Phytoplankton as an Indicator of Improving Water Quality in the Golden Horn Estuary   总被引：4，自引：0，他引：4  

Seyfettin Tas  I. Noyan Yilmaz  Erdogan Okus 《Estuaries and Coasts》2009,32(6):1205-1224

The variation in phytoplankton community as a response to improving water quality has been studied in the severely polluted Golden Horn Estuary (GHE). Phytoplankton data collected monthly for 4 years and a detailed set of environmental parameters clearly showed the remarkable change in the GHE. The GHE ecosystem did not respond to numerous rehabilitation efforts to improve water quality, unless strict measures were taken to enhance water circulation. The opening of a bridge operating on large buoys and release of high amounts of fresh water from a dam acted as the turning point for the whole system. The weakening of light limitation and anoxia at upper regions is followed by consecutive blooms of different species/groups and resulted in super-saturated dissolved oxygen concentrations and a significant decrease in nutrient concentrations. When compared to the pre-remediation period, average total eukaryotic phytoplankton abundance increased 11-fold in the lower estuary, while the increase in the upper estuary was over 3 × 10⁴ in the post-remediation period. In addition, species richness continuously increased through the study period and community structure showed very strong variability. Since the estuarine ecosystem is controlled by precipitation in the last decade, the increase in anthropogenic/terrestrial inputs following heavy rainfall had adversely affected water quality and phytoplankton.  相似文献   

Adaptive neuro-fuzzy modeling for the swelling potential of compacted soils   总被引：1，自引：1，他引：0  

C. Kayadelen  T. Taşkıran  O. Günaydın  M. Fener 《Environmental Earth Sciences》2009,59(1):109-115

This paper aims to present the usability of an adaptive neuro fuzzy inference system (ANFIS) for the prediction swelling potential of the compacted soils that are important materials for geotechnical purposes such as engineered barriers for municipal solid waste, earth dams, embankment and roads. In this study the swelling potential that is also one of significant parameters for compacted soils was modeled by ANFIS. For the training and testing of ANFIS model, data sets were collected from the tests performed on compacted soils for different geotechnical application in Nigde. Four parameters such as coarse-grained fraction ratio (CG), fine-grained fraction ratio (FG), plasticity index (PI) and maximum dry density (MDD) were presented to ANFIS model as inputs. The results obtained from the ANFIS models were validated with the data sets which are not used for the training stage. The analyses revealed that the predictions from ANFIS model are in sufficient agreement with test results.  相似文献   

基于个体行为的多尺度城市空间重构及规划应用研究框架   总被引：2，自引：0，他引：2  

柴彦威  刘天宝  塔娜 《地域研究与开发》2013,32(4):1-7,14

中国城市转型面临多尺度的空间重构,从社区、中心城市到都市区、城市群等不同空间尺度。一方面,每个尺度上的空间组织特征及居民行为模式彻底改变;另一方面,一系列社会环境和自然环境问题出现并累积。面对城市发展的新格局和新问题,需要依托行为研究,梳理多尺度城市空间的概念体系,揭示其形成机理,判断其环境响应,并以低碳和和谐城市为导向,提出规划策略。具体内容包括:整合GPS、手机、网络、问卷和访谈等多种行为数据,建立中国城市多时空尺度居民行为数据库;分析城市、都市区和城市群尺度的城市空间组织模式和居民行为特征,创建基于个体行为的中国城市空间理论体系和研究范式;解析多尺度城市空间组织及居民行为模式与社会矛盾和碳排放之间的关系;以社会公正、和谐和低碳为导向,提出不同尺度城市空间调整优化策略和居民行为引导策略,面向居民生活质量和城市发展可持续性的提升,推动形成多尺度的居民生活圈和城市空间单元。  相似文献   

Energy approach to unsaturated cyclic strength of sand     

Volkan Okur  Seyfettin Umut Umu 《Bulletin of Earthquake Engineering》2013,11(2):503-519

