电子数字式水准仪的性能及测量原理

电子数字式水准仪于90年代初推出以来,对传统的水准测量起到了革新作用.电子数字式水准仪利用了条形码水准标尺得到的光学图像转换成数字电子图像并且进行数字处理,从而减少了对作业人员目估分划的误差,大大提高了测量精度和工作效率.     

乘员占位传感器开发设计解析

本文从零件工作原理、功能设计、硬件设计、试验验证4个方面,阐述乘员占位传感器如何开发设计。     

阀门液压遥控系统在海洋工程中的设计研究

摘要：阐述了阀门液压遥控系统的泵站组成基本原理。讨论了海洋工程中常用的阀门遥控系统的几种基本形式及选用原则、应急系统的操作应用和设计选用对策,研究提出了设计选型的关键原则以及安装、投油的重要性及注意事项和调试的方法等。     

FWD在道路工程中的应用

在研究目前国内外技术成果的基础上,结合道路工作实践, 对FWD的工作原理及检测方法作了简单介绍,对FWD的应用作了一些分析和概括。     

Multilane first-order traffic flow model with endogenous representation of lane-flow equilibrium

In this study, we develop a multilane first-order traffic flow model for freeway networks. In the model, lane changing is considered as a stochastic behavior that can decrease an individual driver’s disutility or cost, and is represented as dynamics toward the equilibrium of lane-flow distribution along with longitudinal traffic dynamics. The proposed method can be differentiated from those in previous studies because in this study, the motivation of lane changing is explicitly considered and it is treated as a utility defined by the current macroscopic traffic state. In addition, the entire process of lane changing is computed macroscopically by an extension of the kinematic wave theory employing IT principle; moreover, in the model framework, the lane-flow equilibrium curve is endogenously generated because of self-motivated lane changes. Furthermore, the parsimonious representation enables parameter calibration using the data collected from conventional loop detectors. The calibration of the data collected at four different sites, including a sag bottleneck, on the Chugoku expressway in Japan reveals that the proposed method can represent the lane-flow distribution of any observation site with high accuracy, and that the estimated parameters can reasonably explain the multilane traffic dynamics and the bottleneck phenomena uphill of sag sections.     

Coordinated cruise control for high-speed train movements based on a multi-agent model

This paper investigates the coordinated cruise control strategy for multiple high-speed trains’ movement. The motion of an ordered set of high-speed trains running on a railway line is modeled by a multi-agent system, in which each train communicates with its neighboring trains to adjust its speed. By using the potential fields and LaSalles invariance principle, we design a new coordinated cruise control strategy for each train based on the neighboring trains’ information, under which each train can track the desired speed, and the headway distances between any two neighboring trains are stabilized in a safety range. Numerical examples are given to illustrate the effectiveness of the proposed methods.     

集成式空气处理单元工作原理及装配应用

在国内外商用车行业,制动系统大部分功能需通过空气介质来实现,空气经过进气系统进入空压机管路,需空气处理单元模块对空气进行杂质过滤、除油、除水干燥后,才能满足制动系统各阀类及零部件使用,以实现整车制动系统相关功能。集成式空气处理单元相比较于传统的非集成式空气处理单元,体积小、便于装配、成本降低,对空气介质的处理性能更好,文章将从集成式空气处理单元的结构组成进行分析和介绍,并从总装配工艺方面对其在装配过程中的应用情况进行系统阐述。     

光学对中器快速对中方法简介

光学对中器快速对中法具有对中整平相互影响小、反复次数少、操作简便、效率高、对中精度高等优点 ,尤其是对光滑度较好的金属三脚架 ,其优点更为突出 介绍了光学快速对中的基本原理及其操作步骤     

Nonlinear free vibration analysis of thin-walled curved beam with non-symmetric open cross section

A finite element formulation was presented for the nonlinear free vibration of thin-walled curved beams with non-symmetric open across section. The kinetic and potential energies were derived by the virtual principle. The energy function includes the effect of fiexural-torsional coupling, the torsion warping and the shear centre location. For finite element analysis, cubic polynomials were utilized as the shape functions of the two nodal thin-walled curved elements. Each node possesses seven degrees freedom including the warping degree of freedom. The nonlinear eigenvalue problem was solved by the direct iteration technique. The results are compared with those for straight beams as available in the literature. The results for nonlinear free vibration analysis of curved beams for various radii and subtended angle are presented.     

基于最大熵原理的喷雾液滴尺寸和速度联合分布函数

应用最大熵原理和动量守恒定律, 从理论上建立了喷雾液滴尺寸和速度联合分布函数。应用该方程编制数值计算程序, 对纯柴油与质量掺混比为30%(L30)的柴油/液化石油气(LPG)混合燃料的喷雾液滴尺寸和速度联合分布进行了数值计算, 比较了两种燃料的雾化特性。比较结果表明: 由于L30闪急沸腾效应的影响, 其液滴尺寸分布曲线的峰值明显高于柴油的分布曲线峰值, 且峰值和曲线整体趋势都向小颗粒方向偏移, 说明喷射L30产生的液滴颗粒比柴油颗粒小; L30的速度分布曲线峰值较高, 且位于小速度范围, 说明小速度液滴所占的比例更大。液滴尺寸与速度(D-u)等高线图表明: 液滴颗粒越小, 其速度分布范围越广; 液滴速度越小, 其尺寸分布范围越大。L30液滴尺寸与速度联合分布的收敛速度较快, 说明L30喷雾所产生的小颗粒和小速度液滴更加密集, 雾化质量更佳。