不同优化方法对斜拉桥成桥状态的影响分析探究

参考工程案例实用数据,借助有限元数理计算方式,基于零点移位法和最小屈曲应变能法,对斜拉索桥成桥状态数理计算开展专题分析探究。经过相关索力、弯矩及线形比对,分析了不同优化计算方法对该类型桥梁成桥状态的影响,以为同类斜拉索桥工程应用提供研究和技术参考,助力建设安全牢固的斜拉索桥梁。     

实现快速调整某转向前桥转向角

转向前桥在汽车上一个非常重要的功能就是实现汽车转向,而转向角是决定转向前桥性能的一个非常重要的参数,本文解决了在桥总成装配线快速调整某转向前桥转向角问题。     

Robust optimization for the correlated MIMO downlink with imperfect channel state information

To reduce the performance deterioration induced by imperfect channel state information (CSI) in cor-related multiple input multiple output(MIMO) downlink, the linear transmit/receive filters should be optimized to be robust to imperfect CSI. A sub-optimization algorithm based on minimizing sum MSE conditional on available imperfect CSI estimates subject to a per-user power constraint is proposed. The algorithm adapts the existing MMSE algorithm from uncorrelated single-user MIMO system with perfect CSI to correlated MIMO downlink with imperfect CSI. Simulation shows that the suboptimal algorithm can effectively mitigate the performance loss induced by imperfect CSI and has a good convergence performance. In addition, the effect of spatial correlation on the performance of the proposed algorithm is also simulated.     

论新形势下大型国有施工企业的安全管理

近年来,中国的经济增长和结构调整,及加速城市化进程等方面的需求,极大地增加了对于基础设施服务的市场需求和投资需求,国家基建投资大幅上扬,建筑企业的安全生产管理工作压力突显。该文结合当前建设市场形势下建筑施工企业尤其是国有施工企业中出现的安全管理问题,提出了一些对策性研究,以便和同行交流。     

Application of time-variant predictive control to modelling driver steering skill

The paper addresses the need for improved mathematical models of human steering control. A multiple-model structure for a driver's internal model of a nonlinear vehicle is proposed. The multiple-model structure potentially offers a straightforward way to represent a range of driver expertise. The internal model is combined with a model predictive steering controller. The controller generates a steering command through the minimisation of a cost function involving vehicle path error. A study of the controller performance during an aggressive, nonlinear steering manoeuvre is provided. Analysis of the controller performance reveals a reduction in the closed-loop controller bandwidth with increasing tyre saturation and fixed controller gains. A parameter study demonstrates that increasing the multiple-model density, increasing the weights on the path error, and increasing the controller knowledge range all improved the path following accuracy of the controller.     

汽车转向泵恒流量控制的计算分析

通过模拟汽车转向泵恒流量控制的工作原理，给出合理的流量控制过程的理论分析方法，并计算分析转向泵的流量控制特性，确定其影响因素，同时也分析了令很多工程技术人员费解的两个流量控制现象。     

Generalised multi-axle vehicle handling

The familiar two-axle bicycle model and associated basic concepts of vehicle handling are reviewed and used to introduce minor changes in convention from the literature. The two-axle model is extended to a three-axle vehicle to illustrate the effectiveness of the notation combined with a simplifying mathematical identity found in the two-axle vehicle literature. A generalised model is then developed that produces dynamic equations of motion by inspection for a vehicle with an arbitrary number of steerable and non-steerable axles. Furthermore, the vehicle dynamic concepts of understeer and wheelbase are generalised and can be directly computed for various arbitrary vehicle configurations.     

A closed-loop dynamic simulation-based design method for articulated heavy vehicles with active trailer steering systems

This paper presents a closed-loop dynamic simulation-based design method for articulated heavy vehicles (AHVs) with active trailer steering (ATS) systems. AHVs have poor manoeuvrability at low speeds and exhibit low lateral stability at high speeds. From the design point of view, there exists a trade-off relationship between AHVs’ manoeuvrability and stability. For example, fewer articulation points and longer wheelbases will improve high-speed lateral stability, but they will degrade low-speed manoeuvrability. To tackle this conflicting design problem, a systematic method is proposed for the design of AHVs with ATS systems. In order to evaluate vehicle performance measures under a well-defined testing manoeuvre, a driver model is introduced and it ‘drivers’ the vehicle model to follow a prescribed route at a given speed. Considering the interactions between the mechanical trailer and the ATS system, the proposed design method simultaneously optimises the active design variables of the controllers and passive design variables of the trailer in a single design loop (SDL). Through the design optimisation of an ATS system for an AHV with a truck and a drawbar trailer combination, this SDL method is compared against a published two design loop method. The benchmark investigation shows that the former can determine better trade-off design solutions than those derived by the latter. This SDL method provides an effective approach to automatically implement the design synthesis of AHVs with ATS systems.     

基于NI CompactDAQ的轨道状态分布式在线监测系统

针对日益增加的城市轨道交通线路钢轨安全和减振降噪方面的需求,介绍一种基于NI Compact DAQ的轨道状态分布式在线监测系统。阐述了系统的基本组成、功能和软硬件总体设计。系统采用以NI Compact DAQ为核心的机箱,通过对关键路段不同站点间的振动、噪声、脱轨系数、钢轨动态位移、轨道结构沉降等动态参数进行实时在线监测,为实时掌握轨道动态参数建立一个开放式的监测平台。     

论国库集中支付制度执行的障碍及对策

随着国库集中支付制度的推行，预算单位通过实拨资金帐户办理支付的业务将萎缩，各项业务将主要通过财政直接支付和授权支付。本文分析了阻碍国库集中支付制度改革的各种原因，并提出了应对措施。