Models for life cycle assessment of manufactured products

One of the objectives of the life cycle is to evaluate environmental burdens with a product, process or activity by quantifying energy and materials used and wastes released to the environment. The assessment includes the entire life cycle of the product encompassing extraction and processing raw materials, manufacturing, transportation, recycling and disposal. This paper describes a set of mathematical models and a logic framework to systematically arrive at these assessments. This is done by emphasizing the physical aspect of manufacturing systems whose function is to transform raw materials into useful products using physical energy and skill specific human time. Under this theoretical structure, the production system is modularized into networks of processing centers, each of which is represented mathematically by models derived from material and energy balance equations