Grouting to Prevent Sulfate Corrosion on Coal Mine Shaft

Gang-Gang Xu,Shuan-Cheng Gu,Xiao-Dong Wang,Hai Wang,Shi-Bin Zhu 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.11

In the area of high sulfate concentration in China, the problem of sulfate corrosion in coal mine shaft is increasingly prominent. Currently, shaft repair methods are limited to diversion, interception, and backwall grouting. However, after conventional cement stabilization, shafts still must contend with poor durability and weak resistance to sulfate corrosion. To solve these problems, this study combined theoretical research, laboratory tests, and field tests to reveal the corrosion mechanism of shafts, explored novel anti-sulfate corrosion grout, and built a model for the migration of sulfate ions (SO42−) in strata and shafts. According to the results of this study, shaft corrosion was a process of continuous penetration towards the concrete interior following a cycle of concrete compaction, expansion, and cracking. Laboratory tests show that the specimens of ordinary Portland cement mortar with 20 – 30% fly ash not only have good long-term strength, but also have a significantly improved resistance capacity to sulfate solution. Based on the laboratory test results, the HSR42.5 mixed with 20% fly ash was used for wall grouting, and the water-cement ratio of the slurry was 1:1. After wall grouting, the water inflow was effectively controlled in the grouting area in the main shaft, auxiliary shaft, and air shaft, reducing from 18.5 m3/h, 20.9 m3/h, and 10.0 m3/h to 3.5 m3/h, 4.6 m3/h, and 3.2 m3/h, respectively. Moreover, after nearly three years of continuous monitoring, the water inflow did not show any significant increase in the shafts. Based on the migration law of SO42− in concrete, a shaft geological model and a salt solution migration model after grouting reinforcement under sulfate corrosion conditions were constructed. In addition, the analysis of the migration law of sulfate ion in the shaft and grouting reinforcement formation revealed that the service period of the grouting shaft can be extended for approximately 6 – 8 years.

Serum lipocalin-2 is a potential biomarker for the clinical diagnosis of nonalcoholic steatohepatitis

( Gang Xu ),( Yu-min Wang ),( Miao-miao Ying ),( Sui-dan Chen ),( Zong-rui Li ),( Hong-lei Ma ),( Ming-hua Zheng ),( Jian Wu ),( Chunming Ding ) 대한간학회 2021 Clinical and Molecular Hepatology(대한간학회지) Vol.27 No.2

Background/Aims: Nonalcoholic steatohepatitis (NASH) is a progressive form of nonalcoholic fatty liver disease (NAFLD) characterized by hepatic steatosis, inflammation, hepatocellular injury, and fibrosis. We aimed to investigate the usefulness of a key biomarker, lipocalin-2 (LCN2), for the detection of NASH progression. Methods: A mouse NASH model was established using a high-fat diet and a high-sugar drinking water. Gene expression profile of the NASH model was analyzed using RNA sequencing. Moreover, 360 NAFLD patients (steatosis, 83; NASH, 277), 40 healthy individuals, and 87 patients with alcoholic fatty liver disease were recruited. Results: Inflammatory infiltration, focal necrosis in the leaflets, steatosis, and fibrosis were documented in the mouse liver. In total, 504 genes were differentially expressed in the livers of NASH mice, and showed significant functional enrichment in the inflammation-related category. Upregulated liver LCN2 was found to be significantly interactive with various interleukins and toll-like receptors. Serum LCN2 levels were significantly increased in NAFLD patients. Serum LCN2 levels were correlated with steatosis, intralobular inflammation, semiquantitative fibrosis score, and nonalcoholic fatty liver disease activity score. The area under the curve of serum LCN2 was 0.987 with a specificity of 100% and a sensitivity of 93.5% for NASH diagnosis, and 0.977 with almost the same specificity and sensitivity for steatosis. Conclusions: LCN2 might be involved in the transition from NAFL to NASH by mediating inflammation. Serum LCN2 levels might be a novel biomarker for the diagnosis of NASH. (Clin Mol Hepatol 2021;27:329-345)

Customer Sentiment Analysis: Take Restaurant Online Reviews as an Example

Xu Gang 사단법인 미래융합기술연구학회 2020 아시아태평양융합연구교류논문지 Vol.6 No.6

The customer's sentiment analysis can fully grasp the customer's consumption trends and the popularity of the product. This article takes the restaurant's online reviews as an example and uses machine learning algorithms to analyze the customer's sentiment tendency. The research describes the overall process of sentiment analysis, and discusses the implementation methods of corpus acquisition, feature extraction, feature selection, expanded sentiment dictionary construction, and determination of class labels. The training method of machine learning sentiment analysis model is analyzed. After the experimental analysis of the obtained corpus, the experimental results are given through the chart. The C4.5, Bagging, Multinomial naïve bayes algorithm has achieved good results.

