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531.
J. Y. Kim C. H. Jeong M. J. Jung J. H. Park D. H. Jung 《International Journal of Automotive Technology》2013,14(6):965-970
Traffic accidents are caused by various factors, which can be classified into human factors, vehicle factors and environmental factors. Recently, human factors have been drawing particular attention as efforts are being made to enhance the safety performance of vehicles and improve road conditions. Driving distraction caused by an increased driving workload is a representative human factor. Various studies in the past have attempted to quantify the driving workload by using EEG activities. However, they have failed to consider vibration properties generated from vehicle engines. A number of noise signals were included in brainwave signal processing, which resulted in a failure to obtain reliable outcomes. Thus, this study suggests driver EEG activities free of vehicle engine secondary vibration in order to develop a method that analyzes the driving workload with high statistical reliability. By using the analytical method developed in this study, standard values of driving workload for straight and left-turn driving that has statistical significance could be calculated. The analytical method for driving workload created by this study can be applied to HVI and road design. 相似文献
532.
S. B. Han Y. H. Chang E. Y. Lee Y. J. Chung B. Suh 《International Journal of Automotive Technology》2010,11(1):105-110
Hybrids combine a combustion engine with an electric motor and battery. The two technologies can be combined to reduce fuel
consumption and exhaust emissions. This paper presents the concept of hybrid electric vehicles (HEVs) applied to truck or
van vehicles with diesel engines. The simulation results from the advanced vehicle simulator (ADVISOR) demonstrate that the
required power may be properly shared between the internal combustion engine and electric motor. The simulation can also be
used to prove that the technique is useful for improvements in driving performance; additionally, the technique is suitable
for hybrid electric vehicles, allowing for good fuel economy and low emissions performance. 相似文献
533.
B. H. Lee J. H. Song Y. J. Chang C. H. Jeon 《International Journal of Automotive Technology》2010,11(6):783-791
The diesel combustion process is highly dependent on fuel injection parameters, and understanding fuel spray development is
essential for proper control of the process. One of the critical factors for controlling the rate of mixing of fuel and air
is the number of injector holes in a diesel engine. This study was intended to explore the behavior of the formation of spray
mixtures, combustion, and emissions as a function of the number of injector hole changes; from this work, we propose an optimal
number of holes for superior emissions and engine performance in diesel engine applications. The results show that increasing
the number of holes significantly influences evaporation, atomization, and combustion. However, when the number of holes exceeds
a certain threshold, there is an adverse effect on combustion and emissions due to a lack of the air entrainment required
for the achievement of a stoichiometric mixture. 相似文献
534.
This paper describes an optimum distribution method for yaw moment for use with unified chassis control (UCC) with limitations
on the active front steering (AFS) angle. Although the UCC has been assumed to have no AFS angle limitation in the literature,
a physical limitation exists in real applications. To improve upon the previous method, a new optimum distribution method
for yaw moment is proposed that takes this limitation into account. This method derives an optimum longitudinal/lateral force
using the Karush-Kuhn-Tucker (KKT) optimality condition, and a simulation is performed to validate the proposed method. The
simulation results indicate that the limitation on the AFS angle increases longitudinal braking force and, therefore, reduces
the vehicle speed and the side-slip angle. 相似文献
535.
A comprehensive procedure for mathematical modeling and validation of a fuel cell hybrid vehicle (FCHV) is presented in this
paper. The subsystems are modeled based on lab testing and in-field vehicle testing results from the Tongji University Start
prototype vehicle. An FCHV-SIM (fuel cell hybrid vehicle simulation) model is then developed based on the experimental data.
Model validation results confirm that the FCHV-SIM model is reasonably accurate and suitable for model-based control development. 相似文献
536.
In fuel-cell-powered vehicles, the fuel-cell system requires a thermal-management subsystem to dissipate heat released during
the reaction of hydrogen with oxygen. When the stack generates power at a high rate, a large amount of heat is also generated.
If cooling by the radiator is insufficient, a supplementary stack-cooling system is needed to maintain a safe operating temperature.
In this study, the performance of a CO2 air-conditioning unit for stack cooling was investigated under various conditions, and the relationship between cabin cooling
and stack cooling was also studied. The coefficient of performance (COP) increased from 1.9 to 2.4, with an increase in cabin-air
inlet flow rate from 0 to 8 m3/min. When the air-conditioning unit was turned off, the cooling capacity of the stack cooler was increased; correspondingly,
as the cabin-cooling capacity was increased, that of the stack cooler decreased. With an increase in ambient-air inlet temperature
from 38°C to 45°C, the COP decreased by 24%. Additionally, both the stack-cooling capacity and cabin-cooling capacity were
decreased by about 12% and 16%, respectively, due to reduced heat transfer in the gas cooler as the ambient air inlet temperature
was increased. It is expected that the experimental results can serve as a resource in designing a stack-cooling system using
a CO2 air-conditioning unit to enhance stack power generation and efficiency. 相似文献
537.
