Allelopathy at the land/sea interface: microalgae and Brazilian pepper     

Hargraves PE 《Marine environmental research》2008,66(5):553-555

Microalgae are significant contributors to biodiversity and primary production in shallow coastal habitats. The invasive Brazilian pepper (Schinusterebinthifolius) can occupy former mangrove habitats in disturbed areas, and its allelopathic capability can affect growth rates of microalgae. The four microalgae tested against dilution extracts of Schinus fruits varied in their growth response, suggesting variable but unpredictable impacts on microalgal biodiversity, primary production, and community structure.  相似文献   

Benthic primary production, respiration and remineralisation: in situ measurements in the soft-bottom Abra alba community of the western English Channel (North Brittany)     

Aline Mign  Dominique Davoult  Jean-Jacques Bourrand  Guy Boucher 《Journal of Sea Research》2005,53(4):223

In situ measurements of ammonium and carbon dioxide fluxes were performed using benthic chambers at the end of spring and the end of summer in two soft-bottom Abra alba communities of the western English Channel (North Brittany): the muddy sand community (5 m, about 10% of surface irradiance) and the fine-sand community (19 m, about 1% of surface irradiance). High rates of ammonium regeneration were measured in the two communities at the end of summer (296.03±40.07 and 201.7±62.74 μmolN m⁻² h⁻¹, respectively) as well as high respiration rates (2.60±0.94 and 2.23±0.59 mmolC m⁻² h⁻¹, respectively). Significant benthic gross primary production (up to 6.11 mmolC m⁻² h⁻¹) was measured in the muddy sand community but no benthic primary production was measured in the fine-sand community. It suggests that microphytobenthic production values used in simulations previously published for these two communities were overestimated while values of community respiration were underestimated. The study confirms that this benthic system is heterotrophic and strengthens the idea that an important pelagic-benthic coupling is required for the functioning in such coastal ecosystems.  相似文献   

Evaluation of Stress Intensity Factors Subjected to Arbitrarily Distributed Tractions on Crack Surfaces     

刘钧玉  林皋 《中国海洋工程》2007,21(2):293-303

The stress intensity factors (SIF) considering arbitrarily distributed surface tractions are evaluated based on the scaled boundary finite element method (SBFEM). The semi-analytical solving process for the stress intensity factors including the effects of surface tractions is presented. Provided are the numerical examples for the evaluation of mode Ⅰ and Ⅱ stress intensity factors with linear and non-linear distributing forces loaded on the crack surfaces. The crack problems of anisotropy and bimaterial interface are also studied and the stress intensity factors of single-edge-cracked orthotropic material and bi-material interface problems with surface tractions are calculated. Comparisons with the analytical solutions show that the proposed approach is effective and possesses high accuracy.  相似文献   

基于WebGIS的地学虚拟环境研究     

蔡鲁湘  赵龙  杨英力 《海洋测绘》2004,24(2):43-46

在介绍了WebGIS和地学虚拟环境技术特征的基础上，研究了WebGIS技术在地学虚拟环境中的应用。从系统结构、用户界面、数据模型等三个方面，对WebGIs技术用于地学虚拟环境的深层次系统框架进行了研讨，并对WebGIS技术与地学虚拟环境技术进行结合的实际过程进行了说明。  相似文献   

Friction Characteristics at the Pipe-Soil Interface     

Yan Shuwang Yan Chi Professor 《中国海洋工程》1994,(2)

-In order to analyze the stability of pipelines on the sea bed, the friction characteristics at the pipe-soil interface were examined by means of special direct shear tests. High density polythene was used as the surface of the pipe, which is a widely-utilized material for the outer cover of the pipe to prevent sea water corrosion. Sands of different gradings were tested. The reconstituted soft clay taken from the Bohai area was consolidated to different degrees of consolidation by the vacuum preloading technique, and tested.  相似文献   

