Application of Input-Output Modeling to the Environmental Characterization and Improvement of Manufacturing Processes

Huanran Xue | PhD | 2003

Abstract:

To achieve environmentally responsible manufacturing requires a careful examination of the processes employed and the maneuver in which they are operated. Decision-makers may encounter difficulty in making environmentally friendly choices when they make efforts to improve the environmental performance of manufacturing processes. This difficulty arises largely because of the nascency of environmentally responsible manufacturing. There is a sparsity of environmental information on processes and a variety of seemingly unconnected tools, methods, concepts, etc.

To develop tools for effective environmental decisions for manufacturing processes, this thesis proposes a systematic framework for characterization, analysis, and improvement of manufacturing processes from an environmental perspective. To help decisions-makers understand the nature of a process and identify the appropriate tools/methods that maybe most suited to reducing environmental impact, a new classification system for manufacturing processes is established. Methods and tools for environmentally responsible manufacturing are then identified for each class.

A novel material input-output modeling methodology for environmental impact analysis of manufacturing processes is developed. Emphasis is placed on the flow of materials in manufacturing processes and their contributions to environmental consequences. The traditional input-output structure is modified for the purpose of assessing the environmental impact of manufacturing processes. An enhanced material input-output model with a non-zero intercept is further proposed in order to support generic material input-output modeling and to understand dynamic behavior of material flows of manufacturing processes. The proposed material input0output models can be used to identify opportunities to reduce the environmental impacts associated with manufacturing processes. The environmental performance improvement can be achieved by changing material inputs and technical coefficients of the process being considered. Several manufacturing processes are used as examples to illustrate the applications of the material input-output model.

A methodology for aggregation of material input-output models at process level has been developed. Material input-output models at process level has been developed. Material input-output models of manufacturing processes can be aggregated into a system model without bias. It is possible to further aggregate such models into a material input-output model for more complex manufacturing network. The aggregated material input-output model provides a means to support improvement opportunity analysis of the environmental performance of manufacturing systems.

This thesis also explores the application of optimal control to manufacturing processes in order to achieve environmental performance improvement. A modeling method based on input-output data and optimal control strategy are developed. Simulation and experimental verification of the proposed optimal control strategy are performed.

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