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RISS 인기검색어
- 검색키워드
- 저자 : Aimin Yuan (검색결과 5 건)
- 무료
- 기관 내 무료
- 유료
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Behavior and Efficiency of Corrosion Damaged Half-bottle Shaped Struts
Aimin Yuan,Donghui Xu,Shoulong Qian 대한토목학회 2018 KSCE Journal of Civil Engineering Vol.22 No.11
This study investigated the behaviors, strut efficiency factor, and the effective width of corrosion-damaged half-bottle shaped struts. Six half-bottle shaped struts were subjected to varying aimed corrosion levels (0%, 3%, 6%) with different reinforcement mat rotation angles (0o, 45o), and their behaviors and typical failure modes ascertained. Strut efficiency factors and effective width were calculated and evaluated. Average strength of 6% corroded struts was 30% less than those of uncorroded struts. The AASHTO LRFD 2013 process predicted strut efficiency factor of corrosion damaged struts better than ACI 318-14 and EN 1992. Strut effective width also reduced with increasing reinforcement corrosion. The theoretical effective width near the load bearing plate was underestimated compared to the measured effective width, while the effective width far from the load bearing plate was overestimated.
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Aimin Yuan,Tongyi Wang,Jinjian Gu,Xinge Miao,Jianrong Xu 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.10
Prefabricated post-tensioned prestressed concrete (PTC) girders with high degrees of prestressing have been developed continuously in recent bridge designs to reach longer spans, higher quality, and larger load-bearing capacity. However, during the prefabrication process, several inclined and horizontal cracks were observed at the ends of a new style post-tensioned concrete girder, which could have a negative impact on the girders' longevity. In this study, a nonlinear finite element analysis technique was utilized to illustrate how concrete reacts and the mechanisms behind typical cracking patterns during the actual post-tensioning sequence. The prestressing load of a PTC girder was simulated with an improved cooling temperature method that accounts for immediate prestress losses. The field of principle tensile strain patterns and primary strain trajectories explained the overall mechanism underlying typical cracking behaviors. The results showed that the horizontal cracks under the anchorage plate (behavior 1) were generated by the bursting force, whereas the inclined cracks (behavior 2) and the horizontal cracks between the strands N1 and N2 anchor plates (behavior 3) were caused due to the spalling force. The effects of self-weight, girder end forms, as well as the transfer length of the prestressing strands, were discussed. The result demonstrates that both the self-weight and girder end shapes have a considerable effect on the behaviors of the anchorage zone. It is suggested that the transfer length of the anchor head be greater than 26 times of strand diameter to achieve the same effective stresses as the theoretical values.
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Aimin Ji,Xu Yin,Minghai Yuan 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.9
There are two problems in Collaborative optimization (CO): (1) the local optima arising from the selection of an inappropriate initialpoint; (2) the low efficiency and accuracy root in inappropriate relaxation factors. To solve these problems, we first develop the Latinhypercube design (LHD) to determine an initial point of optimization, and then use the non-linear programming by quadratic Lagrangian(NLPQL) to search for the global solution. The effectiveness of the initial point selection strategy is verified by three benchmark functionswith some dimensions and different complexities. Then we propose the Adaptive relaxation collaborative optimization (ARCO)algorithm to solve the inconsistency between the system level and the disciplines level, and in this method, the relaxation factors are determinedaccording to the three separated stages of CO respectively. The performance of the ARCO algorithm is compared with the standardcollaborative algorithm and the constant relaxation collaborative algorithm with a typical numerical example, which indicates thatthe ARCO algorithm is more efficient and accurate. Finally, we propose a Hybrid collaborative optimization (HCO) approach, whichintegrates the selection strategy of initial point with the ARCO algorithm. The results show that HCO can achieve the global optimalsolution without the initial value and it also has advantages in convergence, accuracy and robustness. Therefore, the proposed HCO approachcan solve the CO problems with applications in the spindle and the speed reducer.
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Hanyu Zhu,Yuan Yuan,Juan Liu,Liesheng Zheng,Liguo Chen,Aimin Ma 한국미생물학회 2016 The journal of microbiology Vol.54 No.5
To gain insights into dimorphism, cell wall polysaccharides from Tremella fuciformis strains were obtained from alkaliextracted water-soluble fractions PTF-M38 (from the mycelial form), PTF-Y3 and PTF-Y8 (from the yeast form) of T. fuciformis strains were used to gain some insights into dimorphism study. Their chemical properties and structural features were investigated using gel permeation chromatography, gas chromatography, UV and IR spectrophotometry and Congo red binding reactions. The results indicated that the backbones of PTF-M38, PTF-Y3 and PTF-Y8 were configured with α-linkages with average molecular weights of 1.24, 1.08, and 1.19 kDa, respectively. PTF-M38 was mainly composed of xylose, mannose, glucose, and galactose in a ratio of 1:1.47:0.48:0.34, while PTF-Y3 and PTF-Y8 were mainly composed of xylose, mannose and glucose in a ratio of 1:1.65:4.06 and 1:1.21:0.44, respectively. The sugar profiles of PTF-M38, PTF-Y3 and PTF-Y8 were also established for further comparison. These profiles showed that all three polysaccharides contained the same sugars but in different ratios, and the carbon sources (xylose, mannose, glucose, and galactose) affected the sugar ratios within the polysaccharides.
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Jianzu Liao,Weihua Zhou,Jie Xu,Xiangcheng Yuan,Yuxian Liang,Yajuan Guo,Hui Huang,Sheng Liu,Aimin Long 한국해양과학기술원 2019 Ocean science journal Vol.54 No.4
The effects of a simulated climate change scenario, i.e., increased ultraviolet radiation (UVR) and dissolved organic carbon (DOC), on the growth and photosynthesis of tropical coastal phytoplankton were evaluated in Sanya Bay, northern South China Sea, in summer. Microcosm experiments were conducted at two contrasting stations (Stns S1 and S2) with three different UVR treatments and two DOC addition treatments. Our results showed that natural sunlight UVR or increased UV-B did not affect phytoplankton biomass and primary production. However, increased UV-B significantly decreased the proportion of picophytoplankton and the efficiency of carbon fixation at Stn S2. DOC enhancement caused negative effects on primary production under natural sunlight UVR only at Stn S1. Interactive effects of UVR and DOC addition on phytoplankton biomass and primary production were detected at Stn S1, due to the negative effects of DOC being eliminated under the increased UV-B condition. The lack of interactive effects at Stn S2 were likely due to the differences with Stn S1 in terms of light acclimation and biological interaction. In summary, this future climate change scenario will probably not affect the photosynthetic CO2 fixation and biomass of natural phytoplankton in Sanya Bay.
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