## 4 Analyses of the Applications of Digital Twin Models
### Manufacturing
#### 4.1.1 Application and Adoption of Digital Twin in Manufacturing  
Starting from the study conducted in [27], traditional production has been known as an industrial process primarily focused on converting raw materials into finished products. However, with technological advancements and increasing quality demands, there has been a shift from conventional to intelligent processes. This transition has led to the introduction of the Digital Twin concept in production, facilitating seamless communication and interaction between the physical and digital realms. Moreover, recent technological strides have enabled the automation of production processes, with the Digital Twin aiding in visualizing real manufacturing processes and comparing physical products with their virtual counterparts. This fosters collaboration and real-time information gathering about products under production. In ref. [28], [PERSON] et al., demonstrated how Digital Twin technology contributes to transforming cyber-physical production systems into autonomous ones. Additionally, in ref. [29], [PERSON] et al., illustrated the implementation of a Digital Twin  
Figure 10: The process of digital transformation of real-world entities. that aids in addressing personalized production challenges and issues encountered in distributed production systems. The Digital Twin contributes to process optimization and asset management, supporting interaction between humans and robots. In the context of dynamic production planning with the aid of the Digital Twin, through the integration of real-time sensor data, data obtained from simulation processes, and via Enterprise Information Systems (EISs), [PERSON] and [PERSON] [30] highlighted how this technology facilitates the adaptation of production plans to changes in the manufacturing environment. In this context, the Digital Twin enhances the efficiency and adaptability of manufacturing processes, with a wide range of industrial applications. Following a detailed analysis, [PERSON] et al. [27] concluded that the Digital Twin is personalized, reflecting the behavior of the physical twin with a high degree of fidelity. Additionally, the authors emphasized the importance of multi-physics aspects and continuous updating of the model throughout the product lifecycle. Another characteristic of the Digital Twin is controllability, whereby changes at one twin level control the other, thus closing the loop between digital and physical twins and facilitating the convergence between digital and physical environments. Integrating the concept of Product-Service Systems (PSSs), with the concept of Digital Twins throughout the life cycle of a product facilitates the creation of real-time physical-virtual and virtual-physical connections. The combination of a multitude of frameworks, methods, tools, and models can be achieved using the analysis--evaluation validation process. In ref. [31], the authors presented a solution for the use of DTs in the PSS field, including both models in which connections could not be made between P2V (Physical to Virtual), V2P (Virtual to Physical), and their counterparts, as well as case studies that have been based on various notions related to Digital Twin, Product Avatar, and Digital Thread. The use of DTs can be achieved in each stage of a product's life cycle: design, manufacturing, and end-of-life. At the beginning of life (in the product design stage), as mentioned in [32], DTs can be used to pre-identify customer requirements and correctly interpret the data based on some design parameters, using the results obtained by following the interaction with the product. Acting as a \"shadow\" and being defined as a proposal for PSS, [33] details the advantage of using DTs in the design phase of PSS to better understand business systems and the relationships between all their components. Similarly, in the design phase [34], knowledge from transversal domains can be integrated into a unitary database of knowledge to achieve a robust thinking mechanism and high autonomy in the PSS system design process.