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331.
The intake system in an automotive engine has a short duct compared with that of the exhaust system. The filtered-x LMS (FX-LMS)
algorithm has been applied to the active noise control (ANC) system in a short acoustic duct. This algorithm design is based
on the FIR (finite impulse response) filter; however, it has a slow convergence issue due to a large number of zero coefficients.
To improve the convergence performance, the step size of the LMS algorithm was modified from fixed to variable. However, this
algorithm is still not suitable for the ANC system of a short acoustic duct because the reference signal is affected by the
backward acoustic wave propagated from a secondary source. Therefore, the recursive filtered-u LMS algorithm (FU-LMS) based
on the infinite impulse response (IIR) is developed to consider backward acoustic propagation. Generally, this algorithm has
a stability problem. The stability issue was improved using an error-smoothing filter. In this paper, the recursive LMS algorithm
with a variable step size and smoothing error filter is designed. This recursive LMS algorithm, the FU-VSSLMS algorithm, uses
an IIR filter. With fast convergence and good stability, this algorithm is suitable for the ANC system in a short acoustic
duct, such as the intake system of an automotive engine. This algorithm is applied to the ANC system of a short acoustic duct.
The disturbance signals used as primary noise source are a sinusoidal signal embedded in white noise and the chirp signal,
which has a variable instantaneous frequency. The test results demonstrate that the FU-VSSLMS algorithm has a superior convergence
performance when compared with the FX-LMS and FX-LMS algorithms. The algorithm can be successfully applied to the ANC system
in a short duct, such as the intake duct. 相似文献
332.
A. Boukehili Y. T. Zhang Q. Zhao C. Q. Ni H. F. Su G. J. Huang 《International Journal of Automotive Technology》2012,13(6):987-998
The power management strategy in many hybrid vehicles is based on expert rules and thresholds. These rule-based strategies can result in good efficiency in term of fuel economy and emissions if their thresholds and rules are accurate. However, due to the complexity and the non-linearity of the hybrid powertrain, determining accurate thresholds and rules is neither explicit nor straightforward, and experts in most cases fail to define these thresholds and rules with enough accuracy. Based on this fact, the objective of this paper is to propose a method to improve this rule-based strategy by refining its thresholds and rules. To achieve this, we used an optimization method (dynamic programming) to calculate the optimal power management, determine the optimal control signals, and extract efficient thresholds and rules that can be used in real time. Finally, simulation results for the three strategies (optimal, simple and refined strategy) are shown and discussed. 相似文献
333.
K. Jeon H. Hwang S. Choi S. Hwang S. B. Choi K. Yi 《International Journal of Automotive Technology》2012,13(7):1067-1075
This study presents a few fail-safe control strategies based on reliability evaluation scenarios for the electronic brake systems of green cars in several critical cases. CarSim and MATLAB Simulink were used to develop the FCEV model with regenerative braking involving EWBs and EMBs. The proposed reliability evaluation scenarios were simulated, and a few fail-safe control algorithms were verified using the proposed reliability evaluation scenarios with the developed FCEV simulation model. The reliability evaluation scenarios were developed using a combination of driving modes and FMEA results for these electronic brake systems. 相似文献
334.
There have not been many studies on the factors that affect chest deflection, although the US NCAP thoracic injury criterion was recently shifted from the 3-msec clip to chest deflection. This study explored these factors and proposed a design methodology for the factors to minimize chest deflection. Because injuries can become severe if the driver crashes against the vehicle interior, this study also sought a solution using a penalty function to prevent crashes with the interior and minimize injuries. First, a MADYMO model was made to simulate US NCAP and EURO NCAP tests by one-to-one and stochastic verifications. Second, a sensitivity analysis was conducted to find the major factors that affect chest deflection. Lastly, the factors identified via the sensitivity analysis were optimized to propose design guidelines that helped vehicles receive high star ratings in US NCAP and EURO NCAP tests and helped minimize the possibility of hard contact between the driver and the vehicle interior by utilizing a penalty function and the Taguchi method. 相似文献
335.
In this study, a control strategy for a dual mode power split-type hybrid electric vehicle (HEV) is developed based on the powertrain efficiency. To evaluate the transmission characteristics of the dual mode power split transmission (PST), a mechanical loss model of the transmission (TM loss) is constructed. The transmission efficiency, including the TM loss, is evaluated for the dual mode PST. Two control strategies for the dual mode PST are proposed. An optimal operation line (OOL) control strategy is developed to maintain a high engine thermal efficiency by controlling the engine operation point on the OOL. A speed ratio (SR) control strategy is proposed to obtain a greater transmission efficiency by shifting the engine operation point when the dual mode PST operates near the mechanical points. Using the TM loss and the proposed control strategies, a vehicle performance simulation is conducted to evaluate the performance of the two control strategies for dual mode PST. The simulation results demonstrate that, for the SR control strategy, the engine efficiency decreases because the engine operates beyond the OOL. However, the transmission efficiency of the dual mode PST increases because the PST operates near the mechanical point where the PST shows the greatest transmission efficiency. Consequently, the fuel economy of the SR control strategy is improved by 3.8% compared with the OOL control strategy. 相似文献
336.
