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2009年

Rosenberg, Alexa E. (Alexa Edwards), Massachusetts Institute of Technology. Dept. of Urban Studies and Planning.

美国 | 英文

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(cont.) Since an important political turnover in the year 2000 and the death of Enda;;s founder in 2002, Enda has been attempting to align its internal structure and functioning with its external institutional context. The challenge for Enda is to develop a system that will grant its teams the flexibility to experiment while supporting them with evaluation for learning and adaptation. This is essential for Enda;;s renewed visibility and influence in urban development in Dakar.

    2009年

    Kim, Sung Joong, Ph. D. Massachusetts Institute of Technology, Massachusetts Institute of Technology. Dept. of Nuclear Science and Engineering.

    美国 | 英文

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    (cont.) Wettability of the surface was substantially increased for heater coupons boiled in alumina and zinc oxide nanofluids, and such wettability increase seems to correlate reasonably well with the observed marked CHF enhancement for the respective nanofluids. Interpretation of the experimental data was conducted in light of the governing surface parameters and existing models. It was found that no single parameter could explain the observed HTC or CHF phenomena. The existing models were limited in studying the surface effects, suggesting that more accurate models incorporating surface effects need to be developed. Finally, the research activities performed in this thesis help identify the research gaps and indicate future research directions.

      2009年

      Ortiz Duran, Sebastian, Hawks, Richard, Massachusetts Institute of Technology. Engineering Systems Division.

      美国 | 英文

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      The focus of this research is creating a framework to accurately assess the benefits of hub capability in an international distribution network for fast moving consumer packaged goods. The traditional inventory centralization dilemma requires an evaluation of whether the reduction in holding costs outweighs the increases in transportation and handling costs. We developed a mixed integer programming model to determine the benefits of adding hub capability to Consumer Co.;;s Northwest Latin American import supply chain. Consumer Co.;;s NWLA division imports products from Argentina, Brazil and Mexico to eleven countries within Central and South America, each operating a distribution center. By adding hub capability in the Colon Free Trade Zone, our model determined that the lowest cost could be achieved using a ;;Hybrid;; solution, where some channels flowed through the hub and others were shipped direct. This network design would result in a 4.4% reduction in annual relevant costs. A counter-intuitive revelation was the fact that transportation costs could actually decrease. Similar to airlines, carriers can sometimes offer lower rates for indirect shipments passing through a high volume transit point instead of shipping the product directly through a less traveled route. Hub capability in the Colon Free Trade Zone also provides Consumer Co. with the flexibility to tailor their supply chain to potential changes in the fluctuating Latin American environment. Increasing customer expectations can lead to scenarios with higher safety stocks, for which centralization can provide the highest benefits.

        2009年

        Johnson, David W. (David William), S.M. Massachusetts Institute of Technology, Leaders for Manufacturing Program.

        美国 | 英文

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        (cont.) Equally important, the prior non-standard process is now standardized, enabling future Test Wafer improvement projects and allowing root cause analysis on previously unsolvable problems.

          2009年

          Fu, Haitao, Massachusetts Institute of Technology. Dept. of Materials Science and Engineering.

          美国 | 英文

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          In this thesis report, both quantitative and qualitative approaches are used to provide a comprehensive analysis of lithium ion (Li-ion) batteries for plug-in hybrid electric vehicle (PHEV) and battery electric vehicle (BEV) from technological and economical perspectives. Five key factors including power density, energy density, safety, durability, and cost are employed to compare four types of Li-ion batteries. Utility analysis indicates that all the Li-ion batteries are able to satisfy both power density and energy density targets, but only two of them are able to meet safety and durability requirements. Currently, the main challenge for their automotive application is cost reduction, since the cheapest LiFePO₄ battery costs $247.8/kWh which is 1.65 times the cost target established by USABC. Economical values of PHEV and BEV are presented from an end user;;s point of view. Various sensitivity analysis have been used to identify the impact of key factors such as battery pack cost reduction, driving distance, gasoline price, and government subsidizations on cost effectiveness of PHEV and BEV. Results show that $4,270 and $7,726 of U.S. government subsidizations to an individual user are needed for PHEV and BEV to breakeven. Lastly, the lithium ion battery based electric vehicle systems have also been evaluated in the implementation models in Singapore. The conclusion is that it is not feasible to adopt electric vehicle system in Singapore under current government incentives.

            2009年

            Neilson, Sarah (Sarah Jane), Massachusetts Institute of Technology. Dept. of Urban Studies and Planning.

            美国 | 英文

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            One-third of the municipal solid waste stream is organic material that, when processed in landfills, produces methane, a highly potent greenhouse gas. Composting is a proven strategy for organic waste management, which also creates a nutrient-rich soil amendment. This thesis begins with a review of three North American cities (Portland, Toronto, San Francisco) that have implemented successful composting programs, but rely on trucking the material to distant processing facilities. In New York City, the Department of Sanitation has not yet implemented a citywide composting program. In this thesis I explore four small-scale compost programs in New York City. I find that citizens, working outside the purview of city government, have developed their own innovative, local approaches to composting, which suggest viable alternatives to trucking. New York has a proven capacity for managing compost locally; I argue that these models should be replicated throughout the city. I conclude that to process organic waste material properly, it should be reclassified as a food product, and its management shifted to a new city agency that would launch and support local compost programs. Case studies are compost programs operating in Central Park, Battery Park City, Fort Greene community gardens, and the North Brooklyn Compost Project in McCarren Park.