粉砂性土层中盾构施工措施的优化改进

文章以杭州地铁一号线隧道工程为依托,分析了土压平衡盾构在粉砂性土层中推进易碰到的问题,并进行了相应的改进;针对实际掘进中盾构刀盘和螺旋机叶轮的磨损规律,通过试验对比,提出了切实有效的耐磨加固措施,并取得了很好的效果;通过对原泡沫系统的不足进行优化改进,使泡沫系统简单化、成本节约化;针对不同大小的推进力进行试验,得到了该地层施工中的最优推进力。通过一系列优化改进措施,本工程得以安全、高效地完工,可为今后粉砂性土层盾构隧道施工提供借鉴。     

多水平模型在公交站间准点率影响因素分析中的应用

公交运行准点率是评价公共交通服务质量的重要指标,是促进公交优先发展,提高公交运行效率和服务质量的有力保证。分析多水平模型的基本原理,然后按照公交线路分层,采用分层整群抽样的方法,抽取江阴市运营中的公交车作为样本,以公交车个体为观察单位,充分考虑研究数据的层次结构特征,采用多水平模型建模分析公交站间准点率的影响因素。结论证明多水平模型能更精确地反映影响公交站间准点率的因素,不同因素对准点率的影响大小以及影响因素间的交叉作用。     

城市轨道交通对城市发展的支持和引导作用——以北京城市轨道交通为例

城市轨道交通对城市的发展具有极大的支持和引导作用。本文以北京市轨道交通规划和建设情况为例,分析了北京市轨道交通线网规划和北京城市总体规划的关系,分析阐述了轨道交通与城市形态、土地利用的相互作用。分析表明轨道交通可以促使中心城土地功能布局的调整和优化,引导新城的合理发展,要通过科学合理的规划控制,为建设宜居城市提供有力保障,实现城市的可持续发展．     

Real-time catenary models for the hardware-in-the-loop simulation of the pantograph–catenary interaction

Hardware-in-the-loop (HIL) simulation is a promising technique to study the pantograph–catenary interaction problems by realising the interaction of a physical pantograph with a mathematical model of the overhead equipment (catenary). However, the computing power presently available on real-time CPUs only allows to run simplified models of the overhead equipment. Therefore, it is important to define catenary models that are suitable for real-time simulation and at the same time capable of accurately representing the dynamic behaviour of the catenary. In this paper, the use of a catenary model based on modal superposition is considered, and the effect of changing the number of modelled spans and the number of modal components allocated to the contact and messenger wires is investigated in view of finding the best model compatible with real-time simulation. Comparisons between HIL simulation results and line measurements are presented, to quantify the accuracy of the hybrid simulation method developed.     

Indicators for Evaluating the Impact of Artificial Islands on the Barcelona Coast

Artificial islands have been constructed next to large cities due to the need for extra space in highly populated areas. These emerged structures have been used by many countries as platforms for developing infrastructure (airports, harbors, highways, etc.), rebuilding ecological areas, and creating new spaces for tourism or residential areas. In this study, two state-of-the-art numerical models for wave propagation and nearshore circulation are used to simulate the effects of an emerged artificial island on the Barcelona coast. Several sea indicators (wave height, intensity and direction of currents, and mean water level) are analyzed to assess the changes likely to be induced by an artificial island. Three different situations are studied and the indicators are compared across the different tests to obtain information that can be used in the planning process of these structures. In two-meter wave conditions, the tests show that wave height is generally reduced in the sheltered area, which leads to improved safety for beach users (bathing is prohibited when wave height exceeds the two-meter threshold). However, the numerical models also reveal that velocities in the sheltered area usually decrease, which must be controlled to prevent stagnation in the bathing area.     

6S50MC-C柴油机活塞头的优化设计

基于活塞头-活塞环-缸套组合结构稳态传热得出的温度场和热流分布,分析增加振荡冷却孔深度和倒圆角对强度的影响,得出活塞头的温度场和应力分布。原设计结构最高温度为448.4℃,最大热应力和耦合应力分别为694MPa和677MPa,最大应力小于材料的许用应力。随着冷却孔深度的增加,活塞头的最高温度、最大热应力和耦合应力都降低,增加冷却孔深度可以有效的降低最高温度和最大应力。倒角可以有效的降低应力集中,选取倒角5.5mm为优化设计方案。     

基于相对差距和法的改装船舶优选

提出基于MATLAB、Microsoft SQL Server和VB. NET混合编程的相对差距和法。在民船动员的过程中,得到一个任务后,需要快速的选择一条适合的改装船舶。利用VB.NET作为程序设计语言,Microsoft SQL Server数据库存放船舶数据,MATLAB对船舶的参数进行大量的计算,结合MATLAB、Microsoft SQL Server与VB. NET这3种工具的优势,通过三者的混合编程实现利用相对差距和法快速选择改装船舶。通过实例证明该方法是可行的、快速的。     

智能车辆自由换道轨迹规划研究

针对目前传统换道模型存在的两个缺陷:一是忽略了换道过程中前轮转向角为0的情况;二是存在侧向加速度过大、产生跃变或轨迹曲率不连续等问题。通过对其它车辆换道模型的比较,并结合等速偏移轨迹函数其侧向加速度恒为0的优点和正弦函数换道轨迹具有优异平滑性的特点,提出了一种新的换道模型,该模型能够较好的解决已有的一些车道变换模型存在的不足。并用MATLAB仿真实验对几个换道模型进行比较,证实所提出的换道规则的可行性和优势。     

船用蠕动式连续拖曳行走装置运动分析及优化

为了实现大型海洋工程装备在船舶或浮体等运动物表面的稳定、连续、快速行走运动,对船用蠕动式连续拖曳行走装置进行了研究。介绍了在模拟尺蠖蠕动基础上增加了交替拖曳功能的行走装置运动原理,并设计了相应的机械结构及液压驱动系统。对行走装置进行了运动分析,建立了以被拖体运动速度最大为目标,以液压系统流量限制为约束条件的优化数学模型,对行走装置垂向及横向运动时间进行了优化。最后通过某海底管线铺设装备上配置的行走装置样机试验,验证了其运动性能以及各环节运动时间对被拖体运动速度的影响情况。     

Rationalizing Reliable Imputation Durations of Genetically Designed Time Delay Neural Network and Locally Weighted Regression Models

Abstract

Estimating missing values is known as data imputation. Previous research has shown that genetic algorithms (GAs) designed locally weighted regression (LWR) and time delay neural network (TDNN) models can generate more accurate hourly volume imputations for a period of 12 successive hours than traditional methods used by highway agencies. It would be interesting and important to further refine the models for imputing larger missing intervals. Therefore, a large number of genetically designed LWR and TDNN models are developed in this study and used to impute up to a week-long missing interval (168 hours) for sample traffic counts obtained from various groups of roads in Alberta, Canada. It is found that road type and functional class have considerable influences on reliable imputations. The reliable imputation durations range from 4–5 days for traffic counts with most unstable patterns to over 10 days for those with most stable patterns. The study results clearly show that calibrated GA-designed models can provide reliable imputations for missing data with ‘block patterns’, and demonstrate their further potentials in traffic data programs.