**4.2 Software architecture**

106 Fossil Fuel and the Environment

session and the corresponding rules generated by the editor, which are used during the execution of CLIPS as tutoring system. In such way, the ES is responsible of tracking the status of the simulation to determine the group of rules that should be fired. Due to its inference engine, and according to the configuration of the simulation exercise, the ES is able to modify the simulation process, because it can insert malfunctions, modify values of selected process variables, and change the status of the simulation without the intervention

The use of ES is especially suitable for training standalone systems, because these systems incorporate: a simulator of a power plant, an intelligent tutor to guide the training session, and besides it can include the trainee evaluation and study material in some multimedia format as theoretical support of the training objectives. Naturally, the HMI for the trainee must be designed bearing in mind that the user, in addition of its operation interfaces, will

According to the different simulator types described in the second section, the required hardware is characteristic for each one of them; therefore the next description of hardware is

The hardware requirements are exemplified in Figure 11, where there are four PC interconnected through a fast Ethernet local area network. Each PC must have the processor and memory required to execute the simulator smoothly, and to support high processing demand functions like execution faster than real-time. The monitors of the operator consoles must be of a similar size of the ones in the actual power plant. In the case of the Figure 11, the configuration depicts monitors of 20" and 50". During the training session, the trainee

of a human instructor.

need "a window" to observe the tutor messages.

based on a full-scope replica simulator.

**4.1 Hardware architecture** 

Fig. 11. Hardware architecture.

**4. Hardware-software architecture of a simulation system** 

The simulation software is designed with the purpose that the response of simulator is comparable with the results observed in the reference plant under similar conditions. As expected, besides the mathematical models, it is required the execution software or simulation environment. Tavira-Mondragón et al. (2010a) describes the software architecture for a simulation environment. The software architecture of the simulation environment has four main parts: the real-time executive, the operator module, the instructor console module, and mathematical models. Each one of these modules can be hosted in the same or in different PC, and they are connected through the TCP/IP protocol under Windows operating system. A brief description of each module is shown in the following paragraphs (the mathematical models are discussed in the next section).

