Scaling of foreign attractiveness for countries and states     

《Applied geography (Sevenoaks, England)》2016

People’s behavior on online social networks, which store geo-tagged information showing where people were or are at the moment, can provide information about their offline life as well. In this paper we present one possible research direction that can be taken using Flickr dataset of publicly available geo-tagged media objects (e.g., photographs, videos). Namely, our focus is on investigating attractiveness of countries or smaller large-scale composite regions (e.g., US states) for foreign visitors where attractiveness is defined as the absolute number of media objects taken in a certain state or country by its foreign visitors compared to its population size. We also consider it together with attractiveness of the destination for the international migration, measured through publicly available dataset provided by United Nations. By having those two datasets, we are able to look at attractiveness from two different perspectives: short-term and long-term one. As our previous study showed that city attractiveness for Spanish cities follows a superlinear trend, here we want to see if the same law is also applicable to country/state (i.e., composite regions) attractiveness. Finally, we provide one possible explanation for the obtained results.  相似文献   

Rheological and physical characteristics of crustal-scaled materials for centrifuge analogue modelling     

《Journal of Structural Geology》2016

We characterize a set of analogue materials used for centrifuge analogue modelling simulating deformation at different levels in the crust simultaneously. Specifically, we improve the rheological characterization in the linear viscoelastic region of materials for the lower and middle crust, and cohesive synthetic sands without petroleum-binding agents for the upper crust. Viscoelastic materials used in centrifuge analogue modelling demonstrate complex dynamic behaviour, so viscosity alone is insufficient to determine if a material will be an effective analogue. Two series of experiments were conducted using an oscillating bi-conical plate rheometer to measure the storage and loss moduli and complex viscosities of several modelling clays and silicone putties. Tested materials exhibited viscoelastic and shear-thinning behaviour. The silicone putties and some modelling clays demonstrated viscous-dominant behaviour and reached Newtonian plateaus at strain rates < 0.5 × 10⁻² s⁻¹, while other modelling clays demonstrated elastic-dominant power-law relationships. Based on these results, the elastic-dominant modelling clay is recommended as an analogue for basement cratons. Inherently cohesive synthetic sands produce fine-detailed fault and fracture patterns, and developed thrust, strike-slip, and extensional faults in simple centrifuge test models. These synthetic sands are recommended as analogues for the brittle upper crust. These new results increase the accuracy of scaling analogue models to prototype. Additionally, with the characterization of three new materials, we propose a complete lithospheric profile of analogue materials for centrifuge modelling, allowing future studies to replicate a broader range of crustal deformation behaviours.  相似文献   

数字求积仪安置值M的通用公式研究     

钟业勋 《测绘工程》1998,7(4):47-51

提出一个数字求积仪安置值Ｍ的通用公式。此公式与地图比例尺、求积仪、图纸与测量环境等影响测量精度的因素相关联。通过调节Ｍ值,这些影响已基本上被消除并为实例验证。  相似文献   

Scaling the Vertical Structure of Sea Breezes Revisited     

D. G. Steyn 《Boundary-Layer Meteorology》2003,107(1):177-188

The sea-breeze scaling of Steynis extended by incorporating data fromtwo additional locations. This is done primarily to remove concerns that the original scaling laws contain featuresspecific to the Vancouver data upon which they were based. This new analysis also employs the integrated, ratherthan instantaneous, heat flux proposed by Tijm. The analysis results in well-defined scaling laws for allthree locations, and include explicit latitude dependence, which was not possible in the earlier study. The integratedheat flux reveals systematic diurnal behaviour that is shown to result in a separate scaling law for diurnalevolution of sea breezes at a single location.  相似文献   

基于东北玉米区域动力模型的低温冷害预报应用研究   总被引：35，自引：7，他引：35       下载免费PDF全文

刘布春  王石立  庄立伟  卢志光  史学丽  宋永佳 《应用气象学报》2003,14(5):616-625

在田间试验资料基础上，采用改进的发育模型和分区作物参数，结合前人有关研究成果建立了东北玉米区域动力模型，并利用模型模拟了12站40年 (1961~2000年) 玉米生长发育过程。确定抽雄期延迟天数为低温冷害指标，分析了历史低温冷害年及减产情况。模拟了典型冷害年和40年气候平均的0.25°×0.25°网格点玉米生长发育过程, 探讨了与区域气候模式结合进行低温冷害预报的方法。主要结论有:①玉米发育模型能够较好地模拟玉米发育期和发育期对低温冷害的响应，以抽雄期延迟天数为冷害指标评估的历史冷害发生状况基本符合历史实况。②模型有一定的模拟玉米生长量对低温冷害响应的能力，但还需要更多的试验数据校正品种参数，完善模型。③利用GIS技术，结合区域化的作物参数运行区域作物模型，是作物模型区域化应用的一种解决方案。④东北玉米区域动力模型解释性好，根据确定的害指标，以区域气候模式输出结果驱动玉米模型可以模拟和预测低温冷害，是农业气象灾害预测预报的一个有益的尝试。  相似文献   

