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Modification of rock mass rating system:Interbedding of strong and weak rock layers 被引量:8
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作者 Mohammad Mohammadi Mohammad Farouq Hossaini 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2017年第6期1165-1170,共6页
Rock mass classification systems are the very important part for underground projects and rock mass rating(RMR) is one of the most commonly applied classification systems in numerous civil and mining projects. The typ... Rock mass classification systems are the very important part for underground projects and rock mass rating(RMR) is one of the most commonly applied classification systems in numerous civil and mining projects. The type of rock mass consisting of an interbedding of strong and weak layers poses difficulties and uncertainties for determining the RMR. For this, the present paper uses the concept of rock bolt supporting factor(RSF) for modification of RMR system to be used in such rock mass types. The proposed method also demonstrates the importance of rock bolting practice in such rock masses. The geological parameters of the Shemshak Formation of the Alborz Tunnel in Iran are used as case examples for development of the theoretical approach. 展开更多
关键词 Rock mass rating(RMR) strong and weak rock layers Interbedding Rock bolt supporting factor(RSF) Alborz tunnel
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ON NUMBER OF LIMIT CYCLES FOR THE QUADRATIC SYSTEMS WITH A WEAK FOCUS AND A STRONG FOCUS 被引量:1
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作者 Zhang Pingguang Zhao ShenqiDept.ofMath.ZhejiangUniv.,Hangzhou310027. 《Applied Mathematics(A Journal of Chinese Universities)》 SCIE CSCD 2001年第2期127-132,共6页
It is proved that the quadratic system with a weak focus and a strong focus has at most one limit cycle around the strong focus, and as the weak focus is a 2nd order(or 3rd order) weak focus the quadratic system ha... It is proved that the quadratic system with a weak focus and a strong focus has at most one limit cycle around the strong focus, and as the weak focus is a 2nd order(or 3rd order) weak focus the quadratic system has at most two(one) limit cycles which have (1,1) distribution ((0,1) distribution). 展开更多
关键词 Quadratic differential system number of limit cycle weak focus strong focus.
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Key Technical Points of Wheat Moisture-resistant Strain Sowing and Management of Promoting Seedlings from Weak to Strong in Daiyue District
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作者 Juqing GE 《Plant Diseases and Pests》 CAS 2022年第2期27-29,共3页
According to the meteorological conditions of sowing period and the characteristics of seedling in each key growth period,the measures of rushing drainage,rushing harvest stubble,rushing sow,implementing late sowing,s... According to the meteorological conditions of sowing period and the characteristics of seedling in each key growth period,the measures of rushing drainage,rushing harvest stubble,rushing sow,implementing late sowing,strengthening field management before winter and in spring are taken in Daiyue District during the autumn planting period of wheat,which reduce the influence of natural disasters and increase the yield of wheat. 展开更多
关键词 Moisture-resistant strain Late sowing technique Field management Promoting seedlings from weak to strong
