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471.
M. H. Lee H. M. Lee K. S. Lee S. K. Ha J. I. Bae J. H. Park H. G. Park H. J. Choi H. H. Chun 《International Journal of Automotive Technology》2011,12(5):733-744
In this paper, a hardware-in-the-loop simulation (HILS) system was developed before the development of an electric power steering
(EPS) system in a vehicle. This study was focused on the establishment of the HILS system. Driving conditions are simulated
with the HILS system. The actual steering input parameters are confirmed on the monitor while driving the HILS system. The
steering forces observed in the simulation with the developed HILS system are similar to those in real vehicle tests. The
developed HILS system can be applied in the development of various types of EPS systems. 相似文献
472.
This paper presents a system to identify road and non-road regions from monocular color images of paved and unpaved roads. Despite being a single object, the road in these images is subject to large changes in appearance due to environmental effects and track materials. This condition has challenged the practical application of road identification. The proposed system combines random forest with color correlogram to overcome such conditions and offers a classifier for road and non-road regions in traffic images. As a color feature, the color correlogram depicts the spatial correlation of color changes in an image. Using random forest, road identification is formulated as a learning paradigm. The combined effects of color correlograms and random forest create a robust system capable of identifying roads even in variable situations in real time. This combination is more effective than other combinations, such as a color histogram plus random forest, a color correlogram plus neural network, or a color histogram plus neural network. 相似文献
473.
Compensation factor method for modeling springback of auto parts constructed with high-strength steel 总被引:1,自引:0,他引:1
X. -K. Zhang G. J. Zheng J. -N. Hu C. G. Li P. Hu 《International Journal of Automotive Technology》2010,11(5):721-727
To more accurately manufacture an auto-body workpiece, a predictive compensation factor method was used to predict the workpiece’s
springback, and the factors influencing springback are introduced. Based on this method, a numerical simulation was produced
to simulate the springback compensation after distortion of the workpiece. After analyzing the simulation results, a compensation
method was introduced to reduce the springback influence on an actual workpiece. Here, we used a fortified B-pillar, which
is a kind of longitudinal stand-frame workpiece, made with a high-strength steel material (TRIP700). The simulation results
indicated that the proposed method is feasible and can be efficiently used for predicting the distortion of springback compensation
of an auto-body workpiece. 相似文献
474.
As driver assistant systems (DAS) and active safety vehicles (ASV) with various functions become popular, it is not uncommon
for multiple systems to be installed on a vehicle. If each function uses its own sensors and processing unit, it will make
installation difficult and raise the cost of the vehicle. As a countermeasure, research integrating multiple functions into
a single system has been pursued and is expected to make installation easier, decrease power consumption, and reduce vehicle
pricing. This paper proposes a novel side/rear safety system using only one scanning laser radar, which is installed in the
rear corner of the driver’s side. Our proposed system, ISRSS (integrated side/rear safety system), integrates and implements
four system functions: BSD (blind spot detection), RCWS (rear collision warning system), semi-automatic perpendicular parking,
and semi-automatic parallel parking. BSD and RCWS, which operate while the vehicle is running, share a common signal processing
result. The target position designation for perpendicular parking and parallel parking situations is based on the same signal
processing. Furthermore, as system functions during running and those during automatic parking operate in exclusive situations,
they can share common sensors and processing units efficiently. BSD and RCWS system functions were proved with 13025 and 2319
frames, respectively. The target position designation for perpendicular and parallel parking situations was evaluated with
112 and 52 situations and shows a success rate of 98.2% and 92.3%, respectively. 相似文献
475.
J. M. Lee N. W. Sung G. B. Cho K. O. Oh 《International Journal of Automotive Technology》2010,11(3):307-316
An analytical study of the performance of a radial-type, metal foam diesel particulate filter is reported. A mathematical
model for the filtration and regeneration of soot in a metal foam filter was developed. Nickel foam was selected for the filter
medium due to its large specific area, high porosity, and high thermal resistance. For various metal foams, the filtration
efficiency and the pressure drop through the filter were calculated, as was the deposition of soot. The results from the analytical
model were compared with experimental data. In comparison with a conventional wall flow filter, the metal foam diesel particulate
filter (DPF) is effective in utilizing the volume of material, due to the porous structures. As the size of the metal foam
pores in the DPF increases from 580 μm to 800 μm, the filtration efficiency decreases from 90% to 50%, and the pressure drop
decreases from 380 mbar to 20 mbar. The metal foam DPF with a large pore size is effective in utilizing the volume of material
with a small pressure drop. The regeneration is completed within four minutes by the flow of hot exhaust gases under full
load conditions. 相似文献
476.
