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242 results on '"Chen, Zuyu"'

7. Boundary-Aware Polyp Segmentation Network

Author

Lu, Lu, Zhou, Xitong, Chen, Shuhan, Chen, Zuyu, Yu, Jinhao, Tang, Haonan, Hu, Xuelong, Goos, Gerhard, Founding Editor, Hartmanis, Juris, Founding Editor, Bertino, Elisa, Editorial Board Member, Gao, Wen, Editorial Board Member, Steffen, Bernhard, Editorial Board Member, Yung, Moti, Editorial Board Member, Yu, Shiqi, editor, Zhang, Zhaoxiang, editor, Yuen, Pong C., editor, Han, Junwei, editor, Tan, Tieniu, editor, Guo, Yike, editor, Lai, Jianhuang, editor, and Zhang, Jianguo, editor

Published
2022
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44. Erosion-control mechanism of sediment check dams on the Loess Plateau

Author

Shu Yu, Qiang Zhang, Chen Zuyu, Hao Jianwei, Zhaoyin Wang, and Wang Yu

Subjects
Hydrology, geography, geography.geographical_feature_category, Erosion control, Stratigraphy, 0207 environmental engineering, Foundation (engineering), Reforestation, Sediment, Geology, 02 engineering and technology, Vegetation, 010501 environmental sciences, 01 natural sciences, Tributary, Erosion, 020701 environmental engineering, 0105 earth and related environmental sciences, Check dam
Abstract

Severe soil erosion occurs on the Loess Plateau in China, which makes the Yellow River the most sediment-laden river in the world. Construction of about 60,000 sediment check dams has remarkably controlled soil erosion on the Loess Plateau and reduced the sediment load of the middle and lower Yellow River. Nonetheless, little is known about the mechanism of erosion control and vegetation development of sediment check dams. The function of a single check dam mainly is trapping sediment, while the function of a train of check dams comprising dozens of or over hundreds of check dams in a gully encompasses controlling bed incision and reducing erosion energy. A formula was proposed to calculate the potential energy of bank failure and slope failure in a gully, which essentially constitutes the erosion energy. The erosion energy increases when gully incision occurs, which is induced by the incision of the Yellow River and its tributaries on the Loess Plateau. Sediment deposition in many gullies due to construction of check dams reduces the erosion energy to almost zero, which in turn greatly reduces soil erosion and sediment yield. Construction of check dams promotes vegetation development. The vegetation-erosion dynamics model was used to study the effect of check dams on vegetation development. Simulation results show that reforestation without check dam construction might result in an increase of vegetation cover in the first ten years and then a drop of vegetation cover to less than 10% in the later years. The check dams provide a foundation for vegetation development.

Published
2021

45. Experimental study on the process of overtopping breach of concrete-faced sand-gravel dam

Author

Chen Zuyu, Lin Wang, Yanlong Li, Wen Qiu, and Lifeng Wen

Subjects
Pore water pressure, Environmental Engineering, Slab, Process (computing), Geotechnical engineering, Geology, Civil and Structural Engineering, Leakage (electronics)
Abstract

A concrete-faced sand-gravel dam (CFSGD) is likely to experience a dam breaching accident once there is leakage through the concrete face slab joints or overtopping of the dam. This study aimed to ...

Published
2021

46. Risk analysis for clustered check dams due to heavy rainfall

Author

Dang Weiqin, Xieping Huang, Cao Wei, Yangqiang Wang, Shu Yu, and Chen Zuyu

Subjects
Hydrology, Upstream (petroleum industry), Return period, geography, geography.geographical_feature_category, Warning system, Stratigraphy, 0207 environmental engineering, Geology, Storm, 02 engineering and technology, 010501 environmental sciences, 01 natural sciences, Current (stream), Flood control, Tributary, Environmental science, 020701 environmental engineering, reproductive and urinary physiology, 0105 earth and related environmental sciences, Check dam
Abstract

Check dams are commonly constructed around the world for alleviating soil erosion and preventing sedimentation of downstream rivers and reservoirs. Check dams are more vulnerable to failure due to their less stringent flood control standards compared to other dams. Determining the critical precipitation that will result in overtopping of a dam is a useful approach to assessing the risk of failure on a probabilistic basis and for providing early warning in case of an emergency. However, many check dams are built in groups, spreading in several tributaries in cascade forms, comprising a complex network. Determining the critical precipitation for dam overtopping requires a knowledge of its upstream dams on whether they survived or were overtopped during the same storm, while these upstream dams in turn need the information for their upstream dams. The current paper presents an approach of decomposing the dam cluster into (1) the heading dam, (2) border dams, and (3) intermediate dams. The algorithm begins with the border dams that have no upstream dams and proceeds with upgraded maps without the previous border dams until all the dams have been checked. It is believed that this approach is applicable for small-scale check dam systems where the time lag of flood routing can be neglected. As a pilot study, the current paper presents the analytical results for the Wangmaogou Check Dam System that has 22 dams connected in series and parallel. The algorithm clearly identified 7 surviving dams, with the remaining ones being overtopped for a storm of 179.6 mm in 12 h, which is associated with a return period of one in 200 years.