基于微信公众平台的天地图地名更新技术应用研究     

张伟  相恒茂  涂振发  杨浚  张存业 《地理信息世界》2016,(4):90-94

针对目前天地图地名数据更新存在的针对性差、专业性强、频率低等问题,本研究利用微信等新媒体获取地图变化信息并进行地名数据更新,提出了基于微信公众平台的当前地理位置主动式获取更新方法、电子地图发现式更新和指定条件查询式更新等方法,在天地图山东地名数据更新中得到了应用,相对于传统的地名更新模式,此方式数据更新频率更快、成本更加低廉,有助于保证天地图山东的数据现势性。  相似文献   

基于Matlab的地图投影程序设计     

张帅  邱春霞  杨存英  钱磊  苏卉 《测绘与空间地理信息》2016,(9):206-209

随着地理信息系统(GIS)的发展与应用,地图投影转换成为GIS软件是当前面临的一个主要问题。本文首先分析和阐述了Matlab的程序设计基础、图形用户界面及地图投影整体程序设计,然后结合Matlab的计算程序,实现了高斯投影正算与反算、高斯投影换带、高斯投影与UTM投影之间转换的计算。通过实例验证了程序的可行性,满足了工程需要,为基于Matlab的地图投影程序设计提供了重要的参考依据。  相似文献   

灌注桩混凝土界面检测仪器的研发          下载免费PDF全文

祝世平  刘春生  王伏春  涂国强  章传明 《探矿工程》2016,43(1):36-39

灌注桩混凝土与泥浆界面检测一直是困扰施工行业的难题,常规的手工量测误差随着空孔段的加深越来越大。利用混凝土的密度和电阻抗与其它介质不同的物性原理,研发了灌注桩混凝土界面自动检测仪,介绍了仪器的主要结构组成、软件设计、现场试验等。试验结果表明,该检测仪器能够有效解决灌注桩混凝土灌注过程中混凝土与泥浆界面检测问题,具有很好的经济、社会效益。  相似文献   

A statistical analysis of the distribution of cordierite and biotite in hornfels from the Bugaboo contact aureole: implications for the kinetics of porphyroblast crystallization          下载免费PDF全文

A. Petley‐Ragan  F. Gaidies  D.R.M. Pattison 《Journal of Metamorphic Geology》2016,34(1):85-101

The three‐dimensional disposition of cordierite and biotite crystals in a hornfels from the contact aureole of the Bugaboo Batholith is quantified using high‐resolution X‐ray micro‐computed tomography and global as well as scale‐dependent pattern statistics. The results demonstrate a random distribution of cordierite and biotite crystal sizes for all scales across the entire rock volume studied indicative of interface‐controlled prograde metamorphic reaction kinetics. The reaction considered responsible for the mineral assemblage and the formation of cordierite and biotite in the hornfels is Ms + Chl + Qtz = Crd + And + Bt + . Rock‐specific phase equilibria point to metamorphic conditions of ~520 –550 °C and 3 kbar for this reaction. The common approach to approximate the shape of crystals as spherical underestimates the influence of the Strauss hard‐core process on rock texture and may be misinterpreted to reflect ordering of crystal sizes by inhibition of nucleation and growth commonly associated with diffusion‐controlled reaction kinetics. According to our findings, Strauss hard‐core ordering develops at length scales equal to and less than the average major axis of the crystal population. This is significantly larger than what is obtained if a spherical crystal geometry would be assumed, and increases with deviation from sphericity. For the cordierite and biotite populations investigated in this research, Strauss hard‐core ordering developed at length scales of up to ～2.2 and 1.25 mm, respectively, which is almost 1 mm longer than the scales that would be obtained if a spherical geometry would have been assumed. Our results highlight the importance of a critical assessment of the geometrical model assumptions commonly applied in the three‐dimensional analysis of crystal size distributions, and underline the need for a quantitative understanding of interface processes in order to appreciate their role in the kinetics of contact metamorphic reactions and rock texture formation.  相似文献   

产生安全椭圆曲线的MPI并行实现     

杨浩淼  江春华 《成都信息工程学院学报》2005,20(2):138-141

快速产生安全的椭圆曲线是椭圆曲线密码体制(ECC)理论研究和实际应用的前提和基础，构造给定阶的椭圆曲线的复乘(CM)方法，是实践中构造安全椭圆曲线最常用的方法。基于消息传递接VI(MPI)的并行实现了复乘方法，实验表明，在两台主机上加速比达到了1．38。  相似文献