安庆长江铁路大桥主桥桥面系受力分析

安庆长江铁路大桥主桥为主跨580 m的六跨连续钢桁梁斜拉桥,桥面系采用正交异性钢桥面系。为验证该桥整体桥面系结构受力是否合理以及能否有效参与主桁结构的共同受力,采用有限元分析程序ANSYS分别建立3号桥塔支座附近E17～E23六个节间和中跨跨中E37～E43六个节间的钢桁梁节段模型,对桥面系中纵梁、横梁及横肋、桥面顶板的应力进行分析。分析结果表明:在设计荷载作用下,桥面系中纵梁、横梁、桥面顶板的应力水平均满足规范要求;桥面系受力横向分配比较均匀,结构整体刚度好;同一主桁断面处桥面顶板和纵梁的纵向应力分布较均匀,桥面系结构能有效参与主桁共同受力。     

新疆地区公路路面弯沉变化规律研究

为了得到新疆地区路面弯沉年变化规律,根据地形及水文条件将全疆分为5个区,在此基础上搜集全疆96条公路弯沉历史检测数据,汇总得到各分区弯沉年变化情况,采用1st Opt数学优化分析软件对弯沉检测数据进行拟合,得到各分区弯沉变化函数关系式及曲线。结果表明:新疆Ⅰ区、Ⅱ区、Ⅲ区及Ⅴ区路面弯沉变化规律相近,交工后1~3年弯沉衰减缓慢,年均衰减率4 %~15 % ;3年后弯沉衰减严重,年均衰减率达20 %以上,新疆Ⅳ区路面弯沉交工后1~2年弯沉值逐年减小,2年后弯沉为交工检测弯沉的85 %,2~4年后弯沉逐渐增大,年均增长率为15 %。     

黄土路基沉降变权重组合模型预测方法研究

利用兰武二线路基沉降观测数据,对黄土路基沉降变权重组合模型预测方法进行分析研究。研究结果表明:根据拟合精度选择单个模型时,要尽量选择相对误差偏离方向相反且大小相差不多的单个模型;在单个模型预测精度相差不大时,单个模型的数量越多,组合模型的精度会越高;单个模型的拟合精度越高,对应的组合模型的拟合精度也越高;组合模型相对误差与单个模型的相对误差的偏离方向和大小有关;在相同预测精度要求下,组合模型需要的观测时间比单个模型要短。     

高速排水型船舶方尾条件的数值实现

讨论了高速排水型船舶的方尾条件.给出了方尾条件的若干改进形式,其中一种在数值实现方尾条件时显得更加有效和稳定.采用高阶面元法得到的高速船舶相应的兴波计算数值结果令人鼓舞.     

Real-time optimization of ship energy efficiency based on the prediction technology of working condition

Ship energy efficiency management and control is an effective strategy to improve the marine economy and reduce CO₂ emission. The determination of the best navigation speed under different working conditions is the basis and premise for real-time improvement of ship energy efficiency. In this paper, the working condition in short distance ahead of the ship related to navigation environment factors was predicted by the method of wavelet neural network, and then the best engine speed for the optimal energy efficiency under different working conditions could be determined through the established ship energy efficiency real-time optimization model. Further, by presetting the ship engine at this optimal speed, the ship energy efficiency could be guaranteed at the optimal state when the ship arrived at the navigation environment ahead of the ship, thus achieving real-time optimization of ship energy efficiency under different navigation environment factors. Experimental studies showed that the proposed optimization model was effective in energy saving and emission reduction, which could provide theoretical guidance for optimal sailing of the ship in service. Compared to traditional setting speed navigation methods, our proposed method has more practical significance to the improvement of ship energy efficiency.     

Review on Theoretical Delay Estimation Model for Signalized Intersections

Traffic delay is an effective index for estimating the performance of a signalized intersection. In this study, we provide a comprehensive review of the theoretical delay estimation model over the last ca. 90 years. For fixed-time signalized intersections, we classified the estimation development process into three stages. Stage 1 covered 1920s–1970s, when approaches based on steady-state theory were derived. These methods obtain accurate predictions with low degrees of saturation, but overestimate the delay with higher saturation and cannot provide reasonable results for oversaturated conditions. To accommodate high saturation, time-dependent models were proposed and improved in Stage 2, 1970s–2000s, using coordination transformation techniques. Progression factors to account for the filtering impact from upstream intersections were also introduced during this period. Due to inaccurate approximation of certain specific traffic conditions, some modified approaches and supplementary terms were derived from 2000 onwards (Stage 3), which facilitate the evolution of the delay estimation method and improved approximation results. Some new techniques, including artificial intelligence algorithms, were also introduced into delay estimation in this era. We also describe theoretical delay measurement methods for actuated control intersections with a similar time line. From our summary of the evolution of theoretical delay models, we highlight some deficiencies and future research directions.     

发动机气缸套磨损谱编制方法研究

通过对气缸套-活塞环进行润滑分析,得到了不同曲轴转角位置活塞环的微凸体载荷分布及磨损速率。结合动载荷特点对Archard磨损计算模型进行了修正,同时根据载荷分级对发动机工况进行了离散,计算得到了各离散网格单元内的磨损参数,基于发动机整机载荷谱,采用时间插值方法,编制了典型任务剖面下的气缸套磨损谱。     

大跨度悬索桥锚跨索股张力计算参数影响分析

为提高悬索桥锚跨索股张力控制精度,针对锚跨索股的构造特点,基于解析法推导了锚跨索股张力控制精度的一般表达式;结合大型通用有限元计算程序,建立了锚跨索股的两种不同的力学等效计算模型,分析了拉杆的边界条件、物理特性、长度比值等因素对锚跨索股张力计算结果的影响幅度及规律。研究结果表明:拉杆的边界条件对计算结果的影响较大,且拉杆边界条件的特性随索股内部张力的变化而变化,即边界条件由铰接状态向固结状态演变;拉杆弯曲刚度对锚跨索股张力计算结果的影响,主要是由连接拉杆的长度比值决定,当拉杆长度比值小于一定限值或索股应力处于某特定状态时,可将锚跨内的双连接拉杆简化为单连接拉杆进行分析,对应的计算结果仍具有较高精度。     

钻井工况下悬臂梁结构强度的理论分析与试验研究

针对目前自升式悬臂梁钻井工况的特点,描述了悬臂梁在重载条件下的理论分析方法,以一台井架中心最大偏心57.5ft的自升式钻井平台为例进行了有限元分析,数值研究了悬臂梁的应力和变形情况,并通过驳船替代钻井载荷的方式进行了重载试验研究,通过对比理论与试验数据,二者吻合较好,并得出了重要的结论,为今后悬臂梁的优化设计奠定了基础。     

飞来峡二、三线船闸闸底长廊道输水系统模型试验

飞来峡水利枢纽位于北江中游,新建的二、三线船闸并列布置有效尺度为220 m×34 m×4.5 m(长×宽×门槛水深),船闸最大设计水头14.44 m,采用闸底长廊道侧支孔输水系统双明沟消能布置形式。通过1∶30的物理模型,对船闸输水系统的布置形式及水力学特性进行试验研究。结果表明:闸室输水时间、水力学指标、闸室停泊条件、进出口布置形式均能满足规范要求,优化后的闸室停泊条件较好。