The mechanical response to cyclic loading of saturated cohesionless soils is usually investigated by means of effective stress method considering pore water pressure changes that lead to reduced strength and stiffness. On the other hand, the behavior of partially saturated sands is different from the behavior of saturated sand deposits. The development of negative pore water pressures in particular makes it difficult to estimate the behavior of partially saturated sands. The response of partially saturated sands, however, can be examined in a physically understandable manner by investigating their energy characteristics independently of pore pressure behavior. To establish a general framework for understanding the behavior of partially saturated sand, a total of 52 resonant column and dynamic torsional shear tests were conducted under undrained conditions. The effects of factors such as the amplitude of shear strain, relative density, saturation ratio and confining pressure on the dynamic characteristics of the sand and on energy dissipation were studied. The use of the energy concept in the evaluation of partially saturated soils is shown to be a promising method for the evaluation of the cyclic behavior of partially saturated sands.  相似文献   

Current Vertical Motion Analysis of Northwestern Margin of Ordos Based on Precise Leveling     

Guo Baozhen  Ta L  Zhou Haitao  Su Guangli 《中国地震研究》2018,32(1):113-118

Ordos block was squeezed by the Qinghai-Tibetan block and North China block, and the tectonic activity was intense. In the periphery of Ordos block, there was a series of folds zones and compressed faults with complicate structures. This paper used three-phase data of 1980,1990 and 2014 to calculate vertical velocity of Northwestern margin of Ordos and the analytical results indicated that ① the Hetao basin between the rise of Yinshan fault block and Ordos fault block showed relatively subsidence, in which Linhe basin was the most evident and the subsidence rate was about 2-4mm/a. The subsidence rate of Jartai -Yinchuan rift zone on the western margin of Ordos block was about 2mm/a; ② the whole testing zone exhibited the evident inherited movement characterized by mountain rise and basin subsidence; ③the two leveling section through the northern margin fault and Dengkou-Benjing fault showed that the difference between vertical velocities on two sides of the fault was less than 0.5mm/a.  相似文献   

Hypothesis testing methods to detect spoofing attacks: a test against the TEXBAT datasets     

Troglia Gamba  Micaela  Truong  Minh Duc  Motella  Beatrice  Falletti  Emanuela  Ta  Tung Hai 《GPS Solutions》2017,21(2):577-589

GPS Solutions - The hazardous effects of spoofing attacks on the global navigation satellite system (GNSS) receiver are well known. Technologies and algorithms to increase the awareness of GNSS...  相似文献   

基于POI数据的上海市餐饮业空间分布特征及影响因素   总被引：2，自引：0，他引：2  

唐锦玥  何益珺  塔娜 《热带地理》2020,40(6):1015-1025

以上海市为研究对象，基于兴趣点（POI）数据，运用核密度分析刻画餐饮业空间格局，并构建OLS模型、空间滞后模型、空间误差模型探究餐饮业空间分布的影响因素。结果发现，餐饮业空间分布呈块状聚集、多中心发展的格局。其中，西餐业高度集中于内环线以内，呈东西向延伸；快餐业在中心城区和高校集聚的城郊结合部大规模集聚。空间计量回归结果表明，餐饮业分布受到人口、经济、交通、空间4类要素的影响：区域经济发展水平高、人口规模大、交通优越、相关业态丰富会促进集聚，而周边业态的混合度过高则会抑制集聚，城市空间结构也会影响餐饮业分布，商圈、中心城区的餐饮业密度更高；中餐、西餐、正餐、快餐4类餐饮业分布的影响因素存在差异性，西餐企业倾向于分布在地价较高的地区，中餐企业对交通可达性有更高的需求，正餐企业的分布与当地区域经济发展水平显著相关，快餐企业的分布与各类文娱公共设施的分布有密切联系。  相似文献   

Downstream fining in contrasting reaches of the sand‐bedded Yellow River     

Wanquan Ta  Haibin Wang  Xiaopeng Jia 《水文研究》2011,25(24):3693-3700

Compared to downstream fining of a gravel‐bedded river, little field evidence exists to support the process of downstream fining in large, fine sand‐bedded rivers. In fact, the typically unimodal bed sediments of these rivers are thought to produce equal mobility of coarse and fine grains that may discourage downstream fining. To investigate this topic, we drilled 200 sediment cores in the channel beds of two fine‐grained sand‐bedded reaches of the Yellow River (a desert reach and a lower reach) and identified a fine surface layer (FSL) developed over a coarse subsurface layer (CSL) in the 3‐m‐thick bed deposits. In both reaches downstream, the thickness of the FSL increased, while that of the CSL decreased. Comparison of the depth‐averaged median grain sizes of the CSL and the FSL separately in both reaches shows a distinct downstream fining dependence to the median grain size, which indicates that at a large scale of 600‐800 km, the CSL shows a significant downstream fining, but the FSL shows no significant trends in downstream variations in grain size. This result shows that fine sediment supply (<0·08 mm median grain size) from upstream, combined with lateral fine sediment inputs from tributaries and bank erosion, can cause a rapid fining of the downstream channel bed surface and can develop the FSL layer. However, in the desert reach, lateral coarse sediment supply (>0·08 mm median grain size) from wind‐borne sediments and cross‐desert tributaries can interrupt the FSL and coarsen the channel bed surface locally. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

