Period-Luminosity Relations for Classical Cepheids     

H. V. Abrahamyan 《Astrophysics》2003,46(4):455-464

BVIJHK period-luminosity relations for classical cepheids in the galaxy and magellanic clouds which pulsate in the fundamental mode are obtained on the basis of four samples. The period-luminosity relations for the BVI bands obtained here are more accurate than the analogous relations existing up to the present. Period-luminosity relations in terms of W functions are also obtained for these samples and have the same accuracy as the currently existing analogous relations.  相似文献   

Deservedness, development, and the state: Geographic categorization in the US Agency for International Development’s Foreign Assistance Framework     

Jamey Essex 《Geoforum》2008,39(4):1625-1636

The institutions, practices, and discourses of US development policy and foreign assistance are undergoing profound changes. Central to these has been the creation of a new framework for foreign aid, built around a complex taxonomy of developing states and governance issue areas, with geographic and governance categories predicated on notions of state stability and fragility, strategic geopolitical position, and development progress. Given its long-standing position as the primary federal agency responsible for development and foreign aid, the US Agency for International Development (USAID) has played an important role in these policy changes, even as its political status and standing have suffered in recent years. The new framework is beset by contradictions, stemming both from the problematic relationship between development, security, and liberalization in agency rhetoric and strategies, and from intensive restructuring processes affecting USAID’s internal character and external relations. This paper investigates the new framework for foreign aid, linking internal restructuring at USAID to broader trends in state development strategies. I argue that shifts in US development and aid policy - toward emphases on “transformational development” abroad and centralization over strategic decision making domestically, crystallized in the new framework - are based in contradictory understandings of aid deservedness that stem from the tensions between economic and geopolitical aims within the current security-focused US state project of neoliberalization. These contradictions and tensions are displaced onto USAID via the Foreign Assistance Framework.  相似文献   

移动区域时空关系变化建模研究     

吴静  高宇 《测绘科学》2017,(12):39-43

针对二维欧氏空间内的移动区域对象在时空关系变化建模中存在的问题,该文提出了一种时空关系变化序列模型,并建立了时空关系变化概念邻域图。采取基于时间片的时空数据模型,通过分析移动区域间随时间变化的拓扑、距离和方位关系,解决时空关系变化的集成建模问题。该方法能有效刻画移动区域的动态时空特征。  相似文献   

引入二维交细分类型的地表覆盖矢量数据增量更新     

周晓光  汪红松  吴志强 《测绘学报》2017,46(1):114-122

通过遥感影像与基准年数据对比获得变化信息是目前地表覆盖数据增量更新的主要变化数据来源,但现有方法不能直接更新地表覆盖矢量数据。本文设计了一种包含变化对象的空间位置和类型信息的地表覆盖增量数据模型,发展了一种引入面/面二维交细分类型的地表覆盖矢量数据增量更新方法。该方法首先采用基于目标整体交、差结果的欧拉数的E-WID层次拓扑关系模型区,分析了地表覆盖矢量数据更新中的14种二维交细分拓扑关系类型;然后根据这些二维交细分类型,设计了9条自动更新处理规则。最后开发了一套基于根据二维交细分类型处理规则的地表覆盖数据增量更新原型系统,并用实际数据验证了其正确性。  相似文献   

《国际水道非航行使用法公约》被认可的区域差异性   总被引：1，自引：0，他引：1  

余世维  冯彦  王文玲 《地理学报》2017,72(2):303-314

《国际水道非航行使用法公约》是第一个生效、旨在实现跨境水资源公平合理利用的全球公约,但《公约》原则与条款争议造成缔约国数量有限,综合影响力受到削减。利用《全球跨境流域》、《国际淡水条约数据库》、《世界环境协定》等数据库信息等,确定《公约》缔约国的国际河流地理位置,结合各缔约国水资源及利用现状、跨境水资源分布及区域合作开发状况、《公约》原则和争议条款等,分析、判断缔约国的区域及目标差异特征,结果表明：① 缔约国仅分布于欧洲、亚洲和非洲3个地区36国家,《公约》被认可程度低、影响力有限;② 《公约》在平衡上下游权利与义务中对下游国谋求水开发利益更为有利,下游国缔约意愿更强、对其认可度最高;《公约》对中游、边界及上下游均衡及支流地区的流域国有制衡作用,影响着流域国的缔约愿意;③ 缺水状况和位居下游、国际河流地位重要及对跨境水资源的依赖驱使相关国家不断寻求增强对跨境水资源管控能力的途径,缔结《公约》成为一项重要选择;④ 区域性水法的发展与实践是流域国缔结《公约》的基础,绝大多数国家的缔约意愿多源于对水资源合作开发实践,而流域下游及中游国家则源于跨境水资源合作机制建设和水资源合作开发两个方面的经验。  相似文献   

