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21.
Estimation of intersection turning movements is one of the key inputs required for a variety of transportation analysis, including intersection geometric design, signal timing design, traffic impact assessment, and transportation planning. Conventional approaches that use manual techniques for estimation of turning movements are insensitive to congestion. The drawbacks of the manual techniques can be amended by integrating a network traffic model with a computation procedure capable of estimating turning movements from a set of link traffic counts and intersection turning movement counts. This study proposes using the path flow estimator, originally used to estimate path flows (hence origin–destination flows), to derive not only complete link flows, but also turning movements for the whole road network given some counts at selected roads and intersections. Two case studies using actual traffic counts are used to demonstrate the proposed intersection turning movement estimation procedure. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
22.
Numerical analysis is used to optimize the gate shape of the mold part in the molding process. The objective of this research was to develop a procedure that will optimize the gate shape of the mold part by using Design of Experiments approach. The computer-aided engineering software Moldflow was used to simulate the plastic injection molding process and the Minitab software was used to analyze the computational results from Moldflow. The Bulk Molding Compounds (BMC) UNI-203S thermoset material was chosen as the molding material. Four different types of gate shapes were analyzed to find the gate shape to be used in the optimization. The Type 3 gate shape was selected as basis for the gate optimization because this shape yielded the minimum shear rate around the gate among all. The thickness, width, length and angle of the gate were selected as the design variables. Erosion around a gate due to repetitive shear flow during molding process was considered as an important issue to extend the service life of the expensive mold. It is normally very difficult to prevent erosion due to high injection pressure and repetitive use of the mold, especially in certain molding parts as BMC reflector in automotive parts, so it has become the subject of researches. The effectiveness of design variables was evaluated by observing shear rate around the gate. The objective of the optimization was to minimize the average shear rate around the gate. Response Surface Method was applied to identify the optimum values of the design variables. The computed optimum values were validated numerically. The optimized gate shape showed the reduced shear rate by about 11%. 相似文献
23.
Reliability-based topology optimization based on bidirectional evolutionary structural optimization using multi-objective sensitivity numbers 总被引:1,自引:0,他引:1
K. -H. Cho J. -Y. Park S. -P. Ryu J. -Y. Park S. -Y. Han 《International Journal of Automotive Technology》2011,12(6):849-856
Reliability-based topology optimization (RBTO) is used to obtain an optimal topology satisfying given constraints, as well
as to consider uncertainties in design variables. In this study, RBTO was applied to obtain an optimal topology for the inner
reinforcement of a vehicle’s hood based on bidirectional evolutionary structural optimization (BESO). A multi-objective topology
optimization technique was implemented to obtain the optimal topology for two models with different curvatures while simultaneously
considering the static stiffness of bending, torsion, and natural frequency. A performance measure approach (PMA) with probabilistic
constraints formulated in terms of the reliability index was employed to evaluate the probabilistic constraints. The optimal
topology obtained by RBTO was evaluated and compared to that obtained by deterministic topology optimization (DTO). A more
suitable topology was obtained through RBTO than DTO even though the final volume obtained by RBTO was generally slightly
greater than that obtained by DTO. The multiobjective optimization technique based on BESO can be applied very effectively
with topology optimization for a vehicle’s hood reinforcement. 相似文献
24.
Ryu Unsok Wang Jian Pak Unjin Kwak Sonil Ri Kwangchol Jang Junhyok Sok Kyongjin 《Transportation》2022,49(3):951-988
Transportation - There are significant spatiotemporal correlations among the traffic flows of neighboring road sections in the road network. Correctly identifying such correlations makes an... 相似文献
25.
Water management is an important factor in the optimal performance of a polymer electrolyte fuel cell (PEFC). In this paper,
a PEFC model that facilitates the control of PEFC membrane humidity is presented. An efficient modeling procedure using a
combination of mathematical and experimental techniques is proposed. A simple mathematical structure for the model is adopted,
and experiments to measure PEFC irreversibilities and net water transport across the membrane electrode assembly (MEA) are
performed. The developed PEFC model effectively quantifies the irreversibilities in the PEFC output voltage and clarifies
the relationship between PEFC performance and steady state water transport through the MEA. The proposed modeling procedure
can effectively save time and cost during the controller / control algorithm design phase in PEFC system development. 相似文献
26.
Rollover mitigation for a heavy commercial vehicle 总被引:1,自引:0,他引:1
Y. I. Ryu D. O. Kang S. J. Heo J. H. In 《International Journal of Automotive Technology》2010,11(2):283-287
A heavy commercial vehicle has a high probability of rollover because it is usually loaded heavily and thus has a high center
of gravity. An anti-roll bar is efficient for rollover mitigation, but it can cause poor ride comfort when the roll stiffness
is excessively high. Therefore, active roll control (ARC) systems have been developed to optimally control the roll state
of a vehicle while maintaining ride comfort. Previously developed ARC systems have some disadvantages, such as cost, complexity,
power consumption, and weight. In this study, an ARC-based rear air suspension for a heavy commercial vehicle, which does
not require additional power for control, was designed and manufactured. The rollover index-based vehicle rollover mitigation
control scheme was used for the ARC system. Multi-body dynamic models of the suspension subsystem and the full vehicle were
used to design the rear air suspension and the ARC system. The reference rollover index was tuned through lab tests. Field
tests, such as steady state cornering tests and step steer tests, demonstrated that the roll response characteristics in the
steady state and transient state were improved. 相似文献
27.
正鼓励电动汽车的大规模推广需要哪些条件?L.E.K(.艾意凯)咨询最新研究显示,要改变消费者的购买行为,不仅需要在公共充电基础设施上进行大量投资,还需要从根本上增强电动汽车相比于内燃发动机汽车在总体拥有成本方面的竞争力。近几年,针对电动汽车的投资日益增加。如表1所示,越来越多的政府正积极鼓励大众使用电动汽车。同时,越来越多的汽车制造商也正在计划生产开发更多不同型号的电动汽车。据分析人士估计, 相似文献
28.
The purpose of this study is to understand the operational characteristics of a diesel engine that uses BD20 reformed by ultrasonic
energy irradiation. In particular we study the effects of tuning injection delay and EGR rate. BD containing about 10% oxygen
has attracted attention due to soaring crude oil prices and environmental pollution. This oxygen decreases soot by promoting
combustion, but it also increases NOx. To solve this problem, injection timing may be delayed or an EGR system may be applied.
These adjustments normally lower engine power and increase exhaust emission but, in using fuel reformed by ultrasonic energy
irradiation (which is changed physically and chemically to promote combustion), we may hope to circumvent this problem. To
control the duration of the ultrasonic energy irradiation, the capacity of the chamber in an ultrasonic energy fuel supply
system was tested at 550cc and 1100cc capacities. As for the results of the experiment, we could identify the optimum EGR
rate by investigating the engine performance and the characteristics of exhaust emissions according to the injection timing
and the EGR rate while ultrasonically irradiated BD20 was fed to a commercial diesel engine. With UBD20 (at an injection timing
of BTDC 16°), the optimum EGR rate, giving satisfactory engine performance and exhaust emissions characteristics, was in the
range of 15∼20%. 相似文献