可调四杆函数发生器的综合

介绍了利用多自由度五杆机构综合四杆可调函数发生器的方法。它可在不改变四杆机构活动构件尺寸的条件下,通过变动五杆机构一连架杆的角位置对所发生的函数进行调整,使四杆机构两连架杆转角在机架两种安装相位下实现两个给定的函数关系。     

美国联邦公路局路阻函数探讨

路阻函数在交通分配过程中左右着路径的选择，目前广泛采用的路阻函数是美国公路局提出的BPB函数．但在交通分配的实践过程中使用美国公路局推荐BPB参数得到的结果并不理想。论文对国内外关于BPB函数的修正模型研究进行了介绍；分析了现存BPB模型的优点与缺陷；提出了BPB函数适用情况的思考。     

VLOOKUP函数在学生信息管理中的应用

电子表格Excel软件作为一种功能强大的数据处理工具，在高校学生管理工作中的应用日益广泛。本文以举例分析的方式探讨Excel工作表中VLOOKUP函数在学生信息管理工作中的运用，证明使用该函数在进行不同数据库的对接和交叉引用时能显著提高工作效率。     

巴尔姆流的模拟与应用

巴尔姆流是交通运输生产与控制过程中普遍存在的一种事件流 ;通过对巴尔姆流的模拟 ,提出了一种将排队服务系统马尔可夫化的方法 ;运用该方法能科学定量地分析排队服务系统的各项运营指标 ;所提出的理论在交通运输生产过程与控制的研究中有广泛的应用价值     

基于阻力和伴流不均匀度的多用途船型线优化

为探究多用途船首尾型线变化对船舶水动力性能的影响,采用RBF(Radial Basis Functions)曲面变形方法分别对多用途船首尾型线进行变换,使用优化拉丁超立方法设计计算样本,引入Kriging近似模型解决传统CFD计算耗时的问题。在此基础上,以船舶的阻力性能以及桨盘面伴流不均匀度作为优化目标,利用带精英策略的非支配排序遗传算法(NSGA-Ⅱ)完成整个型线优化流程。计算结果表明,对于该多用途船,船首形状朝V型发展有利于减小兴波阻力,船尾的V型横剖面在接近推进器处逐渐向U型转变,可以在获得更均匀伴流场的同时对阻力性能影响较小。     

Capacity investment model for airport facilities under demand uncertainty

This paper addresses strategic airport facility planning under demand uncertainty. Existing studies are improved by (1) allowing capacity contraction and (2) adopting more flexible delay functions. A mixed‐integer nonlinear program, which incorporates scale economies in construction, time value of money, nonlinear congestion effect, and other factors, is proposed for optimizing the capacity expansion/contraction decisions over time for multiple airport components. The stochastic problem is converted into its deterministic equivalent because the number of demand scenarios considered is finite. A discrete approximation technique is used to remove the nonlinearities. Numerical studies are presented to demonstrate the capability of the proposed model and the computational efficiency of the solution method. The “Flaw of Averages” due to faulty decisions based on the average future condition is illustrated, and trade‐offs among various costs are discussed in the numerical analyses. Copyright © 2016 John Wiley & Sons, Ltd.     

新建银川至西安铁路庆阳至西安段建设方案研究

为了确定银西线庆阳至西安段合理的建设方案,重点研究客货共线方案、客运专线方案和先接西平、部分缓建3个方案。综合考虑项目功能定位、通道走向、地形条件,结合路网运量,建设时序、路网分工、投资规模等多方面因素进行综合分析比较研究,研究结论为:银西线庆阳至西安段应按照客货共线方案一次建成。     

船舶回转性能分析

在对船舶作回转性能分析时，采用战术直径表征其他回转特征量，计算出不同舵角、航速、纵倾及排水体积下的回转圈战术直径。衡量各因素对战术直径的影响程度，总结战术直径随各因素变化的规律，得到不同排水量之间战术直径的简化算法，为试航回转试验的特征量从设计吃水转化为满载吃水提供了一种较简捷的近似换算方法。     

平流层通信在交通运输行业中的应用

平流层通信是指利用位于平流层的高空平台电台代替卫星作为基站的通信。文章基于平流层通信的特点及发展现状,介绍了平流层通信在交通运输行业中的用途,阐述了平流层通信存在的平台搭载、频谱分配、可靠性方面的问题,并提出了相应的解决措施及建议。     

Adaptive sliding control of active suspension systems with uncertain hydraulic actuator dynamics

An adaptive sliding controller is proposed in this article to control the active suspension systems of a quarter-car model with hydraulic actuator. The highly nonlinear actuator dynamics is assumed to have some time-varying uncertainties with unknown bounds. Owing to its time-variant nature, traditional adaptive designs are not feasible. As the variation bounds are not given, the conventional robust controllers cannot be applied either. In this article, we use the function approximation technique to represent the uncertainties with finite combinations of some basis functions, and the Lyapunov method is employed to find update laws for the coefficients of the approximating series. The actuator force can track the desired force generated from the skyhook dynamics with ultimately bounded performance. If a sufficient number of basis functions are used and the approximation error can be ignored, asymptotic convergence performance can be proved. If the bound of the approximation error is available, asymptotic convergence of the output error still can be obtained with some modifications of the proposed control law. Simulation results show that the controller proposed can give significant improvement of ride comfort when compared with the performance of its passive counterpart.