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551.
The purpose of this paper is to examine the factors influencing and inducing leisure travel; to convey the sensitivity of rail travel receipts to the performance of the economy and more particularly family and personal disposable incomes; to examine the potential for further market research; and finally, to determine ways and means of attracting marginal revenue in the sustainable recreation/tourism sphere to a major public sector asset. The paper focuses on leisure marketing by Britain's national railway corporation, British Rail (BR), and the relevant activities of its three passenger business sectors: Network SouthEast (NSE), which operates regional and local services in London and the South East (though not the London ‘tube’ system); Regional Railways, which operates regional and local services elsewhere in Great Britain; and InterCity, which operates the long distance express services. The paper reviews BR's fares promotions of recent years and in particular draws on some examples taken from Regional Railways. This sector is now the only business of British Rail which in principle is subject to a significant public grant, to meet the obligation of a minimum level of service on social grounds. Of the other two passenger businesses, Network SouthEast receives a grant but the current intention is that it should operate on a breakeven basis from the 1992/93 financial year; InterCity runs on a purely commercial basis. 相似文献
552.
依托新建北京至张家口高速铁路延庆下行联络线跨大浮坨村烽火台特大桥主跨连续梁0^#段工程施工,详细地介绍了连续梁0^#段预制完成后吊装就位的施工技术,并制定了安装过程施工质量和安全控制措施。采用该技术,连续梁0^#段和桥梁主墩可同时施工,不仅能保证工程施工质量和工期,而且在北方寒冷地区高空中无法实现冬施措施的项目中具有很强的推广价值。通过新建京张高速铁路桥梁工程的连续梁工程的快速施工,验证了该技术的可行性。 相似文献
553.
空气悬架系统作为高档公路大客车的关键部件,已经在国外高档客车上普及,商用车上使用的比例也在迅速提升,其独特的变刚度、低振动频率、抗道路凹凸冲击等诸多优越性越来越受人们重视。目前国内没有一家企业能设计出成熟的产品,加快空气悬架的设计研发,尤其是电子控制空气悬架(ECAS)的研发是大势所趋,谁先掌握了汽车空气悬架的开发技术,谁先开发出配置空气悬架的成熟车型,谁就掌握了今后若干年内商用车市场的先机和主动。 相似文献
554.
《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2012,50(5):385-412
This paper presents an approach to design the H ∞/GH 2 static-output feedback controller for vehicle suspensions by using linear matrix inequalities (LMIs) and genetic algorithms (GAs). Three main performance requirements for an advanced vehicle suspension are considered in this paper. Among these requirements, the ride-comfort performance is optimized by minimizing the H ∞ norm of the transfer function from the road disturbance to the sprung mass acceleration, while the road-holding performance and the suspension deflection limitation are guaranteed by constraining the generalized H 2 (GH 2) norms of the transfer functions from the road disturbance to the dynamic tyre load and the suspension deflection to be less than their hard limits, respectively. At the same time, the controller saturation problem is considered by constraining its peak response output to be less than a given limit using the GH 2 norm as well. A four-degree-of-freedom half-car model with active suspension system is applied in this paper. Several kinds of H ∞/GH 2 static-output feedback controllers, which use the available sprung mass velocities or the suspension deflections as feedback signals, are obtained by using the GAs to search for the possible control gain matrices and then resolving the LMIs together with the minimization optimization problem. These designed H ∞/GH 2 static-output feedback controllers are validated by numerical simulations on both the bump and the random road responses which show that the designed H ∞/GH 2 static-output feedback controllers can achieve similar or even better active suspension performances compared with the state-feedback control case in spite of their simplicities. 相似文献
555.
ABSTRACTAccurate identification of vehicle inertial parameters is essential to the design of vehicle dynamics control systems. In this paper, a novel vehicle inertial parameter identification method based on the dual H infinity filter (DHIF) for electric vehicles (EVs) is proposed. The filter algorithm employs a nonlinear longitudinal vehicle model with three vehicle states. A hierarchical framework is engaged by the DHIF to estimate the vehicle states and inertial parameters concurrently. In order to minimise the disturbance of unknown noise, the vehicle states are estimated by using the linear H infinity filter (LHIF), while the nonlinear H infinity filter (NHIF) utilises the observed states to identify the vehicle inertial parameters. Finally, the proposed estimation method is verified and compared through the dSPACE based hardware-in-the-loop (HIL) simulation experiments. The results indicate that the DHIF-based estimation method is effective to identify the vehicle inertial parameters with high precision, remarkable robustness, and quick convergence. 相似文献
556.
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558.
《白虎通义》的声训在训诂学史上有一定的地位和影响。其声训有助于音韵学研究,有助于推求语源,有助于系联同源词,有助于破假借;但也存在很多不足。文章对《白虎通义》声训的学术价值和不足之处作了简要的分析。 相似文献
559.
视频监控及会议视讯综合方案 总被引:1,自引:0,他引:1
方案介绍了视频监控系统及会议视讯系统在煤矿运输企业中的应用,2个系统的有效结合,不但提高了设备的利用率,而且降低了工程投资. 相似文献
560.
“十五”时期,铁路运输工作取得了前所未有的好成绩,铁路旅客周转量、货物发送量、运输密度、总换算周转量等主要指标已稳居世界领先位置。其主要成功经验和做法是:部党组紧紧把握“发展是硬道理”,确立了铁路跨越式发展战略;坚持不懈实施提速战略;始终坚持走挖潜扩能之路;运输管理体制改革和生产力布局调整实现重大突破;全力以赴确保重点物资运输。“十一五”时期,客贷运输新的目标要求是:客运方面,要在高速铁路和既有线再提速、充分发挥客运专线和城际铁路能力、全面提高客运服务质量,以及客运专线的运营管理上取得新突破;贷运方面,要在运输结构调整、推进大客户战略、贷运快捷运输、优化运输组织、深入挖潜提效上取得新突破。 相似文献