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20 results on '"Shao, Guo-jian"'

7. Safety Evaluation Method for High-Piled Wharf Structures Based on the Disturbing-Energy Method

Author

Su, Jing-Bo, Yang, Gan-Quan, Zhang, Li Min, Shao, Guo-Jian, Zhu, Rui-Hu, Su, Jing-Bo, Yang, Gan-Quan, Zhang, Li Min, Shao, Guo-Jian, and Zhu, Rui-Hu

Abstract

Many high-piled wharves were built in the last century, and some wharf members have been damaged over decades of operation. It is important to use effective means to evaluate the safety status and durability of these high-piled wharf structures and guide reinforcement efforts. At present, the most common safety status evaluation methods for high-piled wharves are site inspections, crack detection, and concrete strength tests. However, it is difficult to provide quantitative safety indicators using these methods. In this paper, a disturbing-energy method is proposed for the safety assessment of high-piled wharves based on the variational principle and minimum potential energy principle. The geometric nonlinear effect is introduced, and formulations are derived for calculating the disturbing energy. A concentric compression bar example is presented to validate the proposed method through a comparison analysis between the Euler method and disturbing-energy method. Through several cases involving different loads applied to the same high-piled wharf structure, the same load applied to different structures, overall stiffness degradation, and member damage, the disturbing-energy method is shown to reflect very well the safety condition or damage condition of the high-piled wharf structure. The disturbing-energy method can also be used to identify the failure path of the structure and optimize the form of the wharf structure. © 2020 American Society of Civil Engineers.

Published
2020

11. Influence of heterogeneity on mechanical and acoustic emission behaviours of stratified rock specimens.

Author

Li, Ang, Shao, Guo-jian, Su, Jing-bo, Sun, Yang, Yu, Tian-tang, and Shi, Hou-gai

Subjects
*ROCKS, *ACOUSTIC emission, *COMPUTER simulation, *COMPRESSION loads, *FINITE difference method, *DIGITAL image processing
Abstract

This paper investigates the influence of heterogeneity on mechanical and acoustic emission (AE) behaviours of stratified rock specimens under uniaxial compression using a digital image processing (DIP)-based finite difference method (FDM). In the DIP, a developed image segmentation algorithm based on seeded region growing (SRG) is proposed to fully acquire the mesostructure of stratified rock specimens, instead of the traditional threshold value method. To sufficiently capture the heterogeneity of stratified rock, Weibull statistical manner is adopted to describe mechanical properties of each material component. Three schemes are adopted to study the effect of heterogeneity with different homogeneity index and different mesostructure under two compression loading conditions. The results show that heterogeneity has a great influence on the mechanical and AE behaviours of stratified rock. As the homogeneity of material components increases, the peak strength and brittleness of rocks increase, and the macro elastic modulus improves as well. Simultaneously, the AE modes change from swarm shock to main shock. Under the same component content, the macro-property is better while the component distribution is concentrative relatively, especially to the property of strength. For the coupling effect of mesostructure and heterogeneity arising from material components, mesostructure is considered to cause the visible increase of AE counts. And the numerical results agree well with the previously numerical results and experimental data. [ABSTRACT FROM AUTHOR]

Published
2018
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20. DUSP2 deletion with CRISPR/Cas9 promotes Mauthner cell axonal regeneration at the early stage of zebrafish.

Author

Shao GJ, Wang XL, Wei ML, Ren DL, and Hu B

Abstract

Axon regeneration of central neurons is a complex process that is tightly regulated by multiple extrinsic and intrinsic factors. The expression levels of distinct genes are changed after central neural system (CNS) injury and affect axon regeneration. A previous study identified dusp2 as an upregulated gene in zebrafish with spinal cord injury. Here, we found that dual specificity phosphatase 2 (DUSP2) is a negative regulator of axon regeneration of the Mauthner cell (M-cell). DUSP2 is a phosphatase that mediates the dephosphorylation of JNK. In this study, we knocked out dusp2 by CRISPR/Cas9 and found that M-cell axons of dusp2 -/- zebrafish had a better regeneration at the early stage after birth (within 8 days after birth), while those of dusp2 +/- zebrafish did not. Overexpression of DUSP2 in Tg (Tol 056) zebrafish by single-cell electroporation retarded the regeneration of M-cell axons. Western blotting results showed that DUSP2 knockout slightly increased the levels of phosphorylated JNK. These findings suggest that knocking out DUSP2 promoted the regeneration of zebrafish M-cell axons, possibly through enhancing JNK phosphorylation., Competing Interests: None

Published
2023
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