城市物流风险.ppt

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城市物流风险
Outline
1 Concepts of city logistics
2 Class of risks related to city logistics
3 Vehicle routing and scheduling problems with time windows (VRPTW)
4 VRPTW with uncertainty of travel times
5 Multi-agent simulation with ambiguity
6 Conclusion
Source: Annual Statistical Report on Automobile Transport: Information and Research Department, Policy Bureau, Ministry of Land, Infrastructure and Transport
Truck loading efficiency
City logistics is the process for totally optimising the logistics and transport activities by private companies with the support of advanced information systems in urban areas considering the traffic environment, its congestion, safety and energy savings within the framework of a market economy (Taniguchi et al. 2001)
1 Concepts of city logistics
Structure of visions for city logistics
Resilience
2 Class of risks related to city logistics
Congestion
Crash
Hazardous material transport
Flood
Earthquake
Bush fire
Snowfall
Frequency
complexity
Uncertainty
Ambiguity
Day-to day
Rare
VRPTW
VRPTW-D VRPTW-P
Multi-agent model
3 Vehicle routing and scheduling problems with time windows (VRPTW)
2
Depot
k = 1, 2, … K
6
7
10
8
3
9
5
4
Vehicle Routing and scheduling Problems with Time Windows (VRPTW) is defined as to find the minimum cost routes for k vehicles to service all the clients.
Constraints: A vehicle can not serve more clients than its capacity. Delivery at each client must be within some pre-defined time windows.
[ 2 – 3 pm]
[ 4 – 7 pm]
[ 7 – 8 pm]
[ 10 – 12 am]
[ 1 – 5 pm]
[ 10 – 11 am]
[ 10 – 11 am]
[6 – 7 pm]
[ 3 – 4 pm]
VRPTW Variants
Hard Time Windows
Delivery is not possible outside the specified Time Windows (VRPHTW).
Soft Time Windows
Delivery is possible outside the specified Time Windows with penalties (VRPSTW).
Time
Penalty cost
[ ]
ai bi
∞
∞
Hard Time Windows (HTW)