with the rise in urban populations and changes in people’s habits, particularly in developing countries. Moreover, government policy plays an important role associated with municipal waste management. Thus, this research proposes the regional location routing problem (RLRP) model and multi-depot regional location routing problem (MRLRP) model, which are extensions of the location routing problem (LRP), to provide a better municipal waste collection process. The model is constructed to cover the minimum number of depot facilities’ policy requirements for each region due to government policy, i.e., the large-scale social restrictions in each region. The goal is to determine the depot locations in each region and the vehicles’ routes for collecting waste to fulfill inter-regional independent needs at a minimum total cost. This research conducts numerical examples with actual data to illustrate the model and implements a hybrid genetic algorithm and simulated annealing optimization to solve the problem. The results show that the proposed method efficiently solves the RLRP and MRLRP.

Accelerating supply chains with Ant Colony Optimization across a range of hardware solutions

Ant Colony algorithm has been applied to various optimisation problems, however, most of the previous work on scaling and parallelism focuses on Travelling Salesman Problems (TSPs). Although useful for benchmarks and new idea comparison, the algorithmic dynamics do not always transfer to complex real-life problems, where additional meta-data is required during solution construction. This paper explores how the benchmark performance differs from real-world problems in the context of Ant Colony Optimization (ACO) and demonstrate that in order to generalise the findings, the algorithms have to be tested on both standard benchmarks and real-world applications. ACO and its scaling dynamics with two parallel ACO architectures - Independent Ant Colonies (IAC) and Parallel Ants (PA). Results showed that PA was able to reach a higher solution quality in fewer iterations as the number of parallel instances increased. Furthermore, speed performance was measured across three different hardware solutions - 16 core CPU, 68 core Xeon Phi and up to 4 Geforce GPUs. State of the art, ACO vectorisation techniques such as SS-Roulette were implemented using C++ and CUDA. Although excellent for routing simple TSPs, it was concluded that for complex real-world supply chain routing GPUs are not suitable due to meta-data access footprint required. Thus, our work demonstrates that the standard benchmarks are not suitable for generalised conclusions.