整流罩对深海立管水动力影响的数值模拟研究

应用CFD大涡模拟方法,对附有整流罩的深海立管的水动力影响效果进行了三维数值模拟。对不同的弦厚比在雷诺数分别为3 900、10 000和20 000条件下进行模拟分析,得到立管后方阻力系数、升力系数、斯特劳哈尔数及其频谱等特性。模拟结果表明:整流罩对立管升力和阻力有明显的抑制效果,相较于光滑立管,阻力系数均值降幅最大达到24.1%,升力系数均方根值降幅最大达到81.1%。阻力系数均值随弦厚比的增加先减小后趋于平稳升力系数均方根值随弦厚比的增加而增加。对比结果显示,弦厚比为1.2~1.6时,整流罩对立管的升力和阻力抑制效果较好。     

Inverse optimal control for speed-varying path following of marine vessels with actuator dynamics

A controller which is locally optimal near the origin and globally inverse optimal for the nonlinear system is proposed for path following of over actuated marine crafts with actuator dynamics. The motivation is the existence of undesired signals sent to the actuators, which can result in bad behavior in path following. To attenuate the oscillation of the control signal and obtain smooth thrust outputs, the actuator dynamics are added into the ship maneuvering model. Instead of modifying the Line-of-Sight (LOS) guidance law, this proposed controller can easily adjust the vessel speed to minimize the large cross-track error caused by the high vessel speed when it is turning. Numerical simulations demonstrate the validity of this proposed controller.     

Weekly container delivery patterns in liner shipping planning models

This paper addresses a fundamental question related to nearly all container liner shipping planning models: whether the implicit assumption of identical container delivery pattern every week is valid in a situation of identical shipping services and identical cargo demand every week. We prove that when the number of containers transported from one port to the next is formulated as a continuous variable, the resulting mathematical model with an identical container delivery pattern is equivalent to the model with general container delivery patterns which can be different in different weeks. When the number of containers transported is formulated as an integer variable, the model with an identical container delivery pattern is not equivalent to the model with general container delivery patterns. However, the difference between the optimal objective values of the two models is negligible for practical applications. In sum, little, if not nothing, is lost by assuming an identical container delivery pattern in liner shipping planning models.     

基于灵敏度的雷达组网性能分析

文章介绍了雷达组网的概念及其优势。灵敏度是评估雷达系统性能的最重要参数之一,在雷达组网系统中,由于收、发装置的空间位置分布不同,其灵敏度在2维和3维空间上的仿真分布也不同,通过对灵敏度的仿真分析,来对雷达组网性能进行评估。     

关于铁路会议电视系统组网的探讨

介绍铁路会议电视一期和二期的网络结构，比较分析2套系统，对铁路会议电视系统充分利用现有资源，合理组网进行探讨，并提出具体解决方案。     

船舶轮机控制与管理一体化系统

本文介绍了我国自行开发研制的船舶轮机控制与管理一体化系统，并对其可靠性进行了理论分析。该系统由主机遥控、自动电站、油水与压载自控、船舶浮态自控、监测调控及轮机管理中心等子系统组成。其体系结构为控制级、操作级和管理级三级结构，由舰船２＋实时网联网。该系统利用网络实现了多重冗余设计，以计算机实时仿真系统取代了传统的控制系统与柴油主机、发电机组的陆上联调与配机试验。     

碎石桩结合土工格栅加固高原软土地基的实践

结合工程实例,介绍碎石桩结合土工格栅加固高原软土地基的工作原理、施工要点,并进行地基处理效果分析,确保铁路路基施工后沉降和抗滑稳定性能满足设计要求。     

S226海滨大桥连续箱梁挂篮悬浇施工

该文从挂篮荷载计算、施工流程、支座及临时固结施工、挂篮安装及试验、合拢段施工、模板制作安装、钢筋安装、混凝土的浇筑及养生、测量监控等方面入手,介绍了S226海滨大桥主桥连续预应力混凝土变截面箱梁2#～7#块、8#、8'#块合拢段采用挂篮悬浇的施工方法。     

浅埋偏压连拱隧道监控量测特征分析

结合云南某浅埋偏压连拱隧道,根据各施工阶段的地表沉降、拱顶下沉和水平收敛及洞内三维裂缝等现场监控量测,分析软弱浅埋偏压条件下连拱隧道的量测结果特征,给出量测结果的内在规律和联系。实践证明,上述量测项目和结果分析可以有效地反映浅埋偏压连拱隧道的稳定性情况,指导隧道的现场施工。文章旨在为同类工程现场监控量测的方案设计、分析方法和隧道的安全施工提供借鉴和参考。     

雁门关隧道左线糜棱岩构造破碎带特征及防治措施

重点研究了发育在雁门关隧道左线糜棱岩构造破碎带的特征 ,分析了它形成发展的规律 ,着重研究了该断层在不同构造应力场的作用下 ,所产生的不同期次、不同性质构造运动的力学行为 ,并由此推断出该断层对隧道施工可能造成的影响 ,提出了行之有效的治理措施