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51.
This paper presents an approach to estimate the effects of a managed recharge experiment in a multilayer aquifer characterized by the presence of perched water tables in the Medina del Campo groundwater body, Douro basin, central Spain. A numerical model was developed to evaluate the effect of artificial recharge on the shallow sector of a regional-scale aquifer and on formerly active wetlands. The model was developed in the Visual MODFLOW Pro v.2011.1 environment in order to represent and analyse the regional impact of this artificial recharge event. Results suggest that the assumption of a single perched system may prove useful in regional contexts where data is limited. From a study site perspective, managed recharge is observed to increase shallow storage along the riverbanks, which is considered valuable for environmental purposes. However, downstream wetlands are unlikely to experience a significant recovery. Furthermore, only a small percentage of artificial recharge is expected to reach the deep regional aquifer. This method can be exported to settings characterized by the presence of perched aquifers and associated groundwater dependent ecosystems.  相似文献   
52.
In Arcachon Bay, a macrotidal coastal lagoon in southwest France, growth rates of cockles Cerastoderma edule (L.) differ greatly between locations. Sampling of populations at different tidal levels showed that the mean shell length was significantly and positively correlated with immersion time, whereas no correlation was found with population density and microphytobenthos biomass. Transplants of cockles between two intertidal sites were used to examine the relative importance of habitat and site of origin for growth rate and condition index. Artifacts due to manipulation were assessed, i.e. the impact of enclosures on growth, conditon index and mortality. During a 5-mo reciprocal transplant experiment, growth rates of the transplanted cockles and the cockles already present were similar, whereas the sites of origin did not affect growth rate. Condition index, however, displayed significant differences in relation to both transplant and origin sites. During a further 6-mo experiment in which cockles were transplanted from one site to four new sites, growth was mainly influenced by tidal level. These results indicate that net growth started when cockles were immersed 30% of the time. It is concluded that, on the scale of Arcachon Bay (156 km2), differences in growth and condition between cockle populations are largely phenotypic. Tidal level (i.e. food supply and emersion stress) accounts for most of these differences, but the existence of genetically or physiologically different populations cannot be excluded.  相似文献   
53.
54.
In light of the many improvements within 3D urban modeling and Location‐Based Services, this article provides a timely review of the state‐of‐the‐art on integrating indoor and outdoor spaces in pedestrian navigation guidance aids. With people moving seamlessly between buildings and surrounding areas, navigation guidance tools should extend from merely outdoor or indoor guidance, to provide support in the combined indoor‐outdoor context. This article first examines the challenges and complexities of integrating indoor and outdoor spaces into a single navigation system. Next, by using objective selection criteria, 36 relevant studies were withheld and further reviewed on their specific developments in data model requirements, and algorithmic and context support for integrated IO navigation systems. This review shows that the challenges of dealing with both indoor and outdoor space structures, while taking into account pedestrian's freer use of space, currently complicate the proposition of a unified IO space concept for navigation. However, there are some ongoing developments (e.g. context definitions, algorithmic extensions, increased data availability, growing awareness of pedestrians’ perception during wayfinding) that will help to bring outdoor and indoor spaces closer together in the realm of combined geospatial analysis.  相似文献   
55.
根据俚岛镇海湾22个海洋观测点的水质监测数据,依据人工神经网络与模糊理论,建立模糊神经网络模型,对研究区海水水质进行了综合评价.结果表明,区域内40.91%的采样点属于Ⅰ类海水水质标准,其余为Ⅱ类海水水质.其中,水质Ⅱ类区位于临络湾与俚岛湾的半封闭海域,因该区造船业对水体造成污染且海水对流强度较弱,不利于污染物的扩散;而海水水质Ⅰ类区域靠近黄海,工业活动较少,水体对流较强,利于污染物扩散.  相似文献   
56.
