## 2 Methodology, Fundamentals, and Materials
### Functions Development during Industrial Revolutions
Furthermore, while current systems are optimized toward a precise execution of a given set of parameters, self-optimizing systems need to be optimized toward product quality, and this can only be achieved if expert knowledge about the process and the boundary conditions is embedded [3]. Maintenance refers to all the actions that lead to the restoration of an item to its initial condition [16] in the most cost-effective way. Different maintenance strategies have emerged and evolved throughout history. The role of maintenance has emerged from mainly corrective maintenance activities to a key element for enabling process performance, availability, quality, and stability [17]. Maintenance is one of the most important activities during a products' lifecycle [16]. Throughout a product's lifecycle, maintenance consumes large amounts of time and financial resources. In order to minimize its effect, there is an effort towards integrating novel technologies that will facilitate relative technical knowledge distribution, even from remote locations [18]. Until the 1940s, corrective maintenance was predominant. Since the 1940s, the evolution of industrial maintenance can be explained in four stages. In the first stage of preventive maintenance [19], the breakdown and repair of machinery were regarded as necessary and not as costs with the potential to increase a company's profitability [20]. In the second stage, industrial maintenance planning and management systems were developed [19]. For this purpose, systematic studies on the service life of technical systems using statistics of failure intervals and duration were used [21]. In the third stage, the \"total productive maintenance (TPM) system\" was established in 1969 with the transfer of routine maintenance procedures to machine operators [22]. In the fourth stage, presently, maintenance needs to go beyond keeping up with maintenance and ensuring availability [19]. In maintenance, the condition monitoring of machines has established itself as a remote service by continuously recording and analyzing the physical parameters of a machine. This allows potential errors to be identified early, avoiding machine failures [23]. Over the last decade, organizations have continuously increased their revenues from the service business, and they have begun to expand their business by offering product-related services. In particular, they offer maintenance, repair, and overhaul (MRO) services as well as technical support for their products, resulting in an increased importance of the service business for manufacturing organizations [24]. Over the last 50 years, a transition from the producers' market to the customers' markets has occurred [25]. During the 1950s and 1960s, each operation within each stage of the supply chain tried to minimize its own costs, which defined an intracompany intraoperation scope [26]. It was represented by the classic transport, transshipment, and storage (TTS) logistics, which looks for the optimization of delimitated functions [27]. In the 1970s, the scope was expanded including the optimization of cross-functional processes [28]. Moreover, quality problems came to the forefront of enterprise management and total quality management (TQM) was established [25]. The cost pressure already established in the 1980s--caused by the saturation of markets and an increasing competition situation--created new quality and efficiency requirements on the enterprise process management [27]. Therefore, Kanban was implemented for controlling the material flow in production [28]. This period is also characterized by efforts for optimal inventory management and a reduction in production cycles [25]. At the end of the 1980s, the first cross companies' logistics concepts were developed. The introduction of the just-in-time (JIT) concept in the automobile industry and the efficient customer response (ECR) in trading are two examples of cross companies' logistics between supplier and producer and between producer and trader [28].