长江上游塘土坝河段水流特性及河床演变分析

分析了塘土坝上游来水来沙条件,结果表明:该河段为典型山区河流,河岸组成较为坚硬,河床变形以推移质运动为主,河段年际间来水来沙变化不大。结合三峡大坝蓄水运行后该河段水沙条件的变化及实测地形资料,深入分析了塘土坝河段河床演变规律,并预测了洲滩演变趋势。为该河段航道维护和治理提供了理论依据。     

Numerical analysis of ducted propeller performance under open water test condition

This paper investigates the open water performance of the Ka-series propellers at various pitch and expanded area ratios in combination with the 19A duct by employing the panel method panMARE and the RANSE code ANSYS-CFX. An efficient method, Caly, is developed in order to generate the 3D-geometry and the surface numerical grid of the ducted propellers. Caly can be coupled with ANSYS-TurboGrid to automatically produce 3D-grids for the RANSE solver. The numerical results are compared with published experimental data and the flow details are concluded and compared. The influences that the grid resolution, the panel arrangements of duct and blade, and the flow in gap between inside wall of the duct and blade tip on the numerical results are studied. Grids verification, turbulence model dependency analysis and Reynolds number scantling are also discussed.     

港口工程混凝土结构物全寿命成本分析

通过调研研究了对港口工程混凝土结构物全寿命成本分析的折现率和成本构成进行了统计、分析和研究。结果表明港口工程混凝土结构物的全寿命成本分析的折现率在0—30a之间取4％,30a之后取3％。港口工程全寿命成本主要有初建成本、运营期成本和风险成本构成。根据折现率和成本构成的研究结果,采用费用现值法建立了港口工程混凝土结构物的全寿命成本的计算模型。     

混凝土耐久性监测系统在埃及塞得东港集装箱码头工程中的应用

钢筋混凝土耐久性监测对于确保结构的设计使用寿命具有重要意义。文章介绍了以阳极梯系统为主的耐久性监测系统的工作原理及其在埃及塞得东港二期集装箱码头工程中的应用。初步监测结果表明,混凝土外部环境及其施工工艺对耐久性监测结果具有重要影响。对不同位置的阳极梯系统不能采用单一判据判断和预测腐蚀,必须实施长期监测以观察阳极梯电压及电流的突变,才能作出准确判断。     

基于漏磁原理的钢丝绳缺陷检测装置设计

针对钢丝绳缺陷检测装置中材料的选择及结构尺寸的设计,建立了简化的磁偶极子数学模型,通过Matlab软件对模型数学关系进行仿真。设计出一种缺陷检测装置并通过ANSYS仿真,最后结合实验数据证明了理论分析、模型仿真及此种装置结构设计的可行性,为以后信号处理及缺陷类型识别创造了条件。     

粗集料棱角性对水泥稳定碎石强度的影响

为研究粗集料棱角性对水泥稳定碎石强度的影响,基于数字图像处理技术,采用等效椭圆法评价粗集料的棱角性对石灰岩碎石与破碎鹅卵石的棱角性进行了对比分析,且对不同棱角性集料的工况组合水泥稳定碎石的强度性能进行了室内正交试验.研究结果表明:不考虑水泥因素的影响,无侧限抗压强度与棱角性正性相关;替换率相同条件下,19.0～26.5...     

沥青路面预防性养护过程中再生沥青的应用

文章简单介绍了公路沥青路面预防性养护的概念及其常用的养护技术,阐述了使用沥青再生进行公路沥青路面预防性养护的适用条件,分析了沥青再生技术的作用机理及效果。以工程实例来说明沥青再生技术的使用效果,旨在为解决公路沥青路面的早期病害,提高公路的安全性。     

Traffic conflict assessment for non-lane-based movements of motorcycles under congested conditions

Traffic conflict under congested conditions is one of the main safety issues of motorcycle traffic in developing countries. Unlike cars, motorcycles often display non-lane-based movements such as swerving or oblique following of a lead vehicle when traffic becomes congested. Very few studies have quantitatively evaluated the effects of such non-lane-based movements on traffic conflict. Therefore, in this study we aim to develop an integrated model to assess the traffic conflict of motorcycles under congested conditions. The proposed model includes a concept of safety space to describe the non-lane-based movements unique to motorcycles, new features developed for traffic conflict assessment such as parameters of acceleration and deceleration, and the conditions for choosing a lead vehicle. Calibration data were extracted from video clips taken at two road segments in Ho Chi Minh City. A simulation based on the model was developed to verify the dynamic non-lane-based movements of motorcycles. Subsequently, the assessment of traffic conflict was validated by calculating the probability of sudden braking at each time interval according to the change in the density of motorcycle flow. Our findings underscore the fact that higher flow density may lead to conflicts associated with a greater probability of sudden breaking. Three types of motorcycle traffic conflicts were confirmed, and the proportions of each type were calculated and discussed.     

高精度钢丝绳悬挂载荷水平运动系统的设计与研究

为研究探测器对空中飞行物体的探测、识别、跟踪等功能,建立一个空中飞行目标的模拟系统,并以钢丝绳实现其传动与荷载.从计算钢丝绳的张紧力入手,设计出能够适应大悬挂的安全运动系统;同时设计出模拟系统的运动控制方法,推导出控制量的计算公式,为系统的高精度控制提供理论基础.     

BOP吊车安装精度控制工艺方法研究

分析大连开拓者号钻井船上的BOP吊车安装特点和难点,对安装过程及精度控制要点进行分解,给出有针对性的精度控制方法,保证BOP吊车顺利完成安装.