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排序方式: 共有446条查询结果,搜索用时 15 毫秒
421.
S. K. Kim S. S. Kim Y. G. Cho H. K. Jung 《International Journal of Automotive Technology》2016,17(2):255-263
Tolerance design of vehicle suspension is an important factor that affects the ride and handling quality and cost of the vehicle. Also, applying geometric tolerance to an analysis model is found to be a difficult process. This paper presents a method for tolerance analysis of wheel alignment of vehicle suspension. Monte-Carlo simulation method is applied to multibody elasto-kinematic model to analyze the accumulated geometric tolerances. As an example, Macpherson Strut Type front half car model is used, and wheel alignment dispersion and contribution ratio to the dispersion by accumulated geometric tolerances is computed. This paper also presents an efficient modeling and analysis method for elasto-kinematic model of vehicle suspensions by computing the stiffness matrix analytically. The simulation results of a Macpherson Strut Type demonstrates the validity and accuracy of the proposed method. 相似文献
422.
Kwang Hyo Jung Ho Hwan Chun Hee Jung Kim 《Journal of Marine Science and Technology》2008,13(4):317-327
The aerodynamic characteristics of NACA6409 in the vicinity of the ground were experimentally studied in a wind tunnel. Lift
and drag forces, the pitching moment, and the center of pressure were measured with respect to various major aerodynamic parameters,
such as the ground clearance, the angle of attack, the aspect ratio (AR), and the endplate type, which resulted in a total
number of 420 conditions. In addition, a smoke trace test was conducted to visualize the flow pattern around NACA6409 in the
vicinity of the ground. As a result of the ground effect and the influence of the endplate, the lift-to-drag ratio increased
at low ground clearance and the center of pressure moved forward to the leading edge; that is, the endplate and ground effects
were equivalent to the aerodynamic advantage that results from increasing the AR of the wing. Extended experimental results
are useful for understanding the aerodynamic characteristics influenced by each aerodynamic parameter during ground effect
as well as for verifying numerical simulation. 相似文献
423.
Jaecheol Cho Yongseok Lee Woojung Kim Siyoul Jang 《International Journal of Automotive Technology》2018,19(3):463-472
A frictional torque was generated by a lubricated slip contact between a wet clutch pad and a steel separator during a wet clutch engagement. It is necessary to understand the generation of frictional torque to improve the performance of the frictional torque transfer and the durability of the wet clutch system. The analytical modeling of wet clutch torque transfer considers the effects of surface roughness, permeability, the elastic modulus of the frictional material, lubricant viscosity, temperature, etc. Experimental apparatus for wet clutch engagement was designed for the measurement of frictional torque transfer during wet clutch engagement. The experimental results were compared with the analytical results under various operational conditions for the verification of the theoretical analysis to evaluate the performance of the wet clutch system. Some correlations were investigated between the experimental and analytical results. We found that computation by analytical modeling can predict the effects of oil temperature, applied force, and slip speed, as well as engagement period and frictional torque transfer shapes. 相似文献
424.
Hyunsoo Kim Jaehwan Yang Kang-Dae Lee 《Transportation Research Part D: Transport and Environment》2009,14(5):291-299
This paper presents a vehicle routing approach for the transport of end-of-life consumer electronic goods for recycling in South Korea. The objective is to minimize the distance of transportation of end-of-life goods collected by local authorities and major manufacturers’ distribution centers to four regional recycling centers located. A vehicle routing problem is constructed for each regional center, and a Tabu search is applied to solve it. Computational results using field data show that the method outperforms existing approaches to reverse logistics. 相似文献
425.
This paper presents a new controller design method based on a data-mining polynomial algorithm. We show application of a polynomial
data-mining algorithm, where an input-state linearized polynomial vehicle model is developed for very low speed operation
and, without introducing any processes with fudge factors, control inputs of a nonlinear system are obtained in the original
coordinates. We verify the developed modeling method and controller design method through numerical experiments. 相似文献
426.
