Sequential Series Systems and Their Risk Assessments

System reliability models are critical in both theory and engineering. Although there are many system reliability models, they still cannot cover some practical situations. In this article, three sequential series systems are introduced in terms of some real backgrounds. An order profile for the system working is also introduced, because it can be used to describe the working component contribution for the system clearly. As the systems become more and more complicated and important, the safety issue is a hot topic. Risk analysis is one of the important ways for safety studies and implements. The formulae for some risk measures for the sequential systems are presented from a safety point of view. A numerical example is given to illustrate the details of the procedure and formulae.