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1.
以烟田普查和系统调查为主要手段明确了2013年奉节烟区的主要病害种类及其发生流行规律,并在实践基础上根据病害的发生流行规律组配了主要病害的防控对策。2013年奉节烟区主要发生病害种类有烟草野火病、烟草赤星病、烟草黑胫病、烟草普花叶病毒病、烟草气候斑点病等5种病害。此5种病害的发生流行规律各不相同,防治时机和对策也各不相同。在防治上,不同病害的防治重点不同,主要以"预防为主、综合防控"的原则进行。  相似文献   

2.
空心板梁桥"单板受力"病害机理及其加固处治研究   总被引:2,自引:0,他引:2  
首先建立了6种跨度空心板梁桥的梁单元模型,分析得出荷载横向分布规律.通过对一10 m跨度桥梁实体模型的数值分析,讨论了桥梁"单板受力"病害产生的原因,并提出了4种加固方案.然后通过比较分析底板竖向位移、横向应力以及等效应力;综合各方案的优缺点,确定了最优加固方案,为"单板受力"病害的防治提供了理论依据.最后提出了增加结构横向刚度、保证施工质量等措施,以期能有效地防治"单板受力"病害.  相似文献   

3.
程立志 《广东科技》2012,(3):121-122,124
通过对水泥混凝土路面在"改善工程"施工中出现裂缝、断板等病害的观察,并认真分析产生各种病害的原因,提出如何从改善施工工艺、加强初期养护、杜绝病害成因等方面进行预防和控制的探讨。  相似文献   

4.
青藏公路高路基病害的形成及其机理   总被引:3,自引:0,他引:3  
为研究以纵向裂缝为主的青藏公路高路基病害的形成及其机理,在大量实地调查研究的基础上,分析了高路基病害形成的原因,分析认为高路基病害不仅与融化盘有关,还与融化夹层、冻结核和冻土环境等相关。研究结果表明:高路基病害与路基高度及坡向直接相关;路基高度大于2.5m的路基内高路基病害占总量的75.7%,且阳坡侧病害占总量的66.5%;当路基高度小于临界高度时,融化盘及其偏移是形成路基病害的主要原因;反之,在高温冻土区,融化夹层则是主要因素,而在低温冻土区,冻结核形成的"凸"滑动面与阳坡侧坡脚下融化盘的联合作用引发了一系列高路基病害;施工质量与冻土环境的破坏等构成了影响高路基病害的人为因素;高路基病害的治理应因地制宜,结合病害的形成特点采取不同的治理方案。  相似文献   

5.
寒区大温差环境下封闭工程结构层覆盖于地基上,导致水分聚集在结构层底部形成"锅盖效应",引起地基承载力降低,加剧工程冻融病害.随着"一带一路"的推进,寒区高等级公路、油气站场、机场跑道建设涉及的锅盖效应病害亟需解决.调查了寒区公路路基、高铁无砟轨道基床、机场跑道、输油站场面临的锅盖效应病害,从病害特征、形成机理、理论模型、防控技术等四个方面,综述了寒区工程锅盖效应形成机理及病害防治的最新进展.同时,在总结当前锅盖效应研究不足的基础上,提出了今后寒区工程锅盖效应理论研究和灾害控制措施的方向:①关注水汽含量的测试和多年冻土区锅盖效应形成条件研究;②构建考虑空气-水汽两相流和土体变形规律的水-汽-热-力耦合模型,以此来预测工程构筑物的稳定性;③开展基于"阻-通-截"理念的综合防治措施研究,以期为寒区工程设计和病害防治提供理论支持和科学对策.  相似文献   

6.
通乡油路工程是国家"十一五"期间实施的一项惠民工程,修建里程较长,已成为县乡公路养护管理的重点。主要调查了沥青表处路面存在的病害,结合实际分析了造成沥青表处路面病害的原因,并提出了相应的处治措施。  相似文献   

7.
某泥岩地基无砟轨道高速铁路出现路基上拱病害;但泥岩根据多部规范大部分被判定为"无膨胀性"。通过钻芯取样与X射线衍射等试验对病害成因进行分析。研究结果表明:规范中判定为"无膨胀性"的低黏土矿物含量泥岩实际具有微弱的膨胀性。该地区泥岩岩层非常厚、地下水丰富与无砟轨道的高精度变形要求多方面因素是病害发生的原因。  相似文献   

8.
微型桩整治隧底填充结构裂损病害的原理及效果分析   总被引:1,自引:1,他引:0  
汪旵生 《科学技术与工程》2013,13(20):5861-5866
某隧道进口段仰拱填充结构在施工期出现大量未贯通的"V"字形裂缝。根据隧底填充结构裂损特征,结构现场工程地质条件、水文地质条件、地形地貌及隧道地下水排导系统设计与施工情况,得出作用在仰拱填充结构上的水压力是导致其开裂的主要原因。提出了通过发挥微型桩受拉特征整治水压力作用下隧底填充结构裂损病害的措施。通过数值分析、现场测试和观察得出了微型桩加固能有效减少或抑制仰拱隆起,防止隧道仰拱填充结构的"V"字形裂缝产生和发展。论证了利用微型桩整治水压力作用下隧底填充结构裂损病害的有效性,为类似隧道病害整治提供了参考依据。  相似文献   

9.
暴雨导致的高铁隧道轨隆病害(称"轨隆")时有发生,严重影响线路行车秩序,为此,系统归纳近年来轨隆案例,统计分析其病害特征及地质与降雨因素,依托典型案例,采用3D打印技术构建其精细化高铁隧道模型及排水设施,开展轨隆病害可视化模拟试验,探讨隧道排水量、结构外水压力和结构位移的规律;基于轨隆病害特点,提出病害整治流程及不同处...  相似文献   

10.
水泥混凝土路面的病害对于行车速度、安全及舒适性具有重要影响。分析了水泥混凝土路面的四大类病害:断裂类病害、竖向位移类病害、接缝类病害、表层类病害,对各类病害的类型及轻重程度分级进行了详细讨论,而后探讨了水泥混凝土路面病害的处治对策,并提出了相应的预防建议。  相似文献   

11.
Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.  相似文献   

12.
何延凌 《科技信息》2008,(4):258-258
Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women's language from these perspectives: pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women's language, more attention should be paid to language use in social context. What's more, the linguistic phenomena in a speaking community can be understood more thoroughly.  相似文献   

13.
理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。  相似文献   

14.
As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.  相似文献   

15.
正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-  相似文献   

16.
We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-  相似文献   

17.
正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that  相似文献   

18.
For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the  相似文献   

19.
Franck-Condon factors bridge the gap between theoretical modeling and experimental observations for molecular electronic spectroscopy and electron transfer.Under the displaced harmonic oscillator approximation,multidimensional Franck-Condon factors are decomposed into a product of many one-dimensional(1D)Franck-Condon(FC)factors,and each 1D-FC factor is associated with one Huang-Rhys factor that determines the leading contribution of  相似文献   

20.
<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with  相似文献   

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