Influence of Isosceles Trapezoid Cross-section on the Reinforcement Effect of Stabilizing Piles

Changdong Li,Xinwang Liu,Qingtao Liu,Tao Liu 대한토목학회 2016 KSCE JOURNAL OF CIVIL ENGINEERING Vol.20 No.7

The paper conducts the study on the influence of isosceles trapezoid cross section on the reinforcement effect of stabilizing piles by employing the numerical modeling approach. On the basis of soil arching theory with end-bearing soil arching and friction soil arching, the modified mechanical model for the arbitrary isosceles trapezoid cross-section piles was proposed. The impacts of different slope ratios of the sidewall of the isosceles trapezoid cross-section piles on the displacement and load sharing of driving force were examined utilizing the explicit finite-difference software FLAC3D. The result of displacement contour graphs indicates that the stabilizing piles with trapezoid cross-section are better capable of resisting the deformation under the action of driving force. The logarithmic function between the load sharing percentage of end-bearing soil arching and slope ratio, and power function between the load sharing percentage of the friction soil arching and slope ratio were established for inner isosceles trapezoid crosssection piles. Similarly, the power function between the load sharing percentage of end-bearing soil arching and slope ratio was proposed for outer isosceles trapezoid cross-section piles. Furthermore, the reaction of soil arching on the stabilizing piles in view of the stress distribution discipline around piles was investigated. The result shows that the maximum vertical stress occurs in the back corners of stabilizing piles; consequently, the strength and rigidity of the back corners of stabilizing piles should be strengthened to resist the concentrated stress.

Orders-of-magnitude enhancement in conductivity tuning in InGaZnO thin-film transistors via SiNx passivation and dual-gate modulation

ChangDong Chen,ChenNing Liu,JiWen Zheng,GongTan Li,Shan Li,QianWu,JinWu,Chuan Liu 한국정보디스플레이학회 2019 Journal of information display Vol.20 No.3

The mobility of pristine amorphous indium gallium zinc oxide (a-IGZO) thin-film transistors (TFTs) is insufficient to meet the requirement of the future ultra-high-definition displays. Reported herein is the fabrication of hydrogenated long-channel IGZO TFTs exhibiting a transconductance and an on/off ratio that are orders of magnitude superior to those of the regular devices. The gate bias stability of the treated IGZO TFTs was greatly enhanced, with the threshold voltage shifting by less than 1 V after 1 h stress. Experimentally, the hydrogenation of the active layer was achieved via the deposition of a SiNx/SiOx bilayer on top of the IGZO via plasma-enhanced chemical vapor deposition followed by post-annealing under optimized conditions. The elemental depth profiles indicated that this enhanced performance originated from the hydrogen doping of the IGZO film. Furthermore, a dual-gate structure was fabricated to alleviate the deterioration of the subthreshold properties induced by the excess hydrogen doping.

Experimental and Modeling Analysis of Hydrogen Motion Behavior in Welding Zone of 2.25Cr–1Mo–0.25 V Steel Welded Joint with Hydrogen Corrosion

Changdong Yin,Dongdong Ye,Zhou Xu,Jianjun Chen,Yiwen Wu,Houli Liu,Xin Ge,Qiang Liu,Guiling Zeng 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.8

Understanding and solving the problem of hydrogen damage due to the degradation of service performance of high-strengthsteel caused by hydrogen penetration is a milestone for the reliability improvement of high-end hydrogen energy equipment. From the perspective of microscopic hydrogen movement behavior, this study investigated the permeability of hydrogenin base metal (BM) and welded metal (WM) of 2.25Cr–1Mo–0.25 V steel welded joint through electrochemical hydrogenpermeation test, and the analytical models of hydrogen penetration and hydrogen diffusion in the welding zone were established,and the effect of adding hydrogen-resistant coatings (HRCs) on hydrogen movement behavior in steel substrate wasstudied. The results showed that the diffusivity of hydrogen in WM of the welded joint was significantly lower than thatin BM, and the hydrogen concentration in BM was higher than that in WM at the beginning of hydrogenation without theaddition of HRCs protection, while it tended to be consistent at the later stage. However, the hydrogen concentration in WMwas lower than that in BM after adding HRCs and would be always higher than that in BM after a certain period of time,and the difference was directly related to the hydrogen resistance of the coatings. Additionally, the difference between theintermediate and outer layers for the welding zone steel substrate with and without HRCs presented a trend of rapid increasefollowed by a slow decrease. These findings could provide an important reference value for hydrogen damage protectionmeasures and related researches on HRCs.

