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891.
介绍「台湾桃园国际机场联外捷运系统建设计划」中机场区段地下工程的设计成果,并探讨施工时将面临的主要工程问题如,潜盾隧道穿越营运中的机场滑行道下方需考虑对其进行保护、隧道遭遇既有地锚的处理方式,及明挖覆盖隧道或车站于卵砾石层进行开挖,临时挡土措施及潜盾隧道的掘进作业,需考虑卵砾石大粒径与高硬度的特性等等设计考虑.现有数据显示,透过适当的机具改良、辅助工法的应用及良好的施工管理,即使是在高地下水压的卵砾石层,施作地下连续壁及以潜盾机施作隧道并无太大困难,且施工引致的地表沉陷及施工精度亦可获得良好的控制. 相似文献
892.
Elias Kassa Clas Andersson Jens C. O. Nielsen 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2006,44(3):247-258
Dynamic train-track interaction is more complex in railway turnouts (switches and crossings) than that in ordinary tangent or curved tracks. Multiple contacts between wheel and rail are common, and severe impact loads with broad frequency contents are induced, when nominal wheel-rail contact conditions are disturbed because of the continuous variation in rail profiles and the discontinuities in the crossing panel. The absence of transition curves at the entry and exit of the turnout, and the cant deficiency, leads to large wheel-rail contact forces and passenger discomfort when the train is switching into the turnout track. Two alternative multibody system (MBS) models of dynamic interaction between train and a standard turnout design are developed. The first model is derived using a commercial MBS software. The second model is based on a multibody dynamics formulation, which may account for the structural flexibility of train and track components (based on finite element models and coordinate reduction methods). The variation in rail profile is accounted for by sampling the cross-section of each rail at several positions along the turnout. Contact between the back of the wheel flange and the check rail, when the wheelset is steered through the crossing, is considered. Good agreement in results from the two models is observed when the track model is taken as rigid. 相似文献
893.
Arvin R. Savkoor C. T. Chou 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1999,32(4):345-374
This exploratory study considers applications of active aerodynamic devices for suppressing parasitic motion and for improving the response of vehicles to steering, within the scope of the linear dynamic behaviour. A three DOF linear model is chosen to describe the side slip, yaw and roll motion of a baseline front-wheel steered vehicle. The improvements in performance of the base-line vehicle that are achievable by the application of direct yaw and roll moments are determined when either an open loop control pre-filter or a state feedback control law based on LQR design is applied. Unlike the former control, the state feedback control is unable to make the body side-slip angle vanish. The feedback control performance of each of the two moment actuators has been examined separately and then jointly. The advantages of combining the open loop and feedback dual actuator configurations are demonstrated using the two-degree of freedom control scheme. It is found that the scheme yields a spectacular performance but demands unreasonably large moments from the actuators in the context of available aerodynamic forces. On the other hand, the demand on direct yaw and roll moment of actuators is modest when the actuators are controlled using the LQR feedback only and if the control design is used to track a desired yaw rate trajectory and simultaneously to reduce the parasitic rolling motion. Significant improvements in handling and dynamic stability of a base-line vehicle can be achieved by aerodynamically generated direct yaw and roll actuator moments provided the target control performance is reasonable. The configurations of aerodynamic actuators considered are feasible for improving vehicle handling in cornering on motorways but more work remains to be done to explore alternative aerodynamic configurations that give rise to less side effects and higher lift coefficients. 相似文献
894.
The race towards the creation of ever-larger containerships will not be slowed by the world' s current economic turbulence, according to Lutz Wittenberg, director of projects and marketing at Classification Society Germanischer Lloyd(GL) . Wittenberg told delegates at the port design and operation technology conference in Singapore this week that GL has taken an active part in the development of an 8000 TEU containership by a German consortium ledby German builder HDW. 相似文献
895.
C. -L. Wang C. -L. Yin T. Zhang L. Zhu 《International Journal of Automotive Technology》2009,10(5):589-596
The powertrain of an ultra-capacitor-based parallel hybrid electric vehicle (HEV) was developed. Innovations, such as the engine management system, floating ISG (Integrated Starter and Generator), electronic-controlled double-clutch system and dual-driven air conditioning system were realized. Hybrid control strategies to improve the fuel economy and reduce emissions were analyzed briefly. In order to ensure the vehicle emission performance, the engine management system calibration was performed. The vehicle emission test was also conducted, showing that the vehicle emission satisfied the EURO III standard and has great potential for improvement. The hybrid start test was introduced in detail. We realized the hybrid function and start parameter optimization of the engine and ISG. 相似文献
896.
S. -S. Cho C. S. Shin C. S. Lee H. Chang K. W. Lee 《International Journal of Automotive Technology》2010,11(1):75-80
An engine cylinder head-block joint is a gasketed, bolted joint. Assessment of sealing performance and fatigue durability of the joint during engine development relies entirely on the engine dynamometer test because the rig test cannot mimic the engine run condition and finite element analysis employs gasket and bolt models that are too simple to provide the stress data for fatigue assessment. This paper introduces finite element-based assessment of the gasket and the bolt and a model that improves the analysis accuracy without increasing computation time. Experimental data for the deformation of joint members under thermo-mehanical load are presented to demonstrate the accuracy of the model. 相似文献
897.
The dynamic stability of a vehicle depends on various maneuvering features, such as traction, braking, and cornering. This study presents nonlinear vehicle models for estimating the stability region and simulating the dynamic behavior of a vehicle. Two types of vehicle models were found by considering the degrees of freedom and linearity. A simple model with nonlinear tire dynamics is useful for determining the stability region, while a complex model (a multi-body dynamic model in MSC.ADAMS) is appropriate for carrying out accurate simulations. Actual data for a mid-sized passenger car were used, and the models were validated by comparison with test results. 相似文献
898.
T. H. S. Li C. J. Huang C. C. Chen 《International Journal of Automotive Technology》2010,11(4):581-592
A novel tracking and almost disturbance decoupling problem of multi-input, multi-output (MIMO) nonlinear systems based on feedback linearization and a multi-layered feedforward neural network approach has been proposed. The feedback linearization and neural network controller guarantees exponentially global uniform ultimate bounded stability and almost disturbance decoupling performance without using any learning or adaptive algorithms. The new approach renders the system to be stable with the almost disturbance decoupling property at each step when selecting weights to enhance the performance if the proposed sufficient conditions are maintained. One example, which cannot be solved by the existing approach of the almost disturbance decoupling problem because it requires the sufficient conditions that the nonlinearities that multiply the disturbances satisfy structural triangular conditions, is proposed to exploit the fact that the tracking and the almost disturbance decoupling performances are easily achieved by the proposed approach. In order to demonstrate the practical applicability, a famous half-car active suspension system is investigated. 相似文献
899.
C. Zhu H. Liu J. Tian Q. Xiao X. Du 《International Journal of Automotive Technology》2010,11(2):257-261
Because of their outstanding advantages over other transmissions, rubber V-belt pulley drive CVTs have been extensively used in low-power vehicles, such as scooters and snowmobiles. A rubber V-belt CVT installed on a snowmobile is used here to research transmission efficiency. The power loss of CVTs, including torque loss and speed loss, is studied based on an analysis of the transmission mechanism of CVTs. Experiments on CVT efficiency are conducted on a specific CVT test bench, on which the values of torque, speed, and displacement, etc., are measured. Results show that the variation trend of the efficiency is close to the operating conditions of CVTs and optimal structural parameters are given that can serve as a beneficial references for designing and tuning CVTs. 相似文献
900.