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Journal of Integrative Agriculture 2012年第4期11卷 600-610页

作者： SHEN Yi-ping ZOU Li-fang LI Yu-rong ZOU Hua-song liu xi-ling CHEN Gong-you School of Agriculture and Biology Shanghai Jiao Tong University/Key Laboratory of Urban （South） Ministry of Agriculture Shanghai 200240 P.R. China Department of Plant Protection Nanjing Agricultural University/Key Laboratory of Integrated Management of Crop Diseases and Pests Ministry of Education Nanjing 210095 P.R. China

Xanthomonas oryzae ***（Xoc） causes a destructive bacterial leaf streak disease in *** of the gene products annotated as hypothetical proteins in the genome of Xoc may contribute to its virulence in rice.A mutant,Mxoc1679,screened from our previous Tn5-tagged mutant library for Xoc strain RS105,showed reduced virulence in *** this mutant,a gene named as Xoryp_08180 was disrupted by Tn5 ***_08180 encodes a 1 306-aa hypothetical protein which is highly conserved in Xanthomonas ***-polar mutation of Xoryp_08180 in RS105 strain led to a significant reduction in bacterial virulence and growth in rice,a delayed hypersensitive response（HR） in non-host tobacco,and a decrease in extracellular protease *** deficiencies above were restored to wild-type level in the complementary strain by expressing Xoryp_08180 in *** addition,the expression of Xoryp_08180 was repressed in hrpG and hrpX mutants in planta but not in a nutrient-rich *** results suggested that Xoryp_08180 is a virulence factor required for extracellular protease production,HR induction and full virulence of Xoc.

关键词： Xanthomonas oryzae pv.oryzicola Xoryp_08180 hypothetical protein virulence hypersensitive response extracellular protease

Acoustic emission characteristics of rock under impact loading

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Journal of Central South University 2015年第9期22卷 3571-3577页

作者：刘希灵李夕兵洪亮尹土兵饶蒙 School of Resources and Safety Engineering Central South University Norman B. Keevil Institute of Mining Engineering University of British Columbia School of Civil Engineering Hunan City University

Acoustic emission tests were performed using a split Hopkinson pressure bar system(SHPB) on 50-mm-diameter bars of granite, limestone, sandstone and skarn. The results show that the amplitude distribution of hits is not well centralized around 50 d B, and that some hits with large amplitudes, usually larger than 70 d B, occur in the early stages of each test, which is different from the findings from static and low-loading-rate tests. Furthermore, the dominant frequency range of the recorded acoustic emission waveforms is between 300 k Hz and 500 k Hz, and frequency components higher than 500 k Hz are not significant. The hit with the largest values of amplitude, counts, signal strength, and absolute energy in each test, displays a waveform with similar frequency characteristics and greater correlation with the waveform obtained from the elastic input bar of the split Hopkinson pressure bar system compared with the waveforms of the other hits. This indicates that the hit with the largest values of amplitude, counts, signal strength, and absolute energy is generated by elastic wave propagation instead of fracture within the rock specimen.

关键词： rock acoustic emission(AE) split Hopkinson pressure bar(SHPB) hit driven features frequency characteristics correlation analysis

Effect of loading rate on fracture behaviors of shale under mode I loading

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Journal of Central South University 2020年第10期27卷 3118-3132页

作者： xiE Qin LI Sheng-xiang liu xi-ling GONG Feng-qiang LI xi-bing School of Resources and Safety Engineering Central South UniversityChangsha 410083China School of Civil Engineering Southeast UniversityNanjing 211189China

