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An effective method for laboratory acoustic emission detection and location using template matching

Journal of Rock Mechanics and Geotechnical Engineering 2022年第5期14卷 1642-1651页

作者： Xinglin Lei Tomohiro Ohuchi Manami Kitamura Xiaying Li Qi li National Institute of Advanced Industrial Science and Technology(AIST) Tsukuba305-8567Japan Geodynamics Research Center Ehime UniversityMatsuyama790-8577Japan State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan430071China University of Chinese Academy of Sciences Beijing100049China

In this paper, a template matching and location method, which has been rapidly adopted in microseismic research in recent years, is applied to laboratory acoustic emission(AE) monitoring. First, we used traditional methods to detect P-wave first motions and locate AE hypocenters in three dimensions. In addition, we selected events located with sufficient accuracy(normally corresponding AE events of relatively larger energy, showing clear P-wave first motion and a higher signal-to-noise ratio in most channels) as template events. Then, the template events were used to scan and match other poorly located events in triggered event records or weak events in continuous records. Through crosscorrelation of the multi-channel waveforms between the template and the event to be detected, the weak signal was detected and located using a grid-searching algorithm(with the grid centered at the template hypocenter). In order to examine the performance of the approach, we calibrated the proposed method using experimental data of different rocks and different types of experiments. The results show that the proposed method can significantly improve the detection capability and location accuracy, and can be applied to various laboratory and in situ experiments, which use multi-channel AE monitoring with waveforms recorded in either triggering or continuous mode.

关键词： Acoustic emission Template matching and location Waveform cross-correlation Grid search

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Influence of bedding structure on stress-induced elastic wave anisotropy in tight sandstones

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Journal of Rock Mechanics and Geotechnical Engineering 2021年第1期13卷 98-113页

作者： Xiaying Li Xinglin Lei Qi li Dianguo Chen State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan430071China University of Chinese Academy of Sciences Beijing100049China National Institute of Advanced Industrial Science and Technology(AIST) Tsukuba305-8567Japan Chongqing Dizhiyuan Geology and Engineering Testing Co. LtdChongqing401329China

To understand the evolution of stress-induced elastic wave anisotropy,three triaxial experiments were performed on sandstone specimens with bedding orientations parallel,perpendicular,and oblique to the maximum principal stress.P-wave velocities along 64 different directions on each specimen were monitored frequently to understand the anisotropy change at various stress levels by fitting Thomsen’s anisotropy equation.The results show that the elastic wave anisotropy is very sensitive to mechanical loading.Under hydrostatic loading,the magnitude of anisotropy is reduced in all three specimens.However,under deviatoric stress loading,the evolution of anisotropic characteristics(magnitude and orientation of the symmetry axis)is bedding orientation dependent.Anisotropy reversal occurs in specimens with bedding normal/oblique to the maximum principal stress.P-wave anisotropyε0 is linearly related to volumetric strain Sv and dilatancy,indicating that stress-induced redistribution of microcracks has a significant effect on P-wave velocity anisotropy.The closure of initial cracks and pores aligned in the bedding direction contributes to the decrease of the anisotropy.However,opening of new cracks,aligned in the maximum principal direction,accounts for the increase of the anisotropy.The experimental results provide some insights into the microstructural behavior under loading and provide an experimental basis for seismic data interpretation and parameter selection in engineering applications.

关键词： Elastic wave anisotropy Stress-induced anisotropy Anisotropy reversal Bedding orientation Microstructure Tight sandstone

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A method to model the effect of pre-existing cracks on P-wave velocity in rocks

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Journal of Rock Mechanics and Geotechnical Engineering 2020年第3期12卷 493-506页

作者： Haimeng Shen Xiaying Li Qi li Haibin Wang State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan430071China University of Chinese Academy of Sciences Beijing100049China

Crack closure is one of the reasons inducing changes of P-wave velocity of rocks under compression.In this context,a method is proposed to investigate the relationships among P-wave velocity,pre-existing cracks,and confining pressure based on the discrete element method(DEM).Pre-existing open cracks inside the rocks are generated by the initial gap of the flat-joint model.The validity of the method is evaluated by comparing the P-wave velocity tested on a sandstone specimen with numerical result.As the crack size is determined by the diameter of particles,the effects of three factors,i.***.number,aspect ratio,and orientation of cracks on the P-wave velocity are discussed.The results show that P-wave velocity is controlled by the(i.***.number) of open micro-cracks,while the closure pressure is determined by the aspect ratio of crack.The reason accounting for the anisotropy of P-wave velocity is the difference in crack number in measurement paths.Both of the number and aspect ratio of cracks can affect the responses of P-wave velocity to the applied confining pressure.Under confining pressure,the number of open cracks inside rocks will dominate the lowest P-wave velocity,and the P-wave velocity of the rock containing narrower cracks is more sensitive to the confining pressure.In this sense,crack density is difficult to be back-calculated merely by P-wave velocity.The proposed method offers a means to analyze the effect of pre-existing cracks on P-wave velocity.

