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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
51

Vergleichende Untersuchungen zur Wasseraufbereitung mit getauchten Membranen

Seidel, Tosca 08 February 2004 (has links) (PDF)
Die vorliegende Ausgabe beschäftigt sich mit dem Thema vergleichende Untersuchungen zur Wasseraufbereitung mit getauchten Membranen. Es werden drei Verfahren zur Aufbereitung von Oberflächenwasser zu Trinkwasser unter technischen, ökonomischen und ökologischen Gesichtspunkten verglichen. Das Verfahren der Ultrafiltration mit getauchten Membranen wurde dazu für drei Monate in einem kleintechnischen Pilotversuch an der Aare, Schweiz, getestet und hinsichtlich der Filtrationsleistung unter Variation typischer technischer Parameter bewertet. Für das konventionelle Verfahren mit Mehrschichtfiltration und die Ultrafiltration mit Rohrmodulen wurden die Ergebnisse vorangegangener Untersuchungen ausgewertet. Die anschließende Planung der Großanlagen bildet die Grundlage für den Vergleich. Keines der betrachteten Verfahren kann sowohl im technischen, ökonomischen als auch ökologischen Vergleich eindeutig seine Vorteilhaftigkeit herausstellen. Während die Ultrafiltration mit getauchten Membranen technisch die besten Noten erhält, ist die Wirtschaftlichkeit des konventionellen Verfahrens mit Mehrschichtfiltration mit dem höchsten Kapitalwert am günstigsten bewertet. Im Ergebnis der ökologischen Betrachtung wird das Verfahren der Ultrafiltration mit getauchten Membranen als umweltfreundlichste Variante identifiziert.
52

Feature-Based Hierarchical Knowledge Engineering for Aircraft Life Cycle Design Decision Support

Zhao, Wei 09 April 2007 (has links)
The design process of aerospace systems is becoming more and more complex. As the process is progressively becoming enterprise-wide, it involves multiple vendors and encompasses the entire life-cycle of the system, as well as a system-of-systems perspective. The amount of data and information generated under this paradigm has increased exponentially creating a difficult situation as it pertains to data storage, management, and retrieval. Furthermore, the data themselves are not suitable or adequate for use in most cases and must be translated into knowledge with a proper level of abstraction. Adding to the problem is the fact that the knowledge discovery process needed to support the growth of data in aerospace systems design has not been developed to the appropriate level. In fact, important design decisions are often made without sufficient understanding of their overall impact on the aircraft's life, because the data have not been efficiently converted and interpreted in time to support design. In order to make the design process adapt to the life-cycle centric requirement, this thesis proposes a methodology to provide the necessary supporting knowledge for better design decision making. The primary contribution is the establishment of a knowledge engineering framework for design decision support to effectively discover knowledge from the existing data, and efficiently manage and present the knowledge throughout all phases of the aircraft life-cycle. The second contribution is the proposed methodology on the feature generation and exploration, which is used to improve the process of knowledge discovery process significantly. In addition, the proposed work demonstrates several multimedia-based approaches on knowledge presentation.
53

Environmental comparison of Michelin Tweel and pneumatic tire using life cycle analysis

Cobert, Austin 03 September 2009 (has links)
Recently Michelin has been developing a new airless, integrated tire and wheel combination called the Tweel. The Tweel promises performance levels beyond those possible with conventional pneumatic technology because of its shear band design, added suspension, and decreased rolling resistance. However, many questions remain as to what kind of environmental impact this radical new design will have. The environmental impact of the Tweel will be compared to a current radial tire used on BMWs, but because of the complexity in manufacturing, using, and disposing these tires it is somewhat difficult to compare environmental problems. Currently there are environmental issues all throughout a tire's lifespan from rubber manufacturing emissions to tire disposal, and the rapidly growing method to evaluate all of these points is Life Cycle Analysis (LCA). LCA is the essential tool required by businesses in order to understand the total environmental impact of their products - cradle-to-grave. By considering the entire life cycle of a Tweel from manufacturing, through use and disposal, and comparing it to knowledge of current tires, an accurate assessment of the entire environmental impact of the Tweel will be made. Since the Tweel is currently still in the research phase and is not currently manufactured and used however, there are uncertainties with respect to end-of-life scenarios and rolling resistance estimates that will affect the LCA. Thus, it will be important to consider a range of options to determine which one will have the most environmental benefits while still keeping the strengths of the Tweel design intact.
54

Life-cycle cost-benefit analysis of green roofing systems: the economic and environmental impact of installing green roofs on all atlanta public schools