Buses are an integral part of the national transportation system of each country. A rollover event is one of the most important
hazards that concerns the safety of the passengers and the crew in a bus. In the past, it was observed after the accident
that the deforming superstructure seriously threatens the lives of the passengers. Thus, the stiffness of the bus frame is
the first thing that needs to be considered. The unfortunate side of strengthening the bus superstructure is that it usually
causes the bus weight to increase. This paper presents an efficient and robust analysis method with which to design the bus
superstructure for a reduction in occupant injuries from rollover accidents while the weight of the strengthened bus is maintained
at the same level. First, the absorbed energy of the bus frame and its components during a rollover were investigated by using
a LS-DYNA numerical study. The highest energy absorption region, which is the side section of the bus frame, was found and
focused on for the investigation of a means to re-distribute the energy-absorption ability of the side frame component. Then
the thickness parameters that were obtained from the re-distribution of the energy-absorption ability were used in the analysis
to optimize the design. Finally, a prototype of the bus with a reasonable thickness for the window pillars and the side wall
bars, which was based on the optimized parameters, was verified to ensure it satisfied ECE R66. In this paper, an effective
usage of materials and an efficient and robust analysis method were presented to design the bus superstructure. Although the
optimization process for increasing the stiffness is simple, this study improves the upper displacement by 39.9% and the lower
displacement by 49.3% (versus the bus survivor space) while maintaining the bus weight at the existing level. 相似文献
477.
Subjective well-being related to satisfaction with daily travel 总被引:1,自引:0,他引:1
Cecilia Jakobsson Bergstad Amelie Gamble Tommy Gärling Olle Hagman Merritt Polk Dick Ettema Margareta Friman Lars E. Olsson 《Transportation》2011,38(1):1-15
Previous research demonstrates an impact on subjective well-being (SWB) of affect associated with routine performance of out-of-home
activities. A primary aim of the present study is to investigate whether satisfaction with daily travel has a positive impact
on SWB, either directly or indirectly through facilitating the performance of out-of-home activities. A secondary aim is to
determine whether emotional-symbolic or instrumental reasons for car use results in higher satisfaction with daily travel
than other travel modes. A survey of a population-based sample of 1,330 Swedish citizens included measures of car access and
use, satisfaction with daily travel, satisfaction with performance of out-of-home routine activities, and affective and cognitive
SWB. The results confirmed that the effect on affective and cognitive SWB of satisfaction with daily travel is both direct
and indirect via satisfaction with performance of activities. Percent weekly car use had a small effect on satisfaction with
daily travel and on affective SWB, although fully mediating the effect of satisfaction with performance of the activities.
This suggests that car use plays a minor role for satisfaction with daily travel and its effect on SWB. This role may be larger
if investigated after a forced reduced car use. 相似文献
478.
Konstantina Gkritza Matthew G. Karlaftis 《Transportation Research Part A: Policy and Practice》2011,45(2):148-160
This paper studies public transport demand by estimating a system of equations for multimodal transit systems where different modes may act competitively or cooperatively. Using data from Athens, Greece, we explicitly correct for higher-order serial correlation in the error terms and investigate two, largely overlooked, questions in the transit literature; first, whether a varying fare structure in a multimodal transit system affects demand and, second, what the determinants of ticket versus travelcard sales may be. Model estimation results suggest that the effect of fare type on ridership levels in a multimodal system varies by mode and by relative ticket to travelcard prices. Further, regardless of competition or cooperation between modes, fare increases will have limited effects on ridership, but the magnitude of these effects does depend on the relative ticket to travelcard prices. Finally, incorrectly assuming serial independence for the error terms during model estimation could yield upward or downward biased parameters and hence result in incorrect inferences and policy recommendations. 相似文献
479.
480.
Simplified transport models based on traffic counts 总被引:4,自引:0,他引:4
L. G. Willumsen 《Transportation》1981,10(3):257-278
Having accepted the need for the development of simpler and less cumbersome transport demand models, the paper concentrates on one possible line for simplification: estimation of trip matrices from link volume counts. Traffic counts are particularly attractive as a data basis for modelling because of their availability, low cost and nondisruptive character. It is first established that in normal conditions it may be possible to find more than one trip matrix which, when loaded onto a network, reproduces the observed link volumes. The paper then identifies three approaches to reduce this underspecification problem and produce a unique trip matrix consistent with the counts. The first approach consists of assuming that trip-making behaviour can be explained by a gravity model whose parameters can be calibrated from the traffic counts. Several forms of this gravity model have been put forward and they are discussed in Section 3. The second approach uses mathematical programming techniques associated to equilibrium assignment problems to estimate a trip matrix in congested areas. This method can also be supplemented by a special distribution model developed for small areas. The third approach relies on entropy and information theory considerations to estimate the most likely trip matrix consistent with the observed flows. A particular feature of this group is that they can include prior, perhaps outdated, information about the matrix.These three approaches are then compared and their likely areas for application identified. Problems for further research are discussed and finally an assessment is made of the possible role of these models vis-a-vis recent developments in transport planning. 相似文献