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891.
Recently, to reduce environmental pollution and the waste of limited energy resources, there is an increasing requirement
for higher engine efficiency and lower levels of harmful emissions. A premixed charge compression ignition (PCCI) engine,
which uses a 2-stage type injection, has drawn attention because this combustion system can simultaneously reduce the amount
of NOx and PM exhausted from diesel engines. It is well known that the fuel injection timing and the spray angle in a PCCI
engine affect the mixture formation and the combustion. To acquire two optimal injection timings, the combustion and emission
characteristics of the PCCI engine were analyzed with various injection conditions. The flame visualization was performed
to validate the result obtained from the engine test. This study reveals that the optimum injection timings are BTDC 60° for
the first injection and ATDC 5° for the second injection. In addition, the injection ratio of 3 to 7 showed the best NOx and
PM emission results. 相似文献
892.
Sliding-mode-based parameter identification with application to tire pressure and tire-road friction
This paper presents a method of simultaneous estimation of tire pressure and tire-road friction. A sliding-mode scheme is
designed to identify the system state and the parameter variation of a torsional tire system, which greatly depend on the
change in tire pressure. Then, the recursive least-squares method with a forgetting facto is used to estimate the parameter
variations of the tire system and the tire-road friction force without a friction model using the information retrieved from
the equivalent input for sliding motion. A simulation study is performed to illustrate the effectiveness of the proposed method. 相似文献
893.
B. Assadsangabi F. Daneshmand N. Vahdati M. Eghtesad Y. Bazargan-Lari 《International Journal of Automotive Technology》2011,12(6):921-932
In this paper, first a new design for a disk-type magneto-rheological (MR) brake for automotive applications is proposed and
then, a finite element analysis is performed to analyze the resulting magnetic field intensity distribution within the MR
brake configuration. This finite element model of the brake is then utilized in a optimization process which incorporates
Genetic Algorithm (GA) to obtain optimal design parameters. The optimization process goal is to increase the braking torque
capacity of the brake while keeping the weight of the brake as low as possible. Although, the braking torque of the present
design is larger compared to the previous designs, the braking toque capacity of the present design is still smaller than
the required braking torque for automobiles. 相似文献
894.
M. S. Kim S. B. Yu S. Y. Lee M. C. Lee 《International Journal of Automotive Technology》2011,12(5):755-762
For developing telematics devices, traditional development methods include the unit function test, compatibility test and
T-Car, which have some limitations. Telematics devices have various functions that require accounting for the interactions
among three major elements of automotive electronics: the vehicle, the device unit and driver. The KAAS (KATECH Advanced Automotive
Simulator) system is a virtual-reality-based test environment designed to test and analyze the three elements in one place.
One of the difficult functions when constructing such VR (Virtual Reality)-based telematics test environment is to develop
a test method for the LBS (Location-Based Service) function such as a car navigation demanding the GPS (Global Positioning
System) satellite signals because KAAS is in a fixed laboratory. To overcome these problems, a real-time GPS simulation system,
which can be integrated with KAAS, is needed because the location of the vehicle in virtual space is determined purely by
the driver’s personal intention while driving virtually. This paper presents new concepts needed to construct a VR-based telematics
test environment to generate a GPS RF signal, which reflects the continuously changing vehicle location during virtual driving
in real-time. To construct this system, the coordinate transform must be conducted from a rectangular coordinate system that
is compatible with a virtual 3D DB that is used to construct a 3D image for KAAS using a WGS84 and a longitude-latitude coordinate
system compatible with a GPS simulator. Moreover, the real-time HILS (Hardware In Loop Simulation) systems and the CDMA (Code
Division Multiple Access) simulation system are developed to evaluate telematics devices. Finally, we show its applications
and results. 相似文献
895.
S. -J. Kim W. -J. Jeon J. -J. Park B. -S. Moon Y. -J. Cho Y. -I. Seo N. -K. Park K. Son 《International Journal of Automotive Technology》2011,12(6):951-958
A perturbation mark is occasionally produced on the velocity indicator of the cluster panel of a vehicle during a vehicle
collision. This mark can be used to estimate the velocity of the vehicle at the moment of the vehicle’s impact. In this study,
the effect of the impact velocity and the deceleration of the vehicle on the perturbation mark were investigated, and an analysis
of the driver’s injury was also conducted through a numerical pulse representation and computer simulations. Sled and pendulum
tests were used to replicate the conditions that produce a perturbation mark on the velocity indicator of a cluster panel.
It was verified that a higher peak acceleration is more likely than the impact velocity to cause a perturbation mark. According
to the computer simulation results, a driver’s injury could be more severe at higher peak accelerations with a constant impact
velocity. If a perturbation mark, which can be used to estimate the impact velocity, is found while investigating a vehicle
accident, this mark reveals that the acceleration was higher than that listed in the related crash report. Therefore, the
injuries of the occupants could be more serious than those expected at the reported impact velocity. 相似文献
896.
This paper investigates the impact of a variety of travel information types on the quality of travel choices. Choice quality
is measured by comparing observed choices made under conditions of incomplete knowledge with predicted choice probabilities
under complete knowledge. Furthermore, the potential impact of travel information is considered along multiple attribute-dimensions
of alternatives, rather than in terms of travel time reductions only. Data is obtained from a choice experiment in a multimodal
travel simulator in combination with a web-based mode-choice experiment. A Structural Equation Model is estimated to test
a series of hypothesized direct and indirect relations between a traveler’s knowledge levels, information acquisition behavior
and the resulting travel-choice quality. The estimation results support the hypothesized relations, which provides evidence
of validity and applicability of the developed measure of travel-choice quality. Furthermore, found relations in general provide
some careful support for the often expected impact of information on the quality of travel choices. The effects are largest
for information services that generate previously unknown alternatives, and lowest for services that provide warnings in case
of high travel times only.
