库水位循环作用下架空斜坡式码头力学性能研究

依托云南省富宁港一期工程,建立架空斜坡式码头三维有限元模型。基于水岩相互作用,考虑岸坡岩土体在库水位循环作用下的劣化损伤,定性分析得到架空斜坡式码头桩基及轨道梁的弯矩、剪力及轴力变化特点,为进一步研究库水位循环作用下架空斜坡式码头整体性能及力学退化特性提供基础,为实际工程中库区码头运营后的监测及防护提供建议。     

智能水箱风扇电动机控制系统

介绍商用车水箱风扇电动机控制系统的一种优化方式,精确控制水箱风扇电动机工作的温度范围,从而提升整车性能。     

水动反冲击力及其应用

船艇迎浪前进时,在风浪冲击下,艏部会高高翘起、而后又在波谷中跌落,形成纵摇、拍击、颠簸、失速、航速下降、稳定安全性降低等缺点。为了克服这样的不良航态,必须在水动力流场中,造成克服这些弱点的水动力和相应的水动力矩沿船体合理分布。为此,提出设置不同于常规船艇的船底浸湿面外形,使之产生足够强大的水动反冲击力、水动升力及相应的水动航向稳定扶正力矩,确保船艇不偏离目标;凭借足够强大的的水动升力和相应的船艇纵向稳定扶正力矩,消除船艇的纵摇拍击;以相应的船体横向稳定扶正力矩来克服船艇的横摇摆动。最终确保船艇平稳高速地破浪前进。而在风浪中转弯时所激起的强大水动离心力、水动反冲击力、水动升力和相应的水动助回转力矩、水动抗船体向心倾覆扶正力矩又能使船艇以很小的回转半径高速、稳定、安全地在风浪中转弯。     

远破波大波高波浪作用下沉箱抗浪稳定性验算

岸壁码头施工中,沉箱受波高为13.62 m的远破波作用极其罕见,在如此大的波高下,沉箱受波峰压力和波谷压力作用,对沉箱的稳定性影响非常大。为提出合理的方案解决该问题,通过受力分析、计算、物模试验相结合的方法,对烟台西港区一期工程C6,C7,C8沉箱,进行了抗滑和抗倾覆稳定性计算,结果和物理模型试验结果相吻合。利用土力学原理,对远破波大波高作用下的已安装并回填的沉箱,可以通过沉箱背后土压力和孔隙充砂增重相结合的方案,利用土压力抵抗波浪力作用的方法,达到沉箱抗滑和抗倾覆稳定性的要求,确保工程的施工安全。     

初次支护结构对围岩塑性区和位移的影响研究

为了探索初期支护对隧道围岩稳定性的影响,采用岩土工程三维有限元分析软件Z_Soil3D对隧道施工中锚杆和钢架的作用进行了模拟分析。计算结果表明:增加锚杆长度或钢架惯性矩,围岩塑性区厚度和围岩位移都减小,锚杆长度及钢架惯性矩存在优化值,当锚杆长度或惯性矩超过优化值后对进一步改善围岩稳定性的作用不明显;永久钢架主要起拱的作用,其内力以轴向压力为主,在节点处存在局部弯矩,永久钢架构件内力与施工顺序相关,最早施加的构件轴力是后施加的数倍;临时钢架为压弯构件,存在较大轴力和弯矩,水平和竖向临时钢架的弯矩相差不大,2层水平钢架构件的轴力相差较大,竖向构件的轴力与上层水平构件的轴力相当,但明显大于下层水平构件的轴力。     

预应力混凝土曲线梁桥支承设计初探

以实际工程为背景,介绍了曲线混凝土桥的受力特点,采用三维空间程序对小半径预应力混凝土曲线梁桥的空间效应进行分析,考虑了不同支承形式对主梁转矩、墩柱内力和支座反力的影响,指出了曲线梁桥根据平面杆系计算不能完全反映各支座的受力情况,还需进行空间计算来确定各支座反力,提出了采取支座预设偏心的措施来改善曲梁扭转效应的方法,探讨了曲线梁桥腹板开裂病害产生的原因。     

水翼艇翼航时稳性探讨

文章探讨V形割划式水翼艇翼航时初横稳性的计算,主要涉及水翼艇翼航时水翼浸深、横倾时左右翼升力的合力、回复力矩和稳性临界速度;提出了水翼艇翼航时稳性临界航速的概念和计算方法.文中的计算和讨论可为V形割划式水翼艇的设计提供参考.     

高速列车监测数据处理及故障诊断

车体性能好坏直接影响列车的行车安全,文章利用安装在车体上的传感器所采集到的振动信号,选取合适的信号特征提取方法进行评估,达到列车故障早期预警的目的。试验数据表明,车体的振动信号具有非线性、非平稳的特点,先对振动信号提取小波包能量矩特征进行时频域分析,发现该特征提取方法可以直观地反映车辆横向和垂向振动情况。引入基于局部分析的拉普拉斯特征映射算法(LE),对故障工况的小波包能量矩熵特征所构造的高维特征向量空间进行降维,发现能够从垂向加速度信号识别出空气弹簧失气工况,从横向加速度信号识别出抗蛇行减振器故障和横向减振器故障。这与车辆动力学分析结果一致,同时也证实了流形学习方法对列车性能评估具有一定的作用。     

On the fundamental diagram for freeway traffic: A novel calibration approach for single-regime models

The speed-density or flow-density relationship has been considered as the foundation of traffic flow theory. Existing single-regime models calibrated by the least square method (LSM) could not fit the empirical data consistently well both in light-traffic/free-flow conditions and congested/jam conditions. In this paper, first, we point out that the inaccuracy of single-regime models is not caused solely by their functional forms, but also by the sample selection bias. Second, we apply a weighted least square method (WLSM) that addresses the sample selection bias problem. The calibration results for six well-known single-regime models using the WLSM fit the empirical data reasonably well both in light-traffic/free-flow conditions and congested/jam conditions. Third, we conduct a theoretical investigation that reveals the deficiency associated with the LSM is because the expected value of speed (or a function of it) is nonlinear with regard to the density (or a function of it).     

Equilibrium analysis and route guidance in large-scale networks with MFD dynamics

Recent studies have demonstrated that Macroscopic Fundamental Diagram (MFD), which provides an aggregated model of urban traffic dynamics linking network production and density, offers a new generation of real-time traffic management strategies to improve the network performance. However, the effect of route choice behavior on MFD modeling in case of heterogeneous urban networks is still unexplored. The paper advances in this direction by firstly extending two MFD-based traffic models with different granularity of vehicle accumulation state and route choice behavior aggregation. This configuration enables us to address limited traffic state observability and to scrutinize implications of drivers’ route choice in MFD modeling. We consider a city that is partitioned in a small number of large-size regions (aggregated model) where each region consists of medium-size sub-regions (more detailed model) exhibiting a well-defined MFD. This paper proposes a route guidance advisory control system based on the aggregated model as a large-scale traffic management strategy that utilizes aggregated traffic states while sub-regional information is partially known. In addition, we investigate the effect of equilibrium conditions (i.e. user equilibrium and system optimum) on the overall network performance, in particular MFD functions.