Published
2021

47. A Rapid Gradation Detection System for Earth and Stone Materials Based on Digital Image

Author

Zhang Guoying, Shu Yu, Chen Zuyu, Wen Yanfeng, Qiang Zhang, Hao Jianwei, and Wang Yujie

Subjects
Article Subject, Computer science, business.industry, Compaction, Engineering (General). Civil engineering (General), Thresholding, Edge detection, Digital image, Digital image processing, Earthworks, Gradation, Computer vision, Artificial intelligence, TA1-2040, business, Civil and Structural Engineering
Abstract

Gradation has an important influence on the mechanical properties of earth and stone materials after compaction, and a reasonable gradation is the key to ensure compaction quality. In this paper, a set of earth and stone materials gradation detection system based on digital image processing was proposed, which was suitable for detection in the construction sites. The system obtained images which were taken from multiple directions of materials transport vehicle, used the thresholding method to segment the images, detected particle contours through edge detection algorithm of Canny to realize the image recognition of particle size, and drew the gradation curve of earth and rock materials finally. It was verified by selecting limestone aggregates of different gradations, and the results showed high accuracy. The system can realize on-site detection of the earthwork gradation rapidly and accurately at a dam construction site.

Published
2021

48. Investigations on corrosion and mechanical properties of a 20 year old ground anchor exhumed at a power station site

Author

Wang, Yujie, Ren, Aiwu, Wang, Yanshu, He, Jiquan, and Chen, Zuyu

Subjects
Anchorage (Structural engineering) -- Mechanical properties -- Chemical properties, Hydroelectric power plants, Corrosion and anti-corrosives -- Observations, Earth sciences
Abstract

This paper presents the observed findings and laboratory test results of an anchor exhumed from Manwan Hydropower Station, China, that was installed 20 years ago. The prestressed cables are 25.6 m long with a working load of 1000 kN. It consists of eight strands, and each strand consists of seven wires. The anchor was installed using the 'single protection' technique (i.e., the steel strands without greased sheath and were backfilled directly with cement mortar). The anchor was unearthed by excavating a 1.5 m x 1.7 m tunnel. Visual inspection shows that the steel strands in the free and fixed lengths are basically stainless except for a few places where the grout failed to cover the anchor completely, thereby allowing direct contact of the strands with air. The magnitude of rebound of the tendon during the advancement of the tunnel face was simultaneously measured indicating a gradual release of bonding force, which was up to 62% of the prestressed load. This shows that the existence of the bonding force is provided by the bonding between the strand and the grout, while this bonding does not exist in the 'double protection' system. The results of the mechanical test confirm that the tensile strengths in all the 33 steel wires exceed the requirement as specified by a current Chinese Standard. The concentrations of various chemicals also satisfy the requirements as specified by the China State Bureau of Quality Technical Supervision. The results of the X-ray diffraction test show that the stains taken from the surface of the strand are composed of FeO and FeOOH, both being oxide products of iron. This shows that exposure of the material to air is an important condition to initiate corrosion. By following the ASTM International G1-03 test procedure, the average corrosion rate is found to be between 3 x [10.sup.-4] and 6 x [10.sup.-4] mm/year. This investigation generally supports the use of unprotected steel strands in rock anchor. Key words: ground anchor, long-term serviceability, prestressed tendon. Le present article decrit les resultats d'essais realises en laboratoire et les observations effectuees sur un systeme d'ancrage deterre sur le site de la centrale hydroelectrique de Manwan, en Chine, et mis en place il y a 20 ans. Les cables precontraints sont longs de 25,6 m et peuvent supporter une charge normale de 1000 kN. Ils sont constitues de huit cables de gros diametre, eux-memes composes de sept cables de plus petit diametre. Le dispositif d'ancrage a ete mis en place selon la technique de<>(c.-a-d. que les gros cables en acier n'ont pas ete graisses et gaines et qu'ils ont directement ete recouverts d'un mortier en ciment). Pour deterrer ce dispositif, on a creuse un tunnel de 1,5 m sur 1,7 m. Une inspection visuelle a montre que les gros cables en acier etaient pour la plupart inoxydables dans leur portion non ancree, hormis a quelques endroits ou le coulis de ciment n'avait pas completement recouvert le dispositif d'ancrage, ce dernier etant alors directement en contact avec l'air. L'amplitude de retraction des gros cables a ete mesuree simultanement en divers points a mesure de l'avancee du front du tunnel. On a ainsi pu mettre en evidence une diminution de la force d'ancrage pouvant atteindre 62 % de la precontrainte. Cela montre que la force d'ancrage est due a l'adherence entre les gros cables et le coulis de ciment, cette adherence etant inexistante dans le cas du systeme a <>. Les resultats de l'essai mecanique confirment que les valeurs de resistances a la traction mesurees sur l'ensemble des 33 cables en acier surpassent les exigences figurant dans les normes chinoises actuellement en vigueur. Les concentrations des divers produits chimiques en presence respectent egalement les exigences imposees par le China State Bureau of Technical Supervision. Les resultats de l'analyse diffractometrique aux rayons X montrent que les taches de corrosion presentes a la surface des cables sont composees de FeO et de FeOOH, les deux etant des produits de l'oxydation du fer. Cela montre que l'exposition du cable a l'air est un facteur important qui contribue a amorcer la corrosion. En suivant la methode d'essai G1-03 de l'ASTM International, on obtient une vitesse moyenne de corrosion comprise entre 3 x [10.sup.- 4] et 6 x [10.sup.-4] mm/an. La presente etude est favorable a l'utilisation de cables en acier dans le cas des dispositifs d'ancrage recouverts de roches. [Traduit par la Redaction] Mots-cles: ancrage dans le sol, aptitude au service a long terme, cable precontraint., Introduction While more and more ground anchors have been used in geotechnical engineering, the concerns over their long-term reliability and durability have never been resolved. Based on a review of [...]

Published
2016
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