关键词： Pre-existing cracks P-wave velocity Discrete element method(DEM) Anisotropic rock

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Hydromechanical behaviors of andesite under different stress states during fluid injection

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Journal of Rock Mechanics and Geotechnical Engineering 2021年第4期13卷 727-744页

作者： Miao He Qi li Xiaying Li liang Xu Michael Kühn State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan430071China University of Chinese Academy of Sciences Beijing100049China Fluid Systems Modelling Section GFZ German Research Centre for GeosciencesPotsdamGermany Institute of Earth and Environmental Science University of PotsdamPotsdamGermany

Water reinjection into the formation is an indispensable operation in many energy engineering practices.This operation involves a complex hydromechanical(HM)coupling process and sometimes even causes unpredictable disasters,such as induced seismicity.It is acknowledged that the relative magnitude and direction of the principal stresses significantly influence the HM behaviors of rocks during injection.However,due to the limitations of current testing techniques,it is still difficult to comprehensively conduct laboratory injection tests under various stress conditions,such as in triaxial extension stress states.To this end,a numerical study of HM changes in rocks during injection under different stress states is conducted.In this model,the saturated rock is first loaded to the target stress state under drainage conditions,and then the stress state is maintained and water is injected from the top to simulate the formation injection operation.Particular attention is given to the difference in HM changes under triaxial compression and extension stresses.This includes the differences in the pore pressure propagation,mean effective stress,volumetric strain,and stress-induced permeability.The numerical results demonstrate that the differential stress will significantly affect the HM behaviors of rocks,but the degree of influence is different under the two triaxial stress states.The HM changes caused by the triaxial compression stress states are generally greater than those of extension,but the differences decrease with increasing differential stress,indicating that the increase in the differential stress will weaken the impact of the stress state on the HM response.In addition,the shear failure potential of fracture planes with various inclination angles is analyzed and summarized under different stress states.It is recommended that engineers could design suitable injection schemes according to different tectonic stress fields versus fault occurrence to reduce the risk of injection-induced seismicity.

关键词： Water reinjection Stress state Hydromechanical(HM)coupling Injection-induced seismicity Numerical modeling

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A Precursory Signal of June-July Precipitation over the Yangtze River Basin: December-January Tropospheric Temperature over the Tibetan Plateau

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Advances in Atmospheric Sciences 2023年第11期40卷 1986-1997页

作者： xiaying ZHU Mingzhu YANG Ge liU Yanju liU Weijing li Sulan NAN linhai SUN National Climate Center Beijing 100081China State Key Laboratory of Severe Weather Chinese Academy of Meteorological SciencesBeijing 100081China Collaborative Innovation Centre on Forecast and Evaluation of Meteorological Disasters Nanjing University of Information Science and TechnologyNanjing 210044China

The prediction of summer precipitation over the Yangtze River basin(YRB)has long been challenging,especially during June-July(JJ),when the mei-yu generally occurs.This study explores the potential signal for the YRB precipitation in JJ and reveals that the Tibetan Plateau tropospheric temperature(TPTT)in the middle and upper levels during the preceding December-January(DJ)is significantly correlated with JJ YRB precipitation.The close connection between the DJ TPTT anomaly with JJ YRB precipitation may be due to the joint modulation of the DJ ENSO and spring TP soil temperatures.The lagged response to an anomalously cold TPTT during the preceding DJ is a TPTT that is still anomalously cold during the following JJ.The lower TPTT can lead to an anomalous anticyclone to the east of Lake Baikal,an anomalous cyclone at the middle latitudes of East Asia,and an anomalous anticyclone over the western North Pacific.Meanwhile,the East Asian westerly jet shifts southward in response to the meridional thermal gradient caused by the colder troposphere extending from the TP to the east of Lake Baikal.The above-mentioned circulation anomalies constitute the positive anomaly of the East Asia-Pacific pattern,known to be conducive to more precipitation over the YRB.Since the DJ TPTT contains both the land(TP soil temperature)and ocean(ENSO)signals,it has a closer relationship with the JJ precipitation over the YRB than the DJ ENSO alone.Therefore,the preceding DJ TPTT can be considered an alternative predictor of the JJ YRB precipitation.

