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Yan Hua Wang,Jing Lv,Yan Feng,Bo Wen Dai,Cheng Wang,Jing Wu,Zi Yan Chen 국제구조공학회 2021 Smart Structures and Systems, An International Jou Vol.28 No.2
Substructure pseudo-dynamic hybrid simulation (SPDHS) is an advanced structural seismic testing method which combines physical experiment and numerical simulation. Generally, the key components which display nonlinearity first are taken as experimental substructures for actual test, and the remaining parts are modeled in simulation. Model updating techniques can be effectively applied to enhance the model precision of nonlinear numerical elements. Specifically, the constitutive model of the experimental substructure is identified online by the instantaneously-measured data, and the corresponding numerical elements with similar hysteretic behaviors are updated synchronously. Artificial neural network (ANN) can recognize the system which cannot be represented by definite numerical model, and thus avoids the structural response distortion caused by the inherent numerical model defects. In this study, a framework for online model updating in SPDHS with ANN method is expanded to implement actual test validation. Moreover, the effectiveness of ANN method is demonstrated by practical tests of a two-story frame model with bending dampers. Additionally, the unscented Kalman filter technique and offline ANN identification approach are both examined in the test validation. The experimental results show that, under the identical loading history, the online ANN method can significantly reduce the model errors and improve the accuracy of SPDHS.
Applicability Analysis of Microseismic Technology in Tunnel Water Inrush Monitoring
Yan-hao Chen,Shuai Cheng,Li-Ping Li,Jun-yan Yang,Hong-liang Liu,Wen-feng Tu 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.7
Water inrush disaster is one of the most serious geological disasters in tunnel construction. There are still some problems in the existing researches, such as the activity information of surrounding rock is difficult to obtain, the mechanism of water inrush disaster is unclear, the correlation between water inrush disaster and microseismic (MS) information is missing, which have caused the water inrush disaster to be passively controlled. Combining with the practical experience of tunnel engineering, the application problems of MS technology in tunnel engineering is summarized, which provides ideas for monitoring of surrounding rock activity. The formation mechanism of water inrush disaster caused by rock mass fracturing and filling medium instability has been revealed. The MS characteristics of the water inrush channel in different water inrush disasters have also been revealed. The MS response characteristics of water inrush and rockburst disasters are compared, which provides guidance for the improvement of MS monitoring technology and the analysis of effective MS information. The compression failure test of limestone under saturated and natural conditions is carried out. The results show that the presence of water weakens the ability of rock to store energy. The acoustic emission (AE) phenomenon is weaker in the process of saturated limestone failure, which increases the difficulty of AE monitoring. The number of AE events of natural limestone and saturated limestone shows a slow increase to a sudden increase in the process stress loading, which can be regarded as an important precursor of rock failure.
Rock mechanics and wellbore stability in Dongfang 1-1 Gas Field in South China Sea
Yan, Chuanliang,Deng, Jingen,Cheng, Yuanfang,Yan, Xinjiang,Yuan, Junliang,Deng, Fucheng Techno-Press 2017 Geomechanics & engineering Vol.12 No.3
Thermal effect has great influence on wellbore stability in Dongfang 1-1 (DF 1-1) gas field, a reservoir with high-temperature and high-pressure. In order to analyze the wellbore stability in DF1-1 gas field, the variation of temperature field after drilling was analyzed. In addition, the effect of temperature changing on formation strength and the thermal expansion coefficients of formation were tested. On this basis, a wellbore stability model considering thermal effect was developed and the thermal effect on fracture pressure and collapse pressure was analyzed. One of the main challenges in this gas field is the decreasing temperature of the wellbore will reduce fracture pressure substantially, resulting in the drilling fluid leakage. If the drilling fluid density was reduced, kick or blowout may happen. Therefore, the key of safe drilling in DF1-1 gas field is to predict the fracture pressure accurately.
Yan-Ming Cheng,Cheng Liu,Jing Wu,He-Miao Liu,Il-Kyoo Lee,Jing Niu,조주필,구경완,Min-Woo Lee,우덕근 대한전기학회 2020 Journal of Electrical Engineering & Technology Vol.15 No.6
This paper mainly focuses on the control strategy for phase-shifting full-bridge soft switching electrolytic silver power supply based on Zero Voltage Switching (ZVS) soft switching technology. Taking into consideration the low performance of traditional PID control for phase-shifting full-bridge soft-switching, this paper introduce a PID improved by Back Propagation (BP) neural network with one single learning rate which is used to calculate weights from the input layer to the hidden layer and weights from the hidden layer to the output layer. After testing, it is found that setting independent learning rate for calculation of weights from the input layer to the hidden layer and weights from the hidden layer to the output layer which will not have an adverse eff ect on the design of the controller. Instead, the learning rate can be set according to the respective characteristics of the weights between the two layers, which is called double learning rate BP neural network PID. The simulation results indicate that compared with the single learning rate BP neural network PID control, the double learning rate BP neural network control has higher response speed, less over-shoot, short time to enter the steady state and strong immunity.
A Study of English Morpheme Acquisition Order by Chinese and Korean EFL Learners
Yan Cheng,이보림 대한언어학회 2020 언어학 Vol.28 No.1
The purpose of this study is to evaluate the two contrasting claims for the order of inflectional morpheme acquisition in English as L2: the natural order hypothesis and the hypothesis claiming L1 effects as a fundamental factor. This study also investigates two additional factors that may influence the acquisition of L2 English morphemes: the learner’s English proficiency level and the data elicitation method. For this goal, it involves 38 Korean and 38 Mandarin Chinese learners of English in college, each group of which is in turn divided into two sub-groups according to their English proficiency level. The accuracy scores for six English inflectional morphemes are obtained from two tasks, a freewriting task through journal entries and a fill-in-the-blank type test. Then the results are compared according to the various factors using Spearman’s rank-order correlations based on TLU (target-like use) scores. The results of this study indicate that different L1 groups of the same proficiency level show different acquisition orders, neither of which supports the natural order hypothesis. The data elicitation method and English proficiency, however, do not seem to significantly affect the order of English morphemes. Based on these results, this study concludes that L1 plays a major role in English inflectional morpheme acquisition by EFL learners. It is also noted that input frequency and the amount of classroom instruction can be other important factors affecting English morpheme acquisition, suggesting the need to increase the inputs of low-ranked but important morphemes in the classroom.
Structure and bioactivity of triterpenoids from the stems of Schisandra sphenanthera
Cheng-Qin Liang,Rong-Hua Luo,Ju-Ming Yan,Yan Li,Xiao-Nian Li,Yi-Ming Shi,Shan-Zhai Shang,Zhong-Hua Gao,Liu-Meng Yang,Yong-Tang Zheng,Wei-Lie Xiao,Hong-Bin Zhang,Han Dong Sun 대한약학회 2014 Archives of Pharmacal Research Vol.37 No.2
Two new triterpenoids, schisphendilactoneA and B (1 and 2), together with three known triterpenoids,were isolated from the stems of Schisandra sphenanthera. Their structures were elucidated by spectroscopic methods,and the absolute configuration of 1 was determined bysingle-crystal X-ray diffraction. Compound 2 showedmoderate inhibitory activity against SW480 cancer cellline, and compound 5 exhibited promising anti-HIV-1activity with EC50 value of 0.52 lg ml-1 and therapeuticindex value of 117.12.