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- He, Liang, et al.
(författare)
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Discrete element simulation of porous asphalt mixture clogging law
- 2023
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Ingår i: Jiaotong Yunshu Gongcheng Xuebao/Journal of Traffic and Transportation Engineering. - : Chang'an University. - 1671-1637. ; 23:2, s. 78-91
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Tidskriftsartikel (refereegranskat)abstract
- To reveal the pore clogging law of porous asphalt mixture, the combination study of model experiment and simulation of porous asphalt mixture clogging was conducted. The pore characteristics of the porous asphalt mixture were analyzed based on the CT-scanning and discrete element software PFC3D V5. 0, and the pore data of the porous asphalt mixture were obtained. The aggregates of different particle sizes were put into PFC3D V5. 0, and the compacted virtual specimens were generated according to the pore characteristics. The accuracy of the model was verified by comparing the pore images of actual specimens with the MATLAB slices. In the self-weight condition, the simulation was set with the porous asphalt mixture specimen being intruded by clogging particles with specific gradation composition. The data of indoor experiments were compared and verified. The particle sizes of clogging particles were changed, and the pore decay rates of the specimen were analyzed. The clogging-sensitive particles were identified. In the self-weight condition, the fluid simulation experiment was introduced, and the change law of specimen clogging was analyzed by changing the seepage rate of fluid. Analysis results show that the virtual specimen generated by PFC3D V5. 0 has high accuracy, and the simulation reveals the clogging law of the specimen. The small particles not only accumulate at the throat position causing clogging, but also congregate and interlock with the particles of larger sizes resulting in clogging too. In the self-weight condition, the clogging is mainly concentrated at the upper 30 mm of the mixture specimen, and the size distribution of corresponding clogging-sensitive particles is 0. 150-0. 600 mm. The size distribution of clogging particles has a great impact on the clogging results. In the conditions of gravity and fluid, with the seepage rate increasing from 0. 005 m • s-1 to 0. 030 m • s-1, the changing rate of pore decay rate increases. In addition, the clogging particles remaining in the mixture decrease, accompanied by the reduction of the pore decay rate. Therefore, the local rainfall conditions should also be considered in the design and maintenance of drainage asphalt pavement. 2 tabs, 20 figs, 30 refs. © 2023 Chang'an University. All rights reserved.
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| 2. |
- Wang, R. -M, et al.
(författare)
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Research progress on test scenario of autonomous driving
- 2021
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Ingår i: Jiaotong Yunshu Gongcheng Xuebao/Journal of Traffic and Transportation Engineering. - : Chang'an University. - 1671-1637. ; 21:2, s. 21-37
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Tidskriftsartikel (refereegranskat)abstract
- Five existing definitions of autonomous driving test scenario were expounded, and the definitions of autonomous driving test scenario and related concepts were proposed by combining the logical relationships between test scenario, primitive scenario, and scenario elements. Three test scenario architectures of autonomous driving that are recognized in the industry were compared. From the perspective of scenario data sources, the current situation in the collection and research of traffic accident and naturalistic driving data at home and abroad was summarized. Based on the known data, expert data, test requirements, test objects, and technical characteristics of autonomous driving, the research results on the construction and automatic generation of unknown autonomous driving test scenarios were summarized. Research results show that the definition and architecture of autonomous driving test scenario are closely related to its construction and automatic generation. The autonomous driving scenario can be considered as an organic combination and comprehensive reflection of scenario elements, such as the driving environment, traffic participants, and driving behavior of autonomous vehicle. In addition to these elements, autonomous driving test scenarios should include a dynamic semantic description of initial state of the scenario, the situation of the scenario, and the impact and results at the end of the scenario. Although the existing test scenario architecture is relatively perfect, it is difficult to meet the requirements of different test objectives and test methods. Therefore, in the optimization of test scenario architecture, the design process of test scenario should be considered. However, the collection accuracy and effective characteristics of traffic accident data are not uniform, which makes it difficult to achieve the complete collection of naturalistic driving scenario data, and the collection specifications are not standardized. Therefore, the effectiveness of traffic accident and naturalistic driving data for the construction of autonomous driving test scenarios must be further demonstrated, and the autonomous driving test data are expected to become an important supplement. Improving scenario coverage and accelerating the testing process are important research goals in the construction of autonomous driving test scenarios. The in-depth application of artificial intelligence technology in the field of autonomous driving scenario generation is expected to meet complete or high coverage requirements of test scenarios. The classification of test scenarios for different levels of autonomous driving and the test scenario construction method for accelerated test of autonomous driving will be the next important research directions in test scenario construction for autonomous driving. 7 figs, 103 refs.
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