铰接式浮标性能研究

铰接式浮标作为一种新型助航标志越来越受到海监部门的欢迎。铰接式浮标具有良好的水动力性能，在风流中静倾角及在波浪中摇摆角都较小，而且定位准确。本文对铰接式浮标的结构及其水动力性能计算方法作了介绍，并在国家重点实验室──海洋工程实验室作了系列试验，得出一些有益的结果，为优化设计提供了依据。     

The dynamic response of a three-leg articulated tower

Articulated towers are a compliant type of platform particularly suited for deep water applications. In the design of articulated towers, it is very important that the motion characteristics include sufficient stability, less acceleration in the deck and the smallest possible loading on the articulated joint. The mass distribution along the tower also plays an important role in the motion characteristics of the tower. Multi-leg articulated towers with three or more towers (legs or shafts), which have been developed from the conventional single tower have reduced horizontal movements and have more deck area compared to the single-leg articulated towers. The experimental and analytical investigations on such towers are not available in the published literature. In this paper, both analytical treatment and an experimental program for a three-leg articulated tower model have been reported. The effect of mass distributions on the variations of the bending moment and the deck accelerations are also presented. The model has been tested in a 2 m wave flume for various wave frequencies and wave heights of regular waves. The model is also analysed using a computer program developed, and the comparison of theoretical results with the experimental results is presented.     

Drill holes and shell repair in brachiopods from a Late Cretaceous (Maastrichtian) oyster reef,North Canterbury,New Zealand

Several hundred brachiopods were separated from a bulk sample taken from a single locality of the Late Cretaceous Ostrea Bed at the top of the Broken River Formation in the Weka Pass area of North Canterbury, New Zealand. The specimens were divided among five different species and examined for drill holes and shell repair following failed predatory attacks. The results show that one or more unknown predators and/or parasites apparently selectively preyed on the rhynchonellide Wekarhynchia cataracta, with approximately 16.2% of complete shells showing evidence of attack. The larger, coarsely-ribbed terebratulide Ostreathyris allani was seemingly immune to drilling, while sample sizes for the three other brachiopod species were too small to allow even rudimentary estimates of predation/parasitism rates.