Sediment burial stimulates the growth and propagule production of Spartina alterniflora Loisel.     

Zifa Deng  Shuqing An  Congjiao Zhao  Lin Chen  Changfang Zhou  Yingbiao Zhi  Hongli Li 《Estuarine, Coastal and Shelf Science》2008,76(4):818-826

Spartina alterniflora Loisel., an extensively invasive species on the Chinese coast, is a focus of increasing management concern due to its high expansion rate in estuaries and tidal zone, and the significant damage it causes to native ecosystems. In order to understand the processes and mechanisms of invasion of S. alterniflora in China, the impact of three sediment types (sand, sand–loam mixture and loam) and five buried patterns (unburied, 50% burial of initial plant height, 75% burial of initial plant height, complete burial and repeated burial) on the growth of seedlings or ramets was investigated. Results showed that each of the three factors (sediment types, burial pattern and plant materials) and interactions between/among them, significantly affected height and clonal growth, and biomass accumulation and allocation. Plant height, total biomass and number of new vegetative propagules significantly increased with progressive burial treatments. However, the complete burial treatment resulted in the death of all plant materials, and the maximum values of three parameters were found in the 50% burial or repeated burial treatments. Plant responses were determined by the instantaneous thickness of sediment of each time burial rather than by the total quantity of repeated burial. The growth of S. alterniflora was not shown to be dependent on specific types of sediment in sedimentation environment. In contrast to the unburied control, the proportion of primary tillers produced directly from initial individuals and the ratio between the aboveground and belowground biomass were greater under burial treatments. Seedlings produced more new vegetative propagules than vegetative offspring in all experimental treatments, and the former were apt to produce ramets from rhizomes rather than primary tillers. It is concluded that under various sedimentation environments, the clonal spread efficiency of seedlings was higher than that of vegetative offspring, and there is a positive feedback relationship between sedimentation and the growth of S. alterniflora. Thus, moderate sedimentation may stimulate the invasion of exotic species, S. alterniflora in coastal China.  相似文献   

辽宁省海水入侵成因及防治措施     

寇英杰  王颖 《国土资源》2000,(1)

海水入侵是在自然和人为因素综合作用下形成的地质灾害。辽宁省海水入侵自 70年代以来呈逐渐增加趋势 ,具有入侵面积广、发展速度快等特点。目前海水入侵已成为我国较为突出的地质灾害 ,给工农业生产和人民生活造成很大危害。针对海水入侵形成机制及危害程度的地域性 ,目前已采取不同的防治措施 ,如控制开采 ,人工回灌 ,修建地下水库等 ,取得一定效果。  相似文献   

On finite volume method implementation of poro‐elasto‐plasticity soil model          下载免费PDF全文

Philip Cardiff 《国际地质力学数值与分析法杂志》2015,39(13):1410-1430

Accurate prediction of the interactions between the nonlinear soil skeleton and the pore fluid under loading plays a vital role in many geotechnical applications. It is therefore important to develop a numerical method that can effectively capture this nonlinear soil‐pore fluid coupling effect. This paper presents the implementation of a new finite volume method code of poro‐elasto‐plasticity soil model. The model is formulated on the basis of Biot's consolidation theory and combined with a perfect plasticity Mohr‐Coulomb constitutive relation. The governing equation system is discretized in a segregated manner, namely, those conventional linear and uncoupled terms are treated implicitly, while those nonlinear and coupled terms are treated explicitly by using any available values from previous time or iteration step. The implicit–explicit discretization leads to a linearized and decoupled algebraic system, which is solved using the fixed‐point iteration method. Upon the convergence of the iterative method, fully nonlinear coupled solutions are obtained. Also explored in this paper is the special way of treating traction boundary in finite volume method compared with FEM. Finally, three numerical test cases are simulated to verify the implementation procedure. It is shown in the simulation results that the implemented solver is capable of and efficient at predicting reasonable soil responses with pore pressure coupling under different loading situations. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

室内控制场数码相机检校应用于通用航空摄影测量的可行性研究     

李伟  任超峰 《测绘工程》2012,21(4):49-52

非量测数码相机已广泛应用于计算机视觉、摄影测量等领域,但必须对其进行内定向和构像畸变的校正。常用的检校方法主要有室外检校法和室内检校法两类,其中利用室外三维控制场进行数码相机检校是目前较为成熟的做法,而室内三维控制场检校精度能否达到常规比例尺航空摄影要求尚未进行有效验证。通过论述一整套室内三维控制场相机检校方法,并对比分析两种检校结果表明,室内三维控制场检校精度还无法满足通用航摄精度要求。  相似文献   

