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311.
Pirouz Mojtahed-Zadeh 《GeoJournal》2005,62(1-2):51-58
It is universally accepted that the need for defining precise lines of separation and points of contacts between states is the byproduct of the emergence of nation-states and ‘world economy’ in the 19th century Europe. Nevertheless, it is hard to overlook the fact that these modern notions are rooted in periods prior to the emergence in Europe of nation-states. There are indications that ancient civilizations were familiar with the notion of ‘state’ in connection with the concepts of territory and boundary. Ancient texts reveal that this basic principle existed in ancient Persian literature in respect of matters of state, territory, and boundary. Similarly, the likelihood exists that these Persian notions could have influenced Roman civilization. It is widely believed that a combination of ancient Greco-Roman and Persian civilizations is a major contributor to what culturally constitutes ‘West’. Later in the Sassanid period the inter-linked notions of state, territory, and boundary developed substantially, coming quite close to their contemporary forms. On the other hand, considering that ‘justice’ was the corner stone of ancient Persian Political philosophy, the idea that ancient Persian spatial arrangement might have contributed to the evolution of the concept of democracy in the West may not be too difficult to contemplate. 相似文献
312.
A multi-layered aquifer, typical of riverbank alluvial deposits in Korea, was studied to determine the hydrologic properties.
The geologic logging showed that the subsurface of the study site was comprised of four distinctive hydrogeologic units: silt,
sand, highly weathered and fresh bedrock layers. The electrical resistivity survey supplied information on lateral extension
of hydrogeologic strata only partially identified by a limited number of the geologic loggings. The laboratory column tracer
test for the recovered core of the sand layer resulted in a hydraulic conductivity of 5.00×10−2 cm/s. The slug tests performed in the weathered rock layer yielded hydraulic conductivities of 4.32–7.72×10−4 cm/s. Hydraulic conductivities for the sand layer calculated from the breakthrough curves of bromide ranged between 2.08×10−3 and 2.44×10−2 cm/s with a geometric mean of 6.89×10−3 cm/s, which is 7 times smaller than that from the laboratory column experiment. The trend of increasing hydraulic conductivity
with an increase in tracer travel length is likely a result of the increased likelihood of encountering a high conductivity
zone as more of the aquifer is tested. The combined hydrogeologic site characterization using hydraulic tests, tracer tests,
and column test with geologic loggings and geophysical survey greatly enhanced the understanding of the hydrologic properties
of the multi-layered alluvial aquifer. 相似文献
313.
基于不同人口需要而进行的人类活动对“三江并流”区的地理环境产生了巨大影响,形成了独具特色的人地作用机制。这一作用机制一方面对“三江并流”世界遗产的保护构成了威胁,但另一方面,通过人口生态生产,实现人口数量、质量、结构和分布的生态化,改进人类活动,也可优化“三江并流”区的地理环境,保护“三江并流”世界遗产,实现该地区的可持续发展。 相似文献
314.
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317.
Yakov Afanasyev 《地球物理与天体物理流体动力学》2013,107(2):79-95
Results from a new series of experiments on the geophysically important issue of spontaneous emission of internal gravity waves during unsteady interactions of vortical structures are presented. Vortex dipoles are a common element of a quasi-two-dimensional turbulent flow. Vortex dipoles perform translational motion and can collide with other vortices. During collision events the flow is unsteady and unbalanced and a further adjustment process associated with these events can therefore result in the spontaneous emission of gravity waves. Our laboratory experiments demonstrate that gravity waves are emitted when two translating vortex dipoles interact (collide) in a layered fluid, in accord with the current theoretical results. The emission was evident both in a two-layer system and in a fluid with a linear distribution of density with depth. The waves were generated during the period of deceleration of the secondary dipoles which constitute a vortex quadrupole emerging immediately after the collision of the primary dipoles. 相似文献
318.
