107 research outputs found

    Vibration characteristics of ring-stiffened orthotropic shells of revolution

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    Computer program solves vibration modes and frequencies of thin shells of revolution having general meridional curvature and orthotropic elastic properties in order to evaluate the dynamic behavior of structures with thin shelled components

    A method for calculation of free-space sound pressures near a propeller in flight including considerations of the chordwise blade loading

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    This report presents tabulated values of certain definite integral that are involved in the calculation of near-field propeller noise when the chordwise forces are assumed to be either uniform or of a Dirac delta type. The tabulations are over a wide range of operating conditions and are useful for estimating propeller noise when either the concept of an effective radius or radial distributions of forces are considered. Use of the tabulations is illustrated by several examples of calculated results for some specific propellers

    Nitrogen Balances in High Rainfall, Temperate Dairy Pastures of South Eastern Australia

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    Nitrogen (N) fertilizer use on dairy pastures in south eastern Australia has increased exponentially over the past 15 years, causing increasing environmental concerns. Volatilisation, denitrification and leaching of N were measured for one year (1998-1999) in pastures receiving no N fertilizer (grass/clover), or 200 kg N/ha applied as urea (46%N) or ammonium nitrate (34.5%N). Nitrogen balances were calculated for each treatment. Significantly more N was lost through volatilisation and denitrification when N was applied as urea compared to ammonium nitrate. Nitrate leaching losses were significantly greater with the application of N fertilizer, although the maximum loss was only 4.1 kg N/ha due to low rainfall between May and September. Nitrogen balances were -15, +87 and +82 kg N/ha per year for the grass/clover, 200 kg N/ha urea and 200 kg N/ha ammonium nitrate treatments, respectively. Given the large range in N losses and balances, there is opportunity for improving the N efficiency in dairy pastures, through lower stocking rates and more tactical use of grain and N fertilizer

    Creativity and the computer nerd: an exploration of attitudes

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    This study arises from our concern that many of our best art and design students are failing to make the most of the opportunities provided by IT because of their fear or dislike of computers. This not only deprives them of useful skills, but, even more importantly, deprives many IT based developments of their input. In this paper we investigate the relationship between attitudes to creativity and to computers among students. We quickly discard an approach based on theories of personality types as philosophically and educationally problematic. An approach based on the self-concept of artists and designers, in relation to their own creativity and to their feelings about computers, offers more hope of progress. This means that we do not try to define the attributes of "creative people". Rather, we ask what creativity means to students of art and design and relate these responses to their attitudes to computers. Self-concept depends on how the subjects see themselves within society and culture, and is liable to change as culture changes. One major instrument of cultural change at the present time is the growth of IT itself. We then describe a first attempt at using a psychological method - Kelly's Repertory Grids - to investigate the self-concept of artists and designers. It is hoped to continue with this approach in further studies over the next few years
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