117 5 IMPLEMENTATION CONCEPT 5.3 EVALUATION OF SIMULATION OF THE IMPLEMENTATION CONCEPT The CPNs in figures 18 to 22 have been used to simulate the monitoring and verification process of the observation stage of the Glass Box framework (which is described in section 3.4). In general, a simulation imitates a process by creating another process of which an object or system changes its state in time. Simulations can be used for different reasons: ‘as a technique to investigate the detailed dynamics of a system, as a heuristic tool to develop hypotheses, models and theories, as a substitute for an experiment to perform numerical experiments, as a tool for experimentalists to support experiments and finally as a pedagogical tool to gain an understanding of the process’ (Hartmann, 1996, p. 6). In our case, we have created the CPNs as a means to gain an understanding of the observation stage of the Glass Box framework by visualizing the processes and to check if it is possible to apply the monitoring and verification process to a practical case of autonomous surveillance drones by modelling the Pre-Flight Mission Planning Process and Post-Flight Mission Evaluation Process. Evaluating this simulation by verification of the behavioural properties of CPN models can be conducted using a state space exploration. A state space is a directed graph consisting of a node for each marking and edges corresponding to the events. By computing all reachable states and state changes, it is possible to verify questions regarding the behaviour of a system. The modeler can add tokens to the CPN model to ensure a finite state space so that the behavioural properties can be checked (Jensen, Kristensen, & Wells, 2007). For the evaluation of our simulation, the ASCoVeCo State Space Analysis Platform (ASAP) - developed by Westergaard, Evangelista, and Kristensen (2009)- could be used. ASAP is a tool that supports state space exploration and analysis of CPNs. The ASAP architecture consists of a Graphical User Interface (GUI) and State Space Exploration Engine (SSE engine) that is implemented in Java based on the Eclipse platform. The GUI allows creating and managing verification projects consisting of verification jobs. ASAP could be used to evaluate and verify the behavioural properties of our CPNs. However, to conduct the evaluation with the ASAP architecture the user will need to be experienced with Java and Eclipse to upload the CPNs to the SSE engine. Bearing in mind that not all researchers are proficient with Java and Eclipse, a second approach for evaluation of the simulation could be by querying experts in military drone deployments to verify if the simulated processes represent an actual Pre-Flight Mission Planning Process and Post-Flight Mission Evaluation Process. The evaluation can be conducted by either organizing expert panels (for example based on the Delphi method
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