贯通线三相不平衡引发虚假接地故障的分析

根据10kv电力贯通线单相接地故障（小电流接地故障）和贯通线三相不平衡引发的零序过电压（虚假接地故障）的共同特征,对贯通线三相不平衡引发的虚假接地故障进行了理论分析和潮流计算,为现场判断故障类型和快速检修打下了理论基础。     

基于灰色理论的公路沉降预测研究

以工程实测数据为基础,根据灰色理论中的数列预测理论,针对公路建设中路基沉降监测,建立灰色预测模型.根据预测结果与沉降实际测量数据的对比,分析了模型预测结果的合理性.同时讨论了所用灰色预测模型的特点及其在沉降监测中的应用.     

软弱围岩小净距公路隧道施工技术分析研究

通过对各工法的优缺点及适用性的比较,给出了道冠山隧道小净距段所用工法及其具体施工工艺,及各开挖步对应掌子面间的距离控制要求,并在对超前小导管注浆、预应力对拉锚杆、局部加长系统锚杆等小净距隧道中间岩柱常用加固方法进行比选,以确定道冠山隧道小净距段中间岩柱的加固方案。     

人工填土层中四连拱暗挖隧道设计

人工填土层有土质疏松、稳定性差、无法形成自然应力拱等特点,导致隧道暗挖修建时易出现支护体系受力较大、地面沉降过大甚至塌方等问题。以北京地铁某停车线工程在人工填土层中修建暗挖四连拱隧道为例,采用理论分析结合有限元数值仿真模拟,从支护体系受力、地面沉降、风险控制、施工工期等方面对"导洞法"、"侧洞法"及两者相结合的"导洞+侧洞法"进行比选,得出采用"侧洞法"施工为本工程最优方案。"侧洞法"能有效避免中隔墙的水平位移问题,控制沉降较好,且二次衬砌能尽早封闭成环,减小初期支护受力过大的风险,并在施工中取得成功。     

基于遗传算法的船体分段装配优化

优化装配序列对提高造船生产效率具有非常重要的意义。选择典型的船体分段为研究对象,首先结合生产实际将装配结构层次化,生成子装配体以缩短遗传算法中染色体的长度,加快算法向最优解的收敛速度,提高装配规划效率;然后应用遗传算法得到船体分段最优装配序列;最后利用CATIA软件对分段进行建模,并完成分段虚拟装配过程的仿真演示。实例分析结果验证了应用遗传算法的可行性与有效性,显示其有助于优化船体分段装配顺序。     

三维体系斜拉索桥张拉施工技术应用

该文以天津市新三条石桥为例,介绍了三维斜拉索体系的分级对称张拉工艺及施工操作要点,可供类似工程参考。     

Development of signal optimization models for asymmetric two-leg continuous flow intersections

Despite extensive studies have been reported to address the operational issues of full Continuous Flow Intersection (CFI) in the literature, the asymmetric two-leg CFI, which is more applicable in practice, has not received adequate attentions yet. To satisfy such need, this study develops two signal optimization models for asymmetric CFI based on its unique geometric features. The first proposed model, following a two-step procedure, determines the cycle length, phase design and sequence, and green split in the first step and optimizes intersection offset in the second step. To benefit both intersections’ capacity maximization and signal progression design by optimizing phase plan and sequence, the second proposed model takes the Mixed-Integer-Linear-Programming (MILP) technique to concurrently optimize all signal control variables. With extensive case studies on a field site in Maryland, the simulation results prove that the proposed models can effectively provide signal progression to critical path-flows and prevent the potential queue spillover on the short turning bays/links. Further comparisons between the two proposed models reveal that the second model is more flexible in designing phase plan but the first model performs better in reducing link queue length.     

A multi-path progression model for synchronization of arterial traffic signals

To contend with congestion and spillback on commuting arterials, serving as connectors between freeway and surface-street flows, this paper presents three multi-path progression models to offer progression bands for multiple critical path-flows contributing to the high volume in each arterial link. The first proposed model is a direct extension of MAXBAND under a predetermined phasing plan, but using the path-flow data to yield the progression bands. The second model further takes the phase sequence at each intersection as a decision variable, and concurrently optimizes the signal plans with offsets for the entire arterial. Due to the competing nature of multi-path progression flows over the same green duration, the third model is proposed with a function to automatically select the optimal number of paths in their bandwidths maximization process. The results of extensive simulation studies have shown that the proposed models outperform conventional design methods, such as MAXBAND or TRANSYT, especially for those arterials with multiple heavy path-flows. The research results from this study have also reflected the need to collect more traffic pattern data such as major path-flow volumes, in addition to the typical intersection volume counts.     

基于可靠度的单轨道交通施工区建设方案优化

为降低城市轨道施工对交通流的影响,建立了基于可靠度的施工区形式及建设时序综合优化模型.施工区的规定阈值时间与实际行程时间之差大于零的概率为可靠度,分别建立交叉口及路段施工区的可靠度模型.定义可靠度与施工时长之积为施工效率系数,以全施工周期效率系数折减最少为目标,建立施工区建设方案综合优化模型,优化施工区形式及建设时序.西安市轨道交通汉城南路站方案的测试结果表明,施工区形式及建设时序会使道路交通可靠度产生不同程度的折减.该方法可为城市轨道交通施工方案的制订提供理论依据.     

电气化铁道对电能质量影响的割集分析法

从分析电气化铁道对电网电能质量影响的需求出发,采用割集原理为局部电网建立了适合进行电能质量评估的模型,并利用模拟短路的方法得到了外部电网的广义多端口诺顿等值电路参数。在此基础上考虑多个干扰源共同作用下,评估了胶济电气化铁道负序与谐波对山东电网电能质量的影响。