The spatial implications of the functional proximity deriving from air passenger flows between European metropolitan urban regions     

Malcolm C. Burns  Josep Roca Cladera  Montserrat Moix Bergadà 《GeoJournal》2008,71(1):37-52

Until recently the traditional spatial configuration of the European geography was based upon the core-periphery model. The ‘pentagon’, broadly defined as lying between London, Paris, Milan, Munich and Hamburg, was seen as the core area characterised by having the highest concentration of economic development in the European Union (EU), with the remainder of the European territory viewed as peripheral, albeit to varying degrees. In a number of cases such peripheral areas equated with clear regional disparities. The elaboration of the European Spatial Development Perspective (ESDP) (CEC, European spatial development perspective, towards balanced and sustainable development in the territory of the European Union, 1999) challenged this core-periphery model. European spatial planning policies, aimed at encouraging social and economic, and with ever increasing importance, territorial cohesion, seek amongst other aspects to encourage the development of a balanced and polycentric urban system. This paper adopts a network analysis approach to the analysis of air passenger flows between some 28 principal European metropolitan urban regions. The evaluation of these flows contributes to an enhanced comprehension of the spatial dynamics of the European metropolitan territory which goes beyond that deriving from the more standard analyses of the individual components of the urban system. Several indicators are used, deriving from gravitational modelling techniques, to analyse the complexity of the air passenger flows. A multidimensional scaling (MDS) technique is introduced in order to interpret and visualise the resulting spatial configuration and positioning of the different metropolitan centres within the conceptual European ‘space of air passenger flows’, thereby contrasting with the more traditional map-based geographical image of Europe, based upon Cartesian coordinates.

Malcolm C. BurnsEmail:

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Functional responses for zooplankton feeding on multiple resources: a review of assumptions and biological dynamics     

Wendy Gentleman  Andrew Leising  Bruce Frost  Suzanne Strom  James Murray 《Deep Sea Research Part II: Topical Studies in Oceanography》2003,50(22-26):2847

Modelers often need to quantify the rates at which zooplankton consume a variety of species, size classes and trophic types. Implicit in the equations used to describe the multiple resource functional response (i.e. how nutritional intake varies with resource densities) are assumptions that are not often stated, let alone tested. This is problematic because models are sensitive to the details of these formulations. Here, we enable modelers to make more informed decisions by providing them with a new framework for considering zooplankton feeding on multiple resources. We define a new classification of multiple resource responses that is based on preference, selection and switching, and we develop a set of mathematical diagnostics that elucidate model assumptions. We use these tools to evaluate the assumptions and biological dynamics inherent in published multiple resource responses. These models are shown to simulate different resource preferences, implied single resource responses, changes in intake with changing resource densities, nutritional benefits of generalism, and nutritional costs of selection. Certain formulations are further shown to exhibit anomalous dynamics such as negative switching and sub-optimal feeding. Such varied responses can have vastly different ecological consequences for both zooplankton and their resources; inappropriate choices may incorrectly quantify biologically-mediated fluxes and predict spurious dynamics. We discuss how our classes and diagnostics can help constrain parameters, interpret behaviors, and identify limitations to a formulation's applicability for both regional (e.g. High-Nitrate-Low-Chlorophyll regions comprising large areas of the Pacific) and large-scale applications (e.g. global biogeochemical or climate change models). Strategies for assessing uncertainty and for using the mathematics to guide future experimental investigations are also discussed.  相似文献   

噪声信号源超磁致伸缩换能器设计方法研究     

任绍俊  程宜杰 《海洋技术学报》2007,26(1):61-64,68

针对以往噪声信号发射换能器在实际工作中,存在着诸多影响正常科研试验的问题,并根据噪声信号的技术要求,以及探测方式的技术特征,我们对噪声发射换能器进行了重新设计,从选用超磁致伸缩材料作为换能器的材料入手,结合国内外一些新的设计理念,从材料性能分析,到理论设计,最后到可靠性实施方法,都进行了周密细致的研究,并完成了设计全过程。测试结果和使用性能表明,达到了预期的目的,这也是该材料在国内首次应用于单只宽频水声换能器中,开创了稀土超磁致伸缩材料应用的又一个先列。  相似文献   

Soluble organic compounds in fog and cloud droplets: what have we learned over the past few years?     

Sandro Fuzzi  Maria Cristina Facchini  Stefano Decesari  Emanuela Matta  Mihaiela Mircea 《Atmospheric Research》2002,64(1-4)

We have recently set up a new procedure for characterising the water soluble organic compounds (WSOC) in fog water, for which information is still rather limited. Fog samples collected during the 1998–1999 fall–winter season in the Po Valley (Italy) were analysed following this procedure, which allows a quantitative determination of three main classes of organic compounds (neutral species, mono- and di-carboxylic acids, polycarboxylic acids), together accounting for ca. 85% of the total WSOC. This procedure also provides information on the main chemical characteristics of these three classes of compounds (functional groups, aliphatic vs. aromatic character, etc.). The enhanced chemical knowledge on fog/cloud chemical composition opens new scenarios as far as chemical and microphysical processes in clouds and fogs are concerned.  相似文献   

