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941.
Sara Y. Kenno Sreekanta Das John B. Kennedy Ronald B. Rogge Michael Gharghouri 《Marine Structures》2010,23(3):263-273
This paper provides an in-depth study of residual stress distributions found in stiffened steel plate structures, such as those typically used in ship hulls. The effect of stiffener spacing on the distribution of residual stress components was studied. The welding heat input was also varied between high and moderate to study the effect of heat input level on residual stress distributions. Four specimens, resembling typical stiffened steel plate structures used in ship hulls were built and tested. Steel plates of 9.5 mm thickness were stiffened by welding L127 × 76 × 9.5 steel angles. The test was completed using the neutron diffraction method. The three normal components of residual stress were obtained in this study. It was found that a lower heat input results in higher tensile residual stress and that there exists a critical stiffener spacing somewhere beyond 250 mm that creates a maximum tensile residual stress value near the welded connection. 相似文献
942.
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
943.
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
944.
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
945.
M. Snelder H.J. van Zuylen L.H. Immers 《Transportation Research Part A: Policy and Practice》2012,46(5):828-842
There is a growing awareness that road networks, are becoming more and more vulnerable to unforeseen disturbances like incidents and that measures need to be taken in order to make road networks more robust. In order to do this the following questions need to be addressed: How is robustness defined? Against which disturbances should the network be made robust? Which factors determine the robustness of a road network? What is the relationship between robustness, travel times and travel time reliability? Which indicators can be used to quantify robustness? How can these indicators be computed? This paper addresses these questions by developing a consistent framework for robustness in which a definition, terms related to robustness, indicators and an evaluation method are included. By doing this, policy makers and transportation analyst are offered a framework to discuss issues that are related to road network robustness and vulnerability which goes beyond the disconnected definitions, indicators and evaluation methods used so far in literature. Furthermore, the evaluation method that is presented for evaluating the robustness of the road network against short term variations in supply (like incidents) contributes to the problem of designing robust road networks because it has a relatively short computation time and it takes spillback effects and alternative routes into account. 相似文献
946.
947.
Dong Sik Han Nak Won Choi Sung Lai Cho Jin Saeng Yang Kwang Suk Kim Wan Suk Yoo Chung Hwan Jeon 《Transportation Research Part D: Transport and Environment》2012,17(7):519-524
This study develops a gradient-sensitive driving cycle for vehicles in military areas with paved and unpaved roads over steep and undulating terrain. The methodology develops the driving cycle using micro-trips extracted from real-world data taking into account factors that affect fuel consumption. The accuracy of cycle depended on the root mean square error and information value. 相似文献
948.
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
949.
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
950.
Wojciech Walkusz Joclyn E. Paulic William J. Williams Slawomir Kwasniewski Michael H. Papst 《Journal of Marine Systems》2011,84(3-4):78-84
The distribution and diet of larval and juvenile Arctic cod (Boreogadus saida) were studied during summer 2005 in the coastal Canadian Beaufort Sea. A total of 275 individuals were captured and the highest abundance was observed at station depths of 20–30 m. This corresponds well with the location of the frontal zone where the Mackenzie River plume water and open sea water meet. Diet examinations were performed on 220 Arctic cod, which were found undamaged from sampling. We observed a gradual decrease in prey number per fish and increase in prey size as larvae grew which corresponded to a shift from Rotifera and nauplii towards larger copepodid stages. However, at all sizes, the larvae remain generalists and feed on a broad range of organisms. Environmental changes due to climate warming could have a two-fold impact on fish larvae feeding in the studied region. First, the potential for increased primary production may lead to increased zooplankton production that may impact the feeding and nutrition positively. On the other hand, greater discharge of turbid water from the Mackenzie River may reduce light penetration in the water column that may negatively influence the ability of visual predators to successively forage. 相似文献