Whatley, Melvin B. 05 April 2011 (has links)
This study examines the relationship between environmental sustainability and green schools, seeking to highlight the benefits and determine the Net Present Value (NPV) installing vegetative roofs on all schools in the Atlanta Public Schools District. This study quantifies the costs and benefits of thin-layer, or extensive, green roof systems as they compare to typical flat roofs on Atlanta Public Schools. Quantifiable benefits are detailed and suggestions are made to create the means by which other social benefits may be quantified. The purpose of this thesis is to establish proof to the Atlanta Public Schools District that over a 40 year period there are more benefits associated with installing vegetative roofs on all of their flat roofs than there are costs. While some may argue that greens roof are more costly than traditional roof systems, this study provides evidence that the cumulative benefits over a 40 year life cycle associated with large scale green roof installations, such as on all Atlanta Public Schools, are greater than the initial costs incurred. Factors included in the analysis of benefits were reductions to energy/utility costs, reduced emissions, and avoided best management practices (BMPs). Other considerations include social benefits resulting from the mitigation of storm water runoff, reductions to the urban heat island, productivity level increases (students and teachers), and avoided regulatory fees.
55

Quantifying the life cycle water consumption of a passenger vehicle

Tejada, Francisco Javier 06 April 2012 (has links)
Various studies have pointed out the growing need to assess the availability of water sources in regions around the world as future forecasts suggest that water demands will increase significantly for agricultural, industrial and human consumption while freshwater resources are being depleted. One such emerging issue is the effect of industrial operations on said resources, specifically from automobiles. With numerous localities experiencing stresses on water availability, key stakeholders - suppliers, automakers, and vehicle end-users - need to better realize the effect vehicle manufacturing, usage, and disposal have on water resources. While efforts to improve the overall environmental performance of vehicles have mainly concentrated on improving technologies, there has also been considerable effort devoted to characterizing the life-cycle performance of the vehicle product system. However, much of this work has focused on energy consumption and carbon emissions while few studies have examined water. The difference between water use versus water consumption were highlighted and the life-cycle water consumption of a gasoline-powered midsize vehicle were analyzed from material extraction through production, use, and final disposition/end of life. This analysis examines each of the phases to determine a carâ s water footprint using data from the EcoInvent Life Cycle Analysis database as well as data collected from literature sources. Although water use is typically metered at the factory level, water consumption (i.e., water lost through evaporation and/or incorporation into a material, part, and/or product) is much harder to quantify. As shown in this thesis, the difference can be an order of magnitude or more because much of the water that goes into the different processes is either reused, recycled, or discharged back to its original source. The use phase of a vehicle has the biggest impact on the overall vehicle water consumption, followed by material production, whereas water consumption for the end of life processing seems to be relatively insignificant. It is also shown that the impact of energy consumption as part of the total water footprint is very large when compared to the other processes given the dependence on water for energy production. The assessment in this thesis represents a life-cycle inventory and serves as an initial benchmark as no previous study has been completed to determine the water consumption for the life of a vehicle, let alone for most other products. The impact of water consumption varies by region and locality, and a differentiation of impact would still be needed to determine whether the water consumption actually happens in water scarce regions or not.
56

Determining the environmnetal impact of disposal, recycling and remanufacturing strategies

Govetto, Sophie. January 2007 (has links)
Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2008. / Committee Chair: Bert Bras; Committee Member: Beril Toktay; Committee Member: Shreyes Melkote.
57

Towards vehicular sustainability development of environment impact metrics /

Field, Sari. January 2009 (has links)
Honors Project--Smith College, Northampton, Mass., 2009. / Includes bibliographical references (p. 73-74).
58

Lifecycle analysis of air quality impacts of hydrogen and gasoline transportation fuel pathways

Wang, Guihua. January 1900 (has links)
Thesis (Ph.D. in Civil and Environmental Engineeering)--University of California, Davis, 2008. / Text document in PDF format. Title from PDF title page (viewed on August 26, 2009). "September 2008." Includes bibliographical references (p. 150-154).
59

Thermodynamic input-output analysis of economic and ecological systems for sustainable engineering

Ukidwe, Nandan Uday, January 2005 (has links)
Thesis (Ph. D.)--Ohio State University, 2005. / Title from first page of PDF file. Document formatted into pages; contains xxiii, 306 p.; also includes graphics (some col.) Includes bibliographical references (p. 297-306). Available online via OhioLINK's ETD Center
60

A Design Approach to Achieving the Passive House Standard in a Home Energy Retrofit

Hogan, Matthew Bryan, 1982- 06 1900 (has links)
xiv, 92 p. : ill. (some col.) / Passive House is a voluntary, performance-based energy standard for buildings. Passive Houses use on average 90% less energy for space conditioning than code-designed houses; Passive House therefore offers an ambitious performance target for home energy retrofits. Retrofits built to the Passive House standard in Europe have demonstrated a high level of energy performance. In the U.S., few Passive House retrofits exist to date; for this reason, design and cost information for such retrofits is lacking. This study establishes an exemplar through designing the Passive House retrofit of an older home in Eugene, Oregon. The retrofit's cost-effectiveness was examined by comparing projected "business as usual" (BAU) life cycle costs to those associated with retrofit. While the BAU scenario resulted in the lowest cost over a 30-year life cycle, the difference is relatively small; minor adjustments to key variables make the retrofit financially viable. / Committee in charge: Dr. Alison G. Kwok, Chairperson; Peter Keyes, Member; Jan Fillinger, Member

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