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船舶在冰区航行时,存在冰晶颗粒混合海水流入船舶冷却系统现象。基于颗粒动力学理论,建立适用于海水-冰晶两相流的欧拉-欧拉双流体模型,耦合相间传热传质模型对海水-冰晶两相流在水平直管内流动及传热特性数值模拟。研究表明,冰晶颗粒流动过程中,在管道上部位置R=8~10mm处冰晶体积分数达到最大值,且随着速度增加而增大;当入口含冰率(IPF)为4%时,冰晶速度的最大值出现在管道中心轴线上方。当入口速度为1.0~3.0 m·s-1,含冰率4%~30%时,局部传热系数随入口速度及含冰率增大而增加。 相似文献
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本文探讨了李雅普诺夫函数在自适应控制系统中的应用,讨论了深潜救生艇与失事潜艇的对口控制问题,介绍了模型自适应系统的基本结构,理论计算以及运动方程的确定。 相似文献
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6月6日凌晨1时30分,巴拿马籍“木星“煤轮载着”74449吨煤炭驶离我港煤码头,成为重新开启的日照港至巴西航线的首航船。2004年以前日照港曾开辟了到巴西的航线,后因市场变化等因素停航,此次中国五矿作为代理方重新开辟了该航线。为确保顺利完成装船任务,股份一公司迅速召集有关部门分头召开船前会,研究制定了详细的装船方案。针对“木星”轮装运汾西焦精,需要全程配煤作业的实际,为确保煤炭质量,股份一公司在作业中采取了专人全程跟踪捡杂、 相似文献
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截至10月24日9:40,满载176623吨矿粉的“海洋之光”巨轮,在日照港仅用24小时就接卸完毕。股份二公司以7359吨/小时的矿石卸率,一举刷新了此前矿石卸船6260吨/小时的世界纪录,劲超1099吨。 相似文献
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Objective Ependymal cells are thought to be the primary source of neural stem cells in the adult central nervous system. The purpose of this study is to examine spatial and temporal profiles of ependymal cell proliferation and migration after focal cerebral ischemia. Methods Eighty male Sprague Dawley rats underwent permanent middle cerebral artery occlusion after injection of 10/μL of 0.2% Dil into the lateral ventricle. Rats were sacrificed and brain sections were acquired for pathological evaluation and laser confocal imaging at day 1,3,7,11,14,21 and 28 after ischemia. Results The density of Dil-labeled cells in the ischemic ipsilateral subventricular zone was significantly higher than that in the control group and these labeled cells dispersed in the ischemic ipsilateral subventricular zone and/or were located in ependyma from day 1 to 11. In the ischemic ipsilateral cortex, some Diilabeled cells occurred in peri-infarction and infarction of parietal region at day14 and peaked at day 21 when some Dil-labeled cell nodules were found in this region. During postischemic day 14--28, a significant decrease in labeled celldensity in the ischemic ipsilateral subventricular zone was coincident with a significant increase in labeled cells density in the cortex (peri-infarction and infarction). Conclusion The results indicate that ependymal cells proliferate and migrate after focal cerebral ischemia in the adult rat brain. 相似文献