A methodology for identifying similar days in air traffic flow management initiative planning

This article describes a methodology for selecting days that are comparable in terms of the conditions faced during air traffic flow management initiative planning. This methodology includes the use of specific data sources, specific features of calendar days defined using these data sources, and the application of a specific form of classification and then cluster analysis. The application of this methodology will produce results that enable historical analysis of the use of initiatives and evaluation of the relative success of different courses of action. Several challenges are overcome here including the need to identify the appropriate machine learning algorithms to apply, to quantify the differences between calendar days, to select features describing days, to obtain appropriate raw data, and to evaluate results in a meaningful way. These challenges are overcome via a review of relevant literature, the identification and trial of several useful models and data sets, and careful application of methods. For example, the cluster analysis that ultimately selects sets of similar days uses a distance metric based on variable importance measures from a separate classification model of observed initiatives. The methodology defined here is applied to the New York area, although it could be applied by other researchers to other areas.     

基于滑轮试验台的钢丝绳弯曲疲劳试验研究

钢丝绳的使用寿命是钢丝绳行业内重点关注和研究的核心问题。而在钢丝绳-滑轮系统中,钢丝绳失效的主要型式是弯曲疲劳损伤。本文针对钢丝绳的简单弯曲、角度弯曲和反向弯曲等三种典型弯曲类型特点,专门设计了五滑轮弯曲疲劳试验台。通过调整钢丝绳工作行程和试验载荷,旨在研究钢丝绳在简单弯曲、角度弯曲和反向弯曲中的疲劳寿命。提出了反向弯曲相对简单弯曲的折算方法和折算系数,得出钢丝绳简单弯曲的总寿命次数与载荷的相关函数,为钢丝绳在特定条件下的使用寿命预测提供了试验数据支撑和计算方法。     

从汽车整车电气原理到2D线束的转化设计

以某SUV汽车线束设计为例,阐述了从汽车整车电气原理到2D线束转化设计的一般流程、设计原则、原材料的选取、线束保护设计以及2D线束图的绘制等。把汽车电气原理设计、3D模拟仿真设计和2D线束设计连贯起来形成同一思路,避免线束在工作和装配中出现冲突、干涉等不良现象。     

A fundamental investigation of tilt control systems for narrow commuter vehicles

One way of addressing traffic congestion is by efficiently utilizing the existing highway infrastructure. Narrow tilting vehicles that need a reduced width lane can be part of the solution if they can be designed to be safe, stable, and easy to operate. In this paper, a control system that stabilizes the tilt mode of such a vehicle without affecting the handling of the vehicle is proposed. This control system is a combination of two different types of control schemes known as steering tilt control (STC) and direct tilt control (DTC) systems. First, different existing variations of both STC and DTC systems are considered and their shortcomings analysed. Modified control schemes are then suggested to overcome the deficiencies. Then a new method of integrating these two control schemes that guarantees smooth switchover between the controllers as a function of vehicle velocity is proposed. The performance of the proposed STC, DTC, and integrated systems is evaluated by carrying out simulations for different operating conditions and some experimental work. The design of a second-generation narrow tilting vehicle on which the developed control system has been implemented is presented.     

丝网的辐射特性

提出了一个计算丝网辐射特性的方法,既考虑了散射,又考虑了表面性质的影响。利用了分层迭加原理及双通量模型。计算结果与投影理论及Mie电磁散射理论的结果作了对比。用高温风洞实验进行了旁证,与实验结果符合较好     

国产轻轨车辆的主要技术参数特点

国产轻轨车辆采用铰接式、短轴距转向架及大截面铝合金车体等先进技术,实现了3、4、5辆车灵活编组及单辆车的双向运行。简要介绍车体、转向架、主电路、辅助电源、制动等主要系统和部件的特点及其技术参数。     

曲线桥梁预应力束摩阻损失试验研究

针对空间曲线预应力束摩阻损失较大的问题,结合河口黄河特大桥预应力摩阻损失试验,介绍了空间曲线束摩阻试验的试验方法,利用最小二乘法得出了其预应力损失参数μ,k,针对该桥摩阻损失较大的情况提出了处理方法,为该桥的施工和设计提供依据,为曲线预应力束的预应力损失计算提供一定的参考.     

双丝焊送丝机嵌入式通信系统前期研究

双丝MAG(熔化极活性气体保护焊)焊接的应用越来越广泛.在造船行业中,由于船台焊接作业特点决定了电焊机设备普遍使用几十米的加长控制电缆.利用嵌入式系统,研究焊接电源和送丝机之间控制信号通信系统,实现减少控制电缆的芯数,既可减少生产成本,又可减少断线故障率,提高生产质量和效率、节能降耗,具有重要的现实意义,且对于多丝焊接...     

高速公路路堤下暗挖隧洞施工引起的路基沉降实例分析

在高速公路路堤下进行暗挖隧洞施工将不可避免地对围岩产生扰动,从而引起地层位移和路基沉降,过大的路基沉降将影响高速公路的正常运营,因此分析和控制路基沉降是高速公路路堤下隧洞设计与施工的难点和重点.以黔东火电厂排洪及供水隧洞为实例,采用FLAC3D软件分析了隧洞施工对高速公路路基沉降的影响特点.计算结果表明,加强超前支护是控制地层位移和路基沉降的有效手段,采用大管棚及超前小导管注浆技术能有效控制路基沉降并保证高速公路正常运营.在隧洞施工过程中对路基沉降进行了详细监测,监测结果表明隧洞开挖对高速公路路基有一定扰动,但对高速公路正常运营基本无影响.     

基于GFRP-OFBG筋的桥梁缆索索力测量技术研究

基于内嵌光纤Bragg光栅传感器的光纤光栅．玻璃纤维增强塑料复合筋（GFRP—OFBG筋）,研究了GFRP-OFBG筋自身的应变和温度传感特性,研究结果表明,GFRP—OFBG智能筋具有优异的线性传感性能,筋中光栅测量的应变极限达12000με以上,波长变化达14nm;对于用GFRP-OFBG筋替换普通钢绞线的中丝而得到的GFRP-OFBG智能钢绞线,进行了应变传感、温度敏感和钒绞线松弛试验,试验结果表明,GFRP—OFBG智能钢绞线具有优异的线性传感性能和较低的应力松弛率,并可实现钢绞线受载全过程监测,绞线中光栅测量应变极限为11568．2με,光栅波长变化为15．966nm;对直接增加GFRP—OFBG筋制成的光纤光栅平行钢丝智能索和直接增加GFRP-OFBG智能钢绞线得到的光纤光栅平行钢绞线智能索,进行荷载传感试验,试验结果表明,智能索的感知线性度和重复性都比较好,并可监测70％以上公称破断索力。智能索工程应用案例表明,GFRP—OFBG筋智能拉索在实际工程中很容易得到车辆荷载下的响应曲线。