中国外商旅游饭店业投资的空间动态差异与驱动要素解析   总被引：1，自引：0，他引：1  

李涛  刘家明  王磊  朱鹤  余玲 《地理学报》2017,72(10):1904-1919

旅游饭店作为中国旅游业对外开放的最前沿,一直以来是外商资本配置、汇集和流动较为活跃的领域。外商资本的进入将中国旅游业联接到世界金融体系的同时,随着中国对外开放的深入,其吸引外资的环境也发生了巨大变化,必然导致外商资本在华投资空间格局的演变。研究对1991-2014年中国31省域外商旅游饭店业投资及社会经济面板数据进行分析,发现期间外商投资的空间差异呈整体缩小趋势,并随经济、人口和消费格局演化,其标准椭圆重心向北偏移,且在不同尺度上受对外政策、经济差异、资源条件等要素作用范围影响,空间差异的形成机制与过程差异明显。继而,引入管理学“钻石模型”构建了解释引起这一差异的评价体系,定量化分析了省域旅游饭店业产业环境与市场条件对外商资本空间流动方向、规模和效益所发挥的主导作用。最后,结合当前“一带一路”与“走出去”的战略需求,总结了外商在华旅游饭店业投资空间差异对全球化背景下中国引导外资进入和开展海外旅游投资的启示,并就复杂科学发展背景下旅游地理学发展进行了讨论。  相似文献   

The structural preservation of a titanosaurid (Dinosauria: Sauropoda) vertebral ligament     

《Cretaceous Research》2016

Within the past decade exceptional preservation of original organic components have been reported from several dinosaurian families, including members of Sauropodomorpha. Here we document the partial preservation of a vertebral ligament in the dorsal and sacral series of a titanosaur. Unlike other cases of tissue preservation, this structure does not represent biomineralization of the original organic components. Histology, morphology, and comparative anatomy from extant taxa as well as the preferential placement on the vertebral column suggests that it represents the partial preservation of the nuchal ligament. While preservation of other sauropod connective tissues are known, this case represents the first reported non-biomineralized tissue from a sauropod. In consideration of the location and external and internal morphologies compared to modern vertebral ligaments, we believe this structure to be the micritic replacement of the original tissue via microbially-mediated processes. Along with the suggestive external morphology, internally we interpret some of the unusual structures to represent the remnants of the collagen and elastin fascicles that are strongly overprinted by a clotted, thrombolytic-like fabric recording microbial activity and deposition of micrite prior to lithification. In consideration of the interpreted depositional history, we theorize that post-deposition, bacteria deposited the micrite as a byproduct of metabolization. Subsequently, the recognition of this structure as a vertebral ligament, the largest of such thus documented, substantiates previous findings on the morphological attributes of sauropod vertebral ligaments.  相似文献   

A global stocktake of the Paris pledges: Implications for energy systems and economy     

《Global Environmental Change》2016

The United Nations-led international climate change negotiations in Paris in December 2015 (COP21) trigger and enhance climate action across the globe. This paper presents a model-based assessment of the Paris Agreement. In particular, we assess the mitigation policies implied by the Intended Nationally Determined Contributions (INDCs) put forward in the run-up to COP21 by individual member states and a policy that is likely to limit global warming to 2 °C above pre-industrial levels. We combine a technology-rich bottom-up energy system model with an economy-wide top-down CGE model to analyse the impact on greenhouse gas emissions, energy demand and supply, and the wider economic effects, including the implications for trade flows and employment levels. In addition, we illustrate how the gap between the Paris mitigation pledges and a pathway that is likely to restrict global warming to 2 °C can be bridged. Results indicate that energy demand reduction and a decarbonisation of the power sector are important contributors to overall emission reductions up to 2050. Further, the analysis shows that the Paris pledges lead to relatively small losses in GDP, indicating that global action to cut emissions is consistent with robust economic growth. The results for employment indicate a potential transition of jobs from energy-intensive to low-carbon, service oriented sectors.  相似文献   

多边形间空间关系查询的异构多核架构并行算法     

谢传节  龙舟  马益杭  由志杰 《测绘学报》2016,45(1):119-126

目前在空间关系查询中常用的Plane Sweep算法是一种串行算法,在处理海量空间数据时效率较低,而已有的并行计算方法对于普通的计算机并不适用。本文针对这个问题,提出了一种多边形间空间关系查询的异构多核架构并行算法,该算法先利用STR树索引过滤掉不相交的多边形,然后将过滤后的多边形数据集合分解为点集合和边集合,并对其构建四叉树索引;在保证数据浮点运算精度符合要求的情况下,利用GPU强大的批量运算能力快速处理边与边的相交情况并据此逐步计算得到环间的拓扑关系,再根据环间拓扑关系计算得到多边形间的维度扩展九交模型(DE-9IM)参数值;根据DE-9IM参数值与空间关系查询条件相比对,输出查询结果。最后通过试验验证了算法的准确性与高效性。  相似文献   

A Bibliometrical Analysis of International Cooperation Research in the Field of Tibetan Plateau     

Wang Ting 《地球科学进展》2016,31(6):650-662

Tibetan Plateau, with its unique characteristics and its impact on the global environment, ecology and climate, is an important research region of the international scientific community. The development of international cooperation in the field of Tibetan Plateau was reviewed and the quantitative statistics and data in accordance with the SCI papers of international cooperation in the field of Tibetan Plateau were analyzed during the 35 years of 1980-2014. The experience of international cooperative research in the field of Tibetan Plateau from starting stage to rapid development to tend to mature stage of development was summarized. International cooperative research has become the main organization of research in the field of Tibetan Plateau. Tibet Plateau international collaboration changing from single academic discipline to multi academic disciplines was analized. Changes in major countries of international cooperation research and independent research in the field of Tibetan Plateau were compared and suggestions for strengthening international cooperative research in the field of Tibetan Plateau for China in the future were put forward.  相似文献