# Systems Engineering: Availability and Reliability
## 3 Innovations in Maintenance Strategies  
The key issue in the use of technical facilities is the problem of making optimal decisions. Along with the development of computer aiding techniques and the progressive digitization of production, numerous tools have appeared to facilitate the work of technical services, allowing for the collection and processing of data, information and knowledge about objects and operational processes, thus enabling and facilitating effective decisions regarding the technical systems in use. This applies to both the technical, organizational and economic areas. Optimally made decisions are one of the key conditions for the proper functioning of maintenance services, which means the necessity to determine the value of selected features. Correct exploitation of technical infrastructure facilities requires linking decision-making processes with the performance of maintenance or repair work. There are many mathematical models that constitute the basis for the quantitative assessment of the method and scope of the operation of technical objects. However, there are still several research challenges requiring innovations in maintenance strategies. For example, as mentioned in [5], the supply chain of petroleum products faces major challenges, i.e., demand growth and the complexity of fluid transportation. The petroleum supply chain contains multiple stations extending from oil wells in exploration and production areas to the final destination. Each station has its own difficulties and challenges in the contribution towards the success of the safe and continuous supply. Undoubtedly, meeting a regional demand for petroleum products requires an uninterrupted, safe operation. In addition, the unloading of petroleum products is a complex and potentially dangerous operation since the unloading system contains complex interdependency components. Any failures in one of its components lead to a cut in the petroleum supply chain. Therefore, it is important to assess and evaluate the reliability of the unloading system in order to improve its availability. In this context, [PERSON] et al. [5] present the operation philosophy of the truck unloading system, failure modes of the components within the system, and a bottom-up approach to analyze the reliability of the system. In addition, it provides reliability data, such as failure rates and the mean time between failures of the system components. Furthermore, the reliability of the whole system was calculated and is presented for different time periods. The critical components, which are major contributors towards the system's reliability, were identified. To enhance the system's reliability, a reliability-based preventive maintenance strategy for the critical components was implemented. In addition, the preventive maintenance scheduling was identified based on the reliability plots of the unloading system. The best schedule for preventive maintenance of the system was determined based on the reliability function to be every 45 days for maintaining the system reliability above 0.9. In order to maximize inventory benefits or minimize costs, the reliability and cost of inventory control models need to be identified and analyzed. These importance measures are one important approach to recognize and evaluate system weaknesses. However, the importance measures have fewer applications in inventory systems' reliability. Considering the cost, [PERSON] et al. [6] discuss the reliability change of performance parameters with the importance measures in inventory systems. The calculation methods of differential importance and Birnbaum importance are studied in the inventory control model with shortages. By comparing the importance values of various parameters in the model, the optimization analysis of the inventory model can be used to identify the key parameters so as to effectively reduce the total inventory cost.