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INTERACTION OF STRONG AND WEAK SINGULARITIES FOR HYPERBOLIC SYSTEM OF CONSERVATION LAWS IN MULTIDIMENSIONAL SPACE
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作者 陈恕行 《Acta Mathematica Scientia》 SCIE CSCD 1990年第3期298-302,共5页
In this paper we study the interaction of strong and weak singularities for hyperbolic system of conservation laws in multidimensional space. Under the assumption of transversal intersect of the shock front with the b... In this paper we study the interaction of strong and weak singularities for hyperbolic system of conservation laws in multidimensional space. Under the assumption of transversal intersect of the shock front with the bicharacteristics bearing weak singularities we proved a theorem on regularity propagation across the shock front. 展开更多
关键词 INTERACTION OF strong AND weak SINGULARITIES FOR HYPERBOLIC SYSTEM OF CONSERVATION LAWS IN MULTIDIMENSIONAL SPACE
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The strong versus weak theory debate in the UK advertising industry
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作者 Ziying Li 《致富时代(下半月)》 2010年第4期211-213,共3页
关键词 广告业 广告宣传 广告理论 广告策划
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Global existence of weak solutions to a prey-predator model with strong cross-diffusion
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作者 李慧玲 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 2009年第6期727-740,共14页
Using finite differences and entropy inequalities, the global existence of weak solutions to a multidimensional parabolic strongly coupled prey-predator model is obtained. The nonnegativity of the solutions is also sh... Using finite differences and entropy inequalities, the global existence of weak solutions to a multidimensional parabolic strongly coupled prey-predator model is obtained. The nonnegativity of the solutions is also shown. 展开更多
关键词 prey-predator model strong cross-diffusion entropy functional existenceof weak solutions Orlicz space
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Strong and Weak Property of Travelling Wave Front Solutions for a Class of Degenerate Parabolic Equations
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作者 李正元 刘迎东 叶其孝 《Northeastern Mathematical Journal》 CSCD 2001年第2期195-204,共10页
In this paper we study the strong and weak property of travelling wave front solutions for a class of degenerate parabolic equations. How the strong and weak property changes under the effects of wave speed and reacti... In this paper we study the strong and weak property of travelling wave front solutions for a class of degenerate parabolic equations. How the strong and weak property changes under the effects of wave speed and reaction diffusion terms are showed. 展开更多
关键词 degenerate parabolic equation strong traveling wave front solution weak traveling wave front solution convergence or divergence propety of integral
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基于飞秒激光电子激发标记(FLEET)的高超声速自由流速度测量
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作者 李宇鹏 吴天舒 +5 位作者 栗继伟 王业军 郭成龙 霍宇涛 汪球 赵伟 《力学学报》 北大核心 2026年第2期417-424,共8页
地面风洞实验是研究高超声速流动特性的重要手段,精细化的速度表征有助于深入理解复杂流动现象并验证数值计算结果.相较于其他分子标记测速技术,飞秒激光电子激发标记(femtosecond laser electron excitation tagging,FLEET)以空气中的N... 地面风洞实验是研究高超声速流动特性的重要手段,精细化的速度表征有助于深入理解复杂流动现象并验证数值计算结果.相较于其他分子标记测速技术,飞秒激光电子激发标记(femtosecond laser electron excitation tagging,FLEET)以空气中的N_(2)为示踪粒子,显著降低了实验设计的复杂度.以往研究主要针对纯N_(2)环境下的FLEET速度测量,而O_(2)的存在会大幅缩短FLEET信号的有效寿命,此外,基于大尺度风洞的弱聚焦会进一步降低FLEET图像信噪比,从而影响速度测量精度.本研究依托JF-8A高超声速风洞,以空气为流动介质开展高超声速(Ma 6.5)自由流速度测量.静态实验表明,相较于纯N_(2)条件下的长寿命FLEET信号,聚焦区域内的O_(2)分子和O原子会显著缩短FLEET信号的有效寿命,同时导致标记线随延迟时间增加而逐渐展宽.激波风洞和炮风洞两种运行模式下获得的FLEET荧光标记线相比于参考时刻同样出现了展宽现象.重复性实验得到的自由流平均速度分别为1045.2和995.2 m/s,对应2σ标准差分别为1.98和1.77 m/s.本研究结果表明FLEET技术适用于强猝灭环境以及弱聚焦条件下的高精度速度测量,为基于大尺度风洞和含N_(2)组分的气流介质的速度测量提供了有效手段. 展开更多