Scaling of the Sea-Breeze Strength with Observations in the Netherlands   总被引：1，自引：1，他引：1  

R. J. Wichink Kruit  A. A. M. Holtslag  A. B. C. Tijm 《Boundary-Layer Meteorology》2004,112(2):369-380

In this study we evaluate recently proposed scaling relations for the sea-breeze strength using independent data for a relatively homogeneous area in The Netherlands. We show that several of the scaling relations in the literature incorporate hidden correlation. Furthermore, it appears that the estimate for the sea-breeze strength is better made on the basis of the time-integrated rather than of the instantaneous sensible heat flux. It also turns out that for similar forcing the sea breeze in The Netherlands is about twice as strong as the sea breeze in the Vancouver area of Canada.  相似文献   

Critical reflection on knowledge and narratives of conservation agriculture     

《Geoforum》2015

In the context of contemporary concerns about climate change and food security, Conservation Agriculture (CA) has emerged as a well-supported and central component of the agricultural sector development strategy across sub-Saharan Africa, including in Zambia, which is the focus of this paper. A variety of narratives about the benefits of CA over conventional agricultural systems underpin endeavours towards ‘scaling up’ CA and increasing rates of adoption amongst smallholder farmers nationwide. However, there is a knowledge politics underlying the translation of a weak evidence base around CA into persuasive narratives and financial and political support. In this paper, we trace the evolution of five narratives around CA in Zambia in relation to changing political agendas and the involvement of new public and private sector actors, and review the development of evidence bases and knowledge that support and challenge each of these narratives. We discuss the potential to open up space within this knowledge politics to alternative narratives and the contestation of the pervasive CA scaling up agenda. Critical reflection is essential to ensure that national and local evidence is more effectively used to guide national climate and agricultural policy developments and international donor initiatives.  相似文献   

亚洲国家地震生命损失的标度律及中长期预测研究     

傅征祥  孙丽娜  金学申  齐玉妍  邵辉成 《地震》2011,31(1):52-57

研究了亚洲11个重要地震国家或地区(阿富汗, 巴基斯坦, 菲律宾, 日本, 伊朗, 印度, 印尼, 中国大陆, 中国华北地区, 中国南北带)近代地震造成人员死亡率的自相似指数标度律, 并将其应用于泊松模型中, 预测2025年前亚洲重要地震国家发生地震生命损失千人、 万人和十万人以上巨灾事件的概率。 其中, 中国大陆华北地区、 日本和印尼发生万人以上死亡的巨灾概率可能较高。  相似文献   

A Note on the Concept of ‘Effective’ Bulk Exchange Coefficients for Determination of Surface Flux Densities     

R.J. Ronda  H. A. R. De Bruin 《Boundary-Layer Meteorology》1999,93(1):155-162

Since most land surfaces are non-uniform on meteorological model scales, usually applied flux-profile relationships to obtain surface flux densities cannot be used. Therefore, some modellers assume that these relations are scale-invariant if the local bulk transfer parameters are replaced by effective parameters. This approach leads to wrong results for grid cells that contain subgrid areas that differ largely with respect to stability. Hence, in such cases, the surface energy balance needs to be solved for each subgrid area separately. Therefore, to obtain the correct flux densities in all situations, for each grid cell in the horizontal domain of meteorological models, subgrid areas that differ with respect to stability need to be identified.  相似文献   

象山港浮游动物的分布特征及其中长期变化     

骆鑫  曾江宁  徐晓群  杜萍 《海洋通报》2018,(1):74-87

为更好地了解象山港海湾浮游动物群落的现状,保护海洋生态环境,分别于2015年1、4、7、10月在象山港海域进行了25个站位的4个航次生态综合调查,结果表明:4个航次共鉴定出98种浮游动物和20类浮游幼体,优势种共21种,无4季共有优势种。浮游动物群落具有明显的季节变化,平均丰度(ind/m3):夏季(186.2±96.4)春季(152.6±112.1)秋季(56.8±30.2)冬季(15.4±22.2);平均生物量(mg/m3):春季(90±75)夏季(52±24)秋季(26±19)冬季(14±11);平均多样性指数:秋季(2.305±0.370)夏季(1.908±0.449)春季(1.622±0.578)冬季(1.348±0.474)。聚类和多维尺度分析表明,春、夏和秋季3个季节浮游动物群落结构具有明显区域性差异,港口部和口外部海域的群落聚类明显,与其他群落之间相似度最低。分析象山港近35年的浮游动物历史数据表明,浮游动物丰度和生物量的下降可能与陆源排污、水产养殖污染和滨海电厂建设等人类活动有关。  相似文献