Experimental study and analysis on physicochemical properties of coal treated with clean fracturing fluid for coal seam water injection

Gang Zhou,Cunmin Wang,Qi Wang,Yixin Xu,Zhanyi Xing,Baoyong Zhang,Cuicui Xu 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.108 No.-

In the process of coal seam water injection, the components of different fracturing fluids have differenteffects on coal. To analyze the effect of water injection fracturing fluid on the physical and chemical propertiesof coal, we studied the relationship between guar-based fracturing fluid and cationic clean fracturingfluid (C-VES). Microscopic experiments show that guar-based fracturing fluid has a certain viscosityeffect on coal, while C-VES can adsorb and capture the primary coal dust in coal. FTIR analysis shows thatC-VES has a great change on the content of coal functional groups, and guar-based fracturing fluid haslittle effect on coal. Industrial analysis shows that C-VES can better reduce the ash content of coal andhas a certain impact on the thermal efficiency of coal than guar based fracturing fluid. Combustion characteristicexperiment shows that guar-based fracturing fluid does not affect the combustion effect of coal,and C-VES can expand the exothermic temperature range of coal but has little effect on the main combustionof coal. Molecular dynamics simulation results show that C-VES has the best wetting effect oncoal. This research provides theoretical guidance for dust prevention and improving the use and conversionefficiency of coal.

Numerical simulation of fully nonlinear sloshing waves in three-dimensional tank under random excitation

Xu, Gang,Hamouda, A.M.S.,Khoo, B.C. Techno-Press 2011 Ocean systems engineering Vol.1 No.4

Based on the fully nonlinear velocity potential theory, the liquid sloshing in a three dimensional tank under random excitation is studied. The governing Laplace equation with fully nonlinear boundary conditions on the moving free surface is solved using the indirect desingularized boundary integral equation method (DBIEM). The fourth-order predictor-corrector Adams-Bashforth-Moulton scheme (ABM4) and mixed Eulerian-Lagrangian (MEL) method are used for the time-stepping integration of the free surface boundary conditions. A smoothing scheme, B-spline curve, is applied to both the longitudinal and transverse directions of the tank to eliminate the possible saw-tooth instabilities. When the tank is undergoing one dimensional regular motion of small amplitude, the calculated results are found to be in very good agreement with linear analytical solution. In the simulation, the normal standing waves, travelling waves and bores are observed. The extensive calculation has been made for the tank undergoing specified random oscillation. The nonlinear effect of random sloshing wave is studied and the effect of peak frequency used for the generation of random oscillation is investigated. It is found that, even as the peak value of spectrum for oscillation becomes smaller, the maximum wave elevation on the side wall becomes bigger when the peak frequency is closer to the natural frequency.

Ultrasmall Gd₂O₃ nanoparticles surface-coated by polyacrylic acid (PAA) and their PAA-size dependent relaxometric properties

Miao, Xu,Xu, Wenlong,Cha, Hyunsil,Chang, Yongmin,Oh, In Taek,Chae, Kwon Seok,Tegafaw, Tirusew,Ho, Son Long,Kim, Sung June,Lee, Gang Ho Elsevier 2019 APPLIED SURFACE SCIENCE - Vol.477 No.-

<P><B>Abstract</B></P> <P>Ultrasmall Gd<SUB>2</SUB>O<SUB>3</SUB> nanoparticles can potentially be used as a positive magnetic resonance imaging (MRI) contrast agent owing to their high content of Gd(III), which exhibits the highest spin magnetic moment of all elements due to its seven unpaired 4<I>f</I> electrons. Herein, the above nanoparticles (average diameter = 2.0 nm) were coated with hydrophilic biocompatible polyacrylic acids (PAAs) of different molecular weights (<I>M</I> <SUB>w</SUB> = 1200, 5100, 15000 Da), and the PAA-size-dependent relaxometric properties of the thus obtained composites were investigated. In addition, the biocompatibility of these composites was assessed by <I>in-vitro</I> cell viability measurements. Finally, dose-dependent <I>R</I> <SUB>1</SUB> map images were acquired, proving that PAA-coated nanoparticles can be used as a <I>T</I> <SUB>1</SUB> MRI contrast agent.</P> <P><B>Highlights</B></P> <P> <UL> <LI> PAA-coated ultrasmall Gd<SUB>2</SUB>O<SUB>3</SUB> nanoparticles showed PAA-size dependent relaxometric properties. </LI> <LI> Both <I>r</I> <SUB>1</SUB> and <I>r</I> <SUB>2</SUB> values decreased with increasing PAA size (<I>M</I> <SUB>w</SUB> = 1200, 5100, 15000 Da). </LI> <LI> All samples showed good biocompatibility. </LI> <LI> All samples can be potential <I>T</I> <SUB>1</SUB> MRI contrast agents. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Numerical Analysis on Mechanical Property of Concrete Filled Steel Tube Reinforced Concrete (CFSTRC) Columns Subjected to ISO-834 Standard Fire

