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111.
An investigation of the drift velocity induced by water waves of a contminated surface layer is carried out. The theoretical analysis is based on a thin boundary layer on the free surface. The results of the analysis reveal that the drift velocity of a viscous layer on the water surface is 7/4 times the Stokes prediction ofc(ak)
2 wherec is the wave celerity andak the wave slope. The present experimental investigation confirms the validity of the theoretical prediction for the drift velocity for a lightly contaminated surface layer; however, for a heavily contaminated surface layer, the experimental results exceed the theoretical prediction. An investigation for a heavily contaminated layer is carried out assuming an inextensible surface layer. Thus, in the experiment, vinyl sheets are used to substitute the contaminated layers. By balancing the wave-induced mean thrust force with the mean drag force, the drift velocity is obtained and compared with the experimental results. Based on the theoretical and experimental analyses, formulae for predicting the drift velocities for laminar and turbulent flow conditions are proposed. 相似文献
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113.
Hyuck-Kee Lee Seong-Geun Shin Dong-Soo Kwon 《International Journal of Automotive Technology》2017,18(6):1067-1076
Globally, safety has become an increasingly important issue in the automotive industry. In an attempt to reduce traffic fatalities, UNECE launched a new EU Road Safety Program which aims to decrease the number of road deaths by half by 2020. AEB (Autonomous Emergency Braking) is a very effective active safety system intended to reduce fatalities. This study involves the design of a multi-sensor data fusion strategy and decision-making algorithm for AEB pedestrian. Possible collision avoidance scenarios according to the EuroNCAP protocol are analyzed and a robust pedestrian tracking strategy is proposed. The performance of the AEB system is enhanced by using a braking model to predict the collision avoidance time and by designing the system activation zone according to the relative speed and possible distance required to stop for pedestrians. The AEB activation threshold requires careful consideration. The test results confirm the advantages of the proposed algorithm, the performance of which is described in this paper. 相似文献
114.
Keon Hee Baek Su Bin Choi Hee Rok Hong Nak Tak Jeong Hyeong Uk Moon Eun Seong Lee Hyung Min Kim Sung Uk Choi Myung Won Suh 《International Journal of Automotive Technology》2018,19(5):859-868
Ever since vehicle noise, vibration, and harshness (NVH) reduction technology made dramatic improvements, vehicle interior noises represented by Squeak and Rattle (S/R) becomes an ever more important factor to improve the emotional quality of vehicles. Generally, people detect S/R noises on automotive interior parts, brake system, suspension, Body in White (BIW), etc. Among them, the rear-glass joint is a major source for vehicle interior noise, and can cause S/R noises under a variety of environmental and driving conditions. This study uses, two approaches, experimental and numerical approaches, to define the cause of S/R noise at the rear-glass section. Based on these two approaches, this study confirms that S/R noises generate through the contact between bottom side of molding and BIW. The sealant penetration length, panelmolding distance, and sealant width are the parameters affecting noise generation. In addition, this study created an optimal design with Design of Experiments (DOE) of the rear-glass joint. The design maximized the sealant penetration length, which is a parameter that majorly affects noise. The optimal design comprises of two steps: sealant injections shape optimization and rear-glass joint parameter optimization. Each step is carried out with FEA and validated by sealant penetration experiments. Through these optimizations, this study obtained an optimum combination of design parameters and fignificantly reduced the noise generated by rear-glass section. 相似文献
115.
长江经济带是整个长江流域中最发达的地区,也是全国除沿海开放地区以外,经济密度最大的地带。上海港是中国第一大港,国际集装箱运输业近年来发展迅速(见表1),2000年的集装箱吞吐量更是达到561.2万TEU,跃居世界第六位。上海港之所以有如此骄人的成绩,是与长江经济带的发展密切相关的。 相似文献
116.
Due to additional trip production by land use development, the O‐D travel costs between some O‐D pairs may also change intuitively. This leads to positive and negative impacts on network users traveling between different O‐D pairs. Therefore the equity issue about the benefit distribution gained from the land‐use development problem is raised. This paper proposes an Equity based Land‐Use Transportation Problem (ELUTP) which is intended to examine the benefit distribution among the network users and the resulting equity associated with land‐use development problem in terms of the change of equilibrium O‐D travel cost. In the resulting bi‐level programming model, the upper level sub‐problem maximizes traffic production incorporating equity constraints, while the lower level sub‐problem is a combined trip distribution/assignment user equilibrium problem. Genetic algorithm based method is applied to test the models using an example network. 相似文献
117.
Changing market regulations in South Korea have allowed diesel-fueled passenger cars in the domestic market. The diffusion of diesel cars is tied to issues of environmental impact, energy supply and demand, and changes in tax revenue. Policymakers can influence demand for diesel vehicles to protect social welfare and to observe international environmental protection laws. On the supply side, carmakers need to know consumer preferences regarding new vehicles to arrive at development strategies.This study uses microsimulated demand forecasting to address these issues and predict consumer demand for diesel passenger cars. The model accommodates governmental policies and car attributes such as price and engine efficiency. We find that consumers will likely prefer diesel passenger cars to gasoline ones due to the low operation costs of the former in spite of high purchase price when diesel is relatively cheaper than gasoline. Finally we find that diesel passenger cars will capture a 42% market penetration ratio under the pricing system suggested by the Ministry of Environment of Korea. 相似文献
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119.
Min-Kyu Lee 《Maritime Policy and Management》2013,40(5):516-532
As of late, the Korean government needs quantitative information on economic feasibility analysis for marina port development projects. This study applies a choice experiment to measure public preference for the attributes of marina port in Korea. We consider the trade-offs between price and four attributes of marina port (capacity, access, waterfront, and program) for selecting a preferred alternative and elicit the marginal willingness to pay (MWTP) estimates for each attribute. We also test whether irrelevant alternatives property for the estimation model holds and compare the estimation results of the multinomial logit (MNL) and the nested logit (NL) models. The results show that the NL model outperforms the MNL model. In the NL model, MWTPs for increasing the level of a waterfront from promenade to both promenade and rest area and for the provision of marine leisure experience program are KRW13 384 (USD11.8) and KRW17 937 (USD15.8), respectively. This study is expected to provide policymakers with quantitative information for evaluating marina port construction projects in Korea. 相似文献
120.
This research investigates the underwriting attitude of international commercial banks in lending shipping loans. By adopting the analytic hierarchical process methodology, the underwriting attitude is captured to understand how bankers would deal with shipping loans in response to the current lengthy recession. We find that bankers focus on the criteria of corporate recourse (CR) in their decision-makings. Of the CR factors, the financial strength of shipowner is the most important factor, followed by the shipowner’s business history and the bank–firm relationship. With the current underwriting attitude, the shipping sector may have limited access to shipping loans of international commercial banks due to low corporate ratings caused by the long recession and the nature of industry itself: volatility, fragmentation, capital intensity, high leverage, etc. 相似文献