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Determining the Sequence of Loading and Unloading the Trucks in Cross-docks under the Condition of Uncertainty

Sadeghi, Nafiseh | 2017

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 49883 (01)
  4. University: Sharif University of Technology
  5. Department: Industrial Engineering
  6. Advisor(s): Akbari Jokar, Mohammad Reza
  7. Abstract:
  8. Todays, given the existence of a strong competitive environment in the industry, supply chains should be quick and reactive, in addition to keeping their costs down. Transit warehouses and warehousing issues are one of the most efficient techniques that reduce inventory costs, while increasing the flow of goods and shorter transport cycles. Regardless of how a warehouse system is designed, the allocation and sequencing of input and output trucks to platforms is considered necessary. The inappropriate sequence of input and output trucks on the platforms increases the completion time of the operation. Also, the uncertainty and unpredictable circumstances of the real world make planning and scheduling in the warehouse more complicated. The most uncertainties occur in cross-docks because of uncertain arrival times for trucks. In this paper, the sequencing and allocation of inbound and outbound trucks with the objectives of minimizing truck waiting times and product condensation in front of the outbound docks has been investigated. The arrival time of the trucks is unclear, and the perpetrators of the cross-dock only have information about the windows of the arrival time of the trucks. In other words, a high and low limit is considered for each truck's arrival time. Due to the lack of any additional information, the warehouse perpetrators may use four approaches to determine the allocation and sequencing strategy: the deterministic approach (the expected time of arrival is equal to the middle of the time window), the Pessimistic approach (the latest possible time), the optimistic approach (the earliest possible time) and the hybrid approach (the mean of optimistic and pessimistic approaches). In this research, optimistic and Pessimistic approaches have been formulated as a two-level optimization model. Also, the genetic algorithm has been used to solve the problem of assignment and sequence of the truck to the door for specific entry times. Finally, using the simulation of all approaches, the numerical results obtained from the study of approaches showed that the hybrid approach in the allocation and sequence of trucks is better than all other approaches and FIFS policy
  9. Keywords:
  10. Sequencing ; Scheduling ; Cross Docking ; Supply Chain ; Uncertainty ; Truck Load ; Truck Sequencing

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