137,492 research outputs found

    Bird Migration Through A Mountain Pass Studied With High Resolution Radar, Ceilometers, And Census

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    Autumnal migration was studied with high-resolution radar, ceilometer, and daily census in the area of Franconia Notch, a major pass in the northern Appalachian Mountains. Under synoptic conditions favorable for migration, broadfront movements of migrants toward the south passed over the mountains, often above a temperature inversion. Birds at lower elevations appeared to be influenced by local topography. Birds moving southwest were concentrated along the face of the mountain range. Birds appeared to deviate their flights to follow local topography through the pass. Specific migratory behavior was not associated with species or species groups. Under synoptic conditions unfavorable for southward migration, multimodal movements probably associated with local flights were as dense as the southward migrations described above. Avian migrants reacting to local terrain may result in concentrations of migrants over ridge summits or other topographic features

    It’s more than just books: working with a corporate marketing team to promote library services

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    In 2005, the Library at the University of East London reviewed its printed promotional material and general marketing strategy, working with the University’s communications team. The issues considered included: evaluating the strategy to decide whether it should be short-term or long-term; the problem of information overload; defining the library's "message"; the most appropriate format to use. The main elements involved in the development and implementation of the new promotional brochure are presented, including: design aspects; branding and slogans; editing and checking. Concludes with an assessment of whether the new scheme worked and discusses the experience of working with non-librarians in a project

    Active control of a flexible beam

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    Because of inherent low damping and high flexibility, large space structures may require some form of active control of their dynamics. Because of the apparent inability to accurately model the dynamics of these structures, methods for parameter adaptive control are now being developed at Langley. This approach uses a digital computer to process discrete sensor data, identify modal parameters, calculate modal control gains, and then convert the modal forces to real forces. Some of the problems considered are: (1) the possibility that there may be modes to control with limited amounts of hardware, and (2) the required accuracy of identified structural parameters

    Mapping biodiversity value worldwide: combining higher-taxon richness from different groups

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    Maps of large-scale biodiversity are urgently needed to guide conservation, and yet complete enumeration of organisms is impractical at present. One indirect approach is to measure richness at higher taxonomic ranks, such as families. The difficulty is how to combine information from different groups on numbers of higher taxa, when these taxa may in effect have been defined in different ways, particularly for more distantly related major groups. In this paper, the regional family richness of terrestrial and freshwater seed plants, amphibians, reptiles and mammals is mapped worldwide by combining: (i) absolute family richness; (ii) proportional family richness; and (iii) proportional family richness weighted for the total species richness in each major group. The assumptions of the three methods and their effects on the results are discussed, although for these data the broad pattern is surprisingly robust with respect to the method of combination. Scores from each of the methods of combining families are used to rank the top five richness hotspots and complementary areas, and hotspots of endemism are mapped by unweighted combination of range-size rarity scores

    Laboratory experiments on cohesive soil bed fluidization by water waves

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    Part I. Relationships between the rate of bed fluidization and the rate of wave energy dissipation, by Jingzhi Feng and Ashish J. Mehta and Part II. In-situ rheometry for determining the dynamic response of bed, by David J.A. Williams and P. Rhodri Williams. A series of preliminary laboratory flume experiments were carried out to examine the time-dependent behavior of a cohesive soil bed subjected to progressive, monochromatic waves. The bed was an aqueous, 50/50 (by weight) mixture of a kaolinite and an attapulgite placed in a plexiglass trench. The nominal bed thickness was 16 cm with density ranging from 1170 to 1380 kg/m 3, and water above was 16 to 20 cm deep. Waves of design height ranging from 2 to 8 cm and a nominal frequency of 1 Hz were run for durations up to 2970 min. Part I of this report describes experiments meant to examine the rate at which the bed became fluidized, and its relation to the rate of wave energy dissipation. Part II gives results on in-situ rheometry used to track the associated changes in bed rigidity. Temporal and spatial changes of the effective stress were measured during the course of wave action, and from these changes the bed fluidization rate was calculated. A wave-mud interaction model developed in a companion study was employed to calculate the rate of wave energy dissipation. The dependence of the rate of fluidization on the rate of energy dissipation was then explored. Fluidization, which seemingly proceeded down from the bed surface, occurred as a result of the loss of structural integrity of the soil matrix through a buildup of the excess pore pressure and the associated loss of effective stress. The rate of fluidization was typically greater at the beginning of wave action and apparently approached zero with time. This trend coincided with the approach of the rate of energy dissipation to a constant value. In general it was also observed that, for a given wave frequency, the larger the wave height the faster the rate of fluidization and thicker the fluid mud layer formed. On the other hand, increasing the time of bed consolidation prior to wave action decreased the fluidization rate due to greater bed rigidity. Upon cessation of wave action structural recovery followed. Dynamic rigidity was measured by specially designed, in situ shearometers placed in the bed at appropriate elevations to determine the time-dependence of the storage and loss moduli, G' and G", of the viscoelastic clay mixture under 1 Hz waves. As the inter-particle bonds of the space-filling, bed material matrix weakened, the shear propagation velocity decreased measurably. Consequently, G' decreased and G" increased as a transition from dynamically more elastic to more viscous response occurred. These preliminary experiments have demonstrated the validity of the particular rheometric technique used, and the critical need for synchronous, in-situ measurements of pore pressures and moduli characterizing bed rheology in studies on mud fluidization. This study was supported by WES contract DACW39-90-K-0010. (This document contains 151 pages.

    Coping with a changing world: the UK Open University approach to teaching ICT

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    The rapid pace of change in the ICT field has affected all HE providers, but for the UK Open University (UKOU), used to print-based courses lasting eight years or more, it has been a particular challenge. This paper will present some of the ways the UKOU has been coping with this problem by discussing the design of three courses, the first developed almost a decade ago. All three are distance learning courses that are either core or optional in a variety of bachelors' degrees, including the BSc programmes in: Information and Communication Technology; IT and Computing; and Technology; as well as the BEng (Hons) engineering programme. The first course, Information and Communication Technology: people and interactions is a level 2 (second year undergraduate) course first presented in 2002. It is predominately a print-based course with an eight year lifetime. The second course Networked Living: exploring information and communication technologies is a level 1 (first year undergraduate) course first presented some three-and-a-half years later in 2005. It is expected to have a course life of five years, and uses a mix of print-based (60%) and computer-based (40%) material. Both these courses use assignments as key tools for annual updating. The third course, Keeping ahead in ICT is aimed primarily at equipping students with advanced information searching and evaluation skills that will serve them well in professional life, and is presented at level 3 (final year undergraduate). It was first presented in 2007 and has an expected course life of 8 years. It uses much less print than in most OU courses, and has a greater reliance on third-party resources such as newspaper, conference and journal articles, websites, and other electronic resources. Some elements in each block are designed to change from year to year, in order to retain currency. Finally, the paper will look forward to the development of a new level 2 course with an expected first presentation in 2010, drawing out the lessons learned about course updating, and predicting the approach that the course team may tak

    Simulation of gaseous core nuclear rocket mixing characteristics using cold and arc heated flows

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    Mixing phenomena of cold and arc heated jets from coaxial flows of helium or nitrogen related to gaseous core nuclear rocket
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