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341.
342.
S. Motoyama Engineer H. Uki Engineer K. ISODA Manager H. YUASA Manager 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1993,22(5):455-464
The purpose of this study is to clarify vehicle dynamics effected by traction force distribution, not only between the front and rear wheels but also between the left and right wheels. Contribution of traction force distribution to vehicle turning performance was investigated using a mathematical simulation and an experimental vehicle. The results indicates that the control of traction control distribution between the left and right wheels greatly influences vehicle turning characteristics and improve the performance even in a marginal turning condition. 相似文献
343.
This paper is in the context of studying alternative systems of urban transport in India to determine the costs and performance not only for public transport systems but also for the total transport scenario (i.e. for all vehicles) such that the economic costs are inclusive of costs of time (conservatively), accidents and pollution. In view of inherent deficiencies and delays associated with a traditional transport planning process and its implementation, the paper develops quick response land-use transport planning models for Indian cities to enable integrated, cost-efficient strategies to be evolved, recognizing that urban transport is a function of urban size, form, structure, socio-economic base, etc. A simple statistically significant demand model identified from a basis of appropriate data represents the recommended demand model for Indian cities. This model can be then conveniently used to project trip volume for any Indian city in a future year. A simple gravity model is used to generate the trip assignment for hypothesized city sizes, forms and structures. The results provide a fairly reasonable approximation for the major corridor trip volumes and lengths in the context of the transport requirement for the metropolitan cities in India in 2001 and 2011 A.D. The GOI Study Group arising from the investigations reported in this paper and the discounted cash-flow method of analysis made clear overall recommendations in February 1987 for cities of various populations. 相似文献
344.
Nonlinear Robust Control of Torque Converter Clutch Slip System for Passenger Vehicles Using Advanced Torque Estimation Algorithms 总被引:3,自引:0,他引:3
Jin-Oh Hahn Kyo-Il Lee 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2002,37(3):175-192
In this paper, a torque-estimation-based robust controller for passenger car torque converter clutch slip system is presented. The proposed robust controller uses only the measurements available from inexpensive sensors that are installed in current passenger vehicles for torque estimation and feedback control. A conventional full state observer along with a neural-network-based open-loop hydraulic actuator observer is designed to estimate the unknown driving load, and a neural-network-based turbine torque estimator considering the temperature of oil circulating the torque converter is developed for improved turbine torque estimation accuracy. The stability of the internal dynamics is also investigated, and the performance and robustness of the robust controller is validated by simulation studies. 相似文献
345.
G. S. Jung Y. H. Sung B. C. Choi C. W. Lee M. T. Lim 《International Journal of Automotive Technology》2012,13(3):347-353
Although premixed charge compression ignition (PCCI) combustion engines are praised for potentially high efficiency and clean
exhaust, experimental engines built to date emit more hydrocarbons (HCs) and carbon monoxide (CO) than the conventional machines.
These compounds are not only strictly controlled components of the exhaust gas of road vehicles but are also an energy loss
indicator. The prime objective of this study was to investigate the major sources of the HCs formed in the combustion chamber
of an experimental PCCI engine in order to suggest some effective technologies for HC reduction. In this study, to explore
the dominant sources of HC emissions in both operation modes, a single cylinder engine was prepared such that it could operate
using either conventional diesel combustion or PCCI combustion. Specifically, the contributions of the top-ring crevice volume
in the combustion chamber and the bulk quenching of the lean mixture were investigated. To understand the influence of the
shape and magnitude of the crevice on HC emissions, the engine was operated with 12 specially prepared pistons with different
top-ring crevices installed one after another. The engine emitted proportionally more HCs as the depth of the crevice increased
as long as the width remained narrower than the prevailing quench distance. The top-ring-crevice-originated exhaust HCs comprised
approximately 31% of the total HC emissions in the baseline condition. In a series of tests to estimate the effects of bulk
quench on exhaust HC emissions, intake air was heated from 300K to 400K in steps of 25K. With the intake air heated, HC and
CO emissions decreased with a gradually diminishing rate to zero at 375K. In conclusion, the most dominant sources of HC emissions
in PCCI engines were the crevice volumes in the combustion chamber and the bulk quenching of the lean mixtures. The key methods
for reducing HC emissions in PCCI engines are minimizing crevice volume in the combustion chamber and maximizing intake air
temperature allowed based on the permissible NOx level. 相似文献
346.
