51 research outputs found

    The use of sewage treatment works as foraging sites by insectivorous bats

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    Sewage treatment works with percolating filter beds are known to provide profitable foraging areas for insectivorous birds due to their association with high macroinvertebrate densities. Fly larvae developing on filter beds at sewage treatment works may similarly provide a valuable resource for foraging bats. Over the last two decades, however, there has been a decline in filter beds towards a system of “activated sludge”. Insects and bat activity were surveyed at 30 sites in Scotland employing these two different types of sewage treatment in order to assess the possible implications of these changes for foraging bats. Bat activity (number of passes) recorded from broad-band bat detectors was quantified at three points within each site. The biomass of aerial insects, sampled over the same period as the detector surveys, was measured using a suction trap. The biomass of insects and activity of Pipistrellus spp. was significantly higher at filter beds than at activated sludge sites. In addition, whilst foraging activity of Pipistrellus spp. at filter beds was comparable to that of adjacent “good” foraging habitat, foraging at activated sludge sites was considerably lower. This study indicates the high potential value of an anthropogenic process to foraging bats, particularly in a landscape where their insect prey has undergone a marked decline, and suggests that the current preference for activated sludge systems is likely to reduce the value of treatment works as foraging sites for bats

    Numerical Investigation of Capabilities for Dynamic Self-Shading through Shape Changing Building Surface Tiles

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    A concept for a smart material morphing building surface tile that would utilize adaptive surface wrinkle patterns to improve solar interaction is explored. The effect of the wrinkle patterns is numerically investigated in the context of an objective to reduce solar irradiance entering buildings by changing the shape of the surface (i.e., surface topography) so that the facade is self-shading, thereby reducing energy costs of the building for temperature control. A generally applicable algorithm was utilized and is presented to quantify the area of an arbitrarily shaped/oriented surface that is in shade for any given date/time and geographic location. Numerical case studies are shown that utilize the surface shading algorithm to evaluate the capabilities of various basic wrinkle patterns, both static and dynamically changing, to self-shade a building surface over the course of a day. The results indicate that a morphing wrinkle pattern can substantially increase the amount and duration of surface area in shade over time in comparison to any of the static (non-morphing) patterns, although it is noted that there is an expected tradeoff in the energy cost to change the surface pattern. Furthermore, it is shown that as the location of the proposed tile on the building facade changes, the optimal wrinkle pattern changes as well

    Evaluation of spacecraft modal test methods

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