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901.
Per-Anders Jönsson Sebastian Stichel Cecilia Nilsson 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2015,53(3):341-346
In the present paper, the method for calculation of the dynamic pantograph–catenary interaction developed by the Royal Institute of Technology and the Swedish National Rail/Road administration (Trafikverket) is described and the results of the benchmark exercise are discussed. The method is based on the commercial Finite Element software ANSYS. The geometry of the catenary and pantograph is defined in a pre-processor, BARTRAD, developed by Trafikverket, and is automatically translated into an ANSYS model. Basically all types of catenary systems could be handled as well as different types of non-linearity. There are both 2D and 3D versions of the code existing. The results achieved in this first stage of the benchmark are well in line with the results from the other partners in the benchmark study 相似文献
902.
S. H. Lee T. W. Park K. H. Chung K. H. Choi K. K. Kim K. H. Moon 《International Journal of Automotive Technology》2011,12(1):75-82
HILS (Hardware In the Loop Simulation) and RBT (Requirement-Based Testing) are widely used to evaluate the performance and
reliability of automotive ECUs (Electronic Control Units). The HILS method is used to predict the behavior of ECU-installed
vehicles and to evaluate the performance of ECU controllers. RBT evaluates whether the embedded system satisfies the pre-defined
requirements. In this study, the behavior of a vehicle is regarded as a system requirement, and an embedded system test procedure
that evaluates the system requirement is proposed. In particular, a new method is introduced, which integrates HILS with RBT.
Using the proposed method, the behavior of an articulated vehicle equipped with an AWS (All Wheel Steering) ECU is evaluated
with RBT software. 相似文献
903.
This paper first describes the control strategy used in a hybrid electric public bus and then proposes a torque-balancing
control strategy. Simulations were performed using the designed control strategies, and the results were analyzed under different
conditions. The torque-balancing control strategy was improved on the basis of the efficiency-first ideas of the hybrid system.
Finally, experiments were performed to verify that the efficiency-first and torque-balancing control strategy (EFCS) is both
feasible and reliable. The simulation results showed that, compared with a conventional public bus, the hybrid electric bus
could save approximately 27.3 percent on fuel consumption using the EFCS control strategy in a public bus in China, while
under the Wuhan urban driving cycle. 相似文献
904.
This paper describes a drive controller designed to improve the lateral vehicle stability and maneuverability of a 6-wheel
drive / 6-wheel steering (6WD/6WS) vehicle. The drive controller consists of upper and lower level controllers. The upper
level controller is based on sliding control theory and determines both front and middle steering angle, additional net yaw
moment, and longitudinal net force according to the reference velocity and steering angle of a manual drive, remotely controlled,
autonomous controller. The lower level controller takes the desired longitudinal net force, yaw moment, and tire force information
as inputs and determines the additional front steering angle and distributed longitudinal tire force on each wheel. This controller
is based on optimal distribution control and takes into consideration the friction circle related to the vertical tire force
and friction coefficient acting on the road and tire. Distributed longitudinal/lateral tire forces are determined as proportion
to the size of the friction circle according to changes in driving conditions. The response of the 6WD/6WS vehicle implemented
with this drive controller has been evaluated via computer simulations conducted using the Matlab/Simulink dynamic model.
Computer simulations of an open loop under turning conditions and a closed-loop driver model subjected to double lane change
have been conducted to demonstrate the improved performance of the proposed drive controller over that of a conventional DYC. 相似文献
905.
Torque control of engine clutch to improve the driving quality of hybrid electric vehicles 总被引:1,自引:0,他引:1
H. S. Hwang D. H. Yang H. K. Choi H. S. Kim S. H. Hwang 《International Journal of Automotive Technology》2011,12(5):763-768
As a powertrain for hybrid electric vehicles (HEVs), the automatic transmission (AT) is not only convenient for the driver
but also reduces hybridization costs because the existing production line is used to produce the AT. However, it has low fuel
economy due to the torque converter. To overcome this disadvantage, this paper studies HEVs equipped an AT without a torque
converter. In this case, additional torque control is needed to prevent the driving quality from deteriorating. This paper
suggests three different torque control methods and develops a simulator for an HEV that can simulate the dynamic behaviors
of the HEV when the engine clutch is engaged. The HEV drive train is modeled with AMESim, and a controller model is developed
with MATLAB/Simulink. A co-simulation environment is established. By using the developed HEV simulator, simulations are conducted
to analyze the dynamic behaviors of the HEV according to the control methods. 相似文献
906.
