无人帆船循迹航行的控制研究

提出一种适用于无人帆船循迹航行的控制器,并应用于一条1.5m长风帆艇的湖上航行测试。该控制器包含三个独立模块,局部路径策略模块决定帆艇的转向过程;帆自动控制模块根据帆位角和相对风向角的对应关系获取最佳推进力;舵自动控制模块基于从航海经验中提炼的245条模糊控制规则实现航迹调整。1.5m帆艇的湖上测试结果表明,该控制器在多种风场条件下都可有效完成帆艇的循迹航行,具有在无人帆船上实现长程航行的应用前景。     

西福河大桥T梁架设工艺

文章以广东省道S119线西福河大桥工程施工为例,介绍采用军用六四式轻便杆件现场设计和组装双导梁架桥机跨河架设35～40mT梁的工艺技术,此技术不仅可降低架梁费用;取得较好的经济效益,而且能克服设备进场难和交通干扰等问题。     

Differences in single heavy vehicle crashes at intersections and midblocks

The objective of this research is to identify the factors differentiating between single heavy vehicle collisions at intersections and midblocks by using a binary logit model. Our results show that single vehicle crashes involving heavy vehicle at intersections are more likely to occur on main roads and highways, whereas crashes at midblocks are more likely to occur on divided two‐way roads, roads with special facilities or features (e.g. bridge) and roads with a higher percentage of heavy vehicle traffic. Intersection crashes are also more likely to involve vehicles that are turning left or right, resulting in angle crashes and vehicle overturn, whereas midblock crashes are more likely to involve vehicles on higher posted speed roads. Copyright © 2017 John Wiley & Sons, Ltd.     

海底单层保温管线总传热系数分析

总传热系数K是海底热油管道的运行管理中的一个非常关键的参数.文中通过对中海油涠洲11 -1油田至涠洲12 -1油田之间的海底管道总传热系数进行理论计算,并与投产前根据实际预热数据反算的总传热系数进行对比,得出理论计算的总传热系数与实际预热反算得到的总传热系数相近,同时指出海管接口的散热损失较大,海底管线应对接口部分进行...     

A proposal for cost-related and market-oriented train running charges

This paper examines some key aspects of a charging system for promoting railway transport, including charges reflecting a clear relationship with costs (transparency) and charges reflecting the quality of the infrastructure manager's service. Train running charges recover track-related costs and can help to develop a charging system that meets these requirements. To orient train running charges to the market, a method for processing track maintenance and renewal costs is proposed whereby the quality of the service provided by an infrastructure is measured according to its utility to the railway undertaking. To achieve transparency, a single indicator is used for cost planning and the subsequent levying of costs on railway undertakings. The paper includes an example of how proposed train running charges would be calculated according to data from 14 European countries. The example shows that short-distance trains generate the lowest maintenance and renewal costs, followed by long-distance trains and freight trains.     

A practical capacity model of a single track line

The paper presents a model for determining the practical capacity of a single track line, i.e. the maximum number of trains which can be run along it in a time unit under the condition that each train enters its bottleneck segment with a definite delay.

The input data used in the model are: geometrical characteristics of the bottleneck segment of the line under study, the intensity and structure of demand expressed by a number of trains which are run over the line in a given time unit, the scenario of traffic running over the line under study and the operational tactics of individual train categories processing on the bottleneck segment.

(Two tactics can be applied in the train processing on the line under study; first, the trains of individual categories are given different priorities in the processing, and second, all the trains have the same priority).

The output results of the model are average delays of trains of each category occurring within the train processing performed on the bottleneck segment of the line under study in a given time unit.     

运用操纵模拟器试验进行超大型船舶航道宽度计算研究

运用船舶操纵模拟器模拟试验的方法,通过试验分析风、流压偏角等因素与超大型船舶在航行时航迹带宽度之间的关系,提出了超大型船舶在风、流以及波浪作用下,进出港航行所需航道宽度的计算方法。     

厦漳跨海大桥北汊主桥索塔及其钢锚梁研究

从景观、受力、施工和经济性等几方面对厦漳跨海大桥北汊主桥索塔造型、基础形式及索塔锚固方式进行方案研究比选,最终确定北汊主桥采用钻石型索塔及其钢锚梁锚固方式。     

独塔双索面自锚式无缝悬索桥的设计与分析

考虑柳青河桥的景观效果和满足河道通航要求,设计采用了独塔双索面自锚式无缝悬索桥,桥型优美轻便,主缆直接锚固在加劲梁梁端,节省了庞大的锚碇结构.由于主跨与边跨跨径比很大,在边跨适当配重的基础上,设计采用了半整体式桥台,利用桥台台身的重量来克服端支座拉力,既解决了拉力支座的问题,同时在该桥台处形成了无缝桥梁.重点介绍了柳青河自锚式无缝悬索桥的结构构造、设计要点及计算分析过程,以期供类似桥梁设计借鉴.     

基于截面力设定的纵梁轻量化半经验设计

采用半经验方法,通过分析同级对标车型的纵梁各断面通过力,获得了纵梁通过力的设计目标;根据本文提出的薄壁管梁压溃力公式,反推出纵梁所采用的尺寸、材料;根据结构轻量化原则,在概念设计阶段确定了纵梁的最优设计参数。通过对碰撞加速度、吸能盒、纵梁的试验与仿真结果对比可知,本文所提设计方法合理有效。