关键词： Tibetan Plateau thermal condition Yangtze River precipitation prediction

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Black titanium dioxide nanomaterials for photocatalytic removal of pollutants:A review

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Journal of Materials Science & Technology 2022年第17期112卷 239-262页

作者： Ying liang Guohe Huang xiaying Xin Yao Yao Yongping li Jianan Yin Xiang li Yuwei Wu Sichen Gao State Key Joint Laboratory of Environmental Simulation and Pollution Control School of EnvironmentBeijing Normal UniversityBeijing 100875China State Key Joint Laboratory of Environmental Simulation and Pollution Control China-Canada Center for EnergyEnvironment and Ecology ResearchUR-BNUSchool of EnvironmentBeijing Normal UniversityBeijing 100875China Department of Environmental Systems Engineering University of ReginaReginaSKS4S 0A2Canada State Key Laboratory of Marine Pollution(SKLMP) City University of Hong KongKowloonHong Kong SARChina Faculty of Engineering and Applied Science University of ReginaReginaSaskatchewanS4S 0A2Canada

Semiconductor photocatalysis is one of the most widely used environment-friendly technologies for removing various contaminants.As a well-developed photocatalyst,titanium dioxide(TiO_(2))still has limits in its wide bandgap and rapid recombination rate of photogenerated charge carriers.Recently,black TiO_(2)appears as a strong candidate in the improvement of sunlight harvesting,because of its excellent absorption capacity and utilization of solar radiation.Despite extensive applications in both environmental and energy fields,the use of black TiO_(2)as a photocatalyst in pollutant removal is ambiguous.The primary objective of the review is to comprehensively evaluate the applications of black TiO_(2)in photocatalytic removal of contaminants,including conventional organic contaminants,emerging contaminants,microbes,and heavy metals.The basic properties,photocatalytic mechanism,and synthesis of black TiO_(2)have been summarized and analyzed.Moreover,the stability and recoverability of black TiO_(2)have also been discussed.Finally,the perspectives of the application of black TiO_(2)in pollutant removal have been further discussed.

关键词： Photocatalysis Back TiO_(2) Ti^(3+)self-doping Nanomaterials Pollutant removal

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Comparison of Five Endogenous Reference Genes for Specific PCR Detection and Quantification of Rice

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Rice science 2019年第4期26卷 248-256,I0006,I0007页

作者： ZHANG Xiujie JIN Wujun XU Wentao li xiaying SHANG Ying li Sha OUYANG Hongsheng College of Animal Sciences Jilin University Changchun 130062 China Development Center of Science and Technology Ministry of Agriculture and Rural Affairs Beijing 100176 China Biotechnology Research Institute Chinese Academy of Agricultural Sciences Beijing 100081China College of Food Science and Nutritional Engineering China Agricultural University Beijing 100083China

Endogenous reference genes (ERGs) provide vital information regarding genetically modified organisms (GMOs). The successful detection of ERGs can identity GMOs and the source of genes, verify stability and reliability of the detection system, and calculate the level of genetically modified (GM) ingredients in mixtures. The reported ERGs in rice include sucrose-phosphate synthase (SPS), phospholipase D (PLD), RBE4 and rice root-specific GOS9 genes. Based on the characteristics of ERGs, a new ERG gene, phosphoenolpyruvate carboxylase (PEPC), was selected, and further compared with the four existing genes. A total of 18 rice varieties and 29 non-rice crops were used to verify the interspecies specificity, intraspecies consistency, sensitivity, stability and reliability of these five ERGs using qualitative and quantitative PCR. Qualitative detection indicated that SPS and PEPC displayed sufficient specificity, and the detection sensitivity was 0.05% and 0.005%, respectively. Although the specificity of both RBE4 and GOS9 were adequate, the amplicons were small and easily confused with primer dimers. Non-specific amplification of the PLD gene was present in maize and potato. Real-time quantitative PCR detection indicated that PLD, SPS and PEPC displayed good specificity, with R2 of the standard curve greater than 0.98, while the amplification efficiency ranged between 90% and 110%. Both the detection sensitivities of PLD and PEPC were five copies and that of SPS was ten copies. RBE4 showed typical amplification in maize, beet and Arabidopsis, while GOS9 was found in maize, tobacco and oats. PEPC exhibited excellent detection sensitivity and species specificity, which made it a potentially useful application in GM-rice supervision and administration. Additionally, SPS and PLD are also suitable for GM-rice detection. This study effectively established a foundation for GMO detection, which not only provides vital technical support for GMO identification, but also is of great significance for enhancing the comparability o

