Seasonal dynamics of algal biomass and allochthonous input of coarse particulate organic matter in a low-order sandstone stream (Weidlingbach, Lower Austria)     

Ulrike ArtmannJohann A. Waringer  Michael Schagerl 《Limnologica》2003,33(2):77-91

From December 1997 to December 1998, benthic algal biomass and the input of allochthonous coarse particulate organic matter (CPOM) were investigated in bi-weekly intervals at two sampling stations (shaded and sunny) of the Weidlingbach, a fourth order sandstone stream in the Wienerwald. A total of 41 benthic algal taxa was collected, belonging to the groups Cyanobacteria (4 taxa), Bacillariophyceae (33), Rhodophyta (1), Chrysophyceae (1) and Chlorophyta (2). At the shaded site, periphyton dry mass ranged from 13 g m⁻² in April to 440 g m⁻² in August (annual mean = 93 g m⁻²), at the sunny site from 3 g m⁻² in May to 512 g m⁻² in late fall (annual mean = 70 g m⁻²). Based on the algal carotenoid pattern, Bacillariophyceae were most abundant in fall and winter while Chlorophyceae dominated during summer. Mean annual standing stock of chlorophyll-a was 8.65 μg cm⁻² at the shaded station and 7.53 μg cm⁻² at the sunny site. Annual allochthonous CPOM input rates ranged from 382 to 665 g dry mass m⁻² for aerial input and from 1006 to 1062 g DM m⁻¹ of stream length for lateral input. Lateral input rates were influenced by the bank inclination; the temporal distribution of aerial input showed an autumnal maximum (61-65% of the total). Direct CPOM input was significantly highest (P<0.05) during the period of defoliation from October to November. In the course of this period, 61.1% (shaded) to 64.9% (sunny) of the annual CPOM dropped into the brook, yielding daily input rates of 6.6 to 4.0 g DM m⁻². From December to September, daily direct input rates decreased to 0.84 g DM m⁻² (shaded) and 0.44 g DM m⁻² (sunny). At both sites, retention capacity was high; 70% of marked leaves released along transects were retained by coarse sediment particles within 40 m from the starting point. The annual mean of periphyton dry mass made up 52% of CPOM standing stock at the shaded site and 39% at the sunny site.  相似文献   

一种基于似三棱柱体元的地质三维建模方法研究   总被引：4，自引：0，他引：4  

程朋根刘学斌  史文中王伟 《华东地质学院学报》2004,27(1):73-79

三堆空间建模方法是三堆地劫工程GIS研究的核心问题之一。提出一种基于似三棱柱体元的三堆数据模型，模型包含顶点、线段(棱边、三角形边)、三角形、侧面四边形、三棱柱体元5个基本元素。和点对象、线对象、面对象、体对象、复杂对象、空间对象等6个对象。设计了5个基本元素和3种地质对象的数据结构和它们之间的拓扑关系。以岩体和巷道为例。给出了似三棱柱体建模思路和算法。利用内蒙古某矿区实际钻孔资料和模拟巷道数据对所开发的系统原型进行验证。研究表明。基于似三棱柱体元的数据模型的优势在于可以表示空间对象的表面和内部结构。便于建模和节省存储空间，同时便于不规劓的自然地质体和规则勘探工程建模。  相似文献   

Multiobjective optimal FLC driven hybrid mass damper system for torsionally coupled,seismically excited structures     

A. S. Ahlawat  A. Ramaswamy 《地震工程与结构动力学》2002,31(12):2121-2139

In most of the research work on structural vibration control only two‐dimensional plane structural modelling has been considered, although only a few practical building structures can be modelled as planar structures. Therefore, these methods are not directly applicable to the majority of the practical building structures. This paper discusses the design of a multiobjective optimal fuzzy logic controller (FLC) driven hybrid mass damper (HMD) system for seismically excited torsionally coupled building structures. Floor acceleration and velocity information have been used as feedback to the fuzzy logic controller. A three branch tournament Genetic Algorithm has been used for the multiobjective optimal design of the FLC driven HMD system, where the minimization of the non‐dimensionalized peak displacement, acceleration and rotation of the structure about its vertical axis, have been as the three objective functions. The proposed multiobjective optimal fuzzy logic controller has been verified for an example problem reported in the literature. This HMD system consists of four HMDs arranged in such a way that the system can control the torsional mode of vibration effectively in addition to the flexure modes of vibration. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

基于GIS和AI的城市区域内最佳路径算法研究   总被引：2，自引：1，他引：1  

张水舰  李永树  蔡国林  杨骏 《测绘科学》2008,33(4)

针对传统Dijkstra算法效率低的特点,从GIS和人工智能的角度提出了一种对传统Dijkstra算法进行优化的方式。首先根据城市交通网络的特点建立了交通网络拓扑图,提出了地名节点和交通节点的概念,并用合理的数据结构存储此交通网络,然后在此基础上使用一种新的启发函数以提高搜索效率,使优化过的Dijkstra算法能用于复杂的交通网络。  相似文献   