Lei Xu,Lei Xu,Wen-Da Wang,Jian-Gang Sun 한국강구조학회 2017 International Journal of Steel Structures Vol.17 No.4

The present study established a numerical investigation on the behavior of concrete filled steel tube reinforced concrete (CFSTRC) columns subjected to fire. A finite element analysis (FEA) model was built to simulate the performance of CFSTRC columns under combined loading and fire. The FEA model was verified by the experimental results of CFSTRC columns subjected to fire. The comparison demonstrated an acceptable accuracy for the proposed FEA model. Afterwards, the FEA model was used to analyze the failure modes, the redistribution of internal force, the changes and development of the stress and strain, and the contact stress between the tube and concrete of CFSTRC columns subjected to fire. Influencing factors that may affect the bearing capacity of the CFSTRC columns subjected to fire were analyzed. The bearing capacity and stiffness of the CFSTRC columns gradually decreased in the fire; the parameters such as the fire duration time, sectional dimension, slenderness ratio, and sectional core area ratio significantly influenced the bearing capacity of the CFSTRC columns. Finally, a simplified calculating formula was proposed to calculate the influence factors of the bearing capacity of the CFSTRC columns subjected to ISO-834 standard fire. The formula-calculated results were well in agreement with the finite element analysis results, which provide a simple and feasible method for evaluating the fire-resistance design of these types of components in practical engineering.

Fibulin-5 is a Prognostic Marker that Contributes to Proliferation and Invasion of Human Glioma Cells

Sheng, Xu-Dong,Chen, Hu,Wang, Hui,Ding, Zhi-Bin,Xu, Gang-Zhu,Zhang, Jun-Feng,Lu, Wen-Chao,Wu, Tao,Zhao, Ling Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.2

Fibulin-5 has recently been considered as a potential tumor suppressor in human cancers. Several studies have shown that it is down-regulated in a variety of tumor types and inhibits tumor growth and metastasis. This study was aimed to investigate the clinical significance of fibulin-5 in glioma and its role in cell proliferation and invasion. We found that the expression of fibulin-5 in glioma tissues was significantly lower than those in normal brain (NB) tissues. Negative expression was significantly correlated with advanced clinical stage (grade III+IV). Furthermore, Fibulin-5 negative expression was correlated with a shorter overall survival of glioma patients. Multivariate Cox repression analysis indicated that fibulin-5 was an independent factor for predicting overall survival of glioma patients. Overexpression obviously inhibited cell proliferation in U251 and U87 cells. Furthermore, it significantly reduced the number of migrating and invading glioma cells. In conclusion, impaired expression of fibulin-5 is correlated with the advanced tumor stage in glioma. Otherwise, Fibulin-5 is an independent prognostic marker for predicting overall survival of glioma patients. Mechanistically, it may function as a tumor suppressor via inhibiting cell proliferation and invasion in gliomas.

Connectivity-preserving-based Distributed Synchronized Tracking of Networked Uncertain Underactuated Surface Vessels with Actuator Failures and Unknown Control Directions

Yujing Xu,Chaoli Wang,Gang Wang,Xuan Cai,Luyan Xu,Chonglin Jing 제어·로봇·시스템학회 2021 International Journal of Control, Automation, and Vol.19 No.12

When the actuator faults and the control directions are unknown, the difficulty of the asymptotically tracking control of the surface vessel will increase. In this paper, for actuator failures and unknown control directions, a distributed adaptive asymptotically synchronous tracking control law for multiple uncertain underactuated surface vessels (USVs) is proposed, which can achieve network connectivity and good tracking performance in a limited communication range. First, a distributed nonlinear error surface is introduced to achieve synchronous tracking between USVs and maintain the initial connectivity patterns. Second, a conditional inequality is proposed to solve the problems of unknown actuator failures and unknown control directions. Then, combined with the derived technical lemmas and Barbalat’s lemma, the stability of the closed loop system is proved by the Lyapunov method. Finally, a simulation example verifies the theoretical results.

Research on the design and management of carbide end mill

Zhi-Gang XU,Bang Zhao 제어로봇시스템학회 2006 제어로봇시스템학회 국제학술대회 논문집 Vol.2006 No.10