How should a beginner learn a flowchart?
Description of a flow chart
8 Simple Steps
Figure 4. The Flowchart of the Simulation Model
Figure 4 shows the flow chart of the simulation model. In the simulation, time becomes discretized. As the time step propagates, the taxi customer demands are dynamically fed into the simulation, as per the specification in the dataset. The details of the simulation flowchart in Figure 4 become explained in the following eight steps.
Step 1: The platform receives a new ride request and locates the sub-region it belongs to. Then, the platform selects all the available taxis in the located sub-region as candidates.
Step 2: Feed all the candidates into a reachability-analysis module and identify the candidates. Whose battery states of charge (SOC) are sufficient to fulfill the customer’s travel request.
Step 3: If there is no candidate passing the reachability test, go to Step 6. Otherwise, go to Step 4.
Step 4: Feed all the candidates, passing the reachability test, into the grading module, and calculate their scores. Dispatch the candidate with the highest score to pick up the customer.
Step 5: After the assigned taxi reaches the customer’s destination, check if its battery SOC is below a predetermined threshold. If so, send the taxi to the charging station of the current sub-region. Otherwise, flag the taxi as an available state, and the taxi will stay at the current place to wait for the next assigned ride request.
Step 6: Add the demand to the waiting list. The waiting list follows the first-in-first-out (FIFO) rule. Moreover, at each time step, the ride requests in the waiting list have higher priority than the newly coming requests, implying that the requests in the waiting list should be satisfied first if there are new taxis available.
Step 7: When the customer’s waiting time exceeds a predetermined waiting-time threshold, the platform will attempt to dispatch the taxis from the adjacent areas. If there does exist an available taxi, which can pass the reachability test, in adjacent areas, then dispatch the taxi to pick up the customer.
Step 8: When the customer’s waiting time exceeds a predetermined canceling threshold, decline the ride request.
Note that in Step 5, in charging stations, plug-in electric vehicles(PEVs) can charge batteries only if there are still unoccupied chargers left at stations, and otherwise they need to wait in the queue for the next available chargers.
Doing this makes our simulations capable of accurately modeling the real-time operations of public charging stations and reflecting the interactions of different PEVs’ charging behaviors. To realize the above consideration, similar to , the simulation model utilizes the station operations chart.
Specifically, the station operation chart describes each charging station’s real-time state, whose rows and columns respectively correspond to time steps and station IDs. Each column of the chart records the number of a station’s vacant chargers at different times. We update the chart each time a charger is occupied by a PEV.