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Handbook of Reliability, Availability, Maintainability and Safety in Engineering Design - Part 9

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Handbook of Reliability, Availability, Maintainability and Safety in Engineering Design - Part 9 studies the combination of various methods of designing for reliability, availability, maintainability and safety, as well as the latest techniques in probability and possibility modelling, mathematical algorithmic modelling, evolutionary algorithmic modelling, symbolic logic modelling, artificial intelligence modelling, and object-oriented computer modelling, in a logically structured approach to determining the integrity of engineering design. . | 3.2 Theoretical Overview of Reliability and Performance in Engineering Design 63 Cost estimating concepts The two basic categories of costs that must be considered in engineered installations are recurring costs and non-recurring costs. An example of a non-recurring cost would be the engineering design of a system from its conceptual design through preliminary design to detail design. A typical recurring cost would be the construction fabrication or installation costs for the system during its construction installation phase. Estimating non-recurring costs In making cost estimates for non-recurring costs such as the engineering design of a system from its conceptual design through to final detail design inclusive of first costs and risk costs the project manager may assign the task of analysing the scope of engineering effort to the cognisant engineering design task force group leaders. This engineering effort would then be divided into two definable categories namely a conceptual effort and a design effort. Conceptual effort The characteristic of conceptual effort during the conceptual design phase is that it requires creative engineering to apply new areas of technology that are probed in feasibility studies in an attempt to solve a particular design problem. However creative engineering contains more risk to complete as far as time and cost are concerned and the estimates must therefore be modified by the proper risk factor. Design effort The design effort involves straightforward engineering work in which established procedures are used to achieve the design objective. The estimate of cost and time to complete the engineering work during the preliminary design and final detail design phases can be readily derived from past experience of the design engineers or from the history of similar projects. These estimates should eventually be accurate within 10 of completed construction costs requiring estimates to be modified by a smaller but still significant risk .