Ernst G. Frankel This book has its origin in lecture notes developed over several years for use in a course in Systems Reliability f~r engineers concerned with the design of physical systems such as civil structures, power plants, and transport systems of all types. Increasing public concern with the reliability of systems for reasons of human safety, environmental protection, and acceptable investment risk limitations has resulted in an increasing interest by engineers in the formal application of reliability theory to engineering design. At the same time there is a demand for more effective approaches to the design of procedures for the operation and use of man made systems, more meaningful assessment of the risks introduced, and use such a system poses both when operating as designed and when operating at below design performance. The purpose of the book is to provide a sound, yet practical, introduction to reliability analysis and risk assessment which can be used by professionals in engineering, planning, management, and economics to improve the design, operation, and risk assessment of systems of interest. The text should be useful for students in many disciplines and is designed for fourth-year undergraduates or first-year graduate students. I would like to acknowledge the help of many of my graduate students who contributed to the development of this book by offering comments and criticism. Similarly, I would like to thank Mrs. Sheila McNary who typed untold drafts of the manuscript, and Mr.