888 research outputs found

    User Applications Driven by the Community Contribution Framework MPContribs in the Materials Project

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    This work discusses how the MPContribs framework in the Materials Project (MP) allows user-contributed data to be shown and analyzed alongside the core MP database. The Materials Project is a searchable database of electronic structure properties of over 65,000 bulk solid materials that is accessible through a web-based science-gateway. We describe the motivation for enabling user contributions to the materials data and present the framework's features and challenges in the context of two real applications. These use-cases illustrate how scientific collaborations can build applications with their own "user-contributed" data using MPContribs. The Nanoporous Materials Explorer application provides a unique search interface to a novel dataset of hundreds of thousands of materials, each with tables of user-contributed values related to material adsorption and density at varying temperature and pressure. The Unified Theoretical and Experimental x-ray Spectroscopy application discusses a full workflow for the association, dissemination and combined analyses of experimental data from the Advanced Light Source with MP's theoretical core data, using MPContribs tools for data formatting, management and exploration. The capabilities being developed for these collaborations are serving as the model for how new materials data can be incorporated into the Materials Project website with minimal staff overhead while giving powerful tools for data search and display to the user community.Comment: 12 pages, 5 figures, Proceedings of 10th Gateway Computing Environments Workshop (2015), to be published in "Concurrency in Computation: Practice and Experience

    Nodal photolithography : lithography via far-field optical nodes in the resist

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    Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2008.Includes bibliographical references (p. 53-54).In this thesis, I investigate one approach - stimulated emission depletion - to surmounting the diffraction limitation of optical lithography. This approach uses farfield optical nodes to orchestrate reversible, saturable optical transitions in certain photoresist compounds. After addressing prior work in resolution enhancement via optical nodes (for metastable atom localization, reversible absorbance modulation, and fluorescence microscopy), I examine the issues of resist formulation, optical pulse width bounds due to resist kinetics, and patterning schemes for low- and high-volume throughput. The experimental realization of stimulated emission depletion is described, and challenges for lithography using this technique are discussed.by Donald Winston.S.M

    Metrology for electron-beam lithography and resist contrast at the sub-10 nm scale

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    Exploring the resolution limit of electron-beam lithography is of great interest both scientifically and technologically. However, when electron-beam lithography approaches its resolution limit, imaging and metrology of the fabricated structures by using standard scanning electron microscopy become difficult. In this work, the authors adopted transmission-electron and atomic-force microscopies to improve the metrological accuracy and to analyze the resolution limit of electron-beam lithography. With these metrological methods, the authors found that sub-5 nm sparse features could be readily fabricated by electron-beam lithography, but dense 16 nm pitch structures were difficult to yield. Measurements of point- and line-spread functions suggested that the resolution in fabricating sub-10 nm half-pitch structures was primarily limited by the resist-development processes, meaning that the development rates depended on pattern density and/or length scale.China Scholarship Council (Fellowship)United States. Dept. of Energy. Center for Excitonics (Award DE-SC0001088)Information Storage Industry ConsortiumNanoelectronics Research InitiativeNational Science Foundation (U.S.

    Hydrology and Glaciers in the Upper Indus Basin

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    Examines the state of the science associated with the snow and ice hydrology in the Upper Indus Basin (IUB), reviewing the literature and data available on the present and projected role of glaciers, snow fields, and stream flow. Considerable speculation but little analysis exists concerning the importance of glaciers in the volume and timing of flow in the Indus River and its tributaries, as well as on the potential impact of climate change on these rivers. A simple model estimates that glacier runoff contributes approximately 18 percent of the total flow, making melt water from the winter snowpack the most probable source for a majority of the remaining 82 percent, and leaving future runoff regimes to be determined primarily by changes in winter precipitation and summer temperatures. To improve the hydrologic predictability of the UIB requires major investment in snow and ice hydrology monitoring stations, further scientific research, and forecasting

    Future Climate Scenarios for the Indus Basin

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    Examines the literature and available data on hydroclimatic variability and change on the Indus Basin plains, comparing historical fluctuations in climatic and hydrologic variables and reviewing scenarios of climate change derived from general circulation models (GCMs), including the generation of future scenarios of changing snow and ice melt in the Upper Indus Basin (IUB). Historical trends show statistically significant increasing temperatures and annual precipitation over the last century, and the general findings from a wide range of general circulation model (GCM) outputs show agreement among models regarding continued increases in temperature. Models regarding changes in precipitation (both in magnitude and direction) do not agree, but indicators do show a general trend in increased precipitation during the summer and a decrease during the winter, suggesting the primary impact on the UIB could be a shift in the timing of peak runoff and not a major change in annual volume

    IBMR Updating to IBMR 2008

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    The last version of Indus Basin Model Revised (IBMR) is based on data from 2000 (primarily the Agricultural Statistics of Pakistan and water-related data from the Water and Power Development Authority [WAPDA]) and earlier farm surveys (for example, 1976 XAES Survey of Irrigation Agriculture and the Farm Re-Survey in 1988 as part of the Water Sector Investment Planning Study [WSIPS])

    The Way Forward

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    Draws together findings from the chain of analyses on Pakistan's Indus Basin, distinguishing between the relative significance of different scenarios, impacts, and adaptations, and highlighting recommendations for research, planning, and policies that can help expand the range of options for Indus Basin management. Key findings include: (1)The 1991 Provincial Water Allocation Accord (DIVACRD) remains a critical hydrologic constraint; (2) Future climate risks will likely impact the macro-economy and households; (3) Non-farm household incomes will suffer more due to increased crop prices; (4) An increase in basin-wide storage will increase the hydropower generation and minimize the impacts of extreme events; (5) Different adaptation investments show potential to minimize the impacts of future climate risks and meet food security objectives; (6) Climate change will likely impact future food availability nationwide; and (7) Groundwater depletion in the fresh water area and basin-wide salinity issues will grow worse with no policy intervention
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