tailieunhanh - Marine_Structural_Design Episode 16

Tham khảo tài liệu 'marine_structural_design episode 16', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 578 Part V Risk Assessment Assume that the cash expenses including the initial investment Co associated with the project at the end of each period are c . The present value expression of cash expenses c is H c .o l i Then the NPV of the project denoted by NPV i is defined by the difference between I and c . N Ị N p NPV i y 1 ij1 0 1 0 Ậ3 A positive NPV for a project represents a positive surplus and we should accept the project if sufficient funds are available for it. A project with a negative NPV should be rejected because we could do better by investing in other projects at the market interest rate i or outside the market. Internal Rate of Return IRR The IRR is another time-discounted measure of investments similar to the NPV criterion. The IRR of a project is defined as the rate of interest that equates the NPV of the entire series of cash flows to zero. The project s IRR is mathematically defined by yPK irr f-A- O o l irr A 4 Note that Eqn. is a polynomial function of irr. A direct solution for such a function is not generally possible except for projects with a life of four periods or fewer. Therefore two approximation techniques are generally used one using iterative procedures a trial-and-error approach and the other using Newton s approximation to the solution of a polynomial. Part V Risk Assessment Chapter 33 Human Reliability Assessment Introduction The human reliability analysis plays an important role in the reliability analysis of a manmachine system. Accidents such as Bhopal Three Mile Island Chemyobl and Piper Alpha disasters have actually demonstrated human failures and their catastrophic consequences that could have on a system. According to studies made by Moore 1994 approximately 65 of all catastrophic marine-related accidents are the result of compounded human and organizational errors during operation. In a risk assessment there is therefore a distinct need for properly assessing the risks from human errors and for ways to .