3,803 research outputs found

    The New Illinois Marriage Law*

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    The New Illinois Marriage Law*

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    View looking east on Heriot Row in Edinburgh, Scotland. Writer Robert Louis Stevenson once lived in the house marked with the plaque in the left foreground, with the series of little balconies. The street swerving left at far end of Heriot Row is Abercrombie Place. The trees mark the edge of a private park. (1 October 1950

    Data distribution satellite

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    The Data Distribution Satellite (DDS), operating in conjunction with the planned space network, the National Research and Education Network and its commercial derivatives, would play a key role in networking the emerging supercomputing facilities, national archives, academic, industrial, and government institutions. Centrally located over the United States in geostationary orbit, DDS would carry sophisticated on-board switching and make use of advanced antennas to provide an array of special services. Institutions needing continuous high data rate service would be networked together by use of a microwave switching matrix and electronically steered hopping beams. Simultaneously, DDS would use other beams and on board processing to interconnect other institutions with lesser, low rate, intermittent needs. Dedicated links to White Sands and other facilities would enable direct access to space payloads and sensor data. Intersatellite links to a second generation ATDRS, called Advanced Space Data Acquisition and Communications System (ASDACS), would eliminate one satellite hop and enhance controllability of experimental payloads by reducing path delay. Similarly, direct access would be available to the supercomputing facilities and national data archives. Economies with DDS would be derived from its ability to switch high rate facilities amongst users needed. At the same time, having a CONUS view, DDS would interconnect with any institution regardless of how remote. Whether one needed high rate service or low rate service would be immaterial. With the capability to assign resources on demand, DDS will need only carry a portion of the resources needed if dedicated facilities were used. Efficiently switching resources to users as needed, DDS would become a very feasible spacecraft, even though it would tie together the space network, the terrestrial network, remote sites, 1000's of small users, and those few who need very large data links intermittently

    Medical Mission Notes

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    Free vibrations of delaminated beams

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    Free vibration of laminated composite beams is studied. The effect of interply delaminations on natural frequencies and mode shapes is evaluated both analytically and experimentally. A generalized vibrational principle is used to formulate the equation of motion and associated boundary conditions for the free vibration of a composite beam with a delamination of arbitrary size and location. The effect of coupling between longitudinal vibration and bending vibration is considered. This coupling effect is shown to significantly affect the calculated natural frequencies and mode shapes of the delaminated beam

    Illinois Digital Scholarship: Preserving and Accessing the Digital Past, Present, and Future

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    Since the University's establishment in 1867, its scholarly output has been issued primarily in print, and the University Library and Archives have been readily able to collect, preserve, and to provide access to that output. Today, technological, economic, political and social forces are buffeting all means of scholarly communication. Scholars, academic institutions and publishers are engaged in debate about the impact of digital scholarship and open access publishing on the promotion and tenure process. The upsurge in digital scholarship affects many aspects of the academic enterprise, including how we record, evaluate, preserve, organize and disseminate scholarly work. The result has left the Library with no ready means by which to archive digitally produced publications, reports, presentations, and learning objects, much of which cannot be adequately represented in print form. In this incredibly fluid environment of digital scholarship, the critical question of how we will collect, preserve, and manage access to this important part of the University scholarly record demands a rational and forward-looking plan - one that includes perspectives from diverse scholarly disciplines, incorporates significant research breakthroughs in information science and computer science, and makes effective projections for future integration within the Library and computing services as a part of the campus infrastructure.Prepared jointly by the University of Illinois Library and CITES at the University of Illinois at Urbana-Champaig

    Vibration testing of impact-damaged composite laminates

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    A new test is described that can be used to measure changes in the vibration properties of impact damaged composite materials. Impact-induced delamination was observed to significantly affect natural frequencies of vibration and damping properties in cross-ply graphite/epoxy laminates. Natural frequencies are shown to drop by as much as half of their original value, and modal damping ratios can increase by a factor of up to eight when large amounts of damage are present. A simple finite element model of the damaged impact specimens was used to predict the effect of delamination on certain vibration properties. A comparison of the finite element calculations with the experimental measurements suggests that delamination was the dominant mechanism of flexural stiffness loss resulting from the transverse impact

    Complementary satellite sound broadcasting systems: A NASA assessment for the Voice of America

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    Satellite concepts are examined which offer potentially significant sound broadcast coverage of audio as a complement to VOA's existing and planned terrestrial sound broadcasting system. HF bands are emphasized but additional discussion is included for systems using higher frequencies. Low altitude satellites, shuttle altitude (275 km) and sun synchronous (about 1600 to 1800 km), would not be practical for international broadcasting since many satellites would be required for reliable and widespread coverage. Two concepts are discussed which would offer significant and practical broadcast coverage at HF. One, an 8-hr posigrade equatorial orbit, would offer about 1 hr of widespread, twice daily, coverage to three areas of the globe. The time of coverage is even greater when confined to densely populated areas only (2 to 3 hrs). Another orbit, the Apogee at Constant Time/Equatorial (ACE), provides the same coverage, but only once daily to each area. The latter orbit is highly elliptical, allowing insertion of a greater payload (more broadcast channels) with the existing launch capability. The ACE and 8-hr orbit concepts led to systems of about equal costs, with the ACE being slightly better

    A Phylogenetic Analysis of the African Plant Genus Palisota (family Commelinaceae) based on Chloroplast DNA Sequences

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    The plant genus Palisota (family Commelinaceae, or spiderwort family) consists of approximately 20 species and is distributed throughout the forests of tropical Africa. The genus exhibits several unusual morphological characteristics, and as a result has been difficult to classify based on morphology. Molecular phylogenetic studies have placed it near the base of Commelinaceae, but the exact placement of Palisota within the family is not clear. As the African continent has become more arid in recent geological times, the forests have receded, reducing the habitat for Palisota species and potentially impacting speciation and extinction rates within the genus. The goal of this study is to sequence the chloroplast-encoded gene rbcL in several additional species of Palisota and its relatives in order to: 1) determine the phylogenetic relationship of the genus with respect to other members of Commelinaceae; 2) evaluate phylogenentic relationships among species of Palisota; and 3) infer relative speciation/extinction rates within the genus. Additionally, we are exploring the use of other molecular regions for phylogenetic analysis with the genus
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