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Fossil middle triassic “sea cows” – placodont reptiles as macroalgae feeders along the north-western Tethys coastline with Pangaea and in the Germanic basin

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Natural Science 2011年第1期3卷 9-27页

作者： Cajus G. Diedrich 不详

The descriptions of fossil Triassic marine pla- codonts as durophagous reptiles are revised through comparisons with the sirenia and basal proboscidean mammal and palaeoenvironment analyses. The jaws of placodonts are conver- gent with those of Halitherium/Dugong or Mo- eritherium in their general function. Whereas Halitherium possessed a horny oral pad and counterpart and a special rasp-like tongue to grind seagrass, as does the modern Dugong, placodonts had large teeth that covered their jaws to form a similar grinding pad. The sirenia also lost their anterior teeth during many Millions of years and built a horny pad instead and specialized tongue to fed mainly on seagrass, whereas placodonts had only macroalgae availa- ble. Indirect evidence for Triassic macroalgae is provided by benthic palaeocommunities from different layers and extended European regions in the Germanic Basin. Studies of tooth wear stages for Placodus indicate that anterior teeth may have been used in a similar manner to the procumbent front teeth of modern Dugong. Paraplacodus and Placodus seem to have used these teeth as spatulas to dig out seaplants. Cyamodus and other placodonts such as Placochelys had smaller or reduced anterior teeth. The scarcity of highly worn palatine or maxillary and lower jaw dentary Placodus or Cyamodus teeth (less then 0.5%) suggests that they had a relatively soft diet. The seaplants would only have been squeezed in a similar feeding strategy to that of modern Dugong feeding on seagrass without jaw rotation and grinding. The phylogenetic trend in tooth reduction within the placodonts Paraplacodus, Placodus, especially in Cyamodus but also Placochelys, and Henodus within 11 My appears to have been a result of this plant-feeding adaptation and may even explain the origin or at least close relationship of the earliest Upper Triassic turtles as toothless algae and jellyfish feeders, in terms of the long-term convergent development with the sirens.

关键词： Placodont Reptiles Triassic Convergent Evolutionary Ecological Adaptation Sirenia Macroalgae feeders NW Tethys Shelf Palaeoecology

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Park size and prey density limit occurrence of Eurasian Sparrowhawks in urban parks during winter

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Avian Research 2018年第3期9卷 206-213页

作者： Claudia Schütz Christian H.Schulze Department of Botany and Biodiversity Research University of ViennaRennweg 141030 ViennaAustria

Background: Eurasian Sparrowhawks(Accipiter nisus) increasingly represent successful city-dwellers. Thereby, a rich food supply indicated by high numbers of small birds is believed to be the key driver for this bird-eating raptor species to settle in urban environments. However, as small passerine birds show particularly strong antipredator responses, sparrowhawks may not simply focus on patches of highest prey densities, but rather respond strategically to prey behavior, raising the importance of other parameters in determining the occurrence within urban ***: To deepen our knowledge on habitat requirements of urban sparrowhawks, bird surveys were carried out during winter between December 2005 and January 2017 in 36 city parks in Vienna, Austria. Besides food supply also park size, canopy heterogeneity and the connectivity with other green spaces were ***: Occurrence of sparrowhawks was positively affected by increasing park size, prey density and the interaction between both. Bird feeder density and park connectivity with other green spaces were of minor importance in explaining the presence of this species. Canopy heterogeneity didn't affect city park occupancy by Eurasian ***: Our results suggest that large city parks, particularly when characterized by high prey densities, substantially contribute to protect and preserve ecologically important bird species such as raptors within the urban environment—a landscape already struggling with biodiversity losses and functional homogenization.

关键词： Birds of prey Bird feeders Prey abundance Habitat connectivity Tree cover Urban ecology

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On-Line Independent Tap-Changing of Each Feeder Supplied by a Low Voltage Distribution Transformer

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Journal of Power and Energy Engineering 2014年第4期2卷 388-394页

作者： David Johnston Faculty of Engineering and Environment Northumbria University Newcastle upon Tyne UK

An on-line tap-changing circuit was developed for use with low voltage transformers (10 kV/380 V, or equivalent), in which the tap positions could be set independently for each low voltage feeder. This allows for possible variation in loads and distributed generation between different feeders fed from a given transformer, allowing the line voltages to be kept within limits on all feeders. A combination of computer simulation and practical experiments was used. A model constructed in Excel gave preliminary results, which was used to specify a more detailed model in Matlab? Simulink. A small-scale 220/380 V distribution network was constructed, with currents limited to 5 A per phase. Finally, a rotary switch was constructed, suitable for currents up to 500 A, which would be required for a full-scale low voltage distribution network. The results showed that the voltage could be kept within limits, even with a large difference in load and distributed generation from one feeder to another.

关键词： Tap-Changing On-Line feeders Independent

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Application of Fault Location Mode Based on Travelling Waves for Neutral Non-effective Grounding Systems

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Journal of Measurement Science and Instrumentation 2010年第S1期1卷 133-138页

作者： Tao Ji Qian-qian Yuan Chang-ming Li Ying Sun (Scientific Research Office Weifang University Weifang,China College of Information and Electrical EngineeringShandong University of Science and Technology Qingdao,China) Scientific Research Office Weifang University College of Information and Electrical Engineering Shandong University of Science and Technology

Fault location for distribution feeders short circuit especially single-phase grounding fault is an important task in distribution system with non-effectively grounded *** location mode for distribution feeders using fault generated current and voltage transient traveling waves was *** characteristics of transient traveling waves resulted from each short circuit fault and their transmission disciplinarian in distribution feeders are *** paper proposed that double end travelling waves theory which measures arriving time of fault initiated surge at both ends of the monitored line is fit for distribution feeders but single end traveling waves theory *** to different distribution feeders,on the basis of analyzing original traveling waves reflection rule in line terminal, Current-voltage mode,voltage-voltage mode and current-current mode for fault location based on traveling waves are proposed and aerial mode component of original traveling waves is used to realize fault *** test verify the feasibility and correctness of the proposed method.

关键词： distribution feeders neutral non-effective groundi

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