基于土壤反射光谱特性的广东省稻田土壤快速分类   总被引：1，自引：0，他引：1  

李丹  彭智平  韩留生  王重洋  刘尉  黄思宇  陈水森 《热带地理》2015,35(1):29-34

选择广东省215个村镇稻田的土壤样本,首先利用ASD Field Spec3测量土壤样本在350~2 500 nm的光谱,并采用S-G一阶导数平滑滤波降低样本测量中光照差异的影响,然后将遗传算法（Genetic Algorithm,GA）和支持向量机分类（Support Vector Machine,SVM）分别用于提取分类光谱特征和建立分类模型,分别在土纲、亚纲、土类3个层次进行土壤分类。结果表明：1）在不同的分类层次下,与铁氧化物密切相关的650~710以及900 nm附近光谱,与羟基矿物吸收有关的2 207~2 237和2 377~2 397 nm区间均被作为分类特征变量。2）随着土壤类型的细分,分类所需变量增多。在土类级,对有机质敏感的2 080 nm附近的光谱也被引入分类定标模型中,土纲和亚纲下分类精度＞67%,土类级分类精度为58.67%。利用遗传算法提取光谱特征,进行基于支持向量机的土壤分类具有一定优势。  相似文献   

Simultaneous Growth of Spirulina platensis and Removal of Hardness in Van Lake Water     

Olcayto Keskinkan  Oya Işık  Turan Yılmaz  Behzat Balcı  Leyla H. Uslu  Çağatayhan B. Ersü 《洁净——土壤、空气、水》2012,40(1):34-38

In this study, batch experiments were carried out to investigate simultaneous growth of Spirulina platensis and removal of hardness in the Van Lake Water (VLW). Laboratory‐scale studies showed ample Spirulina growth observed in VLW when exposed to light. Spirulina was the only algal specimen inoculated in the water during the study. VLW percentages were varied between 0.1 and 100% while pH values were 8.7–10.42 in the flasks. On a dry‐weight basis the biomass concentration was 1.18 g L^?1 at pH 10 after 17 days of incubation in the VLW. The increase of pH to above 10.38 associated with Spirulina growth resulted in the precipitation of hardness causing compounds while providing 70% hardness removal from the VLW medium. Experimental results indicated that the proposed method can be used to design batch systems for producing S. platensis and removal of hardness from the VLW.  相似文献   

江苏及邻区地震重新定位和构造特征分析   总被引：16，自引：5，他引：11       下载免费PDF全文

黄耘  李清河  张元生  孙业君  沈红会  金淑梅 《地球物理学报》2008,51(1):175-185

本文将双差定位和遗传算法定位两种方法相结合,对江苏及邻区1980～2005年的地震进行重新定位研究.重新定位后大大改善了原地震定位的精度,地震在空间上更加集中分布在某些区域,地震震源深度分布结果更加合理.江苏及邻区地震主要发生在上地壳和中地壳;研究区不同构造单元的震源深度统计分析表明,下扬子断块江苏段、冀鲁断块和豫皖断块的地震震源深度特点相似,在10～11 km、15～17 km深处存在二个明显的地震优势分布,推测分别在上地壳底面和中地壳;在25 km深处也存在一小的地震优势分布面,但地震频次较低.大别山地区地震的震源深度与下扬子断块、冀鲁断块和豫皖断块内的地震震源深度存在明显的差异,主要差异为大别山地区10 km以上的浅源地震十分发育,在6～7 km的深处有一地震优势分布,该深度附近地震波速度可能较高,而在10 km以下差异不大.  相似文献   

基于LTI和网格界面剖分的三维地震射线追踪算法   总被引：7，自引：4，他引：3       下载免费PDF全文

张东  傅相如  杨艳  秦前清  徐凌 《地球物理学报》2009,52(9):2370-2376

将二维线性走时插值射线追踪算法(LTI)推广应用至三维模型,并结合网格界面剖分方式,提出了一种三维射线追踪算法．该算法既可获得高精度的全局最小走时和射线路径,又具有快速稳定的特点．三维模型计算结果表明,在模型参数包括网格密度完全相同情况下,本文算法较传统的三维最短路径算法在计算效率、走时和射线的计算精度上均有明显改进．  相似文献   

Sewage impacts coral reefs at multiple levels of ecological organization     

Pasinee Reopanichkul  Thomas A. Schlacher  R.W. Carter  Suchai Worachananant 《Marine pollution bulletin》2009,58(9):1356-1362

Against a backdrop of rising sea temperatures and ocean acidification which pose global threats to coral reefs, excess nutrients and turbidity continue to be significant stressors at regional and local scales. Because interventions usually require local data on pollution impacts, we measured ecological responses to sewage discharges in Surin Marine Park, Thailand. Wastewater disposal significantly increased inorganic nutrients and turbidity levels, and this degradation in water quality resulted in substantial ecological shifts in the form of (i) increased macroalgal density and species richness, (ii) lower cover of hard corals, and (iii) significant declines in fish abundance. Thus, the effects of nutrient pollution and turbidity can cascade across several levels of ecological organization to change key properties of the benthos and fish on coral reefs. Maintenance or restoration of ecological reef health requires improved wastewater management and run-off control for reefs to deliver their valuable ecosystems services.  相似文献   

江苏中、南部及邻区地震重新定位及在断层研究中的应用   总被引：1，自引：0，他引：1       下载免费PDF全文

刘建达  李清河  张元生  金淑梅 《地球物理学进展》2009,24(1):58-66

本文分析了地震相对定位的双差法和地壳结构与定位联合反演方法的优势与局限性,在联合反演中用遗传算法最优化,将上述两种方法结合,对江苏省中南部和相邻地区进行地震重新精定位.先对研究区进行地壳结构与定位联合反演,然后用得到的地壳结构,用双差法进行相对定位.就该区主要断层的平面分布及与地震的关系,溧阳6.0级地震、南黄海6.2级地震、常熟-太仓5.1级地震的震源深度与发震构造,常熟一张家港间震群的震源深度进行了分析讨论.  相似文献