50000 DWT半潜船压载系统设计

压载系统是半潜船的关键性系统,设计需要满足半潜船潜装、滚装和吊装等多种装卸货方式的要求。为此以中远航运50 000 DWT半潜船为例,介绍半潜船压载系统的设计要点。包括半潜船上浮时间的确定、半潜船常用排/压载方式的选择、大型排/压载设备的介绍、压载系统的设计和优化以及压载系统满足BWM公约D-2规则要求的研究等。     

舰载机作战任务要求到保障要求转换研究

定义任务周期内舰载机装备保障的相关参数,分析舰载机作战单元任务要求到保障要求相关参数之间的约束关系,建立作战任务到保障要求的转换模型。通过最小叉熵原理构造了指数型的舰载机机群恢复度函数M(t),计算舰载机平均保障准备时间,对于进一步的保障任务优化和调度具有重要意义。     

散货船三维时域波浪载荷计算研究

采用三维势流理论进行船舶运动和波浪载荷预报时,有2种Green函数可供选择:自由Green函数和Rankine源.混合源法,同时使用这2种Green函数,结合了两者的优点.本文对三维时域混合源法开展研究,为了验证该方法的可行性,本文对一艘散货船进行了时域上运动和波浪载荷的计算,并将计算结果转化到频域上以得到RAO.最终把有航速随浪和顶浪工况下该散货船垂向运动和载荷的RAO与WASIM计算结果以及模型试验结果进行比较.比较结果表明,混合源法计算结果与WASIM结果大体一致;在波长较短时,两者计算结果和试验值结果吻合较好,波长较长时两者计算结果都较试验值偏大.随浪海况下2种计算结果较顶浪更贴近试验值.     

Estimation of train dwell time at short stops based on track occupation event data: A study at a Dutch railway station

Train dwell time is one of the most unpredictable components of railway operations, mainly because of the varying volumes of alighting and boarding passengers. However, for reliable estimations of train running times and route conflicts on main lines, it is necessary to obtain accurate estimations of dwell times at the intermediate stops on the main line, the so‐called short stops. This is a great challenge for a more reliable, efficient and robust train operation. Previous research has shown that the dwell time is highly dependent on the number of boarding and alighting passengers. However, these numbers are usually not available in real time. This paper discusses the possibility of a dwell time estimation model at short stops without passenger demand information by means of a statistical analysis of track occupation data from the Netherlands. The analysis showed that the dwell times are best estimated for peak and off‐peak hours separately. The peak‐hour dwell times are estimated using a linear regression model of train length, dwell times at previous stops and dwell times of the preceding trains. The off‐peak‐hour dwell times are estimated using a non‐parametric regression model, in particular, the k‐nearest neighbor model. There are two major advantages of the proposed estimation models. First, the models do not need passenger flow data, which is usually impossible to obtain in real time in practice. Second, detailed parameters of rolling stock configuration and platform layout are not required, which makes the model more generic and eases implementation. A case study at Dutch railway stations shows that the estimation accuracy is 85.8%–88.5% during peak hours and 80.1% during off‐peak hours, which is relatively high. We conclude that the estimation of dwell times at short stop stations without passenger data is possible. Copyright © 2016 John Wiley & Sons, Ltd.     

Conflict‐free time‐based trajectory planning for aircraft taxi automation with refined taxiway modeling

To mitigate airport congestion caused by increasing air traffic demand, the trajectory‐based surface operations concept has been proposed to improve surface movement efficiency while maintaining safety. It utilizes decision support tools to provide optimized time‐based trajectories for each aircraft and uses automation systems to guide surface movements and monitor their conformance with assigned trajectories. Whether the time‐based trajectories can be effectively followed so that the expected benefits can be guaranteed depends firstly on whether these trajectories are realistic. So, this paper first deals with the modeling biases of the network model typically used for taxi trajectory planning via refined taxiway modeling. Then it presents a zone control‐based dynamic routing and timing algorithm upon the refined taxiway model to find the shortest time taxi route and timings for an aircraft. Finally, the presented algorithm is integrated with a sequential planning framework to continuously decide taxi routes and timings. Experimental results demonstrate that the solution time for an aircraft can be steadily around a few milliseconds with timely cleaning of expired time windows, showing potential for real‐time decision support applications. The results also show the advantages of the proposed methodology over existing approaches. Copyright © 2015 John Wiley & Sons, Ltd.     

快速公交（BRT）线路布局优化研究

为探讨现有公共交通线网结构下BRT线路布设优化问题,对快速公交线路布设的内部条件和外部条件进行了分析;在此基础上依据快速公交的发展特点,以乘客总出行时耗最小和车公里成本投入最小为目标,建立了快速公交布局优化的模型,并且给出了优化目标和相应约束条件的函数表达式。通过事例分析对BRT线路布设优化算法进行说明,从而得知优化模型具有较高的应用价值。     

南方某桥坍塌事故的动力推断分析

该文以南方某桥的坍塌事故为例,对事故原因进行了推断性分析。利用有限元时程分析的手段,对车辆的行驶速度与桥梁的相互作用的关系进行了分析研究,得到的结论可供类似工程参考。     

轻型汽车道路行驶阻力的测量及影响因素分析

分析了轻型汽车道路行驶阻力的数学模型,并在阐述滑行法测量道路行驶阻力的试验方法后,通过多组对比试验得出：轮胎和环境温度是影响滑行时间t的主要因素;尤其是试验环境温度与标态温度相差越大,行驶阻力相对偏差越大。并对如何通过提高滑行时间的统计精度p来尽量减少滑行次数提出几点措施。     

控制器样机快速开发在实时测试中的应用

提出一种基于两个目标硬件的控制器样机快速开发的方法,其中一个目标硬件用于执行控制器功能,另外一个则仿真被控对象。它能够进行实时测试,有效检测控制器功能的实时特性。设计中的绝大多数异常或错误能够被准确检测和及时修正。这种方法有效提高了设计的控制器功能的可靠性,缩短了开发周期。它已被用于一款新型变速器控制单元的设计开发过程,证明了其有效性。     

快速路交通流时间序列聚类预测方法与模型

针对快速路路段日交通流曲线的相似特性,提出根据天气好、坏,工作日、非工作日作为特性向量,设计一种时间序列聚类算法对不同时间尺度下快速路交通流进行预测.结果显示:此聚类算法与预测模型充分利用了历史数据,30 min时间尺度下预测精度较高,平均绝对相对误差最低为3.34%.