In this study, NOx conversion characteristics of a urea selective catalytic reduction (SCR) system equipped on a heavy-duty diesel engine were evaluated through engine dynamometer bench tests over a scheduled world harmonized transient cycle (WHTC). Also, based on transient SCR simulations, the thermal management strategy to improve SCR NOx conversion efficiency was investigated. As a result, it was found that a selective increase in exhaust temperature at low temperature period would be a useful measure to increase SCR efficiency on WHTC mode. From the baseline SCR efficiency of around 98 % on WHTC mode, the current simulation results have shown that around 99 % level of SCR efficiency would be achievable by increasing exhaust temperatures with modifying diesel exhaust fluid (DEF) dosage. Another valuable contribution of this study is that the design guidelines for controlling exhaust temperature and DEF injection to obtain a target NOx conversion efficiency are presented for SCR systems of heavy-duty diesel engines on transient operating conditions. 相似文献
427.
This paper presents a space vector current controller for a brushless permanent magnet motor in electric and hybrid electric
vehicles. The proposed current controller selects space vectors based on the sector selection under a three-level hysteresis
comparator to decrease the current ripple. The proposed approach can improve the performance of a brushless PM drive such
as the average switching frequency and the total harmonic distortion (THD) compared with the conventional hysteresis current
control. The experiment is performed first to verify the proposed control. Then, the method is implemented in a hybrid electric
vehicle simulation model with standard driving cycles based on the control strategy to evaluate the drive performance in the
vehicle system. The experimental and simulation results indicate that the presented control can improve the performance of
the brushless PM machine drive. 相似文献
428.
This paper presents a fault detection and diagnosis (FDD) method to enhance the reliability and safety for longitudinal control
of an autonomous all-terrain vehicle (ATV). An integrated approach using decentralized and centralized FDD is proposed to
optimize the tradeoff between sensitivity and robustness. While the decentralized approach is suitable for detecting faults
in actuators and sensors directly connected to a single processor, it is sensitive to noises and disturbances and thus may
result in false alarms. On the other hand, the centralized approach is based on information communicated between multiple
processors, and it detects and diagnoses faults through analyzing concurrent computations of multiple hardware modules. However,
its performance is still limited to isolating faults specifically in terms of components in the single hardware. To incorporate
the advantages of both FDD approaches, a two-layered structure integrating both decentralized and centralized FDD is proposed
and allows us to perform more robust fault detection as well as more detailed fault isolation. Finally, the proposed method
is validated experimentally via field tests of an ATV. 相似文献
429.
U. B. Azimov K. S. Kim D. S. Jeong Y. G. Lee 《International Journal of Automotive Technology》2009,10(3):265-276
The concept of Low Temperature Combustion (LTC) has been advancing rapidly because it may reduce emissions of NOx and soot
simultaneously. Various LTC regimes that yield specific emissions have been investigated by a great number of experiments.
To accelerate the evaluation of the spray combustion characteristics of LTC, to identify the soot formation threshold in LTC,
and to implement the LTC concept in real diesel engines, LTC is modeled and simulated. However, since the physics of LTC is
rather complex, it has been a challenge to precisely compute LTC regimes by applying the available diesel combustion models
and considering all spatial and temporal characteristics as well as local properties of LTC. In this paper, LTC regimes in
a constant-volume chamber with n-Heptane fuel were simulated using the ECFM3Z model implemented in a commercial STAR-CD code.
The simulations were performed for different ambient gas O2 concentrations, ambient gas temperatures and injection pressures. The simulation results showed very good agreement with
available experimental data, including similar trends in autoignition and flame evolution. In the selected range of ambient
temperatures and O2 concentrations, soot and NOx emissions were simultaneously reduced. 相似文献
430.
FMECA (Failure Modes, Effects and Criticality Analysis) is a procedure used to identify potential failure modes, determine
causes and effects of failure modes and mitigate or remove its effects on system functional performance. For the last several
decades, FMECA has been widely used in industry, and specialized versions of FMEA have been developed for several industrial
sectors. For instance, MIL-1629a, SAE-J1739 and IEC-60812 have been mainly used in the military, automotive and electronics
industries, respectively. However, there is no specialized FMECA method for the railroad industry yet, despite a need for
highly reliable systems. Thus, in this study three specifications, MIL-1629a, SAE-J1739 and IEC-60812, were analyzed and compared
with one another, and characteristics and requirements of railroad systems were summarized. Then a specialized FMECA procedure
for railroad systems was proposed based on the processes documented in the specifications, characteristics and requirements
of railroad systems. Finally, the procedure was applied to a railroad system in order to validate its applicability. 相似文献