In this study,the effect of loading rate on shale fracture behaviors was investigated under dynamic and static loading *** straight through Brazilian disc(CSTBD)shale specimens were tested with a split Hopkinson pressure bar(SHPB)setup and INSTRON1346 servo-testing machine under pure mode I loading *** the test,the crack propagation process was recorded by high-speed(HS)camera,and the acoustic emission(AE)signal generated by the fracture was collected by acoustic emission(AE)*** the same time,crack propagation gauge(CPG)was used to measure the crack propagation velocity of the *** results show that the crack propagation velocity and fracture toughness of shale have a positive correlation with the loading *** relationship among the crack propagation velocity,the fracture toughness and the loading rate is established under the static loading *** addition,the characteristics of AE signals with different loading rates are *** is found that the AE signals generated by microcrack growth decrease with the increase of loading ***,the turning point of cumulative counting moves forward as the loading rate increases,which shows that the AE signal generated by shale fracture at low loading rate mainly comes from the initiation and propagation of microcracks,while at high loading rate it mainly comes from the formation of macro large-scale *** fracture mechanism that causes shale fracture toughness and crack propagation velocity to vary with loading rate is also discussed based on the analysis results of AE signals.

关键词： shale loading rate cracked straight through Brazilian disc fracture toughness acoustic emission crack propagation velocity

Experimental investigation on influence of loading rate on rockburst in deep circular tunnel under true-triaxial stress condition

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Journal of Central South University 2020年第10期27卷 2914-2929页

作者： SI Xue-feng HUANG Lin-qi GONG Feng-qiang liu xi-ling LI xi-bing School of Resources and Safety Engineering Central South UniversityChangsha 410083China School of Civil Engineering Southeast UniversityNanjing 211189China

To investigate the influence of loading rate on rockburst in a circular tunnel under three-dimensional stress conditions,the true-triaxial tests were conducted on 100 mm×100 mm×100 mm cubic sandstone specimens with d50 mm circular perforated holes,and the failure process of hole sidewall was monitored and recorded in real-time by the *** loading rates were 0.02,0.10,and 0.50 MPa/*** test results show that the rockburst process of hole sidewall experienced calm period,pellet ejection period,rock fragment exfoliation period and finally formed the V-shaped *** rockburst has a time lag and vertical stress is high when the rockburst *** vertical stress at the initial failure of the hole sidewall increases with loading *** the same period after initial failure,the rockburst severity of hole sidewalls increased significantly with increasing loading *** the vertical stress is constant and maintains a high stress level,the rockburst of hole sidewall under low loading rate is more serious than that under high loading *** increasing loading rate,the quality of rock fragments produced by the rockburst decreases,and the fractal dimension of rock fragments increases.

关键词： rockburst loading rate deep circular tunnel true-triaxial test V-shaped notch

A NEW METHOD OF DETERMING SOURCE TERMS OF POISSON EQUATIONS FOR GRID GENERATION

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Journal of Hydrodynamics 2000年第1期12卷 16-21页

作者： Wei Wen li, Wang De yi, Zhang Zong xiao, liu Yu ling xi′an University of Technology, xi′an 710048, P.R.China xi'an University of Technology Xi'an 710048 P.R.China

This paper is concerned with a new method to determine the source terms P and Q of Poisson equations for grid generation, with which a satisfactory grid can be obtained. The interior grid distribution is controlled by the prior selection of grid point distribution along the boundary of the region, and the orthogonality condition in the neighborhood of the boundary is satisfied. This grid generation technique can be widely used in the numerical solution of 2 D flow in rivers, lakes, and shallow water regions.

关键词： Poisson equations grid generation weighting functions

单轴压缩与劈裂荷载下灰岩声发射b值特性研究

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岩土力学 2019年第A01期40卷 267-274页

作者：刘希灵刘周李夕兵韩梦思中南大学资源与安全工程学院

通过开展灰岩巴西劈裂和单轴压缩声发射试验,探讨两种加载方式下岩石破裂声发射b值特性及b值计算影响因素。结果表明,累积计算b值拟合度高,误差较小;步距为5 dB时不同门槛值下b值随时间变化的总体规律基本一致,选择5 dB的步距和40 dB的... 详细信息