Li2O—B2O3功能材料体系研究概述     

谢贤宁  高海春 《盐湖研究》1996,4(1):73-80

本文介绍了碱金属硼酸盐的一些基本知识，主要回顾了其中Ｌｉ２Ｏ—Ｂ２Ｏ３体系的研究历史，讨论了该体系结构与性质的关系并总结了Ｌｉ２Ｏ－Ｂ２Ｏ３晶态及非晶态物质作为新型功能材料的研究进展。  相似文献   

Distribution and Elimination of Lead Species in Soils Related to GAP of Chinese Medicinal Materials of Ligusticum Chuanxiong Hort     

DENG Tian-long~ 《地球科学进展》2004,(Z1)

In this paper, the sequential extraction procedure was used for the selection of fractions of lead in seven stages corresponding to lead exchangeable, lead bounded to carbonates, to manganese oxides, to organic matters, to amorphous iron, and lead associated to crystallized iron, and to residuals. The vertical distributions of lead species were carried out in the soils related to good agriculture progress (GAP) of Chinese medical materials of Ligusticum chuanxiong Hort in Dujiangyan city and Wenchuan County, Sichuan Province. Based on those researches, it is found that the plant of Glycine Max (L.) Merr. has the character of lead enrichment and sorption, which is not reported in the literature. Using Glycine Max (L.) Merr. alternate planting with Ligusticum chuanxiong Hort is a valuable recommended in order to produce a high quality Chinese medical materials in order to eliminate the barrier on the beyond the lead limit for the import and export of Ligusticum chuanxiong Hort.  相似文献   

Effect of food quality on energy uptake     

Jeffrey S. Ren   《Journal of Sea Research》2009,62(2-3):72

The dynamic energy budget (DEB) theory assumes that the feeding of an organism in relation to food density follows the type-II functional response when food consists of purely digestible organic matter. However when faced with a food source high in inorganic content, an organism needs to adapt physiologically to maximise organic extraction. Indeed filter-feeding marine bivalves inhabiting turbid coastal waters cope with large fluctuations in food quality by selectively ingesting and pseudofaeces production. Data from feeding experiments with the New Zealand greenshell mussel Perna canaliculus have demonstrated that inorganic particles contribute some uncertainty to the estimate of the half-saturation coefficient. Incorporating inorganic matter into the functional response would improve the prediction of energy uptake.  相似文献   

海洋功能区划与海洋生态红线关系探讨          下载免费PDF全文

高月鑫  曾江宁  黄伟  陈全震  寿鹿  徐晓群 《海洋开发与管理》2018,35(1):33-39

海洋生态红线制度是我国"五位一体"文明建设的具体要求。为进一步在自然科学与人文科学的联结点上探求深入开展生态红线工作的可能性,文章对比了实施多年的海洋功能区划与历史新阶段提出的海洋生态保护红线的概念和内涵,剖析了两者之间的区别与联系,指出海洋功能区划与海洋生态红线区划在法律地位和管控制度等方面具有一致性,在划分目标、空间管理及划分方法上具有差异性,海洋功能区划以"使用"为主,海洋生态红线以"保护"引领。在此基础上,建议未来海洋生态红线工作的开展可从海洋功能区划借鉴经验,建立完善的管控评估制度,确立生态保护红线的优先地位,处理好海洋功能区划与海洋生态红线区划的关系。同时,海洋生态红线区划应以维持海洋生态系统结构稳定和提高海洋生态系统服务功能为目标,将区域资源环境承载力评估作为一项参考指标,限制低承载区的开发利用,保证海洋生态环境健康可持续发展。  相似文献   

基于陆海统筹的海岸带空间功能分区——以宁波市为例     

安太天  高金柱  李晋  朱庆林  沈佳纹  丁健 《海洋通报》2022,(3):315-324

海岸带空间功能分区是优化海岸带开发与保护的基础性工作,在国土空间规划体系中具有重要作用。当前我国海陆功能分区在分区层级、分区方法等方面并不一致,导致海岸带保护与开发利用失衡。本文在梳理国内外海岸带空间功能分区研究的基础上,从陆海统筹角度出发,构建海岸带空间功能分区体系,并以宁波市为例进行验证,在优先划定生态保护区基础上,对海陆空间进行适宜性评价,根据评价结果确定功能分区。结果表明：（1）宁波市海岸带功能区中生态保护区面积占比约为60%,海陆一体发展区占比约为22.3%,海洋发展区占比约为12.5%,陆地发展区占比约为5.2%;(2)宁波市开发利用功能区空间分布与以临港产业、海洋服务业和海洋渔业为基础的海洋经济发展导向相符。海岸带空间功能分区要以生态保护为底线,以优化空间布局为导向,为优化海岸带开发与保护提供有力支撑。  相似文献   

福建港口体系结构研究   总被引：2，自引：0，他引：2  

陈斓  伍世代  陈培健 《热带地理》2007,27(3):249-253,283

阐述了福建港湾自然条件和港口开发现状,采用赫希曼-赫芬达尔指数分析近20年来港口体系空间结构的动态演变规律,结果表明,福建港口体系空间结构演变总趋势呈分散化。这说明了港口间的竞争大于合作,职能结构趋同,因而形成合理分工与协作的福建港口群是当务之急。鉴于此,运用模糊聚类、货种区位商等分析技术,对其体系内的港口等级层次、职能结构的基本特征进行探讨,并在此基础上提出了各港口职能分工的发展方向。  相似文献