Effect of various LPG supply systems on exhaust particle emission in spark-ignited combustion engine
J. W. Lee H. S. Do S. I. Kweon K. K. Park J. H. Hong 《International Journal of Automotive Technology》2010,11(6):793-800
The particle size distribution and particle number (PN) concentration emitted by internal combustion engine are a subject
of significant environmental concern because of their adverse health effects and environmental impact. This subject has recently
attracted the attention of the Particle Measurement Programme (PMP). In 2007, the UN-ECE GRPE PMP proposed a new method to
measure particle emissions in the diluted exhaust of automotive engines and a regulation limit (<6.0×1011 #/km, number of particles). The specific PN regulation of spark-ignited combustion engine will be regulated starting on September
1, 2014 (EURO 6). In this study, three types of LPG supply systems (a mixer system and a multi-point injection system with
gas-phase or liquid-phase LPG fuel) were used for a comparison of the particulate emission characteristics, including the
nano-sized particle number density. Each of the three LPG vehicles with various LPG injection systems contained a multi-cylinder
engine with same displacement volumes of 2,000 cm3 and a three-way catalytic converter. The test fuel that was used in this study for the spark-ignited combustion engine was
n-butane basis LPG fuel, which is primarily used for taxi vehicles in Korea. The characteristics of nano-particle size distribution
and number concentration of particle sizes ranging from 20 to 1,000 nm (aerodynamic diameter) that were emitted from the three
LPG vehicles with various LPG supply systems were investigated by using a condensation particle counter (CPC), which is recommended
by the PMP under both the NEDC and FTP-75 test modes on a chassis dynamometer. The experimental results indicate that the
PN emission characteristics that were obtained by the CPC system using the PMP procedure are sufficiently reliable compared
to other regulated emissions. Additionally, the sources of PN emissions in ascending order of magnitude are as follows: mixer
type, gas-phase LPG injection (LPGi) and liquid-phase LPG injection (LPLi) passenger vehicles. The liquid-phase LPG injection
system produced relatively large particle sizes and number concentrations compared to the gaseous system, regardless of the
vehicle driving cycle. This phenomenon can be explained by unburned micro-fuel droplets that were generated due to a relatively
short homogeneous fuel-air mixture duration in the engine intake manifold. Also the particle number emissions from the LPG
vehicle were influenced by the vehicle driving cycle. 相似文献
538.
G. -D. Yin N. Chen J. -X. Wang J. -S. Chen 《International Journal of Automotive Technology》2010,11(1):33-40
A µ-synthesis for four-wheel steering (4WS) problems is proposed. Applying this method, model uncertainties can be taken into consideration, and a µ-synthesis robust controller is designed with optimized weighting functions to attenuate the external disturbances. In addition, an optimal controller is designed using the well-known optimal control theory. Two different versions of control laws are considered here. In evaluations of vehicle performance with the robust controller, the proposed controller performs adequately with different maneuvers (i.e., J-turn and Fishhook) and on different road conditions (i.e., icy, wet, and dry). The numerical simulation shows that the designed µ-synthesis robust controller can improve the performance of a closed-loop 4WS vehicle, and this controller has good maneuverability, sufficiently robust stability, and good performance robustness against serious disturbances. 相似文献
539.
J. Castillo A. P rez De La Blanca J. A. Cabrera A. Sim n 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2006,44(3):207-221
An optical tire contact pressure test bench developed by the IMMa group is described. The measurement system is based on the frustration of total internal reflection (FTIR) of light. The test bench allows performing normal pressure distribution and patch contact shape measurements on passenger car tires. The system is based on the use of a laterally illuminated glass on which the tire leans. Between them a plastic interphase is located that will cause the FTIR of light. A video camera catches the formed shining image through the glass. The brightness level in each pixel of the image can be related to the existing normal pressure. The study of the contact patch provided by the bench makes it possible to characterize tire behaviour under different loading states, inflation pressure, tire defects and toe and camber angles. The bench incorporates a computerized load and control system of the tire operation parameters, an image acquisition module and a data acquisition system that allow monitoring and acting on the experimental variables of interest in the tests such as load on the tire and environmental conditions. A supporting mechanical system incorporated to the bench allows providing the tire with variable toe and camber angles. From the images obtained with this system, the maximum normal pressure points, total force, size and shape of the patch can be determined, which are related to the tire-use conditions. As an application example, results that show the patch size and shape under different load and tire inflation pressures are presented. A further application, which is the use of the system for the detection and study of defective tires is also presented. 相似文献
540.
I. Youn J. Im M. Tomizuka 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2006,44(9):659-674
A 7-DOF full-car model with optimal active control suspension is utilized to evaluate the vehicle dynamic performances which are achieved through proposed controllers. The optimal controller, which includes the integral action for the suspension deflection, considerably improves the attitude control of a vehicle because the rolling and pitching motion in cornering and braking maneuvers are reduced, respectively. In the viewpoint of level control, the integral control acting on the suspension deflection results in the zero steady-state deflection in response to static body forces and ramp road input. The dynamic characteristics of the suspension control system are evaluated in terms of time domain and frequency domain. The simulations in the time domain demonstrate the advantages of the active suspension system obtained by penalizing the integral and derivative of suspension deflections and the derivative of roll and pitch angles in the performance index. The frequency characteristic curves obtained by simulations regarding integral action or derivative action show the increase of both ride comfort and road-holding performances by maximizing the use of suspension deflections. The potential of derivative control is shown by the performances of the car traveling over a bump and braking. 相似文献