Large-scale dune erosion tests to study the influence of wave periods   总被引：1，自引：0，他引：1  

M.R.A. van Gent  J.S.M. van Thiel de Vries  E.M. Coeveld  J.H. de Vroeg  J. van de Graaff 《Coastal Engineering》2008,55(12):1041-1051

Large-scale physical model tests were performed to quantify the effects of the wave period on dune erosion. Attention was focussed on 2D cross-shore effects in a situation with sandy dunes and extreme water levels and wave conditions. Besides profile measurements, detailed measurements in time and space of water pressure, flow velocities and sediment concentrations were performed in the near near-shore area. It was concluded that a longer wave period leads to a larger dune erosion volume and to a larger landward retreat of the dune face. Tests with double-peaked wave spectra showed that the influence of the spectral shape on dune erosion was best represented by the T_m − 1,0 spectral mean wave period, better than the peak wave period, T_p. The effect of the wave period on dune erosion was implemented in a dune erosion prediction method that estimates erosion volumes during normative storm conditions for the Dutch coast. More details of the measurements and additional analyses of physical processes are described in an accompanying paper by Van Thiel de Vries et al. [Van Thiel de Vries, J.S.M., van Gent, M.R.A., Reniers, A.J.H.M. and Walstra, D.J.R., submitted for publication. Analysis of dune erosion processes in large scale flume experiments, In this volume of Coastal Engineering.].  相似文献   

空间钟与基础物理测试     

翟造成 《天文学进展》2007,25(2):161-168

原子钟当前已经发展到很高的水平,它们在空间科学试验中发挥了重要的作用．该文介绍了世界上正在开展的高精度空间钟计划及其对科学测量的意义．对应用空间钟可能进行的某些感兴趣的基础物理测试也进行了描述。  相似文献   

Patterns of genetic and morphometric diversity in the marbled crab (Pachygrapsus marmoratus, Brachyura, Grapsidae) populations across the Tunisian coast   总被引：1，自引：1，他引：0  

Temim Deli  Hiba Bahles  Khaled Sai  Noureddine Chatti 《海洋学报(英文版)》2015,34(6):49-58

The present study reports on population structure analysis of the marbled crabPachygrapsus marmoratus (Fabricius, 1787) from the Tunisian coast, an appropriate location to study biogeographical process...  相似文献   

条斑紫菜SSU 中内含子分析     

李星辰  徐佳杰  林中姮  沈颂东 《海洋科学》2015,39(3):12-18

根据GenBank中已知的条斑紫菜(Porphyra yezoensis)SSU和LSU r RNA基因序列分别设计引物,分别以混合个体和单个个体的基因组DNA以及c DNA为模板进行扩增,测序分析后推测SSU r RNA基因中的内含子转录后加工可能仍被保留,而在LSU r RNA基因上游序列中没有发现内含子。长511bp的内含子位于SSU r RNA基因序列的上游,其插入位点为TCTGGTG-CCAGCAGCC,内含子5′和3′端的核苷酸序列分别为AAC-和-ATGG。该内含子的剪接位点以及保守区P,Q,R,S与I型内含子是不同的。研究发现,在同种紫菜中,不同个体SSU基因中内含子的有无、分布及结构特征是不同的,说明内含子对于分类是不太适合的。但是内含子的长度以及核苷酸序列在种间又具有一定的特异性,可以为红藻种间以及种内亲缘关系较远的亚种和不同地理群的区分和鉴定提供参考。  相似文献   

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吕慧珠  黄文德  闻德保 《大地测量与地球动力学》2015,35(2):283-286

?????????????????????ZTD????????????????????￡???????????????????????????????????????????????ZTD???????????????????????????ZTD???н?????????????????????????????????????????ZTD?????????????б????????????????????????в???AR?????и???????????????????????????????AR??????ZTD??????????????????????????μ??????????cm????  相似文献   

地面气象站环境变化对气温序列均一性影响   总被引：12，自引：3，他引：9  

吴利红  康丽莉  陈海燕  马仙妹 《气象科技》2007,35(1):152-156

为研究浙江省地面气象站环境变化对气温序列均一性的影响程度,采用测站历史沿革资料,对全省测站环境的时空演变进行了分析。采用距平累加、偏差界限值、F值检验法,对36个代表站的年平均气温序列进行均一性检验,并对非均一性产生的原因进行分析。结果表明:1971~2004年,浙江省测站的地理环境有显著改变;36站中有39%的测站为非均一性,产生非均一性的测站中,迁站原因占57%,环境恶化占36%;测站迁站引起的非均一性多发生在1980年以后;测站迁站时,新旧站址海拔高度差大且地理环境差异显著是造成气温序列非均一性的主要原因,迁站后气温序列较旧址存在偏高或偏低现象,其值对累年平均值有影响。指出了测站在迁移或环境变化过程中应注意的事项,以助于减少气温序列非均一性。  相似文献   

资料均一化对沈阳站气温趋势和城市化偏差分析的影响   总被引：2，自引：0，他引：2       下载免费PDF全文

李娇  任国玉  任玉玉  张雷 《大气科学学报》2014,37(3):297-303

利用国家气象信息中心2013年发布的逐日均一化气温资料,对沈阳站资料均一化处理前后平均气温和极端气温指数序列的线性趋势及其城市化影响偏差进行了比较评价。结果表明:1)资料均一化处理对日最高气温及其衍生的极端气温指数序列趋势估计的影响较弱,但对日最低气温及其衍生的极端气温指数序列趋势估计具有显著影响。2)经资料均一化处理后,平均气温序列中的城市化影响偏差有所增大,平均最低气温序列中的城市化影响偏差增大尤其明显;与冷事件有关的极端气温指数序列的城市化影响偏差数值有所减小,与暖事件有关的极端气温指数序列的城市化影响偏差数值有所增加。3)资料均一化处理有效纠正了因迁站等原因造成的地面气温观测记录中的非均一性,但却在很大程度上还原了城市站地面气温观测记录中的城市化影响偏差。  相似文献   

动应力对粉质土变形、强度的影响     

左辉  张留栓 《岩土工程技术》2014,28(6):311-315

研山铁矿设计采用露天开采,最终最大边坡高达600m。边坡上部为粉土和粉砂、中砂、卵石、粉质粘土,下部为砂质粘性土和砾质粘性土。由于边坡高,受环境动应力影响因素大,因此分析粉土和粉质粘土层在动应力作用下对变形和强度的影响,对边坡稳定分析具有重要意义。  相似文献   

Numerical study of the 3D failure envelope of a single pile in sand     

《Computers and Geotechnics》2014

The paper presents a comprehensive study of the failure envelope (or capacity diagram) of a single elastic pile in sand. The behavior of a pile subjected to different load combinations is simulated using a large number of finite element numerical calculations. The sand is modeled using a constitutive law based on hypoplasticity. In order to find the failure envelope in the three-dimensional space (i.e. horizontal force H, bending moment M and vertical force V), the radial displacement method and swipe tests are numerically performed. It is found that with increasing vertical load the horizontal bearing capacity of the pile decreases. Furthermore, the presence of bending moment on the pile head significantly influences the horizontal bearing capacity and the capacity diagram in the H–M plane manifests an inclined elliptical shape. An analytical equation providing good agreement with the 3D numerical results is finally proposed. The formula is useful for design purposes and the development of simplified modeling numerical strategies such as macro-element.  相似文献   

Petrophysical properties of bioclastic platform carbonates: implications for porosity controls during burial     

Delphine Croizé  Stephen N. Ehrenberg  Knut Bjørlykke  François Renard  Jens Jahren 《Marine and Petroleum Geology》2010

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