煤码头露天堆场与封闭堆场的适用性分析

目前,由于煤码头业主、水运行业管理部门、环保部门对煤码头堆场堆存方式的关注点不尽相同,在堆存方式的选择上时常意见不一。拟从码头属性、生产运营、环保、职业卫生、国内外现状等角度对露天堆场与封闭堆场的适用性进行分析,给出不同情况下堆存方式选择的参考性建议。     

柴油机各缸工作不均匀程度对性能的影响分析

利用飞轮处的瞬时转速信号来间接估计柴油机的各缸工作不均匀程度,结合基于电磁阀的时间控制式电控燃油喷射系统,实现了柴油机各缸工作不均匀程度的闭环反馈控制。在此基础上,通过台架试验分析了各缸工作不均匀程度和发动机性能之间的关系。结果表明,在发动机的大负荷工况下,各缸工作不均匀程度对发动机的经济性和烟度排放影响显著,从而验证了实现柴油机分缸均匀性实时检测和闭环控制的重要性。     

考虑内腔空气影响的高速磁浮轨道箱梁日照温度场研究

高速磁浮混凝土轨道梁在日照作用下温度分布不均匀,易引起梁体变形、开裂,影响行车安全.本文以上海浦东地区的气候条件为基础,研究了日照辐射下高速磁浮混凝土轨道箱梁的温度分布规律.首先基于固体传热和流体传热理论计算了浦东地区的太阳辐射值,然后建立了混凝土轨道箱梁有限元模型,并在考虑箱梁内腔空气传热效应的前提下计算了轨道梁整体...     

Experimental study of drillship resistance performance in open and closed state of moonpool北大核心CSCD

[Objective] This paper carries out an experimental study of a multi-function dirllship model with moonpool structure in towing tank, aiming at analyzing the effects of the moonpool structure on the ship resistance in open and closure condition.[Methods]Taking a dirllship as the research object, the ship motion response in regular and irregular waves is investigated. The resistance of the ship in hydrostatic water and waves is measured with tension sensors, and the acceleration characteristics of the bow, midship and stern are analyzed by acceleration sensors.[Results]The results indicate that hull resistance under light load conditions is greater when open moonpool, while hydrostatic water resistance with closed moonpool is greater under design load conditions. The closed moonpool in regular waves reduces stern acceleration by 58.2%, bow resistance by 46.7% and heave response by 41.8%. The peak of resistance at the bow in irregular waves is about ten times higher than that at the stern, and the peak of resistance occurs more often when the moonpool is open at the same time.[Conclusions]The experimental study shows that the difference in load conditions changes the waterplane area and affects the hull resistance in hyrostatic water. In contrast, the closure of the moonpool not only reduces acceleration and resistance, but also improves surge and heave. As such, this paper can provide references for the structural design of drillships with moonpools. © 2023 Journal of Nanjing Agricultural University. All rights reserved.