关键词 飞秒激光电子激发标记 速度测量 高超声速流动 强猝灭 弱聚焦
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散体材料中应力传递的细观机制分析
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作者 王肖肖 刘洋 于鹏强 《岩土工程学报》 北大核心 2026年第3期476-486,共11页
基于离散单元法,对不同密实度的散体试样开展了双轴压缩试验的数值模拟,以细观loop结构作为基本单元,探讨了剪切过程中散粒体内部的应力承载特征与传递机制。通过以平均应力为指标划分强/弱结构loop单元,分析其结构重组与应力响应的演... 基于离散单元法,对不同密实度的散体试样开展了双轴压缩试验的数值模拟,以细观loop结构作为基本单元,探讨了剪切过程中散粒体内部的应力承载特征与传递机制。通过以平均应力为指标划分强/弱结构loop单元,分析其结构重组与应力响应的演化规律。结果表明,不同密实度试样在剪切过程中,loop单元均呈现出应变硬化/软化行为,并逐步演化至各自的细观临界状态。强结构loop倾向沿加载方向取向,形成细长结构链以主导偏应力传递;弱结构loop也沿加载方向取向,但其聚集成块状填充于强结构链空隙中,起到辅助支撑的作用。此外,散粒体强/弱结构更倾向于重组为各向异性较强的高阶6+-cycle单元,且宏观应力水平越高,细观组构各向异性对试样整体贡献越强。在临界状态下,不同初始密实度散粒体内部细观结构趋向于重组成具有相同数量、几何和力学水平的拓扑构型,以此来承载和传递同一围压下的临界常应力,在宏观尺度上表现为临界状态的唯一性。 展开更多
关键词 散粒材料 细观loop结构 应力传递 强/弱结构 离散元法
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强风下输电塔-线体系连续性失效反演研究
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作者 张国强 李治 +5 位作者 董优 李丹煜 贺春 刘俊才 张钰 杨汶鑫 《建筑钢结构进展》 北大核心 2026年第1期128-138,共11页
输电线路作为典型的风敏感结构,不仅分布范围广且极易遭受强风影响,强风作用易引发输电线路受损甚至发生倒塌事故,进而造成严重的经济损失。文中以强风致某输电塔倒塌实际案例为依托,首先建立了输电塔-线体系有限元模型;在风荷载模拟过... 输电线路作为典型的风敏感结构,不仅分布范围广且极易遭受强风影响,强风作用易引发输电线路受损甚至发生倒塌事故,进而造成严重的经济损失。文中以强风致某输电塔倒塌实际案例为依托,首先建立了输电塔-线体系有限元模型;在风荷载模拟过程中,充分考虑脉动风速的随机性与空间相干性影响,进而生成了不同风速与风攻角下风荷载时程曲线。其次基于非线性动力分析方法,对输电塔进行了强风下输电塔-线体系振动响应分析,明确了输电塔位移、节间位移角及关键杆件的应力响应规律,并捕捉了输电塔的连续性失效过程。结果表明:受塔-线耦合效应的影响,脉动风速随机性对输电塔的影响随着风攻角的增大而逐渐降低;当风速为28 m·s-1、风攻角为0°作用时,该输电塔第2、3节间的风振响应相对较大,表明这两个节间为该输电塔的薄弱位置;此外,数值模拟得到的输电塔失效模式与实际失效模式基本相同,输电塔薄弱区间的部分杆件屈曲引发局部区域应力重分布,当更多杆件的应力超过屈服强度后,最终诱发输电塔发生连续性倒塌,本研究以期为强风下输电线路的安全运行提供参考。 展开更多
关键词 输电塔-线体系 连续性失效 强风 薄弱区间 倒塌模式 风荷载时程曲线 振动响应分析
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鄱阳湖圩堤新老堤身渗透破坏机理模型试验研究
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作者 黄明新 刘亮 +2 位作者 杨景超 邓迅达 罗金 《中国农村水利水电》 北大核心 2026年第2期154-159,165,共7页
新老堤身材料差异性大是造成鄱阳湖圩堤汛期存在诸多险情的重要原因之一。基于原型堤角丰堤开展室内模型试验,模拟不同水位条件下堤身的渗流过程,重点分析了强弱透水层接触面附近的渗流特性及渗透破坏发展过程,并对堤身溃决机理进行讨... 新老堤身材料差异性大是造成鄱阳湖圩堤汛期存在诸多险情的重要原因之一。基于原型堤角丰堤开展室内模型试验,模拟不同水位条件下堤身的渗流过程,重点分析了强弱透水层接触面附近的渗流特性及渗透破坏发展过程,并对堤身溃决机理进行讨论。研究结果表明,新老堤身结合处由于渗透系数差异显著,接触面附近易形成较大的水力梯度和渗流集中现象,导致细颗粒被冲刷带走,最终发展为接触冲刷或散浸破坏。接触冲刷主要为渐进性发展,当超过临界水力梯度时,接触冲刷开始发生,进一步可诱发为管涌。散浸主要表现为坡脚土体被水浸泡软弱,进而诱发边坡失稳。试验揭示了堤防溃决的四个阶段:渗流初始阶段、渗流扩大阶段、渗透破坏阶段和堤身溃决阶段。研究结果可为鄱阳湖圩堤的设计、施工和加固提供理论依据和技术支持。 展开更多
关键词 堤防 强弱透水层 接触流失 渗透破坏 模型试验
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Weak gravitational lensing of quantum perturbed lukewarm black holes and cosmological constant effect
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作者 Hossein Ghaffarnejad Mojtaba Amir Mojahedi 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2017年第6期17-36,共20页
The aim of the paper is to study weak gravitational lensing of quantum (perturbed) and classical lukewarm black holes (QLBHs and CLBHs respectively) in the presence of cosmological parameter A. We apply a numerica... The aim of the paper is to study weak gravitational lensing of quantum (perturbed) and classical lukewarm black holes (QLBHs and CLBHs respectively) in the presence of cosmological parameter A. We apply a numerical method to evaluate the deflection angle of bending light rays, image locations θ of sample sourceβ = π- 4, and corresponding magnifications μ. There are no obtained real values for Einstein ring locations θE(β = 0) for CLBHs