Effect on tower crane structural vibration under the lifting-luffing coupling condition

Fu Liu,Jianwei Yang,Jinhai Wang,Changdong Liu,Xiaohui Wang 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.10

The present research aims to investigate parametrically the structural vibration analysis of tower crane under the lifting-luffing coupling condition. Structural vibration greatly affects tower crane stability. The structural dynamics of a crane should be considered for studying motion behavior and vibration feature. The dynamic model of the tower crane is presented based on air resistance, boom deflection, and Lagrange equation under the lifting-luffing coupling condition. The vibration model of the tower crane was validated by an experiment. The experiment was conducted with an accelerating speed until reaching the constant speed and then with decelerating speed. This study analyses structural parameters to acquire the dynamic characteristics and vibration features of the tower crane under the compound working condition. The vibration responses of the mast and the boom are studied with frequency- and timedomain indicators. Results show that payload mass, luffing acceleration, boom length, mast height, and girder length significantly influence the mast vibration. In comparison, payload mass, trolley acceleration, and boom length affect the boom vibration. This research can improve the design of a dynamic system for tower crane safety.

2D Coordination Polymer Derived Co3O4 Nanocrystals as High Performance Anode Material of Lithium-Ion Batteries

Hao Wen,Changdong Shi,Yuanrui Gao,Hongren Rong,Yanyong Sha,Hongjiang Liu,Qi Liu 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2018 NANO Vol.13 No.12

Co3O4 nanocrystals have been synthesized via an ordinary one-step calcination of a cobalt-based 2D coordination polymer [Co(tfbdc)(4,4'-bpy)(H2O)2]. As an anode material for lithium-ion batteries, the obtained Co3O4 nanocrystals exhibit high reversible capacity, excellent cyclic stability and better rate capability. The reversible capacity of the Co3O4 nanocrystals maintains 713mA h g-1 after 50 cycles at a current density of 50mA g-1. Our results confirm that searching for metal oxides nanomaterials used as anode materials of lithium ion batteries via the calcinations of 2D coordination polymer is a new route.

Optimal Isosceles Trapezoid Cross Section of Laterally Loaded Piles based on Friction Soil Arching

Junjie Wu,Changdong Li,Qingtao Liu,Fusong Fan 대한토목학회 2017 KSCE JOURNAL OF CIVIL ENGINEERING Vol.21 No.7

The paper presents a novel analytical solution to determine an optimal isosceles trapezoid cross-section of stabilizing piles subjected to the lateral load. In view of the pile-soil interaction mechanical analysis on the friction soil arching between the adjacent stabilizing piles, a general mechanical model for analyzing the behavior of the laterally loaded stabilizing piles with isosceles trapezoid cross-section is put forward. The reasonable net pile spacing expression for all kinds of isosceles trapezoid section piles is established via the analytical deduction, and it indicates that there is a positive relationship between the reasonable net pile spacing and gradient of pile sidewall. In consideration of the strength failure possibility in the apex of friction soil arching, the complete expressions of both the gradient of pile sidewall and corresponding reasonable net pile spacing of stabilizing piles can be established. The case study of Jinle landslide verifies that the reasonable pile spacing obtained by the presented model is slightly greater than that of the conventional design scheme, which shows that the stabilizing piles with optimal isosceles trapezoid cross-section can results in reducing the investment of the whole stabilizing piles.