Communication Place

The Communication Place (declared as CommunicationPlace Communication_place) simulate the information exchange environment in which the crew members and system are in the same work place. The information appears “on the air” for a moment and disappears. The duration of the moment is ADS is one time step (i.e., a second). If the operators does not perceive the information at this moment, it is assumed that the operator would miss the information.

In the ADS code, the Communication Place temporarily keeps the information discharged from the Command Control Center for a time step. Each piece of information has two attributes indicating the information sender and the intended received. Each time step, each crew member and the control panel would check the information posted in the Communication Place to identify the relevant information to be processed further. The sender and intended received could be the same person to simulate the operators’ cognitive activities. Using the sender and intended receiver mechanism for information reception provides a flexible framework that allows adding additional players into the communication loop without requiring much efforts.

ADS explicitly models information exchanges between crew members and the system. This allows validating the simulation timing by comparing with either real events or simulator exercises. Figure 38 shows two examples of the communication process modeled in ADS and the key process related parameters.

Three kinds of communication paths shown in Figure 38 include:

• Decision Maker asks the Action Taker to check for a piece of system information or perform an action to change the system state. The action taker checks the system and reports the perceived information to the Decision Maker or performs the requested action and reports that the action is performed to the Decision Maker.
• Decision Maker or Action Taker checks the system information by him/herself

The follows are the information processing step for the first type of communication (i.e., Decision Maker asks the Action Taker for a piece of system information):

• 1. Decision Maker forms a decision (i.e., asking the Action Taker to check for a piece of system information).
     • A piece of information with the (sender, intended receiver) as (Decision Maker, Action Taker) is generated and sent the Branch_center.
     • The OperatorDM::Operator:: pause_activity is set to true. This models that the Decision Maker’s attention is focusing on the feedback from the Action Taker and would not make other decision until receiving the feedback from the Action Taker unless there is information perceived in the meantime requiring immediate operator response.
  2. The information goes through Branch_center and Command Control Center, and finally shown in the Communication_place
     • Branch_center incorporates the information generated by the Decision Maker with other branches information generated by other agents to specify the branches information and probabilities. Current branch information is sent to the Command Control Center.
• The Command Control Center performs time delay and sent the information to the Communication Place.
  1. The Action Taker perceives the information, in response the Action Taker forward the same piece of information except changing the (sender, intended receiver) to (Action Taker, Plant) and the delay time (if necessary) to the Branch_center.
     • The information goes through the same steps as described in items 2.
     • OperatorAT::Operator:: pause_activity is set to true.
  2. The Control Panel receives the information from the Communication Place and immediately update the asked system state in the information and change the (sender, intended receiver) as (Plant, Action Taker) in the Communication Place.
     • The control panel response is immediate. I takes no time.
  3. The Action Taker receives the information sent by the Control Panel and send the information to the Branch_center with (sender, intended receiver) changes to (Action Taker, Decision Maker)
     • The information goes through the same steps as described in items 2.
     • OperatorAT::Operator:: pause_activity is set to false.
  4. The Decision Maker perceives the information sent by the Action Taker
     • OperatorDM::Operator:: pause_activity is set to false.

In the above example, the Control Panel (or Plant) is modeled as an agent as the operators. The results a information communication loop as Decision Maker 🡺 Action Taker 🡺 Control Panel 🡺 Action Taker 🡺 Decision Maker.

An other example in Figure 38 show the Decision Maker or Action Taker check system information by him/herself. The communication loop is Operator 🡺 Control Panel 🡺 Operator.

Figure 39 shows that when the Operator::pause_actiovity is set to true, the operator is bypassing the activities in the D and A of the I-D-A blocks.

As shown in Figure 34, the Communication Place only declares pointers that point to the corresponding information. There is not object memory declared in the Communication Place. Table 15 shows the details of Communication Place functions relating to memory management.

**** Note **********************************************************

It’s not necessary to copy the communication place information to the restartInfoNode since at the time of saving the restart node information all the information inside the Communication Place has been checked by all agents.

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Table 17 The memory management function of the Communication Place

Functions	Elements	Objects and Pointers	Pointers only
clearCommunicationPlaceAll()	BranchUnit	X
HW_reliability	X
new_alarm	X
clearCommunicationPlaceForRestart or clearCommunicationPlaceAllPointers	BranchUnit		X
HW_reliability		X
new_alarm		X
copyCommunicationPlace	BranchUnit	X
HW_reliability	X
new_alarm	X

Figure 40 The process of communication between crews and system modeled in the ADS code.

****Notes on Action Time Control **********

Since IDAC generates branches for action time (i.e., the operator’s action to change the system state; currently branches are only generated for the actions that are specified in the procedure input). The action time specified in the procedure is for the operator who physically acting on the system (i.e., the Action Taker currently). Currently ADS use 10 seconds as the nominal communication time for the Decision Maker giving a command to the ActionTaker. The Action Taker performs the command and informs the Decision Maker that the action has been performed at the same time. This is coded in the section relating to Action in the BranchProbability::sendBranchInfoToCommandCenter(). As a result, a procedure instructs the operator to perform an action (e.g., Action_X) to change the system state. The specified time in the procedure for this action is Time_X. The time required for completing this process is:

• The Decision Maker takes 10 seconds to ask the Action Taker to perform Action_X.
• The Action Taker would uses Time_X to complete the Action.
• After the action is performed the Action Taker takes no time to inform the Decision Maker that the Action_X has been performed. All the times indicated above would be adjusted by the parameter action_time_multiplier specified in the file ../input/crew/Action Taker (or Decision Maker).txt.

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Figure 41 When the Operator::pause_activity is true, the activities in the D and A of the I-D-A blocks are bypassed