Characterization of the brittleness of hard rock at different temperatures using uniaxial compression tests

Chen, Guoqing,Li, Tianbin,Wang, Wei,Guo, Fan,Yin, Hongyu Techno-Press 2017 Geomechanics & engineering Vol.13 No.1

The failure mechanism of a deep hard rock tunnel under high geostress and high geothermalactivity is extremely complex. Uniaxial compression tests of granite at different temperatures were conducted. The complete stress-strain curves, mechanical parameters and macroscopic failure types of the rock were analyzed in detail. The brittleness index, which represents the possibility of a severe brittleness hazard, is proposed in this paperby comparing the peak stress and the expansion stress. The results show that the temperature range from 20 to $60^{\circ}C$ is able to aggravate the brittle failure of hard rock based on the brittleness index. The closure of internal micro cracks by thermal stress can improve the strength of hard rock and the storage capacity of elastic strain energy. The failure mode ofthe samples changes from shear failure to tensile failure as the temperature increases. In conclusion, the brittle failure mechanism of hard rock under the action of thermal coupling is revealed, and the analysis result offers significant guidance for deep buried tunnels at high temperatures and under high geostress.

Search for Sliding Surface of Slope Based on Dynamic Strength Reduction Method

( Guoqing Chen ) 대한지질공학회 2019 대한지질공학회 학술발표회논문집 Vol.2019 No.2

The failure of slope is a progressive process where the whole sliding surface gradually evolves from the local damaged region in the slope. Based on the yield weakening of geotechnical material, a new sliding surface search method that can simulate the progressive failure of slope was proposed. The strength parameter of the damaged region was reduced, and then mechanical equilibrium of slope was calculated. Through the continuous local damage reduction of the strength parameters of the damaged slope body, the potential sliding surface damaged gradually and evolved to breakthrough finally. The weak layer is closely associated with the stability of the heterogeneous rocky slope, but traditional calculation method is difficult to determine the failure mode. Present article mainly deals with the analysis of the stability of Dagangshan Mountain slope of Sichuan Province in China. The prevention flow of sliding disaster for heterogeneous rocky slope is presented. At first, Dynamic Strength Reduction Method (DSRM) was used to search the sliding surface, failure position and sliding direction. The case study of Dagangshan Mountain slope shows that DSRM is reasonable and correct when it is compared with the field observations. The study indicates that the sliding disaster of the slope is connected with f231 fault. The calculation results provide theoretical basis for the support and reinforcement program. In conclusion, DSRM provides a new calculation method for the stability and disaster forecast of similar heterogeneous rocky slopes.

Predicting of tall building response to non-stationary winds using multiple wind speed samples

Guoqing Huang,Xinzhong Chen,Haili Liao,Mingshui Li 한국풍공학회 2013 한국풍공학회지 Vol.17 No.2

Non-stationary extreme winds such as thunderstorm downbursts are responsible for many structural damages. This research presents a time domain approach for estimating along-wind load effects on tall buildings using multiple wind speed time history samples, which are simulated from evolutionary power spectra density (EPSD) functions of non-stationary wind fluctuations using the method developed by the authors’ earlier research. The influence of transient wind loads on various responses including time-varying mean, root-mean-square value and peak factor is also studied. Furthermore, a simplified model is proposed to describe the non-stationary wind fluctuation as a uniformly modulated process with a modulation function following the time-varying mean. Finally, the probabilistic extreme response and peak factor are quantified based on the up-crossing theory of non-stationary process. As compared to the time domain response analysis using limited samples of wind record, usually one sample, the analysis using multiple samples presented in this study will provide more statistical information of responses. The time domain simulation also facilitates consideration of nonlinearities of structural and wind load characteristics over previous frequency domain analysis.

Evaluation of passive mixing behaviors in a pillar obstruction poly(dimethylsiloxane) microfluidic mixer using fluorescence microscopy

Chen, Lingxin,Wang, Guoqing,Lim, Chaesung,Seong, Gi Hun,Choo, Jaebum,Lee, Eun Kyu,Kang, Seong Ho,Song, Joon Myong Springer-Verlag 2009 MICROFLUIDICS AND NANOFLUIDICS Vol.7 No.2

Determining the Clinical Characteristics, Treatment Strategies, and Prognostic Factors for Mycoplasma pneumoniae Encephalitis in Children: A Multicenter Study in China

Guoqing Fan,Yi Guo,Fujie Tang,Min Chen,Shuang Liao,Juan Wang 대한신경과학회 2023 Journal of Clinical Neurology Vol.19 No.4

Background and Purpose Most of the knowledge of Mycoplasma pneumonia (M. pneumoniae) encephalitis (MPE) in children is based on case reports or small case series. This study aimed to describe the clinical features and prognostic factors of MPE, and the efficacy of azithromycin with or without immunomodulatory therapy. Methods The medical data of 87 patients with MPE from 3 medical centers in southwestern China over a 7-year period were reviewed. Results MPE was found in children of all ages except for neonates. The most common neurological manifestations included consciousness disturbance (90%) and headache (87.4%), the most common extraneurological manifestations included fever (96.5%) and respiratory system involvement (94.3%); multisystem involvement (98.2%) and elevated C-reactive protein (CRP) (90.8%) were also prominent. M. pneumoniae was detected in cerebrospinal fluid (CSF) less often than in blood and respiratory tract secretions. Azithromycin with intravenous immunoglobulin or/and corticosteroid treatment can shorten the hospitalization duration and the clinical improvement process. Most patients (82.8%) received a favorable prognosis; serum lactate dehydrogenase (LDH) and CSF protein levels were higher in the poor-outcome group than in the good-outcome group (p<0.05). Neurological sequelae are likely to continue when the onset of this condition occurs during teenage years. Conclusions MPE generally presented with nonspecific clinical manifestations. In children with acute encephalitis accompanied by multi-system involvement and prominently elevated CRP, M. pneumoniae should be considered as a possible pathogen. Immunomodulating therapies should be recommended regardless of the duration of the prodromal period. High CSF protein level, blood LDH elevation, and higher age may be associated with an unfavorable outcome.