通过开展灰岩巴西劈裂和单轴压缩声发射试验,探讨两种加载方式下岩石破裂声发射b值特性及b值计算影响因素。结果表明,累积计算b值拟合度高,误差较小;步距为5 dB时不同门槛值下b值随时间变化的总体规律基本一致,选择5 dB的步距和40 dB的门槛值计算b值比较合理,能够降低非岩石破裂信号对b值变化的影响。由动态b值的波动程度可以看出,在劈裂荷载下灰岩损伤演化过程可分为3个阶段,即(0~40%)δ_c(δ_c为峰值强度)、(40%~90%)δ_c和(90%~100%)δ_c,而在单轴加载下可分为:(0~80%)δ_c和(80%~100%)δ_c两个阶段,且不同阶段岩石内部损伤的程度不同。在裂纹扩展阶段,相比单轴加载,劈裂荷载下动态b值增加较为稳定,但在整个破坏过程中劈裂荷载下动态b值波动更大,在单轴压缩和劈裂加载方式下b值的大小取决于灰岩破裂面上的结构性质及破裂模式。

关键词：岩石声发射 b值单轴压缩巴西劈裂影响因素

三轴SHPB加载下砂岩力学特性及破坏模式试验研究

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振动与冲击 2012年第8期31卷 29-32页

作者：宫凤强李夕兵刘希灵中南大学资源与安全工程学院长沙410083 深部金属矿产开发与灾害控制湖南省重点实验室长沙410083

利用改造的三轴SHPB动静组合加载实验装置,对均质砂岩进行不同围压与不同应变率下三轴冲击压缩试验,作为对比利用RMT-150C试验机也进行了部分准静态下三轴压缩实验。根据实验结果,分析围压对砂岩动态冲击性能的影响,并讨论冲击过程中岩... 详细信息

利用改造的三轴SHPB动静组合加载实验装置,对均质砂岩进行不同围压与不同应变率下三轴冲击压缩试验,作为对比利用RMT-150C试验机也进行了部分准静态下三轴压缩实验。根据实验结果,分析围压对砂岩动态冲击性能的影响,并讨论冲击过程中岩石的破坏模式。研究结果表明,在围压一定情况下,岩石的动态压缩强度随应变率的提高而提高;在应变率相同情况下,岩石的动态压缩强度与弹性模量会随着围压的增大而增大。岩石发生破坏的临界入射能,随着围压的增大而增大。岩石单位体积吸收能与应变率之间呈线性递增关系,且递增的程度随围压的增加而增加。三轴冲击加载下,应变率较低时岩石内部形成压剪破裂面但整体不失稳,应变率很大时岩石破碎形成锥形块体形式。

关键词：三轴SHPB 应变率岩石动态压缩强度围压破坏模式

城市峡谷环境下GNSS卫星可见性快速预测方法

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北京理工大学学报 2017年第6期37卷 595-601页

作者：蔡熙刘松林许承东北京理工大学宇航学院北京100081 解放军信息工程大学导航与空天目标工程学院河南郑州450001

城市峡谷环境下全球导航卫星系统(GNSS)性能显著下降,通过建立三维城市模型来预测卫星的可见性是该环境下进行GNSS性能分析最为常见的方法之一.为解决三维城市模型数据量大,使得卫星可见性预测计算消耗大量时间的问题,提出了一种快速预... 详细信息

城市峡谷环境下全球导航卫星系统(GNSS)性能显著下降,通过建立三维城市模型来预测卫星的可见性是该环境下进行GNSS性能分析最为常见的方法之一.为解决三维城市模型数据量大,使得卫星可见性预测计算消耗大量时间的问题,提出了一种快速预测城市中建筑是否遮挡卫星信号的方法.该方法通过分析三角面元的法向量方向、三角面元与用户的相对位置关系以及历史遮挡关系,减少了计算量并缩短了计算时间.仿真结果表明,该方法的相交判断计算次数为传统方法的7.21%,消耗的总计算时间为传统方法的22.38%,平均相对误差为1.89%.该方法具备计算效率高、准确性高的优点.