but we calculate them for QLBHs. As an experimental test of our calculations, we choose mass M of 60 types of the most massive observed galactic black holes acting as a gravitational lens and study quantum matter field effects on the angle of bending light rays in the presence of cosmological constant effects. We calculate locations of non-relativistic images and corresponding magnifications. Numerical diagrams show that the quantum matter effects cause absolute values of the quantum deflection angle to be reduced with respect to the classical ones. The sign of the quantum deflection angle is changed with respect to the classical values in the presence of the cosmological constant. This means dominance of the anti-gravity counterpart of the cosmological horizon on the angle of bending light rays with respect to absorbing effects of 60 local types of the most massive observed black holes. Variations of the image positions and magnifications are negligible when increasing dimensionless cosmological constant ∈ = 16AM2 /2The deflection angle takes positive (negative) values for CLBHs (QLBHs) and they decrease very fast (slowly) by increasing the closest distance x0 of bending light ray and/or dimensionless cosmological parameter for sample giant black holes with 0.001 〈 ∈ 〈 0.01. 展开更多
关键词 gravitational lensing weak - strong - micro - stars black holes
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Application of local polynomial estimation in suppressing strong chaotic noise 被引量:3
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作者 Su Li-Yun Ma Yan-Ju Li Jiao-Jun 《Chinese Physics B》 SCIE EI CAS CSCD 2012年第2期181-186,共6页
In this paper, we propose a new method that combines chaotic series phase space reconstruction and local polynomial estimation to solve the problem of suppressing strong chaotic noise. First, chaotic noise time series... In this paper, we propose a new method that combines chaotic series phase space reconstruction and local polynomial estimation to solve the problem of suppressing strong chaotic noise. First, chaotic noise time series are reconstructed to obtain multivariate time series according to Takens delay embedding theorem. Then the chaotic noise is estimated accurately using local polynomial estimation method. After chaotic noise is separated from observation signal, we can get the estimation of the useful signal. This local polynomial estimation method can combine the advantages of local and global law. Finally, it makes the estimation more exactly and we can calculate the formula of mean square error theoretically. The simulation results show that the method is effective for the suppression of strong chaotic noise when the signal to interference ratio is low. 展开更多
关键词 strong chaotic noise local polynomial estimation weak signal detection
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Strong Completeness of Medium Logic System
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作者 潘正华 朱梧槚 《Journal of Southwest Jiaotong University(English Edition)》 2005年第2期177-181,共5页
The strong completeness of medium logic system is discussed. The following results are proved: medium propositional logic system MP and its extension MP^* are strong complete; medium predicate logic system MF and it... The strong completeness of medium logic system is discussed. The following results are proved: medium propositional logic system MP and its extension MP^* are strong complete; medium predicate logic system MF and its extensions (MF^* and ME^* ) are not strong complete; and generally, ff a consistent formal system is not strong complete, then any consistent extensions of this forreal system are not strong complete either. 展开更多