关键词： endogenous reference gene rice genetically modified crop phosphoenolpyruvate carboxylase gene sucrose-phosphate synthase gene phospholipase D gene starch branching enzyme 4 gene rice root-specific GOS9 gene

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DE-JSMA:面向SAR-ATR模型的稀疏对抗攻击算法

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西北工业大学学报 2023年第6期41卷 1170-1178页

作者：金夏颖李扬潘泉西北工业大学网络空间安全学院陕西西安710072 西北工业大学自动化学院陕西西安710072

DNN易受攻击的特点使得以智能算法为识别手段的SAR-ATR系统也存在一定脆弱性。为验证其脆弱性,结合SAR图像特征稀疏的特点,在显著图对抗攻击算法和差分进化算法基础上提出了DE-JSMA稀疏攻击算法,精确筛选出对模型推理结果影响较大的显... 详细信息

DNN易受攻击的特点使得以智能算法为识别手段的SAR-ATR系统也存在一定脆弱性。为验证其脆弱性,结合SAR图像特征稀疏的特点,在显著图对抗攻击算法和差分进化算法基础上提出了DE-JSMA稀疏攻击算法,精确筛选出对模型推理结果影响较大的显著特征后,为显著特征优化出合适的特征值。为了更全面地验证攻击的有效性,构建了一种结合攻击成功率和对抗样本平均置信度的新指标Fc值。实验结果表明,在没有增加过多耗时,且保证高攻击成功率情况下,DE-JSMA将只能定向攻击的JSMA扩展到了非定向攻击场景,且在2种攻击场景下均实现了可靠性更高、稀疏性更优的稀疏对抗攻击,仅扰动0.31%与0.85%的像素即可达到100%与78.79%以上的非定向与定向攻击成功率。

关键词：合成孔径雷达自动目标识别深度学习对抗攻击稀疏攻击

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Copy number and zygosity determination of transgenic rapeseed by droplet digital PCR

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Oil Crop Science 2017年第2期2卷 84-94页

作者： Yuhua Wu Jun li Xiaying Li Jingang liang Yunjing li Xinhua Zeng Gang Wu Key Laboratory of Biology and Genetic Improvement of Oil Crops Ministry of Agriculture Oil Crops Research InstituteChinese Academy of Agricultural Sciences Wuhan China Science and Technoloty Center of Ministry of Agriculture China

Establishing an accurate and rapid method for copy number and zygosity determination can accelerate genetic engineering research process. In this study, droplet digital PCR (ddPCR), an emerging DNA absolute quantification technology, was used to identify single-copy homozygous transgenic lines from a batch of T0 transgenic rapeseed harboring 11 exogenous elements. Copy number of exogenous gene was evaluated in T0 generation based on calculated ratio between transgene and reference CruA gene, single-copy transformants were selected for selfing followed by subsequent zygosity analysis. Single-copy homozygous transgenic plants were successfully screened out in T1 generation by ddPCR.Segregation analysis with T2 seedlings verified that identification results of ddPCR were accurate and reliable. This study provides a novel rapid and accurate method for copy number and zygosity determination in transgenic rapeseed which overcomes disadvantages of traditional Southern analysis and recently developed real-time quantitative method.

关键词： droplet digital PCR (ddPCR) copy number zygosity homozygotes transgenic rapeseed

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高校实验动物平台管理模式研究

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实验技术与管理 2020年第12期37卷 270-272,276页

作者：李夏莹北京大学生命科学学院实验动物中心北京100871

实验动物是现代生命科学研究的重要组成部分,是生物医学科研的基础和重要支撑条件。实验动物平台是进行实验动物饲养、管理、实验研究的重要场所。该文从北京大学实验动物中心平台建设和管理的实际经验出发,对实验动物设施设计及要求、... 详细信息

实验动物是现代生命科学研究的重要组成部分,是生物医学科研的基础和重要支撑条件。实验动物平台是进行实验动物饲养、管理、实验研究的重要场所。该文从北京大学实验动物中心平台建设和管理的实际经验出发,对实验动物设施设计及要求、动物管理、从业人员的职业安全的要点进行了阐述。

关键词：实验动物平台设施设计动物管理人员安全

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