102 Figure 3. Daily profit comparison over the P50 14-day simulation. Figure 4. Pile inventory over the P50 14-day simulation for the MCTS solver. 4.2. Scenario B: Strict Client Contracts The layer characteristics are the same as in Scenario A (reported in Table 4), except now each layer is considered to be in a separate mine. (This arrangement is equivalent to extracting from all four layers of one mine on each day.) A fixed amount of 500 tonnes is produced by each mine every day. This is to guarantee that there will always be enough feedstock regardless of the circumstances to theoretically ensure client contract fulfillment. Table 6 shows the profit ratio relative to the greedy MILP benchmark for the MCTS and ggMCTS solvers. Both the MCTS and ggMCTS solvers perform better than the benchmark in most simulations, with MCTS achieving a higher profit than greedy in 72% of simulations and ggMCTS achieving a higher profit in 89% of simulations. However, similar to the situation in Scenario A, there is a notable tail end where the MCTS solver performs slightly worse. The 10th percentile of greedy-guided MCTS performance falling only slightly below 100% shows that ggMCTS performs nearly on par with the greedy benchmark even in the worst of cases. Table 7 shows that the greedy benchmark often struggles to fulfill client contracts, while MCTS and ggMCTS fulfill client contracts in most cases. In all cases where client demand is not fulfilled, at least one client delivery did not meet client quality specifications due to feedstock and/or process variability. Over 100 simulations, greedy averaged 9.2 rejected deliveries per 14-day simulation with each rejected delivery averaging 170 tonnes. MCTS averaged 5.0 rejected deliveries per 14-day simulation with each rejected delivery averaging 144 tonnes. Greedy-guided MCTS averaged 4.3 rejected deliveries per 14-day simulation with each rejected delivery averaging 144 tonnes. Table 6 – Profit relative to the MILP benchmark over 100 14-day simulations for Scenario B. Approach P10 (%) P50 (%) P90 (%) MCTS 94.9 105.6 124.1 ggMCTS 99.5 107.6 122.9
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