关键词：城市峡谷全球卫星导航系统(GNsS) 可见性三维城市模型

张拉作用下岩石破裂的声发射特性及P波初动极性

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工程科学学报 2022年第8期44卷 1315-1323页

作者：刘希灵刘清林杜坤李夕兵谢秦中南大学资源与安全工程学院长沙410083

为深入探讨岩石在张拉作用下破裂的声发射特性,设计了一种膨胀剂扩张破裂的声发射实验,详细分析了花岗岩、大理岩和红砂岩声发射信号的特征参数及P波初动极性.实验结果表明:声发射信号的累积计数和能量在三种岩石试样宏观开裂时均呈指... 详细信息

为深入探讨岩石在张拉作用下破裂的声发射特性,设计了一种膨胀剂扩张破裂的声发射实验,详细分析了花岗岩、大理岩和红砂岩声发射信号的特征参数及P波初动极性.实验结果表明:声发射信号的累积计数和能量在三种岩石试样宏观开裂时均呈指数增长;花岗岩、大理岩和红纱岩试样声发射信号的中心频率分别主要集中在100~300 kHz、200~400 kHz、200~500 kHz;花岗岩低频率事件占比最多,大理岩高频率事件占比较多,而红砂岩高频事件占比最多,三种岩样膨胀力荷载后期低中心频率声发射信号增多,说明大尺度破裂增加;三种岩样声发射信号的RA主要集中在0~1.9之间,大理岩和红砂岩AF值主要集中在50~100 kHz之间,花岗岩AF值主要集中在200~250 kHz之间,RA-AF的分布特性表明,实验中岩样主要以张拉破坏为主;通过P波初动极性分析法,获得各岩样声发射信号的初动极性,结果显示,花岗岩、大理岩和红砂岩分别有77.82%、79.5%和87.42%的T-型破裂源,花岗岩、大理岩几乎不产生S-型破裂源,而红砂岩因为天然节理裂隙较多,有9.93%的S-型破裂源.RA-AF分布分析和p波初动极性分析都是统计分析法,可以定性描述岩石破裂类型.

关键词：膨胀剂声发射中心频率 RA-AF分布 P波初动

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复杂空区群露天开采境界三维可视化及其应用

中南大学学报（自然科学版） 2011年第10期42卷 3118-3124页

作者：刘科伟李夕兵刘希灵宫凤强杜坤中南大学资源与安全工程学院深部金属矿产开发与灾害控制湖南省重点实验室湖南长沙410083

为了预防露天开采境界下复杂空区群对矿山生产造成重大安全事故,研究以不规则三角网(TIN)为基础的复杂地质体三维可视化建模技术,并以Surpac软件为平台制定出相应的复杂空区群露天开采境界三维可视化实施方案。将该方案应用于某矿区,建... 详细信息

为了预防露天开采境界下复杂空区群对矿山生产造成重大安全事故,研究以不规则三角网(TIN)为基础的复杂地质体三维可视化建模技术,并以Surpac软件为平台制定出相应的复杂空区群露天开采境界三维可视化实施方案。将该方案应用于某矿区,建立该矿区内露天开采境界地表、地下矿体以及复杂空区群的三维可视化模型,重点对空区群内部错综复杂的通透关系进行三维描述。研究结果表明:复合模型的建立明确了地表、地下矿体及各水平采空区之间的空间位置关系,可利用其分析空区群的安全隐患及空区间的连带破坏作用,为露天境界内复杂空区群的灾害控制、安全性评判及矿区地表开采的施工设计提供了参考依据,从而解决了多空区矿山的盲目开采问题,有效预防了重大安全事故的发生。

关键词：复杂空区群三维可视化不规则三角网(TIN) Surpac软件通透关系