Experimental Study on the Effect of Black Shales and Water Interactions on Concrete

( Xin Liao ),( Qingfeng Wang ),( Sixiang Ling ),( Xiyong Wu ),( Wenda Zhang ) 대한지질공학회 2019 대한지질공학회 학술발표회논문집 Vol.2019 No.2

Black shales, usually containing pyrite, are easily oxidized and generate acidic porewater. This acidic environment is non favorable for tranditional engineering material, e.g., concrete, and is likely to affect the durability of the engineering structure. This study investigated the corrsions of concrete by acid water from black shale at different immersion depth. Electrical conductivity (EC) and pH values of the solution were monitored at intervals. Concentrations of major ion species were determined for immersion solutions. Micro-fissure development within the rock and concrete samples were determined by comparing the ultrasonic before and after the immersion tests. Mineral and strength analysis was conducted with X-ray diffraction and uniaxial compressive strength apparatus. The results indicate that: 1) capillary action was significant for the water-solid interactions of black shale and concrete, where the chemical reaction of black shale mainly occurred; 2) the immersion solution caused corrosion in the surface of black shale and concrete, which dramatically reduced the compressive strength of black shale but increased that of concrete slightly in the immersion period. This change can be attributed to the products formed by the chemical reaction between the sulfate-rich ion solution and concrete filled in pore structure.

Iterative tuning of decoupling controller for 3-DOF precision motion stage

Wei Teng,Qingfeng Gao,Xin Wu,Haihua Mu 대한기계학회 2012 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.26 No.2

A practical iterative tuning algorithm of a decoupling controller is presented to eliminate intrinsic coupling among 3-DOF precision motion stage. General decoupling control cannot eliminate coupling completely, which will prevent the enhancement of control accuracy in high-precision motion system. The proposed algorithm can be used to tune the parameters of a decoupling controller iteratively through minimizing a quadratic cost function of the tracking error in non-movement direction when the stage moves in one direction. The tuning algorithm addressed for the motion stage needs only measurement signals in an actual motion system rather than a detailed model of the stage. The proposed algorithm is demonstrated by experimental results. It can be applied further in other multi-DOF motion systems.

Concurrent Recrystallization and Precipitation for Combination of Superior Precipitation and Grain Boundary Hardening in Co37Cr20Ni37Ti3Al3 High-Entropy Alloy

Linfei Xia,Qingfeng Wu,Kexuan Zhou,Bin Han,Feng He,Zhijun Wang 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.12

According to the precipitation and recrystallization behavior, the precipitation and recrystallization can be concurrently tunedtoward the excellent mechanical property. In this study, a synergistically strengthened Co37Cr20Ni37Ti3Al3 high-entropyalloy was developed through concurrent recrystallization and precipitation (CRP) approach. After the treatment, the highdensityγ' precipitates were introduced in the matrix, while the fully-recrystallized ultrafine grains and annealing twins wereobtained from the recrystallization. Compared with conventional treatment, the CRP-HEA exhibits a superior combinationof ~ 1.62GPa tensile strength and ~ 28% elongation, which is attributed to the synergistic strengthening of precipitation andgrain boundary. In addition, the deformation mechanisms were characterized by TEM. The cutting-through mechanismdominates the deformation behaviors. Moreover, interesting stacking faults in different slip planes prevail during plasticdeformation. The concurrent recrystallization and precipitation for ultra-fine grain structure with nano-precipitates wouldprovide an effective strategy to achieve outstanding combination of strength and ductility.

Dewatering of a 32.55 m Deep Foundation Pit in MAMA Under Leakage Risk Conditions

Jianxiu Wang,Xiaotian Liu,Jiaxing Liu,Linbo Wu,Qingfeng Guo,Qian Yang 대한토목학회 2018 KSCE JOURNAL OF CIVIL ENGINEERING Vol.22 No.8

A 2,250 mm whirlpool foundation pit is located in Donghai Island, Zhanjiang City, Guangdong Province, China. The layers of theisland are composed of multi-aquifers and multi-aquitards (MAMA). The aquifers are intersected by partial aquitard lenses. A largeconfined aquifer is frequently interbedded and separated into several sub-confined aquifers by partial aquitards. In the 2,250 mmfoundation pit, the water level of two confined aquifers was reduced to satisfy excavation requirements and prevent water inrush. Construction of the 32.55 m deep foundation pit encountered MAMA and potential defects of the diaphragm wall. The pumpingwells in the second confined aquifer were used to reduce the water level to ensure the safety of bottom excavation. The pumpingwells in the first confined aquifer were used to reduce the water level under emergency conditions to prevent potential water inrushand piping from the defects of the diaphragm wall. Field pumping tests and numerical simulations were performed to determine therisk of leakage and verify the capability of the pumping wells to reduce the water level. Quicksand occurred during shallowexcavation because of leakage although the confined aquifer had been cut off and pumped for a long time. Three pumping wells wereinstalled to reduce the water level. When the foundation pit was excavated to a depth of 24 m, water inrush occurred at the middle ofthe pit bottom although the water level of the dewatered aquifer had been reduced to below the excavation face. A 90 m deepborehole was found where the underlying confined aquifer below the first aquifer induced the water inrush. Although the upper waterlevel was reduced, the high water level in the deep part still induced water inrush. The pumping wells in the second aquifer were allopened, and the water level of the underlying confined aquifer was reduced. After the water level was reduced to below the pitbottom, the borehole was filled, and the water inrush stopped. However, water inrush occurred on the cracks of the diaphragm wall aspredicted. The pre-installed pumping wells were opened to control the water inrush. The deepest foundation pit on the island wasconstructed successfully after dealing with the water inrush and leakages.

