Increasing quality, reliability and safety, and reducing risk play a significant role in engineering and social systems’ improvement. Therefore, these criteria should be evaluated accurately to model system behavior. This modeling is helpful to perceive and simulate the current situation of the system. It also provides an opportunity to make efficient decisions. In addition, optimization models aim to find the best level of improvement in terms of considering other factors. This special section on “quality, reliability, safety, and risk modeling and optimization” focuses on new advances in these areas either theoretically or practically in order to investigate system behavior. Topics include, but are not limited to, the following research topics and technologies:

1. Failure behavior modeling
2. System reliability optimization
3. Probabilistic Safety/Risk Assessment (PSA/PRA)
4. Life cycle cost evaluation
5. Quality management and measurement
6. Computational system and risk analysis
7. Fuzzy risk analysis
8. Service quality
9. Quality function deployment (QFD) application
10. Decision making approaches
11. Social security assessment
12. Software reliability