Model development and experimental research on an air spring with auxiliary reservoir 总被引:1,自引:0,他引:1
This paper focuses on the dynamic stiffness and overall equivalent damping of an air spring connected to an orifice and an
auxiliary reservoir, with respect to the displacement excitation frequency, orifice area, and auxiliary reservoir volume.
A theoretical model of this air spring with its auxiliary reservoir is derived by utilizing the energy conservation equation,
gas state equation, and orifice flow rate equation. Simulation results from the presented model reveal that, when the air
spring is subject to harmonic displacement excitation, its dynamic stiffness increases with an increase in excitation frequency
and decrease in orifice area. Smaller orifice areas and lower excitation frequencies result in higher overall equivalent damping.
A validation experiment is also implemented. When compared with experimental results, simulations show consistent varying
trends of the dynamic stiffness and overall equivalent damping. The model developed here can correctly describe the behavior
of the air spring with auxiliary reservoir, indicating that it is reasonable and feasible. 相似文献
907.
J. Abraham 《International Journal of Automotive Technology》2011,12(5):721-732
Under light-load conditions in early-injection stratified-charge compression-ignition (SCCI) engines, excessive premixing
can lead to undesirable levels of unburned hydrocarbons (UHC) and carbon monoxide (CO) emissions. Optimal stratification can
reduce these emissions. In this work, the effects of changes in swirl, injection pressure, injector hole-size and number of
holes, injection timing, and piston geometry on stratification are computationally investigated. It is shown that these parameters
affect the stratification through their influence on the rate of spray penetration, drop vaporization, and fuel/air mixing.
The outcome is characterized by examining the evolution of the spatial distribution of the fuel vapor in the chamber and its
mass-based distribution function. All other parameters remaining the same, decreasing drop size leads to faster vaporization
and richer mixtures. Increasing penetration leads to greater spreading and leaner mixtures. Increasing spray included-angle
leads to greater spreading and leaner mixtures. Increasing injection pressure leads to increased mixing and leaner mixtures.
Increasing injector hole-size leads to richer mixtures at lighter loads because the duration of injection is reduced and the
fuel is confined closer to the axis. Increasing swirl leads to faster breakup of the head-vortex and confinement of the fuel
closer to the axis, and hence richer mixture. 相似文献
908.
OSEK OS (Offene Systeme und deren Schnittstellen für die Elektronik in Kraftfahrzeugen Operating System) is an open, real-time
operating system standard for ECU software in vehicles. Because it was originally designed to be used in an extremely resource-constrained
environment, an OSEK-compliant operating system must incur low processing overhead and memory usage. Unfortunately, as OSEK
OS has evolved over time, it now specifies nontrivial kernel features along with multiple conformance classes and application
modes. This may lead to unwanted dynamic resource usage in a system using OSEK OS unless the standard is carefully interpreted
and designed into an OSEK OS implementation. In this paper, we analyzed the various kernel features of OSEK OS and their interactions
to identify areas in the standard that warrant further resource usage optimization. In particular, we attempted to reduce
the run-time memory footprint. Based on our analyses, we present two kernel mechanisms: (1) stack sharing among tasks and
(2) light-weight ready queue handling specialized for OSEK OS conformance classes. We also offer implementation methods for
the proposed mechanisms by extending OIL and associated tools. Finally, we show the effectiveness of the proposed mechanisms
via extensive experiments. Our mechanisms allow OSEK-based systems to use only 36% of the memory requirements of conventional
OSEK-based systems on average. 相似文献
909.
文化体制变革与文化产业增长反映的是在特定的中国社会转型时期文化制度变迁与文化经济发展的互动关系。传统文化体制之所以阻隔了文化产业的成长,是因为过度依赖行政权力对文化发展的作用,从而遏制了文化市场的产生。三十多年来的文化制度变迁是沿着有限放松管制和体制内优先的路径展开的,对文化产业的发展起到了积极的推动作用。当下文化产业增长遇到了许多制约因素,主要制约因素还是来自制度方面;在技术创新增长路径和制度变革增长路径的选择上,最终必须依靠制度创新才能驱动文化产业的持续增长。 相似文献
910.