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531.
532.
533.
J. Kim 《International Journal of Automotive Technology》2010,11(3):331-337
A methodology is presented for estimating vehicle handling dynamics, which are important to control system design and safety
measures. The methodology, which is based on an extended Kalman filter (EKF), makes it possible to estimate lateral vehicle
states and tire forces on the basis of the results obtained from sinusoidal steering stroke tests that are widely used in
the evaluation of vehicle and tire handling performances. This paper investigates the effect of vehicle-road system models
on the estimation of lateral vehicle dynamics in the EKF. Various vehicle-road system models are considered in this study:
vehicle models (2-DOF, 3-DOF, 4-DOF), tire models (linear, non-linear) and relaxation lengths. Handling tests are performed
with a vehicle equipped with sensors that are widely used by vehicle and tire manufacturers for handling maneuvers. The test
data are then used in the estimation of the EKF and identification of lateral tire model coefficients. The accuracy of the
identified values is validated by comparing the RMS error between experimentally measured states and regenerated states simulated
using the identified coefficients. The results show that the relaxation length of the tire model has a notable impact on the
estimation of lateral vehicle dynamics. 相似文献
534.
In this study, correlation between vehicle fuel efficiency and total fuel energy consumption is analyzed to support the energy consumption and greenhouse gas (GHG) emissions reduction master plan in Korea. The background and highlights of recently amended fuel economy regulations and fuel efficiency labeling standards in Korea are also introduced. 18 representative vehicle groups, classified by class, type, size, and fuel, are selected by investigating vehicle distribution statistics based on market penetration and registration data sets in order to reflect and predict total fuel energy consumption in the overall ground transportation sector in Korea. Validity of the vehicle survival patterns modeled and vehicle classification rules are confirmed by comparing national fuel energy consumption statistics to the total amount of fuel consumed by each selected representative vehicle group. The latter figures are approximated from representative number of registrations, weighted average fuel economy, and average annual distance traveled. 相似文献
535.
The marine shipping industry faces challenges to reduce engine exhaust emissions and greenhouse gases (GHGs) from ships, and in particular, carbon dioxide. International regulatory bodies such as the International Maritime Organization and National Environmental Agencies of many countries have issued rules and regulations to drastically reduce GHG and emissions emanating from marine sources. This study investigates the possibility of using natural gas and hydrogen as alternative fuels to diesel oil for marine gas turbines and uses a mathematical model to assess the effect of these alternative fuels on gas turbine thermodynamic performance. Results show that since natural gas is categorized as a hydrocarbon fuel, the thermodynamic performance of the gas turbine cycle using natural gas was close to that of the diesel case. However, the gas turbine thermal efficiency was found to be slightly lower for natural gas and hydrogen fuels compared to diesel fuel. 相似文献
536.
Z.L. Yang D. Zhang O. Caglayan I.D. Jenkinson S. Bonsall J. Wang M. Huang X.P. Yan 《Transportation Research Part D: Transport and Environment》2012,17(6):478-486
This paper develops a subjective generic methodology for providing ship owners with a transparent evaluation tool for selecting their preferred NOx and SOx control techniques. We quantitatively analyse the merits of the control methods available in marine air pollution control practice using data collected from shipping companies, shipyards and maritime academies. We also prioritize the applicable control techniques with respect to operational shipping environments. 相似文献
537.
The paper proposes a first-order macroscopic stochastic dynamic traffic model, namely the stochastic cell transmission model (SCTM), to model traffic flow density on freeway segments with stochastic demand and supply. The SCTM consists of five operational modes corresponding to different congestion levels of the freeway segment. Each mode is formulated as a discrete time bilinear stochastic system. A set of probabilistic conditions is proposed to characterize the probability of occurrence of each mode. The overall effect of the five modes is estimated by the joint traffic density which is derived from the theory of finite mixture distribution. The SCTM captures not only the mean and standard deviation (SD) of density of the traffic flow, but also the propagation of SD over time and space. The SCTM is tested with a hypothetical freeway corridor simulation and an empirical study. The simulation results are compared against the means and SDs of traffic densities obtained from the Monte Carlo Simulation (MCS) of the modified cell transmission model (MCTM). An approximately two-miles freeway segment of Interstate 210 West (I-210W) in Los Ageles, Southern California, is chosen for the empirical study. Traffic data is obtained from the Performance Measurement System (PeMS). The stochastic parameters of the SCTM are calibrated against the flow-density empirical data of I-210W. Both the SCTM and the MCS of the MCTM are tested. A discussion of the computational efficiency and the accuracy issues of the two methods is provided based on the empirical results. Both the numerical simulation results and the empirical results confirm that the SCTM is capable of accurately estimating the means and SDs of the freeway densities as compared to the MCS. 相似文献
538.
K. Baynal M. Makaraci K. Gulbudak 《International Journal of Automotive Technology》2010,11(5):701-710
A completely safe engineering solution to the automotive assembly line knuckle ball-joint pull-out problem is achieved using
failure analysis based on the “Design of Experiment” (DOE) method. During use, some ball-joints move in their housings or
come loose under heavy loads. The purpose of this study is to determine critical production parameters that will eliminate
this failure. In this research, the knuckle-ball-joint pull-out problem is examined, and knuckle housing and ball-joint outer
diameter limits are re-defined. Four levels of interference between knuckle and ball-joint diameters and 2 levels of knuckle
thickness are specified. Experiments are repeated five times using General Variance Analysis. Required pull-out force is determined,
and necessary interference is found. New knuckle housing and ball-joint diameters, based on recommended interference values,
are determined. It is also found that thickness of knuckle boss does not affect the results. Therefore, the design is unchanged
in this region and this reduces costs. 相似文献
539.
Due to rapid progress in LED (Light Emitting Diode) technology, LEDs have become increasingly prevalent in applications to
automotive lighting. This paper studies recent trends of LED headlamps along with various experiments regarding photometric
characteristics, glare, and visibility. Experimental results are compared to those of halogen and HID (high intensity discharge)
headlamps. LED headlamps are found to be still inferior to conventional headlamps with respect to glare. However, many properties
of LED headlamps (luminous intensity, beam width, energy efficiency, and design) are competitive with halogen and HID headlamps.
The findings in this investigation will henceforth be reported to the Korean Motor Vehicle Safety Standard (KMVSS). 相似文献
540.
Paul S. Szwed 《WMU Journal of Maritime Affairs》2011,10(2):183-208
Given the inherent complexity of the maritime transportation system, developing effective policy can be challenging. Using
risk factors identified by an elicitation and aggregation of expert judgment, a relative-risk rating scheme was developed
in the theory-building tradition of the social sciences. The model was empirically evaluated using 18 months of data from
the US small passenger vessel sector. The model identified that the top 10% of relatively highest risk vessels accounted for
50% of all marine casualties during the period of examination. A policy for deploying the model nationally is proposed. 相似文献