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6 results on '"Wu, Yayue"'

4. Application of Metakaolin in Artificial Hydraulic Lime Repair Mortar.

Author

GU Lilong, SHANG Huaishuai, WU Yayue, MENG Weiguang, and HOU Guanhao

Subjects
LIME (Minerals), MECHANICAL drawing, MORTAR, BOND strengths, HISTORIC buildings, PRESERVATION of architecture
Abstract

In order to prepare a green inorganic restoration material that is suitable for the restoration of historical buildings, based on the XRD test results of the bonding materials of several historical brick masonry buildings in Qingdao, an artificial hydraulic lime repair mortar was prepared by mixing metakaolin. The influence of metakaolin on the artificial hydraulic lime mortar was studied by testing the fluidity, setting time, mass loss rate, dring shrinkage rate and mechanical properties. The results show that metakaolin can reduce the fluidity, shorten the setting time, reduce the dring shrinkage rate and improve the compressive strength and bonding strength of artificial hydraulic lime mortar. When the content is 5.0% and 7.5% (mass fraction), the 56 d compressive strength of artificial hydraulic lime mortar increases by 66. 8% and 94.3%, and the bond strength increases by 22.2% and 25.9%. Finally, XRD and SEM were used to test and analyze the microstructure of the materials. The results show that the main reason for the improvement of the performance of the artificial hydraulic lime mortar by metakaolin is that the active SiO2 and Al2 O3 in metakaolin react directly with the lime, and consume Ca(OH)2, which promotes the hydration of cement and enhances the bonding force between the hydrated products and the aggregate. [ABSTRACT FROM AUTHOR]

Published
2023

5. Estimate Utility Harmonic Impedance via the Correlation of Harmonic Measurements in Different Time Intervals

Author

Qin Shu, Fangwei Xu, Wu Yayue, and Hongru Zheng

Subjects
Field (physics), 020209 energy, Mathematical analysis, Energy Engineering and Power Technology, 02 engineering and technology, Interval (mathematics), Current source, Harmonic analysis, Modal, Norton's theorem, 0202 electrical engineering, electronic engineering, information engineering, Harmonic, Electrical and Electronic Engineering, Electrical impedance, Mathematics
Abstract

The existing methods estimating utility harmonic impedance usually require some assumptions such as the utility side is the dominant harmonic source and the harmonic impedance of customer side is much larger than that of the utility side, etc. However, these assumptions may not always hold in modern power grid. This paper proposes a novel method without any assumption, the estimation process only uses the correlation of the harmonic data measured at a point of common coupling (PCC). Through analysis of various field harmonic data, we find that measured data have short correlation characteristics, and there always exists a common weak correlation interval for the self-correlation and cross-correlation of the measured data. According to Norton equivalent circuit modal, it is easy to deduce that the utility harmonic current source is weak self-correlated in this interval. By selecting the self-correlation of the utility harmonic current source less than a small threshold, the utility harmonic impedance can be estimated accurately, whether the traditional assumptions are valid or not. In addition, the proposed method only requires a small sample size. Performance and effectiveness of the proposed method are verified through the simulation and field cases.

Published
2020

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