Caspar Chorus holds a PhD in Technical Sciences (cum laude) from Delft University of Technology, and is currently an Assistant Professor at Eindhoven University of Technology’s Urban Planning Group. His general interests include traveler behavior research / decision making under knowledge limitations / discrete choice analysis. Theo Arentze received a Ph.D. in Decision Support Systems for urban planning from the Eindhoven University of Technology. He is now an Associate Professor at the Urban Planning Group at the same university. His main fields of expertise and current research interests are decision support systems, activity-based modeling, discrete choice modeling, knowledge discovery and learning-based systems with applications in urban and transport planning. Harry Timmermans received a Ph.D. in Spatial Sciences from the University of Nijmegen. He is Chair of the Urban Planning Group and Director of the European Institute of Retailing and Consumer Services. His main fields of expertise concern behavioral modeling, consumer studies and computer systems in a variety of application contexts including transportation. 相似文献
Caspar G. ChorusEmail: |
Caspar Chorus holds a PhD in Technical Sciences (cum laude) from Delft University of Technology, and is currently an Assistant Professor at Eindhoven University of Technology’s Urban Planning Group. His general interests include traveler behavior research / decision making under knowledge limitations / discrete choice analysis. Theo Arentze received a Ph.D. in Decision Support Systems for urban planning from the Eindhoven University of Technology. He is now an Associate Professor at the Urban Planning Group at the same university. His main fields of expertise and current research interests are decision support systems, activity-based modeling, discrete choice modeling, knowledge discovery and learning-based systems with applications in urban and transport planning. Harry Timmermans received a Ph.D. in Spatial Sciences from the University of Nijmegen. He is Chair of the Urban Planning Group and Director of the European Institute of Retailing and Consumer Services. His main fields of expertise concern behavioral modeling, consumer studies and computer systems in a variety of application contexts including transportation. 相似文献
897.
The influence of built environment to the trends in commuting journeys in the Netherlands 总被引:1,自引:0,他引:1
In this paper we describe commuting trends in the Netherlands in the past decade and examine the influence of urban form and
travel accessibility on commuting journeys over time on the basis of data from the Dutch National Travel Survey. Exploratory
analysis is performed to identify changes in commuting participation, departure time, commuting time, commuting distance and
the modal split. Regression analysis and choice models are used to examine the influence of the built environment on commuting
parameters over time. The results indicate that urban form has consistently influenced the parameters of commuting journey
in the Netherlands in the last 10 years. However, the trend of the influence is unique for each commuting model. Some influences
have become less significant in the last decade and some have become stronger.
相似文献
Kees MaatEmail: |
898.
This "rutter for piracy" begins with a brief update on contemporary piratical incidents and a short review of books and collections
of articles dedicated to the topic of piracy, before presenting the ground-breaking group of scholarly essays which make up
WMU Journal of Maritime Affairs' special issue on piracy at sea. 相似文献
899.
Z. Zhong G. Kong Z. Yu X. Xin X. Chen 《International Journal of Automotive Technology》2012,13(3):487-496
The automated mechanical transmission (AMT) is gaining popularity in the automotive industry, due to its combination of the
advantages of mechanical transmissions (MT) and automatic transmissions (AT) in terms of fuel consumption, low cost, improved
driving comfort and shifting quality. However, the inherent structural characteristics of the AMT lead to disadvantages, including
excessive wear of the clutch plates and jerk and traction interruption during the shift process, that severely affect its
popularity in the automatic transmission industry. The emerging technology of shifting control without the use of the clutch
is a promising way to improve the shifting transients of AMTs. This paper proposes a control algorithm that combines speed
and torque control of the AMT vehicle powertrain to achieve shifting control without using the clutch. The key technologies
of accurate engine torque and speed control and rapid position control of the shift actuators are described in detail. To
realize accurate engine speed control, a combined control algorithm based on feed-forward, bang-bang and PID control is adopted.
Additionally, an optimized closed-loop position control algorithm based on LQR is proposed for the shift actuators. The coordinated
control algorithm based on engine and shift actuator control is described in detail and validated on a test vehicle equipped
with an AMT. The results show that the coordinated control algorithm can achieve shifting control without the use of the clutch
to improve driving comfort significantly, reduce shift transients and extend the service life of the clutch. 相似文献
900.
Emission standards have grown increasingly stricter, consequently triggering greater interest in issues surrounding environmental
pollution. In particular, soot and NOx released from DI diesel vehicles is considered to be the main source of air pollution
in urban environments. However, the mechanics of fuel spray formation and the influence of the operating parameters on the
resulting spray flame are not yet fully understood. In this study, the original KIVA code was modified to incorporate a detailed
chemical reaction mechanism involving various species and multiple reaction steps to better understand the spray characteristics.
n-Heptane, C7H16, was used as the representative fuel for diesel fuel, and the reaction mechanism for this fuel was composed of 66 species
and 274 elementary reaction steps. The accuracy of the predicted results was demonstrated primarily by a comparison with experimental
results. The numerical prediction of a specific operating condition for the parametric investigation correlates well with
the experimental results. 相似文献