Improving pedestrian safety at intersections remains a critical issue. Although several types of safety countermeasures, such as reforming intersection layouts, have been implemented, methods have not yet been established to quantitatively evaluate the effects of these countermeasures before installation. One of the main issues in pedestrian safety is conflicts with turning vehicles. This study aims to develop an integrated model to represent the variations in the maneuvers of left-turners (left-hand traffic) at signalized intersections that dynamically considers the vehicle reaction to intersection geometry and crossing pedestrians. The proposed method consists of four empirically developed stochastic sub-models, including a path model, free-flow speed profile model, lag/gap acceptance model, and stopping/clearing speed profile model. Since safety assessment is the main objective driving the development of the proposed model, this study uses post-encroachment time (PET) and vehicle speed at the crosswalk as validation parameters. Preliminary validation results obtained by Monte Carlo simulation show that the proposed integrated model can realistically represent the variations in vehicle maneuvers as well as the distribution of PET and vehicle speeds at the crosswalk. 相似文献
347.
K. S. Song S. O. Kang S. O. Jun H. I. Park J. D. Kee K. H. Kim D. H. Lee 《International Journal of Automotive Technology》2012,13(6):905-914
This study proposes an aerodynamically optimized outer shape of a sedan by using an Artificial Neural Network (ANN), which focused on modifying the rear body shapes of the sedan. To determine the optimization variables, the unsteady flow field around the sedan driving at very fast speeds was analyzed by CFD simulation, and fluctuations of the drag coefficient (C D ) and pressure around the car were calculated. After consideration of the baseline result of CFD, 6 local parts from the end of the sedan were chosen as the design variables for optimization. Moreover, an ANN approximation model was established with 64 experimental points generated by the D-optimal methodology. As a result, an aerodynamically optimized shape for the rear end of the sedan in which the aerodynamic performance is improved by about 5.64% when compared to the baseline vehicle is proposed. Finally, it is expected that within the accepted range of shape modifications for a rear body, the aerodynamic performance of a sedan can be enhanced so that the fuel efficiency of the sedan can be improved. The YF SONATA, a sedan manufactured by Hyundai Motors Corporate, played a major role in this research as the baseline vehicle. 相似文献
348.
Tire intelligence is vital in the improvement of the safety of vehicles because the tire supports the car body and is the contact point between the vehicle and the road. To create an intelligent tire, sensors must be installed to measure the behavior of the tire. However, it is difficult to apply a wired sensor system on the wheel of the tire. Hence, it is necessary to implement a self-powering, wireless system (a type of energy harvesting system) that can be mounted inside the tire. The purpose of this study is to convert the strain energy caused by deformation of the tire while driving into useful electrical energy to supply the sensor system. A flexible piezofiber is utilized for the energy conversion. The variation in strain, due to changes in speed, load, and the internal pressure of the tire, was measured along two axial directions to evaluate the amount of available strain energy. The amount of strain changed from 0.15% to 0.8%. To predict the amount of available energy from a tire, we perform an analysis of the relationship between the strain and the voltage. In addition, experiments for impedance matching between piezofiber and related circuits were conducted to optimize the external loads for transferring energy efficiently. Based on the procedure mentioned above, at least 0.58 mJ of electrical energy can be generated by using the laterally oriented strain (1500 to 2500 micro strain). The result of this study is expected to enhance the potential realization of self-generating wireless sensor systems for so-called ??intelligent?? tires. 相似文献
349.
The most important factor in gas strut design is determining an optimized layout. If the layout is not optimized, vehicle operators will have a suboptimal experience when opening and closing the tailgate. A poor layout of the gas struts causes operators to work excessively when they open/close the tailgate, and vehicle owners will incur additional expenses due to deterioration in the body quality of the vehicle. Thus, an optimized gas strut layout is very important, even if it does not seem interesting. This paper describes the tailgate operation process and focuses on determining an optimized gas strut layout for opening/closing the tailgate easily. 相似文献
350.
J. U. Cho A. Kinloch B. Blackman F. S. Rodriguez Sanchez M. S. Han 《International Journal of Automotive Technology》2012,13(7):1127-1131
Double-cantilever beam (DCB) and tapered double-cantilever beam (TDCB) specimens are the test configurations most commonly used to measure the fracture toughness of composites and adhesive joints. Strain rates of 1 to 18.47 m/s were applied to the test specimens via high-speed hydraulic test equipment. Because the fracture occurs through the adhesively bonded joints and the cracks grow rapidly, the crack length and beam displacement were recorded by a high-speed camera. An energy range from 0 to 10 J was often observed in the high-strain-rate fracture experiments for nonlinear plastic behavior of the dynamically loaded adhesively bonded DCB and TDCB specimens. The range of energy release rates (fracture energy) for TDCB specimen was 2 to 3 times higher than that of a DCB specimen for all high strain rates. The fracture energy of automotive adhesive joints can be estimated using the experimental results in this study for the fracture toughness (GIC) under high rates of loading. The crack grows as the applied fracture energy exceeds the value of the critical energy release rate (GIC) at the crack tip. The energy release rate was calculated using the fracture mechanics formula. The key fracture mechanics parameter, the fracture energy GIC, was ascertained as a function of the test rate and can be used to assess and model the overall joint performance. 相似文献