82 research outputs found

    Resource Management in Survivable Multi-Granular Optical Networks

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    The last decade witnessed a wild growth of the Internet traffic, promoted by bandwidth-hungry applications such as Youtube, P2P, and VoIP. This explosive increase is expected to proceed with an annual rate of 34% in the near future, which leads to a huge challenge to the Internet infrastructure. One foremost solution to this problem is advancing the optical networking and switching, by which abundant bandwidth can be provided in an energy-efficient manner. For instance, with Wavelength Division Multiplexing (WDM) technology, each fiber can carry a mass of wavelengths with bandwidth up to 100 Gbits/s or higher. To keep up with the traffic explosion, however, simply scaling the number of fibers and/or wavelengths per fiber results in the scalability issue in WDM networks. One major motivation of this dissertation is to address this issue in WDM networks with the idea of waveband switching (WBS). This work includes the author\u27s study on multiple aspects of waveband switching: how to address dynamic user demand, how to accommodate static user demand, and how to achieve a survivable WBS network. When combined together, the proposed approaches form a framework that enables an efficient WBS-based Internet in the near future or the middle term. As a long-term solution for the Internet backbone, the Spectrum Sliced Elastic Optical Path (SLICE) Networks recently attract significant interests. SLICE aims to provide abundant bandwidth by managing the spectrum resources as orthogonal sub-carriers, a finer granular than wavelengths of WDM networks. Another important component of this dissertation is the author\u27s timely study on this new frontier: particulary, how to efficiency accommodate the user demand in SLICE networks. We refer to the overall study as the resource management in multi-granular optical networks. In WBS networks, the multi-granularity includes the fiber, waveband, and wavelength. While in SLICE networks, the traffic granularity refers to the fiber, and the variety of the demand size (in terms of number of sub-carriers)

    ALERT Doctoral School 2012: advanced experimental techniques in geomechanics

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    The twenty-second session of the European Graduate School 2012 (called usually ALERT Doctoral School) entitled Advanced experimental techniques in geomechanics is organized by Cino Viggiani, Steve Hall and Enrique Romero.Postprint (published version

    Pore Space Architecture of Particulate Materials: Characterization and Applications

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    The behavior of particulate materials is of overarching importance across multiple science and engineering fields, given its ubiquitous presence in nature. These materials are typically composed of two phases, solids and voids, and are therefore described as complex multi-phase materials that exhibit non-linear responses when subjected to varying boundary conditions. While the attributes of the solid phase of particulate materials have been extensively characterized both experimentally and numerically, there is much less understanding of the attributes and behavior of the pore phase. Furthermore, classical pore models incorporate idealized assumptions of feature geometries, limiting the accuracy of the information that can be obtained from these features. This study aims to advance digital characterization capabilities for particulate microstructures, focusing on characterizing the geometry and topology of the highly complex pore space within packed particle systems. A new and robust computational algorithm is proposed that quantifies various characteristics of the three-dimensional pore space of a given particulate media, which is unimpeded by assumptions of feature shapes or user dependency. The method is validated against packings of known pore geometries and implemented on real, simulated, and fabricated microstructures of different packing densities, particle sizes, shapes, gradation, and following different specimen preparation techniques to measure its ability in capturing multi-scale responses of microstructures. The study also leverages the emergence of machine learning techniques to scale up the findings to real-world field-scale applications comprising particle-pore systems with 10's of millions of particles. In this regard, the use of deep learning tools for the rapid estimation of pore space properties from three-dimensional images is sought. Finally, the developed techniques and tools are implemented on real granular soils to strengthen the understanding of macro-geomechanical phenomena. The findings highlight the importance of accounting for pore space properties when interpreting the macroscopic response of granular assemblies subjected to external mechanical and precipitational loading.Ph.D

    Space station systems: A bibliography with indexes (supplement 10)

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    This bibliography lists 1,422 reports, articles, and other documents introduced into the NASA scientific and technical information system between July 1, 1989 and December 31, 1989. Its purpose is to provide helpful information to researchers, designers and managers engaged in Space Station technology development and mission design. Coverage includes documents that define major systems and subsystems related to structures and dynamic control, electronics and power supplies, propulsion, and payload integration. In addition, orbital construction methods, servicing and support requirements, procedures and operations, and missions for the current and future Space Station are included

    Research reports: 1985 NASA/ASEE Summer Faculty Fellowship Program

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    A compilation of 40 technical reports on research conducted by participants in the 1985 NASA/ASEE Summer Faculty Fellowship Program at Marshall Space Flight Center (MSFC) is given. Weibull density functions, reliability analysis, directional solidification, space stations, jet stream, fracture mechanics, composite materials, orbital maneuvering vehicles, stellar winds and gamma ray bursts are among the topics discussed

    Review of advanced road materials, structures, equipment, and detection technologies

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    As a vital and integral component of transportation infrastructure, pavement has a direct and tangible impact on socio-economic sustainability. In recent years, an influx of groundbreaking and state-of-the-art materials, structures, equipment, and detection technologies related to road engineering have continually and progressively emerged, reshaping the landscape of pavement systems. There is a pressing and growing need for a timely summarization of the current research status and a clear identification of future research directions in these advanced and evolving technologies. Therefore, Journal of Road Engineering has undertaken the significant initiative of introducing a comprehensive review paper with the overarching theme of “advanced road materials, structures, equipment, and detection technologies”. This extensive and insightful review meticulously gathers and synthesizes research findings from 39 distinguished scholars, all of whom are affiliated with 19 renowned universities or research institutions specializing in the diverse and multidimensional field of highway engineering. It covers the current state and anticipates future development directions in the four major and interconnected domains of road engineering: advanced road materials, advanced road structures and performance evaluation, advanced road construction equipment and technology, and advanced road detection and assessment technologies

    Cumulative index to NASA Tech Briefs, 1986-1990, volumes 10-14

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    Tech Briefs are short announcements of new technology derived from the R&D activities of the National Aeronautics and Space Administration. These briefs emphasize information considered likely to be transferrable across industrial, regional, or disciplinary lines and are issued to encourage commercial application. This cumulative index of Tech Briefs contains abstracts and four indexes (subject, personal author, originating center, and Tech Brief number) and covers the period 1986 to 1990. The abstract section is organized by the following subject categories: electronic components and circuits, electronic systems, physical sciences, materials, computer programs, life sciences, mechanics, machinery, fabrication technology, and mathematics and information sciences
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