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161.
162.
Abstract Based on a review of available data from a database on large‐scale transport infrastructure projects, this paper investigates the hypothesis that traffic forecasts for road links in Europe are geographically biased with underestimated traffic volumes in metropolitan areas and overestimated traffic volumes in remote regions. The present data do not support this hypothesis. Since previous studies have shown a strong tendency to overestimated forecasts of the number of passengers on new rail projects, it could be speculated that road planners are more skilful and/or honest than rail planners. However, during the period when the investigated projects were planned (up to the late 1980s), there were hardly any strong incentives for road planners to make biased forecasts in order to place their projects in a more flattering light. Future research might uncover whether the change from the ‘predict and provide’ paradigm to ‘predict and prevent’ occurring in some European countries in the 1990s has influenced the accuracy of road traffic forecasts in metropolitan areas. 相似文献
163.
This paper applies a novel adaptive approach consisting of Artificial Neural Network (ANN) and Fuzzy Linear Regression (FLR) to improve car ownership forecasting in complex, ambiguous, and uncertain environments. This integrated approach is applied to forecast car ownership in Iran from 1930 to 2007. In this study, the level of car ownership is viewed as the result of demographic, politico-social, and urban structure factors including average family size, total population density, urban population density, urbanization rate, gross national product per capita, gasoline price, and total road length. To capture the potential complexity, uncertainty, and linearity relation between the car ownership function and its determinants, ANN and FLR (including eight well-known FLR) approaches are applied to the collected data. Next, the preferred ANN is selected based on sensitivity analysis results for the test data while the preferred FLR is identified with regard to ANOVA and MAPE results. The results obtained from the performance comparison demonstrate the considerable superiority of the preferred ANN over the preferred FLR regarding the nonlinear and complex nature of the car ownership function in Iran. This is the first study that presents an ANN-FLR approach for car ownership forecasting capable of handling complexity and non-linearity, uncertainty, pre-processing, and post-processing. 相似文献
164.
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
165.
针对传统算法在解决多项式的因式分解过程中,存在着只适用于精确分解而不适合系数为浮点数的多项式的因式分解问题,文中提出一种应用双种群双突变进化策略来对浮点数多项式近似分解的算法,克服了传统算法不能解决浮点数多项式的因式分解的弊端.数值计算结果表明该算法收敛速度快、精度高、稳定性强. 相似文献
166.
Mechanisms with “negative” stiffness are a unique tool used to significantly improve vibration isolation for a vehicle driver
via upgrade of the seat suspension. However, connection of such mechanisms to the suspension results in errors in the function
generation process, and in most cases, makes motion impossible. An approach to type synthesis is presented in order to make
this process more predictable, easy and thus more practical for the upgrade process. Structural classification of the suspensions
is presented, and -an atlas of function-generating mechanisms for suspensions that reveals the effect of “negative” stiffness
is completed. All of the function-generating mechanisms appear in the atlas as result of enumeration. Structural properties
of novel and existing mechanisms are compared. Finally, some advantages in practical use of novel suspensions with “negative”
stiffness are illustrated. 相似文献
167.
W. Ryu N. Cho I. Yoo H. Song H. Kim 《International Journal of Automotive Technology》2009,10(1):115-121
In this study, the performance of a CVT clutch system for a hybrid electric vehicle was investigated. To analyzed the vehicle
performance at restart, the restart delay and driveshaft torque was investigated by simulations and experiments. It was found
from the simulation results that the vehicle restart response depends on the clutch pressure buildup time to the point where
the clutch torque begins to overcome the vehicle road load, and driving comfort at restart is directly related to the rate
change of the clutch pressure. 相似文献
168.
Axel N.Wittig 《国外机车车辆工艺》2006,(1):1-4
为了满足锻造生产厂厂商对自动化生产设备的要求,锻造设备制造厂厂商开发了预锻、锤锻自动化等新设备,提出了新的设备驱动理念,研制了新一代的控制系统。 相似文献
169.
论述基于现场总线技术的标准化、模块化设计的主机遥控系统,对控制软、硬件进行了深入研究并详细剖析了LonWorks神经元。 相似文献
170.
The motion analysis of fire video images based on moment features and flicker frequency 总被引:2,自引:0,他引:2
In this paper, motion analysis methods based on the moment features and flicker frequency features for early fire flame from ordinary CCD video camera were proposed, and in order to describe the changing of flame and disturbance of non-flame phenomena further more, the average changing pixel number of the first-order moments of consecutive flames has been defined in the moment analysis as well. The first-order moments of all kinds of flames used in our experiments present irregularly flickering, and their average changing pixel numbers of first-order moments are greater than fire-like disturbances. For the analysis of flicker frequency of flame, which is extracted and calculated in spatial domain, and therefore it is computational simple and fast. The method of extracting flicker frequency from video images is not affected by the catalogues of combustion material and distance. In experiments, we adopted two kinds of flames, i.e. , fixed flame and movable flame. Many comparing and disturbing experiments were done and verified that the methods can be used as criteria for early fire detection. 相似文献