Shape Description and Retrieval Using Included-Angular Ternary Pattern

Guoqing Xu,Ke Xiao,Chen Li 한국정보처리학회 2019 Journal of information processing systems Vol.15 No.4

Shape description is an important and fundamental issue in content-based image retrieval (CBIR), and anumber of shape description methods have been reported in the literature. For shape description, both globalinformation and local contour variations play important roles. In this paper a new included-angular ternarypattern (IATP) based shape descriptor is proposed for shape image retrieval. For each point on the shapecontour, IATP is derived from its neighbor points, and IATP has good properties for shape description. IATPis intrinsically invariant to rotation, translation and scaling. To enhance the description capability, multiscaleIATP histogram is presented to describe both local and global information of shape. Then multiscale IATPhistogram is combined with included-angular histogram for efficient shape retrieval. In the matching stage,cosine distance is used to measure shape features’ similarity. Image retrieval experiments are conducted on thestandard MPEG-7 shape database and Swedish leaf database. And the shape image retrieval performance of theproposed method is compared with other shape descriptors using the standard evaluation method. Theexperimental results of shape retrieval indicate that the proposed method reaches higher precision at the samerecall value compared with other description method.

Kinetic model of asymmetric reduction of 3-oxo-3-phenylpropionic acid ethyl ester using Saccharomyces cerevisiae CGMCC No.2266

Guoqing Ying,Xiaoyan Chen,Zhimin Ou 한국화학공학회 2010 Korean Journal of Chemical Engineering Vol.27 No.6

The kinetic model of asymmetric reduction of 3-oxo-3-phenylpropionic acid ethyl ester using Saccharomyces cerevisiae CGMCC No.2266 with 10% glucose as co-substrate to realize the regeneration of NADPH was established. The effect factors on reduction, the type and the content of co-substrate and coenzyme, and the changes of the substrate and product content vs. time during the reaction process were investigated. The results indicate that 10%glucose can increase the reaction conversion from 23.0% to 98.4% and NADPH is reducer. The reduction process conforms with sequence mechanisms. The model parameters are as follows: vm=5.0×10−4 mol·L−1·h−1, k1=1.5×10−6 mol·L−1·h−1, k2=3.0×10−3 mol·L−1·h−1. The kinetic model is in good agreement with the experimental data.

Research on corrosion behavior of A6N01S-T5 aluminum alloy welded joint for high-speed trains

Guoqing Gou,Nan Huang,Hui Chen,Hongmei Liu,Aiqin Tian,Zhicheng Guo 대한기계학회 2012 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.26 No.5

"For high speed trains, safety is of utmost importance. Salt fog corrosion, intergranular corrosion tests were employed to observe the corrosion behavior of welded joint of A6N01S-T5 aluminum alloy of high-speed trains. Tensile strength and hardness changed after corrosion was tested. The micro morphologies were observed by metalloscope and laser confocal scanning microscope (LCSM). The corrosion loss and corrosion loss ratio were also investigated. The results showed that the heat affected zone (HAZ) was the most sensitive to corrosion in welded joint in the salt fog corrosion test. The potential of the corrosion of the intermetallic compound on the surface was different from the Al matrix potential, which easily generated corrosion micro-batteries that generated the corrosion pit. The weld zone was the most sensitive to corrosion in the welded joint in the intergranular corrosion test, because much corrosion produced an intermetallic phase such as CuAl2, MgZn2, Mg5Al8, which formed the deficient Cu or Mg zone potential. The potential is low, which acted as an anode and corroded. The residual stress test on the weld of the A6N01S-T5 of the W1 of the exterior surface of roof of high speed train showed there was distributed high tensile stress and compressed stress in the weld zone, HAZ zone and matrix zone. The defects will spread under the high stress and make the corrosion become severe."

Finite Time Output Feedback Control for Ship Dynamic Positioning Assisted Mooring Positioning System with Disturbances

Guoqing Xia,Caiyun Liu,Bo Zhao,Xinghua Chen,Xingchao Shao 제어·로봇·시스템학회 2019 International Journal of Control, Automation, and Vol.17 No.11

This paper investigates finite-time output feedback control for ship dynamic positioning assisted mooring system with external disturbances and without velocity measurement. Firstly, a finite-time observer is designed to estimate the velocity of the positioning ship and the external disturbances. Secondly, based on the proposed observer, a finite-time control law is introduced to bring the ship to the desired position and heading. Furthermore, the stability of the overall closed-loop system is proved by using matrix inequality, homogeneous and Lyapunov stability theory. Finally, the effectiveness of the proposed positioning control is verified by numerical simulations.

Surface-enhanced Raman scattering in nanoliter droplets: towards high-sensitivity detection of mercury (II) ions

Wang, Guoqing,Lim, Chaesung,Chen, Lingxin,Chon, Hyangah,Choo, Jaebum,Hong, Jongin,deMello, Andrew J. Springer-Verlag 2009 ANALYTICAL AND BIOANALYTICAL CHEMISTRY Vol.394 No.7