The double‐spike method with multi‐collector inductively coupled plasma‐mass spectrometry was used to measure the Mo mass fractions and isotopic compositions of a set of geological reference materials including the mineral molybdenite, seawater, coral, as well as igneous and sedimentary rocks. The long‐term reproducibility of the Mo isotopic measurements, based on two‐year analyses of NIST SRM 3134 reference solutions and seawater samples, was ≤ 0.07‰ (two standard deviations, 2s, n = 167) for δ98/95Mo. Accuracy was evaluated by analyses of Atlantic seawater, which yielded a mean δ98/95Mo of 2.03 ± 0.06‰ (2s, n = 30, relative to NIST SRM 3134 = 0‰) and mass fraction of 0.0104 ± 0.0006 μg g?1 (2s, n = 30), which is indistinguishable from seawater samples taken world‐wide and measured in other laboratories. The comprehensive data set presented in this study serves as a reference for quality assurance and interlaboratory comparison of high‐precision Mo mass fractions and isotopic compositions.  相似文献   
57.
应用改进的相干算法提高三维地震资料解释精度   总被引:2,自引:0,他引:2  
作者在文中详细探讨了C1、C2和C3三种相干算法及其。根据三维地震数据体的特点提出了实用的相干算法,并编制了相应的软件。我们对三种相干算法对应相干数据体的解释结果进行了细致的分析,C2相干算法基本能够平衡提高横向分辨率和信噪比之间的矛盾,而C3相干算法则取得了更精确的效果。  相似文献   
58.
The use of energy dissipation systems for the seismic control of steel structures represents a valid alternative to conventional seismic design methods. The seismic devices currently employed are mostly based on the metallic yielding technology due to the large feasibility and efficiency they can provide. Within this context, in the current paper an innovative solution based on the adoption of low‐yield‐strength pure aluminium shear panels (SPs) for seismic protection of steel moment‐resisting frames is proposed and investigated. In order to prove the effectiveness of the system, a wide numerical study based on both static and dynamic non‐linear analyses has been carried out, considering a number of different frame‐to‐shear panel combinations, aiming at assessing the effect of the main influential parameters on the seismic response of the structure. The obtained results show that the contribution provided by aluminium SPs is rather significant, allowing a remarkable improvement of the seismic performance of the structure in terms of stiffness, strength and ductility, with the possibility to strongly limit the damage occurring in the members of moment‐resisting frames. In particular, it is clearly emphasized that the stiffening effect provided by SPs allows a more rational design procedure to be adopted, since the serviceability limit state check does not lead to unavoidable and uneconomical increase of the size of main structural members. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   
59.
基于ARPS3DVAR+WRF (Advanced Regional Prediction and 3-dimensional variational System)快速同化模式对西南地区近几年发生的4次强降水过程进行模拟试验,对12 h降水预报结果采用升尺度方法,计算邻域平均预报、站点概率预报,最终形成邻域概率预报,并细致分析了这三种预报的特点与效果,讨论了升尺度窗区尺度给不同量级降水带来的影响,最后结合AROC评分与邻域空间检验FSS讨论业务概率预报应用的最佳尺度。结果表明:升尺度邻域平均预报在小雨与大暴雨量级降水上表现不稳定,对中雨的预报提高不明显,但是对大雨与暴雨预报有较好的改善效果;站点概率预报具有一定的误导性,而邻域概率预报可以弥补其缺憾,越高分辨率的模式有更多的降水样本,在降水不确定性上能给出更好的概率分级信息;相对邻域平均的升尺度预报TS检验结果,基于邻域概率的FSS和AROC分析有更好的预报技巧指导意义;36 km升尺度窗区既能消除一定程度的强降水预报不确定性,同时也可以保留适当的对流尺度特征,为最佳升尺度窗区。  相似文献   
60.
It is speculated from an empirical point of view that there may be yet unobserved matter around the planet Uranus inside the orbit of Miranda. Such matter, if any, is likely to be emplaced in the form of rings.In December, 1972, this paper — exactly as it is presented here, but with the title On the Posibility of Existence of a Ring of Uranus-was submitted to another scientific journal in the relevant field and was rejected. After the discovery of the Uranian rings, the same journal was requested to reopen the question of publication. This was done, and the paper was again rejected. The author has providedThe Moon and the Planets with proof of the original submission.Paper dedicated to Professor Hannes Alfvén on the occasion of his 70th birthday, 30 May 1978.  相似文献   
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