It is well known that the costs to fix errors increase as the project matures, but how fast do those costs build? A study was performed to determine the relative cost of fixing errors discovered during various phases of a project life cycle. This study used three approaches to determine the relative costs: the bottom-up cost method, the total cost breakdown method, and the top-down hypothetical...

In life-cycle costing analyses, optimal design is usually achieved by minimising the expected value of the discounted costs. As well as the expected value, the corresponding variance may be useful for estimating, for example, the uncertainty bounds of the calculated discounted costs. However, general explicit formulas for calculating the variance of the discounted costs over an unbounded time h...

It is well known that the costs to fix errors increase as the project matures, but how fast do those costs build? A study was performed to determine the relative cost of fixing errors discovered during various phases of a project life cycle. This study used three approaches to determine the relative costs: the bottom-up cost method, the total cost breakdown method, and the top-down hypothetical...

Current software cost estimation models, such as the 1981 Constructive Cost Model (COCOMO) for software cost estimation and its 1987 Ada COCOMO update, have been experiencing increasing difficulties in estimating the costs of software developed to new life cycle processes and capabilities. These include non-sequential and rapid-development process models; reuse-driven approaches involving comme...

Numerical optimization methods offer a powerful new technology for pump users when combined with pumping system analysis software. Whether the design goal is to reduce first costs or life-cycle costs, this technology promises to significantly reduce pumping system costs and energy usage. Optimization methods work by automatically selecting pipe and pump sizes to minimize cost. Design engineers ...

It is well known that the costs to fix errors increase as the project matures, but how fast do those costs build? A study was performed to determine the relative cost of fixing errors discovered during various phases of a project life cycle. This study used three approaches to determine the relative costs: the bottom-up cost method, the total cost breakdown method, and the top-down hypothetical...

This paper presents an exploratory study for identification and quantification of the economic benefits or implications associated with wing cost variations. A hierarchical cost model structure is used to determine life cycle effects of design and manufacturing alternatives for the major structural components of the wing of a High Speed Civil Transport aircraft concept. Preliminary results are ...

During the operation, the distribution transformer performance will deteriorate. The maintenance is an essential task in enhancing the safety of distribution transformer. Based on equal deterioration theory, the relationship among distribution transformer failure rate in each period of maintenance was deduced. After analyzing the maintenance costs and the failure costs in detail, the model of o...

Each stage in the life cycle of coal-extraction, transport, processing, and combustion-generates a waste stream and carries multiple hazards for health and the environment. These costs are external to the coal industry and are thus often considered "externalities." We estimate that the life cycle effects of coal and the waste stream generated are costing the U.S. public a third to over one-half...