Network Traffic Anomaly Detection Based on N-ARMA Model

Pingping Gu,Shijing Zhang,Zhimin Huang,Qingfeng Wu 보안공학연구지원센터 2016 International Journal of Database Theory and Appli Vol.9 No.11

With the rapid development of the Internet and the continuous expanding of the data network, little potential anomaly can seriously affect the normal operation of the network, and even lead to huge economic losses. In order to be more accurate and efficient in the traffic detection, in this paper, we propose an N-ARMA based traffic anomaly detection model. We also conduct extensive experiments to verify the higher accurate ratio and recall ratio of our model by comparing with other traffic anomaly detection methods.

ALMA Reveals Sequential High-mass Star Formation in the G9.62+0.19 Complex

Liu, Tie,Lacy, John,Li, Pak Shing,Wang, Ke,Qin, Sheng-Li,Zhang, Qizhou,Kim, Kee-Tae,Garay, Guido,Wu, Yuefang,Mardones, Diego,Zhu, Qingfeng,Tatematsu, Ken’ichi,Hirota, Tomoya,Ren, Zhiyuan,Liu, Sheng-Yu American Astronomical Society 2017 The Astrophysical journal Vol.849 No.1

<P>Stellar feedback from high-mass stars (e.g., H II regions) can strongly influence the surrounding interstellar medium and regulate star formation. Our new ALMA observations reveal sequential high-mass star formation taking place within one subvirial filamentary clump (the G9.62 clump) in the G9.62+0.19 complex. The 12 dense cores (MM1-MM12) detected by ALMA are at very different evolutionary stages, from the starless core phase to the UC H II region phase. Three dense cores (MM6, MM7/G, MM8/F) are associated with outflows. The mass-velocity diagrams of the outflows associated with MM7/G and MM8/F can be well-fit by broken power laws. The mass-velocity diagram of the SiO outflow associated with MM8/F breaks much earlier than other outflow tracers (e.g., CO, SO, CS, HCN), suggesting that SiO traces newly shocked gas, while the other molecular lines (e.g., CO, SO, CS, HCN) mainly trace the ambient gas continuously entrained by outflow jets. Five cores (MM1, MM3, MM5, MM9, MM10) are massive starless core candidates whose masses are estimated to be larger than 25 M-circle dot, assuming a dust temperature of <= 20 K. The shocks from the expanding H II regions ('B' and 'C') to the west may have a great impact on the G9.62 clump by compressing it into a filament and inducing core collapse successively, leading to sequential star formation. Our findings suggest that stellar feedback from H II regions may enhance the star formation efficiency and suppress low-mass star formation in adjacent pre-existing massive clumps.</P>

Identification of DNA methylation and genetic alteration simultaneously from a single blood biopsy

Chen Xiaomin,Liu Jiahui,Li Jun,Xie Yinpeng,Yu Zichen,Shen Lu,Liu Qingfeng,Wu Wei,Zhao Qiang,Lin Haoxiang,Liu Gaotong,Luo Qiuping,Yang Ling,Huang Yi,Zhao Meiru,Yi Xin,Xia Xuefeng 한국유전학회 2023 Genes & Genomics Vol.45 No.5

Background High-throughput sequencing of blood cell-free DNA (cfDNA) techniques offer an opportunity to characterize and monitor cancer rapidly in a non-invasive and real-time manner. Nonetheless, there lacks a tool within therapeutic arsenal to identify multi-omics alterations simultaneously from a single biopsy. In current times, bisulfite-based sequencing detects 5mC and 5hmC at single-base resolution is the golden standard of DNA methylation, while the degradation of DNA and biased sequencing data are the problems of this method. Objective To identify the consistency analysis of methylation and genetic variation with single library, we presented a platform detecting multi-omics data simultaneously from a single blood biopsy using bisulfite-free method of genomic methylation sequencing (GM-seq) mediated by TET enzyme. Methods We detected methylomic and genetic changes simultaneously from a single blood biopsy in NA12878 and randomly chose ten blood biopsies from colorectal cancer or lung cancer patients to validate the ability of GM-seq. Results Similar cytosine methylation level between whole genome bisulfite sequencing (WGBS) and GM-seq were identified in NA12878. Moreover, longer insert size, CpGs coverage and GC distribution were outperformed than WGBS. In addition, the comparison of the single nucleotide polymorphism (SNP), insertion-deletion (Indel) and copy number variation (CNV) in NA12878 or ctDNA from liver cancer between GM-seq and whole genome sequencing (WGS) show a good consistency, indicating that this method is feasible for detecting genetic variation in blood. Conclusion In conclusion, our work demonstrated a method for identification of the methylated modification and genetic variations simultaneously from a single blood biopsy.