弹性支承块式无碴轨道振动分析新模型

针对弹性支承块式无碴轨道结构特点,提出了一种新的用于竖向振动分析的有限元模型。在该模型中,钢轨模拟为弹性点支承Euler梁;钢轨下面的支承块视为刚体;轨道板视为弹性薄板,并且采用横向有限条与板段单元法对其进行位移插值;钢轨扣件模拟为线性弹簧和阻尼器;轨道板和混凝土底座下的路基模拟为连续分布面弹簧和阻尼器。在此基础上,基于弹性系统动力学总势能不变值原理和形成系统矩阵的"对号入座"法则,推导了弹性支承块式无碴轨道的竖向振动总势能,为建立弹性支承块式无碴轨道竖向振动方程,乃至进行弹性支承块式无碴轨道在高速列车作用下的动力响应分析奠定了良好基础。     

双幅同步转体矮塔斜拉桥设计

广州市增城区新新公路跨广深铁路桥采用(114+96)m双幅预应力混凝土矮塔斜拉桥分幅跨越既有铁路。该桥主桥为塔墩梁固结体系,主梁采用单箱三室截面斜腹板变高箱梁,为平衡跨度不对称引起的不平衡重,主跨与边跨板厚采用不对称设计。桥塔采用顺桥向人字形独柱混凝土塔,桥面以上高31.0 m;斜拉索采用强度为1860 MPa的钢绞线拉索,单索面双排扇形布置;主墩采用矩形实体混凝土墩,群桩基础。采用转体过程角度控制图指导双幅桥同步转体施工,转体结构最大悬臂长114 m,设计转体吨位为3.2万吨。经验算,结构各项性能指标均满足设计要求。     

垂直运输管片的自动升降机设计

在盾构法隧道施工中，管片由地面至井下的垂直运输一般采用行车吊运，存在运输效率低、安全隐患大等问题。现基于垂直升降机工作原理，介绍一种用于垂直运输管片的升降机，其自动化程度高，并详细阐述了该升降机系统的安全性、同步性、可靠性及适应性设计。该自动化升降机，可大幅提升管片的垂直运输效率，降低安全隐患，在盾构法隧道建造中具有广泛的应用前景。     

自适应均衡学习的端到端类人驾驶控制决策网络

针对现有端到端自动驾驶网络对于类人驾驶行为与思维特征模拟不足的问题，从类人驾驶特征出发，设计了一个包含时空特征、历史状态特征及未来特征的端到端类人驾驶控制决策网络。采用多层卷积和长短期卷积时序记忆网络（Conv-LSTM），对前方道路视觉感知图像时间序列进行时空特征提取，同时采用一维卷积和长短期时序记忆网络（Long Short-Term Memory，LSTM） 对车辆状态信息时间序列进行历史状态特征提取，进而采用多任务参数共享方式进行当前时刻和未来序列的方向盘转角、车速的控制决策，并以未来序列作为辅助任务督促当前时刻的主任务学习。为更好地耦合汽车纵横向控制参数学习的过程，还提出一种权衡纵横向控制参数损失量级及学习速度的权重自适应方法，并引入容差阈值，建立衡量纵横向控制参数训练效果的评价方法。依托Comma2k19数据集对所构建控制决策网络进行训练和验证，体现出良好的可行性及优越性。     

A numerical study on the installation configuration design of compliant vertical access riser (CVAR) in deepwater

In oil and gas transportation, the compliant vertical access riser (CVAR) system conducts economic and operational advantages due to its special configuration. In this paper, the static performance of the CVAR is studied by an efficient numerical method. According to the unique configuration of the CVAR, the mathematical model is established based on minimum total potential energy principle. The equilibrium equations are discretized by finite difference method and then solved by Newton-Raphson technique. The accuracy of the numerical method is verified by OrcaFlex software. Detailed parametric analysis is carried out based on practical engineering requirements. The effects of buoyancy section's configuration including buoyancy factor, buoyancy section's length and buoyancy section's location, and external environmental factors including wellhead offset distance, water depth and current velocity on installation shape and mechanical properties of the CVAR are analyzed. The research shows that the presented numerical method has good applicability and flexibility for the early installation configuration design of marine risers which have no touchdown section but only one touchdown point and are equipped with multiple buoyancy blocks subjected to forces of different directions and magnitudes, such as CVARs.     

敦煌市花雨路总体设计方案

花雨路是敦煌市“九横十四纵”路网中“一横”的重要组成部分，道路等级为城市主干路，位于敦煌市沙洲主城区以南，近年来随着敦煌市区逐渐向南发展以及敦煌旅游业的快速增长，对于花雨路的建设已是迫在眉睫，结合花雨路沿线地形、地貌，土地性质、城市规划及城市发展对花雨路平纵横、重要节点及景观方案进行介绍。     

直立堤前stem波的分布规律及对工程的影响*

当波浪沿直立堤以小于某临界角度入射时，将形成沿堤增长的stem波，目前国内外对stem波的研究较少且停留在理论阶段。以某直立堤台风破坏复演的物模试验为例，结合国内外研究成果，对stem波的产生条件、特征以及对工程的影响进行探讨。结果表明：1）stem波的波高和波宽均在沿堤传播中逐渐增大，沿堤比波高的增长呈现前快后慢的特点；2）不同入射波高和波向对于stem波的特征影响较大，详细的规律仍待进一步研究；3）stem波可对工程中直立堤造成蛇行破坏或对端部斜坡衔接段造成破坏，工程规划和结构选型应避免类似布置，宜采用三维物理模型试验验证stem波作用下结构的安全性。目前行业规范未涉及stem波相关内容，本研究成果可为工程设计提供参考     

基于原位试验的砂枕水下漂移规律研究

砂枕自水面抛投后，受重力和水流的推移力作用，在下沉的过程中，会产生顺水流方向的落距。砂枕落入河底后还会具有一定的速度，若这个速度大于砂枕的止动流速，那么砂枕还会继续运动，而砂枕自触碰床面后发生的移动距离为稳定移距(二次漂距)。根据砂枕在动水中的漂移规律进行试验，结合垂线流速分布规律，通过3种漂距计算方法得到砂枕水下漂移到着床稳定全过程的漂移距离计算公式，并进行对比分析。结果表明，当河流的垂线流速为指数型流速分布时，使用惯性力法和综合系数法推导出的漂距公式适用性较好。     

Analysis on maneuvering motion characteristics of submarine under static moment in vertical plane北大核心CSCD

[Objectives]Aiming at the problem of poor depth-changing ability of the stern rudder of submarine at low speed, and the problem of reversing the movement trend is difficult when the stern rudder is stuck and encountering abrupt changes of seawater density in the vertical steering maneuver. This paper conducts the mechanism research of static moment maneuver. [Methods]First, it is proved through theoretical analysis that the static moment maneuver can eliminate the reversed velocity phenomenon of the stern rudder. Then, the surfacing process under the static moment maneuver and the rudder hydrodynamic control is numerically simulated. [Results]The simulation results show that the static moment maneuver can make the submarine maintain good vertical plane maneuverability at low speed, eliminate the reversed velocity phenomenon of the stern rudder, and avoid excessive trim angle of the submarine at high speed. At the same time, the recovery effect of the two emergency situations of rudder jamming and falling deep has been improved. [Conclusions]The static moment maneuver is beneficial to the maneuverability and safety of the submarine. The research in this article can provide a reference for the maneuverability design of submarine. © 2023 The Author(s).