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- 저자 : Biqing Shi (검색결과 2 건)
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Improved the hydrogen sorption properties of MgH2 by CeMnZr solid solution
Ying Cheng,Wei Zhang,Biqing Shi,Siqi Li,Bing Dong,Yulian Quan,Xianbin Ji 한국화학공학회 2023 Korean Journal of Chemical Engineering Vol.40 No.1
Magnesium hydride (MgH2) is one of the promising solid-state hydrogen storage materials because of its high capacity, abundant resource and excellent reversibility. However, the high dehydrogenation temperatures and sluggish kinetics restrict its practical application. It was found that doping catalysts could significantly improve the hydrogen storage properties of MgH2. The solid solution Ce0.8Mn0.1Zr0.1O2 (denoted as CeMnZr) with abundant oxygen vacancy was synthesized and its catalytic influence on the hydrogen sorption properties of MgH2 have been investigated. CeMnZr modified MgH2 composite showed a reduced initial decomposition temperature, almost 62 K lower than the pristine MgH2. At 473 K, MgH2-CeMnZr composite had an absorption capacity of 4.08 wt% hydrogen within 3,500 s, which was about twice better than the pure MgH2 at same condition. MgH2-CeMnZr sample could desorb 2.56 wt% of H2 within 3,500 s at 573 K compared to low desorption rate and 0.85 wt% H2 by as-milled MgH2. The activation energy (Ea) for CeMnZr codoped MgH2 sample is about 50kJ·mol−1 lower than the milled MgH2. Based on the characteration analysis, the in-situ generated MgO and CeH2.51 species as well as abundant oxygen vacancy is believed to play synergistic catalytic effects in enhancing the hydrogen storage properties of MgH2.
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Field measurements of wind effects on a super high-rise building during typhoons
Chunlei Liu,Zhuangning Xie,Lele Zhang,Biqing Shi,Jiyang Fu,Ting Deng 한국풍공학회 2021 Wind and Structures, An International Journal (WAS Vol.33 No.5
Field measurement is the most reliable method to evaluate wind effects on super high-rise building; it is also the only approach to obtain actual structural dynamic properties. A self-developed wireless acceleration sensor was used to continuously monitor a 201 m high building in Shenzhen, and acceleration response signals atop the building during Typhoon Pakhar and Typhoon Mangkhut were obtained. The field data of approximately 58 hours were analyzed using random decrement technique and modified Bayesian spectral density approach, and the variation characteristics of the first two-order modal frequencies and damping ratios of the measured building under strong vibrations were obtained. Finally, field measurements of the maximum peak accelerations were compared with wind tunnel test results. Results show that (1) the frequencies decrease with increasing amplitude. In addition, they decreased initially and then increased with time, showing a “V” shape change. The maximum change rate of the frequencies was 11.5%. (2) During Typhoon Pakhar, the damping ratios were discrete. During Typhoon Mangkhut, the damping ratios increased with increasing amplitude in general, but the damping ratios were relatively discrete at small amplitudes. During Typhoon Mangkhut, the damping ratios increased initially, and then decreased with time. In addition, the first two-order damping ratios during the maximum wind speed were approximately 1.7% and 1.5%. (3) The wind tunnel test results are in good agreement with the field measurement results, thereby verifying the reliability of the wind tunnel test.
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