《Geoforum》2016
This paper examines economic upgrading in the Canarium indicum (Canarium) nut industry in Vanuatu, the Solomon Islands and Papua New Guinea. Canarium is a tree that is indigenous to Melanesia, and has been the subject of several commercialisation attempts since 1988. The paper assesses the outcomes to various actors in the Canarium supply chain from attempts to upgrade industry products and processes by: (1) increasing the available resource in suitable locations; (2) improving nut products and processing techniques; (3) increasing actors’ knowledge and supply chain coordination; and (4) establishing product standards. A two-phase data generation process was implemented. Document analysis and participant observations of industry workshops initiated a set of four economic upgrading interventions that were adaptively implemented. A second stage of workshops and 76 interviews enabled outcomes to be assessed at the project’s end. Findings suggest that a small number of urban-based entrepreneurs benefit and subsequently are lead actors in industry development, but at the expense of benefits being distributed to a larger, more spatially disparate group of smallholder and small commercial growers. These economic upgrading outcomes are circumscribed by core-periphery relations in Pacific small island states and the scale of industry in each country. Thus, spatial inequalities are reproduced through the emerging Canarium industries. We argue that different routes to industry development are required in each country. Development initiatives that capitalise on the benefits of micro-enterprise clusters, joint action and regional institutional arrangements are proposed to overcome the impediments imposed by the particular geographies of Pacific island states. 相似文献
319.
Flow processes and sedimentation in unidirectionally migrating deep‐water channels: From a three‐dimensional seismic perspective 下载免费PDF全文
Chenglin Gong Yingmin Wang Ronald J. Steel Jeff Peakall Xiaoming Zhao Qiliang Sun 《Sedimentology》2016,63(3):645-661
Three‐dimensional seismic data were used to infer how bottom currents control unidirectional channel migration. Bottom currents flowing towards the steep bank would deflect the upper part of sediment gravity flows at an orientation of 1° to 11° to the steep bank, yielding a helical flow circulation consisting of a faster near‐surface flow towards the steep bank and a slower basal return flow towards the gentle bank. This helical flow model is evidenced by the occurrence of bigger, muddier (suggested by low‐amplitude seismic reflections) lateral accretion deposits and gentle channel wall with downlap terminations on the gentle bank and by smaller, sandier (indicated by high‐amplitude seismic reflectors) channel fills and steep channel walls with truncation terminations on the steep bank. This helical flow circulation promotes asymmetrical depositional patterns with dipping accretion sets restricted to the gentle bank, which restricts the development of sinuosity and yields unidirectional channel migration. These results aid in obtaining a complete picture of flow processes and sedimentation in submarine channels. 相似文献
320.
新疆西天山阿吾拉勒铁成矿带内众多铁矿床的围岩火山岩时代、岩石成因和构造背景迄今尚未得到很好地约束。文章对该铁成矿带内的松湖铁矿床围岩粗面英安岩和流纹岩进行了锆石LA_ICP_MS U_Pb测年和地球化学研究。粗面英安岩和流纹岩的锆石206Pb/238U加权平均年龄分别为(326.8±2.7)Ma和(327.3±1.7)Ma。粗面英安岩和流纹岩准铝质,均富集轻稀土元素、Rb、K、Zr、Hf,显示中等Eu负异常,亏损Ba、Sr、P、Ta、Nb和Ti。锆石饱和温度计算结果显示,粗面英安岩的母岩浆温度较高(774~812℃,平均792℃),流纹岩母岩浆的温度较低(713~790℃,平均750℃)。粗面英安岩具有非常低Sr高Yb的特征,Nb/Ta比值为10.8~11.4,具有较高的w(Th)(≥8.1×10-6)和高的Th/Ce比值(≥0.31);流纹岩具有低Sr低Yb特征,Nb/Ta比值为8.5~9.7,w(Th)(≥5.3×10-6)较高,Th/Ce比值为0.14~0.75,据此推测粗面英安岩母岩浆可能是上地壳部分熔融的产物,流纹岩母岩浆可能源于比粗面英安岩母岩浆更深的地壳的部分熔融。松湖铁矿区粗面英安岩和流纹岩具有弧火山岩的地球化学特征,结合构造环境判别图解和区域地质情况,推断其形成于大陆弧环境。 相似文献