# Systems Engineering: Availability and Reliability
## 1 Introduction  
Current trends in Industry 4.0 are largely related to issues of reliability and availability. As a result of these trends and engineering systems' complexity, research and development needs now refer to new solutions in the integration of intelligent machines or systems, with emphasis on changes in production processes aimed at increasing production efficiency or equipment reliability. The emergence of innovative technologies and new business models based on innovation, cooperation networks, and the enhancement of endogenous resources is assumed to be a strong contribution to the development of competitive economies all around the world. Innovation and engineering, focused on sustainability, reliability, and availability of resources, have a key role in this context. The scope of this Special Issue is closely associated with that of the ICIE'2020 conference. This conference and the journal's Special Issue aims to present the current innovations and engineering achievements of top world scientists and industrial practitioners in the thematic areas related to:  
* Reliability and risk assessment;
* Innovations in maintenance strategies;
* Production process scheduling, management and maintenance;
* Systems analysis, simulation, design and modeling.  
The rapid development of industry, especially observed in recent decades, has significantly complicated the functioning of production systems and thus intensified the maintenance process. Nowadays, the reliability of hardware resources and employee safety, as well as low environmental risk, is required while implementing production processes with maximum efficiency, effectiveness and flexibility. At the same time, the awareness of the role of maintenance services in preventing breakdowns and early detection of initial problems with machines and systems is growing, which, in turn, increases the life of production systems, affecting the achievement of a high level of productivity.  
Detecting and diagnosing faults in the early stages of damage is necessary to prevent the incorrect operation of the machine park and its breakdowns during operation. Hence, the growing role of availability and reliability research. Regular monitoring of the actual technical condition of the equipment and the operational efficiency of technological systems allows ensuring the maximum interval between repairs, thus extending the time of effectively using the existing hardware resources. It also minimizes the number and cost of unplanned downtime caused by machine failures, increasing the availability of both individual machines and entire production lines. It also allows making the right decision--repair or replacement--using cost-benefit analysis methods using appropriate optimizationtasks, for example, when determining the maintenance strategy of the machine as a whole or separately for each category of its structural elements. The implementation of such tasks, also based on the methodology of optimal maintenance, requires appropriate knowledge about the course of operation of a given machine or its element in the past, currently and in a certain forecast of future use and its impact on potential failures and overall service life. Measurement systems monitoring the operation of machines and their parameters as well as diagnostic systems are thus extremely helpful. They all record significant amounts of data that require appropriate processing into knowledge and inference. An extremely dynamic digital transformation is taking place here.