CINRAD/SB伺服系统线路设计特点和维修方法   总被引：1，自引：0，他引：1  

潘新民  柴秀梅  王全周  徐俊领  崔炳俭 《气象》2010,36(10):128-133

总结了CINRAD/SB型新一代天气雷达交流变频调速数字伺服系统线路技术特点和与CINRAD/SA线路设计上的差别。根据数字伺服系统信号流程、电源控制保护原理,从状态监测信息、FC文件信息、报警信息、关键点参数测量和关键信号的传输路径入手,详细介绍了数字伺服系统故障诊断方法和技巧,并列举了两个不同类型的典型故障个例的理论分析和处理步骤。提出了伺服系统维修方面的一些建议,为新一代大气雷达技术支持和保障提供借鉴。  相似文献   

不分散低固相钻井液体系在张掖平山湖矿区中的应用          下载免费PDF全文

蔡晓文  纪卫军  阮海龙  李艳宁 《探矿工程》2010,37(8):27-28,31

平山湖矿区第四系、第三系地层属于遇水不稳定地层,钻探施工时,地层造浆严重、孔径扩大率高,造成钻探事故频发、施工效率低。采用以聚合物为主要添加剂的不分散低固相钻井液体系在该矿区进行了应用试验,有效地抑制了粘土造浆及泥页岩水化膨胀,取得了很好的效果。  相似文献   

浅谈孔压静力触探     

田元  张小强 《城市地质》2010,5(1):24-26

本文简单介绍了孔压触探所用设备及准备工作,对孔压触探探头的饱和过程和JTY-3A型静探数据采集仪的操作步骤进行了说明,最后提出了测试有关要求及注意事项。  相似文献   

福建主要港口外轮压舱水生物的分布及其潜在入侵威胁   总被引：1，自引：0，他引：1  

杨清良  蔡良候  高亚辉  苏展  陈长平  李炳乾  许翠娅  林更铭  郑惠东  项鹏 《海洋湖沼通报》2009,(4)

根据2006～2007年间采自福建省4个主要港口12艘外轮(包括8条集装箱船和4条散货船)的压舱水样品,研究压舱水生物的分布特点,结果表明进入该水域的外来船舶压舱水生物物种丰富度和个体丰度高,共发现浮游植物7门86属240种(包括60种赤潮生物)和浮游动物5门30属52种;经3种网目(20,77,和160μm)筛网收集的不同粒径生物的平均丰度分别为:动物38858.3 ind./m~3(粒径77～160μm)和782.3 ind./m~3(粒径>160μm);植物3625.0 cells./ dm~3(粒径20～77μm)和134.1 cells./dm~3(粒径77～160μm).压舱水生物的分布及生存状态与水样的盐度及水龄相关.初步评估外来压舱水生物排放对福建沿海的潜在入侵风险.  相似文献   

一种基于E-Key及Web页面监控的网站防篡改机制研究     

范建华  宋云波 《成都信息工程学院学报》2009,24(4):356-360

通过监控Web页面文件变化和利用E-Key数字证书提高操作安全的网站防篡改机制,可以有效减少甚至消除由于网页遭遇篡改而给企业造成负面影响的目的.特殊设计的Web页面访问过滤监控程序通过计算,比对摘要,可以及时发现被篡改页面并执行删除操作和通知Web页面文件监控程序.Web页面文件监控程序立即停止Web服务,并删除变化文件.Web页面文件监控程序定期向Web页面安全管理服务程序发送心跳包,Web页面安全管理服务程序通过对心跳包的实时监测监控文件变化情况,并及时进行修复还原和报警,同时进行文件更新管理以及文件及其摘要备份.客户端安全控件实现操作者E-Key数字证书和服务器证书间的双向认证,确保web管理者远程操作过程的安全性.  相似文献   

滑坡灾害防治工程中施工组织设计对工程投资概算影响的研究   总被引：1，自引：0，他引：1  

屈晓红  邹艳琴  门玉明  彭建兵 《工程地质学报》2001,9(1):51-56

本文通过对具体地质灾害防治工程初步设计阶段的施工组织设计与工程投资概算之间关系分析, 指出施工组织对工程投资概算的影响不小于工程设计和地质勘查资料的影响, 施工组织设计对概算可靠度的提高有很重要的意义。  相似文献