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151.
H. G. Zhang E. H. Wang B. Y. Fan M. G. Ouyang S. Z. Xia 《International Journal of Automotive Technology》2011,12(2):173-182
Variable Nozzle Turbocharger (VNT) was invented to solve the problem of matching an ordinary turbocharger with an engine.
VNT can harness exhaust energy more efficiently, enhance intake airflow response and reduce engine emissions, especially during
transient operating conditions. The difficulty of VNT control lies in how to regulate the position of the nozzle at different
engine working conditions. The control strategy designed in this study is a combination of a closed-loop feedback controller
and an open-loop feed-forward controller. The gain-scheduled proportional-integral-derivative (PID) controller was implemented
as the feedback controller to overcome the nonlinear characteristic. As it is difficult to tune the parameters of the gain-scheduled
PID controller on an engine test bench, system identification was used to identify the plant model properties at different
working points for a WP10 diesel engine on the test bench. The PID controller parameters were calculated based on the identified
first-order-plus-dead-time (FOPDT) plant model. The joint simulation of the controller and the plant model was performed in
Matlab/Simulink. The time-domain and frequency-domain performances of the entire system were evaluated. The designed VNT control
system was verified with engine tests. The results indicated that the real boosting pressure traced the target boosting pressure
well at different working conditions. 相似文献
152.
License plate extraction method for identification of vehicle violations at a railway level crossing
B. K. Cho S. H. Ryu D. R. Shin J. I. Jung 《International Journal of Automotive Technology》2011,12(2):281-289
The primary cause of most railroad accidents is vehicle entry into railway level crossings despite warning messages. To identify
drivers who violate railway level crossing regulations, vehicle license plate recognition can be applied at railway level
crossings. The purpose of this paper is to present an effective method for extracting the license plate region from vehicle
images taken at railway level crossings. The method proposed in this paper uses the variation in the gray-level values across
the image of a license plate. For license plate region extraction, the character region is first recognized by identifying
the character width and the difference between the background region and the character region. The license plate region is
then extracted by finding the inter-character distance in the plate region. In addition, the license plate type is identified
by the difference in the gray-level value between the background region and the character region. The proposed method is effective
in solving the current challenges in extracting the license plate region from the damaged frames of license plates issued
for domestic use, including new types of license plates. According to the experimental results, the proposed method yields
a high extraction rate of 99.5% for vehicle license plates. 相似文献
153.
154.
A. E. Ismail A. K. Ariffin S. Abdullah M. J. Ghazali 《International Journal of Automotive Technology》2011,12(2):225-232
An assessment was carried out herein to study the eccentricity of cracks subjected to mixed-mode loadings. Several loading locations relative to a central line were selected to induce mixed-mode loadings, which were computed using a finite element method. An adaptive meshing technique was adopted during the simulation of crack propagation to ensure the singularity of stress at the tip of the crack. The stress intensity failure criterion was used and programmed, and the node splitting technique was used when the stress intensity factor reached the fracture toughness of the material to simulate crack propagations. It was found that large variations in the stress intensity factor were observed when off-set cracks were used, and that K II decreased when loading distance increased, but increased when the off-set crack distance was increased. Both crack eccentricity and loading distance played important roles in producing mixed-mode loading, compared to the influence of central cracks. Correction factors were introduced to modify the calculation of stress intensity factors under mixed-mode loadings. Simulations of crack propagation were also conducted to study the effects of crack eccentricities and loading distances. It was found that the crack length, the loading distance relative to the central crack and the crack eccentricity dominated calculations of the integrity of cracked structures. 相似文献
155.
K. Jang I. Park J. Han K. Lee M. Sunwoo 《International Journal of Automotive Technology》2011,12(4):589-597
Because the FlexRay protocol has more than 70 configuration parameters and these parameters correlate with each other, designing
a FlexRay network is a complex and difficult task. In this study, we propose a design framework that optimizes the two main
FlexRay network parameters that are highly relevant to the application algorithm. The design process is composed of two steps
for optimizing parameters. In the first step, the static slot length is optimized using a frame-packing algorithm. This algorithm
binds network signals into static frames based on their periods and signal groups. In the second step, the communication cycle
length is optimally designed with frame-scheduling algorithm and worst-case reponse time analysis. Based on the frame-scheduling
algorithm, the response times are analyzed. The proposed design framework was applied to a unified chassis control system
as a case study, and the analytical results were verified. 相似文献
156.