基于Arc／INFO的地学信息系统的设计与开发   总被引：1，自引：0，他引：1  

姚锐  鲍光淑  戴塔根  邱冬生  谢文兵 《物探化探计算技术》2001,23(4):360-364,369

论文主要研究了基于GIS技术和数据融合技术的地学信息系统的开发问题。采用国际先进的硬件、软件作为开发平台，建立了一个比较完善的湖南省国土资源地学信息系统。系统功能除常规空间信息查询外，还包括缓冲区分析、叠置分析、地质成图等各种复杂的分析功能。它为湖南省国土资源地学信息管理提供了一个重要手段，为区域地质找矿提供了一种新的研究思路。  相似文献   

The Misis–Andırın Complex: a Mid-Tertiary melange related to late-stage subduction of the Southern Neotethys in S Turkey     

Alastair Robertson  Ülvi Can Unlügen  Nurdan nan  Kemal Ta li 《Journal of Asian Earth Sciences》2004,22(5):413

The Mid-Tertiary (Mid-Eocene to earliest Miocene) Misis–Andırın Complex documents tectonic-sedimentary processes affecting the northerly, active margin of the South Tethys (Neotethys) in the easternmost Mediterranean region. Each of three orogenic segments, Misis (in the SW), Andırın (central) and Engizek (in the NE) represent parts of an originally continuous active continental margin. A structurally lower Volcanic-Sedimentary Unit includes Late Cretaceous arc-related extrusives and their Lower Tertiary pelagic cover. This unit is interpreted as an Early Tertiary remnant of the Mesozoic South Tethys. The overlying melange unit is dominated by tectonically brecciated blocks (>100 m across) of Mesozoic neritic limestone that were derived from the Tauride carbonate platform to the north, together with accreted ophiolitic material. The melange matrix comprises polymict debris flows, high- to low-density turbidites and minor hemipelagic sediments.The Misis–Andırın Complex is interpreted as an accretionary prism related to the latest stages of northward subduction of the South Tethys and diachronous continental collision of the Tauride (Eurasian) and Arabian (African) plates during Mid-Eocene to earliest Miocene time. Slivers of Upper Cretaceous oceanic crust and its Early Tertiary pelagic cover were accreted, while blocks of Mesozoic platform carbonates slid from the overriding plate. Tectonic mixing and sedimentary recycling took place within a trench. Subduction culminated in large-scale collapse of the overriding (northern) margin and foundering of vast blocks of neritic carbonate into the trench. A possible cause was rapid roll back of dense downgoing Mesozoic oceanic crust, such that the accretionary wedge taper was extended leading to gravity collapse. Melange formation was terminated by underthrusting of the Arabian plate from the south during earliest Miocene time.Collision was diachronous. In the east (Engizek Range and SE Anatolia) collision generated a Lower Miocene flexural basin infilled with turbidites and a flexural bulge to the south. Miocene turbiditic sediments also covered the former accretionary prism. Further west (Misis Range) the easternmost Mediterranean remained in a pre-collisional setting with northward underthrusting (incipient subduction) along the Cyprus arc. The Lower Miocene basins to the north (Misis and Adana) indicate an extensional (to transtensional) setting. The NE–SW linking segment (Andırın) probably originated as a Mesozoic palaeogeographic offset of the Tauride margin. This was reactivated by strike-slip (and transtension) during Later Tertiary diachronous collision. Related to on-going plate convergence the former accretionary wedge (upper plate) was thrust over the Lower Miocene turbiditic basins in Mid–Late Miocene time. The Plio-Quaternary was dominated by left-lateral strike-slip along the East Anatolian transform fault and also along fault strands cutting the Misis–Andırın Complex.  相似文献