## 1 Introduction
### Theoretical Background
#### 1.1.1 Digital Twins and Their Industrial Applications
The second type called DTI (digital twin instance) gives the data needed for the description of a physical object, which usually includes an annotated 3-D model as well as the materials used currently and in the past, information about the components, the processes that take place in any period of time, test results, records about maintenance and repairs, operating data received from the sensors and monitoring parameters. The third type, referred to as DTA (digital twin aggregate) is a computing system that unifies all digital twins and their real-world prototypes and allows collecting and exchanging data. A digital twin allows using the minimum key parameters to reproduce all the other characteristics of an object. This technology can be used to solve different types of problems involving diagnostics of an object's state, forecasting, streamlining the work and control. Studies by [PERSON] et al., 2018, [PERSON] et al., 2017, [PERSON] et al., 2020 [2; 3] reveal the essence of the digital twin concept, an emerging and fast-growing technology which connects the physical and virtual world. It should be noted that a multitude of terms exists describing similar or partially overlapping phenomena. For example, the term \"digital shadow\" is often used interchangeably with the digital twin--despite it is mainly referring to a digital footprint [4], digital counterpart [5], virtual twin [6], virtual object [7], product agent [8], and avatar [9]. The premise driving the digital twin concept was that each system consisted of two systems, the physical system that has always existed and a virtual system that contained all of the information about the physical system. Through modeling and simulation in a virtual laboratory, we can realize the emergent form and behaviors of systems and diminish the \"I didn't see that coming\" factor. Digital twins can be used in various spheres. They can optimize performance by providing forecasts for long-term planning. In healthcare, they can capture and visualize hospital systems and provide doctors with digital visualization of different parts of the body. They are also capable of improving customer experience by creating a digital twin of the customer-facing applications, getting customer feedback, and improving services accordingly. They are able to improve maintenance by collecting performance data over time, analyzing them, and identifying the required maintenance. In machine building, while a machine is developed, its digital copy is created, which enables simulation and testing of ideas before actual manufacturing starts. Digital twins of real cities can be used to optimize urban sustainability [10]. Thus, digital twins will penetrate every nook and cranny of both manufacturing and other spheres of our life. They will dramatically change industries by boosting efficiency and preventing emergency situations. The concept of a digital twin was introduced in 2003, as part of a university course on product lifecycle management; it was initially published in the aerospace field and was defined as \"a reengineering of structural life prediction and management\", but now more and more studies are conducted into possible applications of digital twins in various spheres. In the manufacturing sector, the digital twin can be regarded as a source of useful information across the entire product lifecycle, for instance, it applies to the building and infrastructure lifecycles. Therefore, the construction digital twin will be conducive to shifting from a smart and lean construction process towards smart lifecycle management [11]. By applying digital twins in their work, engineers can foresee and avoid possible problems as well as take cradle-to-grave responsibility for the constructions they design, taking into account both external and internal factors. The digital twin can be endowed with an abstract model that has all characteristics and fully describes the physical twin at a conceptual level throughout the whole product life-cycle.