关键词 Medium logic Formal system CONSISTENCY weak completeness strong completeness
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大国无战争时代美国弱联盟体系与新型地区秩序竞争 被引量:3
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作者 徐进 薄荣康 《东北亚论坛》 北大核心 2025年第1期3-13,127,共12页
在大国有战争时代,稳固的强联盟是霸权国增加实力、获得战争胜利从而以自身偏好塑造国际秩序的有效途径。大国无战争时代和内嵌型的对手特征增加了霸权国对弱联盟的使用偏好,核武器的出现、主权原则深入人心和经济相互依赖使得大国之间... 在大国有战争时代,稳固的强联盟是霸权国增加实力、获得战争胜利从而以自身偏好塑造国际秩序的有效途径。大国无战争时代和内嵌型的对手特征增加了霸权国对弱联盟的使用偏好,核武器的出现、主权原则深入人心和经济相互依赖使得大国之间爆发战争变得异常困难,同时,作为霸权国的美国面对的竞争对手内嵌于其主导的国际秩序,中国与美国的亚太盟友有着紧密联系,因此弱联盟成为美国参与亚太地区规则秩序竞争的有效补充策略。弱联盟基于实用主义取向,可以基于不同议题不断重新选择小集团成员,更具灵活性塑造基于规则的秩序。美国构建的弱联盟是强联盟的有效补充,具备明显的大国竞争倾向,核心目标仍旧是全面遏制中国崛起,中国需要细致剖析美国在不同领域领导的小集团发展路径,从而加强精准施策,实行“楔子战略”,拉打结合,分化弱化美国反华联盟,为自身发展营造持久有利的周边环境。 展开更多
关键词 弱联盟 强联盟 大国无战争时代 地区秩序竞争 霸权国
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CRITERIA OF STRONG TRANSIENCE FOR OPERATOR-SELF-SIMILAR MARKOV PROCESSES
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作者 吴传菊 张峰 刘禄勤 《Acta Mathematica Scientia》 SCIE CSCD 2006年第1期41-48,共8页
Yamamuro in [1] defines strong and weak transience of Markov processes; gives a criterion for strong transience of Feller processes; and further, discusses strong and weak transience of Ornstein-Uhlenbeck type process... Yamamuro in [1] defines strong and weak transience of Markov processes; gives a criterion for strong transience of Feller processes; and further, discusses strong and weak transience of Ornstein-Uhlenbeck type processes. In this article, the authors weaken the Feller property of the result in [1] to weak Feller property and discuss the strong transience of operator-self-similar Markov processes. 展开更多
关键词 Operator-self-similar processes strong transience ISOTROPIC weak Feller processes
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Developing Strong and Hybrid Formulation for the Single Stage Single Period Multi Commodity Warehouse Location Problem: Theoretical Framework and Empirical Investigation
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作者 R. R. K. Sharma Parag Tyagi +1 位作者 Vimal Kumar Ajay Jha 《American Journal of Operations Research》 2015年第3期112-128,共17页
We note that the Single Stage Single Period Multi Commodity Warehouse Location Problem (SSSPMCWLP) has been first attempted by Geoffrion and Graves [1], and that they use the weak formulation (in context of contributi... We note that the Single Stage Single Period Multi Commodity Warehouse Location Problem (SSSPMCWLP) has been first attempted by Geoffrion and Graves [1], and that they use the weak formulation (in context of contribution of this paper). We give for the first time “strong” formulation of SSSPMCWLP. We notice advantages of strong formulation over weak formulation in terms of better bounds for yielding efficient Branch and Bound solutions. However, the computation time of “strong” formulation was discovered to be higher than that of the “weak” formulation, which was a major drawback in solving large size problems. To overcome this, we develop the hybrid strong formulation by adding only a few most promising demand and supply side strong constraints to the weak formulation of SSSPMCWLP. So, the formulations developed were put to test on various large size problems. Hybrid formulation is able to give better bound than the weak and takes much less CPU time than the strong formulation. So, a kind of trade off is achieved allowing efficiently solving large sized SSSPMCWLP in real times using hybrid formulation. 展开更多
