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101.
When a ship model test is performed in a tank, particularly when the tank is small and the ship model is relatively large, the blockage effect will inevitably occur. With increased ship model scale and speed, the blockage effect becomes more obvious and must be corrected. In this study, the KRISO 3600 TEU Container Ship(KCS) is taken as a model and computational fluid dynamics techniques and ship resistance tests are applied to explore the mechanism and correction method of the blockage effect. By considering the degrees of freedom of the sinkage and trim, the resistance of the ship model is calculated in the infinite domain and for blockage ratios of 1.5%, 1.8%, 2.2%, and3.0%. Through analysis of the free surface, pressure distribution, and flow field around the ship model, the action law of the blockage effect is studied. The Scott formula and mean flow correction formula based on the average cross sectional area are recommended as the main correction methods, and these formulas are improved using a factor for the return flow velocity correction based on comparison of the modified results given by different formulas. This modification method is verified by resistance test data obtained from three ship models with different scale ratios. 相似文献
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安徽省淮南与淮北煤田第四纪“底砾层”的研究,对于煤矿提高上限开采具有重要意义。关于底砾层的成因问题,有多种观点。本文分析研究了两淮地区第四纪底砾层沉积面貌、描述了砾石外观形态(如瓜子形、拖鞋状、葫芦状、马鞍状等)及表构特征,包括泥包砾、镶嵌及缝隙结构等,提出两淮地区底砾层为冰碛物(冰种沉积)。地球化学测试及分析结果表明,两淮地区砾石的几种主要化学成分含量非常接近,从而说明两淮底砾层属同一物源。综合这两方面的论证,提出了底砾层的“停积-融坠型冰碛物沉积模式”,并进行了冰碛物的物源方向问题的探讨。 相似文献
106.
社会性网络服务社区中人际节点空间分布特征及地缘因素分析 总被引:2,自引:0,他引:2
以开心网15个大学群为案例,应用信息熵和度分布两种方法,研究了社会性网络服务社区中人际节点空间分布特征及其地缘因素的影响。人际节点是以"好友"关系建立的链接来表达的,研究数据包括通过"成员"体现的好友和通过"话题"体现的好友2个层次,以便可以将虚拟的可能关系变为虚拟现实的确定关系。研究结果如下:①各大学群中好友空间分布... 相似文献
107.
Aleksandra Stachowska Maciej Łoziński Michał Śmigielski Anna Wysocka Leszek Jankowski Piotr Ziółkowski 《Sedimentology》2020,67(7):3783-3808
The anisotropy of magnetic susceptibility is a well-known geological proxy in revealing the directional tectonic and sedimentological features of rocks, although it can be ambiguous in situations where these two factors co-occur. This paper demonstrates the usefulness of the anisotropy of magnetic susceptibility in determining palaeotransport directions in turbiditic rocks that underwent subsequent thrusting and folding. This study demonstrates that the magnetic lineation is largely unsuitable as a palaeocurrent direction proxy, and suggests that the imbrication of magnetic foliation is better in such cases. Moreover, the anisotropy of magnetic susceptibility results were analyzed in reference to a joint and fold study within the framework of the regional structural geology. Magnetic fabric investigations were conducted in the eastern part of the Outer Western Carpathians (south-east Poland). During the study, a total of 191 oriented palaeomagnetic samples were collected from three outcrops (Nasiczne, Dwernik and Hoczew) in the Krosno Beds, Silesian Unit. For the purpose of sedimentological analysis, 121 m of turbidite successions were documented and 126 directional sedimentary structures were measured. The magnetic anisotropy of sandstones revealed typical sedimentary fabrics, often overprinted by variably intense tectonic deformation. Oblate susceptibility ellipsoids from Nasiczne showed tilt coherent with the palaeoflow direction, whereas the rocks from Dwernik and Hoczew contained triaxial magnetic fabric developed during compressional palaeostress. This paper suggests that medium-grained and coarse-grained sandstones, preferably with high mica content, are the most suitable for palaeotransport reconstructions among the studied lithologies. 相似文献
108.
Spermatozoal enzymes of fish (NAD+- and NADP-dependent dehydrogenases and creatine kinase (CK)) were previously determined to be sensitive to tributyltin (TBT) in laboratory experiments and were thus indicated for use as biomarkers for TBT exposure. However, the potential ability of spermatozoal enzymes as biomarkers of TBT exposure has never been recapitulated in a field study. For this purpose, the kinetic activities of spermatozoal enzymes of the natural turbot Scophthalmus maximus population from the Gulf of Gdańsk (GDA) and the Pomeranian Bay (POM) in the southern Baltic Sea were measured. Gas chromatography/high-resolution mass spectrometry was used to determine the concentrations of TBT and its breakdown products, dibutyltin (DBT) and monobutyltin (MBT), in the muscle, liver and testes of the male turbot. Males from GDA had significantly higher enzymatic activities and butyltin (BT) content in tissues than those from POM. A general linear model (GLM) showed that lactate dehydrogenase (LDH), malate dehydrogenase (MDH), glucose-6-phosphate dehydrogenase (G6PDH) and CK activities increased significantly with BT concentration in the testes and liver. We indicate the potential effects of TBT pollution on the spermatozoal enzymes of Baltic turbot. 相似文献
109.
在γ射线暴( 简称γ暴) 的火球模型下,γ暴余辉存在等时面,面上发射的光子会同时被观测到.通过对等时面积分来计算辐射流量Fν(t) ,结果表明等时面的引入对峰值以及峰值前后流量随观测者时间的变化关系有明显的影响 相似文献
110.
中高层大开间钢筋混凝土异形柱框架结构抗震性能研究 总被引:12,自引:3,他引:12
对一中高层大开间钢筋混土异形柱框架结构1/6比例模型进行了地震模拟振动台试验。研究结构从弹性,开裂,屈服直至破坏等各地震反应,揭示了结构的动力特性及破坏形态,结果表明,该结构体纱具有良好的抗震性能。 相似文献