## 2 Synchronization Issues with Various Part-to-Picker Systems and a Literature Review
### Synchronization Problems in Warehouses  
Warehouses are essential components of any supply chain, and their main responsibilities include buffering material flow, consolidating, and processing value-added materials. The order of these systems is based on two key ideas: order picking and batch picking. According to research by [PERSON] et al. [15], the batch picking system has a higher pick rate. [PERSON] and [PERSON] [16] provided an analytical technique for setting up the network of a fixed-path, closed-loop material handling system in their research. Towlines, automated monorail systems, automated guided vehicle systems, and other types of equipment can all benefit from this method. Phase one involves determining the existence of spurs, carriers needed to satisfy load movements, and guiding path shortcuts. In phase two, simulation is utilized to validate the findings and confirm the control and operational principles. CAN-Q and AGVSim are two methods for estimating vehicle requirements, and the analysis and design of material handling systems can benefit from mixed-integer programming. [PERSON] proposed a look-ahead scheduling rule to prevent long queue delays for high-cost trailers. The supervisor scans the queue and selects the first trailer with the lowest cost instead of assigning the lowest travel cost to an open strip door. This ensures that high-cost trailers are unloaded without unreasonable delay. The efficient unloading of difficult trailers is ensured by this approach. It can reduce labor costs by 15-20% compared to a first-come, first-serve policy and by 3-30% due to travel, depending on the mix of freight and queue length [17]. In the LTL sector, terminals perform three core operations: break-bulk, inbound, and outbound operations. The average workforce consists of an operations manager, 2-4 supervisors, and 2-3 dozen employees. The supervisor's look-ahead scheduling policy affects the layout of freight terminals. Thus, the author built a parametric model of material flows and utilized a local search technique to locate a nearly ideal layout [17]. Terminal managers are able to significantly reduce labor costs by scheduling incoming packaging into strip doors using a look-ahead algorithm. The algorithm is capable of providing valuable guidance for the majority of assignments and can be easily integrated into daily operations. For terminals with similar freight combinations, it may not be as effective. [PERSON] developed a model for an accumulation sortation system that utilizes analysis (AISS). In addition, he presented an analytical model for an order sortation system in automated distribution centers that utilizes stochastic elements [18]. Two common sorting strategies were identified: fixed priority schemes and the next available rule. The model shows that the next available rule performs better than fixed priority schemes in terms of sorting time and system throughput in systems with minimal lane blocking. Manufacters are under increasing pressure to deliver reliable products, with customer satisfaction being the only thing that matters. Centralized distribution centers serve specific markets and provide a single point of shipment for customer orders. In a distribution center, there are two main activities: incoming material storage and order picking, with order picking often being the most labor-intensive activity and cost. Many systems employ a wave approach, where a group of orders are picked simultaneously to balance the workload of shipping lanes. The model proposed in this paper examines the impact of sorting strategies on the time it takes to sort a wave of orders. According to this result, a next available sorting rule outperforms fixed priority rules in terms of wave sorting time and throughput for systems with little lane blocking. Wave generation algorithms and wave release strategies are crucial for improving system performance. [PERSON] and [PERSON] found that reassigning moving vehicles has a significant positive impact on lowering the average load waiting time [19].