V. Alkan S. M. Karamihas G. Anlas 《International Journal of Automotive Technology》2011,12(4):529-535
To investigate static tire enveloping characteristics, a three dimensional (3-D) finite element model is proposed. The vertical stiffness of the tire is studied on a flat surface with and without cleat. Tire rubber materials and cord layers are represented independently using “rebar” elements available in MSC Marc Mentat. Comparisons of numerical and experimental results are given to show the validity of the proposed model. It is shown that after a certain displacement, the results of the proposed model agree well with experimental results. In addition, the model results show that regardless of the type of the cleat placed under the rim center (hub center), all vertical force curves intersect after a certain displacement, which indicates typical static enveloping characteristics. Moreover, another typical characteristic of the radial tires that is unlike those of bias-ply constructions confirms that the contact patch does not expand laterally after a level vertical load is applied to the tire, which is directly related to fuel consumption and tire tread life. 相似文献
157.
Development of hot stamped center pillar using form die with channel type indirect blank holder 总被引:1,自引:0,他引:1
H. S. Choi B. M. Kim K. J. Nam S. Y. Ha S. H. Cha C. G. Kang 《International Journal of Automotive Technology》2011,12(6):887-894
The hot stamping process has been used in the automotive industry to reduce the weight of the body-in-white and to increase passenger safety via improved crashworthiness. However, defects such as fracture and wrinkle occur when hot stamping is performed using a conventional drawing or forming method. In this study, a channel-type indirect blank holder (CIBH) is proposed to develop a high-strength center pillar in form-type hot stamping, so that the aforementioned drawbacks are overcome. This type of blank holder plays an important role in reducing severe wrinkling at the flange; such wrinkling leads to folding after the completion of form-type hot-stamping. First, we investigated the effect of the channel shape on the indirect blank holding force by using a simplified two-dimensional plane-strain stamping process. Second, we selected the slope angle and corner radius of the channel as the main shape parameters by finite element analysis and artificial neural network (ANN). It is known that fracture at the hot formed wall and wrinkle at the flange are significantly affected by the slope angle of the channel, and the appropriate value for eliminating fracture and wrinkle is determined to be 99°. By performing hot stamping using a form die with the selected channel, we can manufacture a high-strength center pillar without wrinkle and fracture. 相似文献
158.
H. H. Lee H. W. Bang S. K. Kauh S. I. Kim 《International Journal of Automotive Technology》2011,12(3):351-358
The development of an inner-piston-chamber temperature measurement system is a necessary step in engine development or when
solving other fundamental problems related to automotive engines. There are various pre-existing measurement methods available,
e.g., the linkage method, piston telemetry, templog, and the electromagnetic induction method. In this study, we first redesigned
the coil sensor used in the electromagnetic induction method using PEEK and then used Taguchi methods to reduce the number
of experiments in the development process and finally utilized piston telemetry via Bluetooth to verify the precision and
accuracy of the redesigned PEEK coil sensor and electromagnetic induction method. The results displayed a reproducibility
within 0.5 degrees and an accuracy within 2 degrees Celsius. 相似文献
159.
With the real time and accurate information of motor torque and rotation speed of the four-in-wheel-motordrive electric vehicles, a slip based algorithm for estimating maximum road friction coefficient is designed using Lyapunov stability theory. Modified Burckhardt tire model is used to describe longitudinal slip property of the tire. By introducing a new state variable, a nonlinear estimator is proposed to estimate the longitudinal tire force and the maximum road friction coefficient simultaneously. With the appropriate selection of estimation gain, the convergence of the estimation error of the tire longitudinal force and maximum road friction coefficient is proved through Lyapunov stability analysis. In addition, the error is exponentially stable near the origin. Finally the method is validated with Carsim-Simulink co-simulation and real vehicle tests under multi working conditions in acceleration situation which demonstrate high computational efficiency and accuracy of this method. 相似文献
160.
V. Pracny M. Meywerk A. Lion 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2007,45(1):1-14
The method of numerical multi-body simulation is an often used and well-understood development tool in the automotive industry. In order to reproduce the ride comfort or handling behaviour of vehicles, mathematical models have to be built up. To achieve accurate simulation results, highly detailed component models are required. However, the formulation of appropriate physically-based model equations of complex automotive components (e.g. air springs, shock absorbers, rubber bearings, tyres, etc.) can be very difficult. To handle this, empirical modelling methods have been developed. Simple algebraic equations are used to describe complex system behaviour. This simplification is very effective, although it largely ignores the natural laws of mechanics and thermodynamics but is still capable to predict the component response. This article illustrates how to take advantage of this approach in numerical simulations. We describe the development of a hybrid automotive shock absorber model based on both spline and neural network (NN) approaches. By combining these different approaches, an accurate model is achieved without loss of variability. Non-isothermal laboratory force-displacement measurements of an automotive shock absorber are being used to estimate the parameters of the NN. As shown, the model replicates the measured data with sufficient accuracy, especially the hysteresis. Finally, we present a set of quarter-car simulations with a built-in hybrid NN shock absorber. 相似文献