5 research outputs found

    Applications of industrial ecology : manufacturing, recycling, and efficiency

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    Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2007.Includes bibliographical references.This work applies concepts from industrial ecology to analyses of manufacturing, recycling, and efficiency. The first part focuses on an environmental analysis of machining, with a specific emphasis on energy consumption. Energy analyses of machining show that in many cases, the energy of actual material removal represents only a small amount of the total energy used in machining, as auxiliary processes can have significant energy requirements. These analyses also show that the embodied energy of the materials that are machined can far exceed the energy of machining. Such energy consumption data, along with material flow data, provide much of the information necessary to evaluate machining on the basis of environmental performance. The second part of this work focuses on material recycling at product end-of-life. In this section, a means of evaluating the material recycling potential for products is presented. This method is based on two measures: the value of the materials used in a product and the mixture of materials used in a product. This simple representation is capable of differentiating between products that are economically worthwhile to recycle and those that are not.(cont.) Such information can in turn be used to help guide product design and recycling policy. The third part of this work focuses on the effectiveness of efficiency improvements in reducing environmental impact. Historical data from ten activities show that improvements in efficiency are rarely able to outpace increases in production. Thus, the overall impact of each of these activities has increased over time. Specific conditions and policies that do allow for efficiency improvements to reduce impact are identified and explored. Together, the three topics presented here provide information, analyses, and recommendations to help move industrial systems towards sustainability.by Jeffrey B. Dahmus.Ph.D

    Non-functional influences on product architecture

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    Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2001.Includes bibliographical references (p. 103-107).by Jeffrey B. Dahmus.S.M

    Modeling the Impact of Product Portfolio on the Economic and Environmental Performance of Recycling Systems

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    hrough the development of a general model of electronics recycling systems, the effect of product portfolio choices on economic and environmental system performance is explored. The general model encompasses the three main functions of a recycling system-collection, processing, and system management-and allows for the effect of both contextual and architectural inputs-including product scope-to be explored. Overall model results indicate that collecting a broader portfolio of products can be economically favorable, even for cases in which lower-value products are added to a recycling system. In these cases, the higher total mass throughputs that are realized by the collection of additional product types can help to drive down the cost per unit mass collected. Expanding product scope can also yield improvements in environmental performance, as the energy per unit mass collected can also decrease with higher mass throughputs

    Molecular Genetics of the RNA Polymerase II General Transcriptional Machinery

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