## 2 Materials and Methods
### Creation of a Proactive System Based on Predictions  
Thanks to the work defined and described in Section 2.1, we now have all relevant process information available. This information flows in real time through our capture and storage system. Hence, all the described data serve as the raw input necessary to create an intelligent process management system. The collected data enable the digital representation of the process using advanced techniques. In fact, these data allow us to develop a proactive intelligent system that anticipates potential problems in the process. Its creation will be carried out through what is known as a digital twin. More accurately, the concept of a digital twin [40] refers to the creation of a virtual and intangible representation based on real data. Its objective is to replicate a physical or real situation. In our case, it focuses on representing the investment casting manufacturing process. The main contribution of a digital twin is to decouple the physical world from the virtual one, enabling analysis of how the process operates and subsequently preventing unexpected deviations in both virtual and real representations. For our use case, the digital twin must facilitate process improvements aimed at defect reduction, energy efficiency, and time-to-market reduction. To achieve these objectives, the digital twin must operate under three clear axioms, as well defined in [41]:  
* Proactivity: The system must be able to anticipate adverse situations. In fact, the digital twin makes use of the digital world through simulations and artificial intelligence. Thus, it will be able to determine the possible state of the production process in the near future (i.e., a temporary state \(t+1\)). * Adjustment: The management of the virtual environment must always work within a specific configuration. This means that the digital twin must meet the requirements of the manufacturing process. In other words, none of the tests or simulations that are developed will break the rules that govern the physical representation of the process. * Business intelligence: The twin will even serve as a knowledge management tool. Specifically, it is a repository of business intelligence that encompasses everything needed to manage all the tasks associated with the actual process. By utilizing the digital twin and providing it with this repository, business knowledge will remain within the company, preventing the much-feared knowledge leakage. For a digital twin to work, it must apply the same methodology that a doctor does. This methodology is called \"diagnosis\", and its basic steps are as follows [22]: (i) Observation: The digital twin is based on observation, which serves as the foundation for the digital representation of the real world. Observation focuses on extracting raw data, as previously explained and defined. This observation is essential because it enables the identification of operational  
Figure 4: Data gathering: overview scheme of data sources, data capture agents, and centralization of information. patterns, trends, and other aspects that will be used in subsequent tasks. It is important to note that without observation--in other words, without a data capture process--developing this type of technology would not be possible. Evaluation: Making use of the knowledge already loaded into the twin, as well as the data that are being produced in real time, our system develops a process known as \"evaluation\". This process performs different simulations based on the current real situation it receives through \"observation\". Subsequently, the further operations required to adjust and optimize the process will depend on the evaluations or predictions obtained in this stage. Decision making: The previous processes, by themselves, do not add value. That is why a correction or adjustment of the monitored activity is needed. Thus, taking into account the results of the observation and evaluation steps, solver algorithms find the appropriate fit for the purpose of the twin.