关键词 SSUWLP SSSPMCWLP strong and weak Constraints HYBRID FORMULATION RMIP
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Study on Design and Safety Evaluation Methods of Mechanical-Thermal Weak-Link
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作者 王飞 张方晓 《Defence Technology(防务技术)》 CAS 2012年第2期104-108,共5页
In an abnormal high-temperature fire environment,a structure with mechanical-thermal weak-link can be used to predict the permanent failure before the failure of some strong-links,such as explosive initiator,thus to p... In an abnormal high-temperature fire environment,a structure with mechanical-thermal weak-link can be used to predict the permanent failure before the failure of some strong-links,such as explosive initiator,thus to protect the latter. An effective design can be defined as that the weak-link fails before the failure of the strong-link,and the system is safe; while an unsuccessful design means that the weak-link fails after the failure of the strong-link,and the system loses in safety. The probability of safety failure exists due to the uncertain failure temperatures of the weak-link and strong-link. In order to obtain the probability of safety failure,a statistical method was used to deal with the uncertainty of the failure temperatures. The integral method and stochastic simulation method were used in calculations. Finally,a sample was given to verify the consistence of the results given by two methods. 展开更多
关键词 safety science strong-link weak-LINK safety evaluation abnormal high-temperature fire environment
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Is the“Weak Form”of CLT Being Adoptedin China ?
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作者 Zhu Xiaoyan 《山东师范大学外国语学院学报(基础英语教育)》 2005年第4期28-33,共6页
This paper, based on the hi sto rical background of CLT(communicative language teaching), mainly addresses the k ey issues concerning the weak form of CLT. This is an area few people have paid attention to in the past... This paper, based on the hi sto rical background of CLT(communicative language teaching), mainly addresses the k ey issues concerning the weak form of CLT. This is an area few people have paid attention to in the past few years in China. Therefore, its main concepts and f e atures are discussed with relevance to literature and an empirical study on four novice teachers of English. Finally, the research shows that the weak form of CLT is being conducted in Chinese secondary schools. 展开更多
关键词 CLT 计算机语言翻译程序 中国 中学 英语教学
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深部强动压软弱煤层沿空煤巷煤柱宽度及非对称控制研究 被引量:4
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作者 吕风 《煤炭工程》 北大核心 2025年第1期120-128,共9页
针对深部强动压软弱煤层沿空掘巷留设煤柱及其围岩支护系统极易发生大范围失稳破坏难题,以东庞矿深部水平沿空煤巷作为研究对象,采用理论分析方法获得了上覆基本顶岩层断裂线位置,明晰了煤柱尺寸与内、外应力场及极限平衡区宽度之间的... 针对深部强动压软弱煤层沿空掘巷留设煤柱及其围岩支护系统极易发生大范围失稳破坏难题,以东庞矿深部水平沿空煤巷作为研究对象,采用理论分析方法获得了上覆基本顶岩层断裂线位置,明晰了煤柱尺寸与内、外应力场及极限平衡区宽度之间的数值关系;引入偏应力分析指标,模拟研究了不同煤柱宽度下的沿空掘巷围岩偏应力与塑性破坏场响应特征,确定了深部强动压软弱煤层沿空掘巷窄煤柱合理宽度为7 m。基于7 m煤柱宽度情况下,模拟研究了回采期间超前工作面不同位置处的巷道围岩偏应力及塑性区分布状态,确定了超前工作面单体支柱加强范围;得出了掘巷稳定后其顶板、实体煤及煤柱帮塑化程度与偏应力峰值带边界线位置;明确了沿空巷道煤柱侧是围岩控制的关键区,阐述了掘巷支护设计时需将锚索穿过围岩偏应力峰值带边界线于围岩深部较完整区内的围岩控制对策,提出了“巷帮非对称槽钢桁架锚索网+顶板槽钢桁架锚索联合点锚索+局部破碎区注浆改性+单体液压支柱超前支护”的围岩综合治理技术。工程实践表明,研究所确定的7 m宽煤柱及围岩综合治理技术可有效控制围岩变形,保障深部强动压软弱煤层工作面的安全回采。 展开更多
关键词 软弱煤层 强动压 沿空掘巷 窄煤柱 非对称控制
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