空气层结对港口细煤粉污染扩散的影响分析

通过分析空气层结对港口细煤粉扩散的影响,得出离源0.5 km处稳定层结、中性层结及不稳定层结3种层结条件下污染物的浓度峰值分别为1.3 mg/m',0.27 mg/m'和0.02 mgW,同时得出5.5 m/s,7 m/s两种风速条件下的污染物浓度峰值.结果表明,湍流处于不稳定层结时,浓度分布峰值相对较小;随着层结逐渐...     

水南特大桥百米超长人工挖孔桩施工技术

结合沪蓉西高速公路水南特大桥4根近百米超长人工挖孔桩基础的施工,介绍该桥在恶劣地质条件下超长人工挖孔桩的施工工艺、技术措施、施工质量和安全控制措施,并对在特定条件下使用这一工艺的特点、事故处理及应用前景做了阐述。     

岩溶地区隧道超前地质预测预报技术

以某岩溶隧道的施工为例,介绍岩溶隧道超前地质预测预报技术,采用常规地质法、TSP203地质预报、地质雷达、地质钻探等组成的综合超前地质预报系统,对隧道工作面前方、环向四周、隧底等不良地质进行探测,确保隧道施工安全.     

预应力张拉中锚固失效的处理方法

在预应力张拉过程中,锚固失效时有发生,文章介绍了几个有效的处理方法,其中包括加装卸锚撑脚法、加装千斤顶法、拆卸千斤顶法和反装千斤顶法,这些方法在工程实践中得到了成功的应用。     

劣化桥梁概率维护模型和维护方案成本优化研究

建立了劣化桥梁服役期耐久性概率评估模型,根据预定义的概率维护模型,推导了桥梁结构在预防性维护策略和基于性能控制维护策略作用的可靠指标和状态指标的时变规律,结合现有的维护技术,分别计算了在单一维护技术和组合维护技术下劣化桥梁的时变可靠指标与状态指标和年度维护成本和累计维护成本。研究发现,维护成本花费越高,桥梁性能指标越高;桥梁的初始性能越好,则后期维护成本越低。将预防性的定期维护和基于性能的维护方法组合的维护技术比单一的维护技术更合理,能维持结构性能的前提下有效的控制维护成本。     

采用X形桩的遮帘式板桩码头结构静力分析

X形桩是一种反拱曲面异型桩,相比于同等截面积的矩形桩和圆形桩,X形桩具有更大的截面周长和惯性矩,受力性能更好。结合京唐港32#泊位遮帘式板桩码头结构,以X形桩代替传统的矩形桩,研究其对结构静力的影响。结果表明:相同桩间中心距时,以X形桩替代后可减小前墙弯矩;在同等桩间净距1.75 m下,两类模型的前墙最大弯矩基本相同。相同荷载作用下,前墙位移主要受桩间中心距影响,X形桩形状影响效应很小;锚碇墙水平位移受桩间中心距和遮帘桩形状的影响均很小。桩间中心距、净距与桩间土体土拱效应直接相关,对前墙弯矩、土压力、遮帘桩弯矩等有显著影响。桩间中心距为4.05 m或桩间净距为1.75 m时,结构内力改善效果较优,可采用该间距的X形桩替代矩形桩,节约工程造价。     

白石窑一线船闸闸室尺度变更后下引航道通航水流条件试验研究

白石窑枢纽位于广东省英德市上游约25 km的北江干流上,是北江干流上的第3个梯级。为提高船闸通过能力,将白石窑一线船闸闸室长度由140 m延长至220 m,船闸尺度为220 m×23 m×4.5 m（长×宽×门槛水深）。通过建立1:100比尺的物理模型,对扩建后下引航道口门区通航水流条件进行研究,提出下引航道口门区通航条件的改善措施。研究表明：开挖三板洲及增设直线隔流堤等措施对改善下引航道口门区通航条件是有效的。     

基于Q-learning 的定制公交跨区域路径规划研究

考虑城市大客流通勤者跨区域出行需求,结合城市公交线网中乘客出行密集、客流走向规律等特点,提出一种跨区域定制公交的搭乘方案. 通过改进的Q-learning 模型对公交线路进行优化,为城市通勤者提供更加便捷和高效的出行服务. 通过综合路段拥堵状态、乘客需求及居民小区位置,设定了Q-learning 强化学习的奖惩函数,提升定制公交区域路径的直线系数、满载率、通行时间. 结果表明,所提出的改进方法能够降低通勤者跨区域通行的旅行时间,有效提高髙峰时段定制公交线网的通行效率.     

Geometric calibration algorithm of polarization camera using planar patterns

Polarization pattern provides additional information besides spectral signatures. It can be used in many applications, such as navigation, defect detection and object identification. A novel polarization camera composed of four synchronized cameras is proposed, and it can realize real-time polarization measurement. This study particularly concentrates on the geometric calibration of the system. The projection model is analyzed and the multi-camera calibration algorithm is proposed. Firstly, each camera is calibrated separately using planar patterns, and then the geometric calibration algorithms are performed. Due to the geometrical constraint, a global optimization method results in smaller estimation uncertainties. A mean rotation error of 0.025° and a mean translation error of 0.26mm are achieved after geometric calibration. The images are rectified to establish a correspondence among cameras and are combined to acquire the polarization measurement. The polarization pattern of the skylight is measured by the system and the results are consistent with the previous studies.     

Uncertainty analysis of value for money assessment for public-private partnership projects

In recent years, private sectors are encouraged to take an active part in franchising of urban infrastructure investments and operations, which promotes the rapid development of public-private partnership (PPP) in infrastructure and public service supply. Value for money (VFM) assessment has been officially proposed to provide a reference for selection of projects planning to adopt PPP. Based on the bottlenecks of VFM application in China and the uncertainties for urban infrastructure PPP projects, a discounted cash flow (DCF) model is established for VFM of infrastructure PPP projects. Then, a Monte Carlo simulation model is established on the basis of uncertainty factors for VFM. Through the analysis of Huai’an trams PPP project, coping strategies of uncertainties for VFM are put forward. Findings of the research may propel the establishment of a complete VFM evaluation system for PPP projects. Key instructional functions of VFM during the process of decision-making can be brought into full play and PPP may develop orderly.