Y. L. Qi L. C. Dong H. Liu P. V. Puzinauskas K. C. Midkiff 《International Journal of Automotive Technology》2012,13(6):861-872
It is well known that in-cylinder flow is very important factor for the performance of SI engine. An appropriate in-cylinder flow pattern can enhance the turbulence intensity at spark time, therefore increasing the stability of combustion, reducing emission and improving fuel economy. In this paper, the effect of intake port design on in-cylinder flow is studied. It is found a vortex existed at the upper side of intake port of a production SI engine used in the study, during the intake stroke, which will reduce both tumble ratio and volumetric efficiency. A minor modification on intake port is made to eliminate the vortex and increase tumble ratio while keeping volumetric efficiency at the same level. It is demonstrated that the increase in tumble in the new design results in a 20 per cent increase in the fuel vaporization. In this study, both KIVA and STAR-CD are used to simulate the engine cold flow, as well as ICEM CFD and es-ice used as pre-processor respectively due to the complexity of engine geometry. Simulation results from KIVA and STAR-CD are compared and analyzed. 相似文献
337.
D. O. Kang S. J. Heo M. S. Kim W. C. Choi I. H. Kim 《International Journal of Automotive Technology》2012,13(1):109-122
This study presents the robust design optimization process of suspension system for improving vehicle dynamic performance
(ride comfort, handling stability). The proposed design method is so called target cascading method where the design target
of the system is cascaded from a vehicle level to a suspension system level. To formalize the proposed method in the view
of design process, the design problem structure of suspension system is defined as a (hierarchical) multilevel design optimization,
and the design problem for each level is solved using the robust design optimization technique based on a meta-model. Then,
In order to verify the proposed design concept, it designed suspension system. For the vehicle level, 44 random variables
with 3% of coefficient of variance (COV) were selected and the proposed design process solved the problem by using only 88
exact analyses that included 49 analyses for the initial meta-model and 39 analyses for SAO. For the suspension level, 54
random variables with 10% of COV were selected and the optimal designs solved the problem by using only 168 exact analyses
for the front suspension system. Furthermore, 73 random variables with 10% of COV were selected and optimal designs solved
the problem by using only 252 exact analyses for the rear suspension system. In order to compare the vehicle dynamic performance
between the optimal design model and the initial design model, the ride comfort and the handling stability was analyzed and
found to be improved by 16% and by 37%, respectively. This result proves that the suggested design method of suspension system
is effective and systematic. 相似文献
338.
The routing and scheduling for trucks and vans in an urban road network depends critically on the state of the road network. Trucks and vans impose significant costs on other road users and the environment, so improved routing and scheduling benefits more than just the logistics industry. However, small and medium size enterprises (SMEs) in the logistics business cannot justify investment in planning systems. In this paper, an autonomous routing and scheduling system which is available to SMEs is proposed and the efficiency of the system is investigated. The proposed system accumulates vehicle location data in a central server and uses it to generate traffic information. Test simulations using a grid network demonstrate the effects of utilizing and sharing vehicle location data on delivery efficiency. The simulation results show that the improvement of delivery efficiency is mainly due to the reduction of penalty cost for early and late arrival at the customer location. It is also shown that the system leads to the buffer effect from variations in traffic conditions on delivery cost and this effect is enhanced by taking travel time uncertainty into consideration. It is further shown that the presence of measurement periods with insufficient data results in unreliable routing and scheduling. For a reliable system, data collection over a wider area is required rather than dense data in a subset of links. 相似文献
339.
340.
Abstract Given that real-time bus arrival information is viewed positively by passengers of public transit, it is useful to enhance the methodological basis for improving predictions. Specifically, data captured and communicated by intelligent systems are to be supplemented by reliable predictive travel time. This paper reports a model for real-time prediction of urban bus running time that is based on statistical pattern recognition technique, namely locally weighted scatter smoothing. Given a pattern that characterizes the conditions for which bus running time is being predicted, the trained model automatically searches through the historical patterns which are the most similar to the current pattern and on that basis, the prediction is made. For training and testing of the methodology, data retrieved from the automatic vehicle location and automatic passenger counter systems of OC Transpo (Ottawa, Canada) were used. A comparison with other methodologies shows enhanced predictive capability. 相似文献