The calculating formulas show that braking distance depends on initial braking speed , road dragging coefficient , mad slope grade , braking force increasing time ; and nothing to do with total mass of crane 计算公式表明：决定汽车起重机制动距离的主要因素是制动初速度、路面阻力系数、道路坡度和制动力增加时间；汽车起重机总质量与制动距离无直接关系。
The measuring principle of brake acceleration , brake speed , height of vehicle gravity center , pitching inertia of sprung mass and efficiency of suspension anti - pitching are also theoretically discussed to provide new methods for vehicle test research 进一步说明了该系统在车辆制动减速度、制动初速度、整车质心高度、簧上质量纵向转动惯量及悬架抗制动点头率的测试或计算方法。
As a part of the civil 863 plans , two multiple - contact models for two kinds of braking system are built in the paper , in which contact fields are described as coons surfaces , initial velocity is programmed in fortran . the thermal - mechanical coupling braking processes are simulated for the first time by msc . marc , the general - used nonlinear fem software . time distributions of the velocity , the stress and the temperature of the components under various initial velocity and brake force are obtained , which offer theoretic gist to study the life of the wheel , the disc and so on 作为国家行业863重大课题《铁路机车车辆虚拟样机系统》的一部分，本文在研究接触问题和热?机耦合问题数值方法的基础上，采用国际上通用的非线性有限元分析软件msc . marc建立了踏面制动和盘形制动主要部件的多体接触计算模型，其中用解析方法描述，即用nurb曲线、高斯曲面来描述接触区域，用fortran语言编写定义初速度的用户子程序，首次对两种制动过程热?机耦合进行了数值仿真，定量给出了主要制动部件在不同初速度、不同制动力下各个时刻的速度、应力和温度的变化规律，为研究车轮、闸瓦以及制动盘寿命提供了理论依据。
At the same time , the mathematical models of the electric field and the flow field distribution were established from the theory of electrostatic enhancement of heat transfer . employed finite differential method and over - relaxation iteration method , according to certain boundary conditions in the wire - plate electrode space , the electric field and the flow field in the wire - plate space were numerically simulated under different initial velocities of r11 stream and different magnitudes of applied voltage . the calculation results agreed with theoretical analysis satisfactorily 同时从静电强化换热理论出发，建立了表征线板电极间的电场和流场分布的数学模型，并根据线-板电极间的边界条件，利用有限差分法和超松弛迭代法，分别就不同气流初速度和不同外施电压的情况下，对线-板空间的电场和流场进行了数值模拟，计算结果与理论分析基本一致。
This paper is to analyze and study on the vibration measurement and analysis technology , especially on the testing modal analysis method . the advantages and disadvantages of the limited - time fourier transform and laplace transform modal analysis are analyzed . by the theoretical analysis and demonstration with real examples , the modal analysis based on the laplace transform is a high precision modal identification method 此外，本文还对于拉普拉斯变换的模态分析方法做了进一步的研究，拉普拉斯变换方法的前提是初始条件为零，即给定的结构或试件在激励前初始位移和初速度均为零，这就对于试验和应用的要求提出了较高的要求，所以，本文对于初始条件的问题进行了进一步的理论推导，并通过实验进行了验证。
