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211.
Metropolitan land-use patterns by economic function: a spatial analysis of firm headquarters and branch office locations in Australian cities 总被引:1,自引:0,他引:1
This paper develops a comparative means by which to understand metropolitan spatial structure through the dynamics of economic activities. Clustering and suburbanization have been key processes within the contemporary urban landscape, but few scholarly accounts have systematically merged the two to explain the geographies of economic activity. Using firm location as a variable to discern sector- and industry-based locational requirements, we explore land-use and economic activity in Australia’s five largest metropolitan areas. Drawing upon the respective headquarters and branch office locations of a set of publically traded firms, we seek to establish general spatial patterns across Australian cities using two proxy measures for clustering and suburbanization, being well-established drivers of firm locational choice. Despite the complexity that post-industrial and suburbanizing processes add to metropolitan land-use patterns, we contend that certain patterns exist that can be generalized from one context to another across urban space, and that certain emerging trends such as the development of CBD-fringe precincts merit greater attention. 相似文献
212.
Short-term effects of fishing on life history traits of fishes 总被引:4,自引:4,他引:4
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215.
对中国海洋大学鱼类标本室保存的部分鲈形目鱼类——鲷科 Sparidae,大眼鲷科 Priacan-thidae,科 Serranidae的几种鱼类的口腔齿进行了研究。结果显示 :科与大眼鲷科的前颌骨、齿骨、犁骨、腭骨、咽骨上都着生有形态较单一的口腔齿 ,但较小 ,不是很坚固 ;而鲷科的几种鱼类口腔齿都着生在前颌骨、齿骨、咽骨上 ,且较强硬 ,形态较多样 ,特别发达。本研究为 3种鱼类的进化关系提供了某些佐证。 相似文献
216.
直立椭圆柱体重力场的谱分析及其应用 总被引:1,自引:0,他引:1
利用傅里叶积分变换法导出了埋藏的直立椭圆柱体的重力场在频率域中的解析公式,依此得了确定此直立椭圆柱体尺寸的公式,提出依据这些重力公式来计算侵入大洋地壳中的地幔柱的尺寸和洋壳厚度的方法。 相似文献
217.
Analysis of influencing factors on fine sediment flocculation in the Changjiang Estuary 总被引:1,自引:0,他引:1
Based on the test data in dynamic water and static water, the main factors, which influence the fine sediment flocculation, are analyzed with a gray model method of correlation theory. It is shown that the main influencing factors are water temperature, settling time, salinity, grain size, sediment concentration and current velocity according to the correlation coefficients. Among them, the salinity and the sediment grain size are critical type influencing factors (CrTIF); the settling time, the sediment concentration and the velocity are continuous type influencing factors (CoTIF); and the water temperature has the characteristics of both. When the critical values of CrTIF are reached or exceeded, the fine sediments will be flocculated, but values of CrTIF will not influence the settlement strength of floes. The influence of CoTIF is continuous. The values of the CoTIF will not only influence the occurrence of flocculation but also the settlement strength of the floes. 相似文献
218.
Probabilistic analyses of soil consolidation by prefabricated vertical drains for single‐drain and multi‐drain systems
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Natural soils are one of the most inherently variables in the ground. Although the significance of inherent soil variability in relation to reliable predictions of consolidation rates of soil deposits has long been realized, there have been few studies that addressed the issue of soil variability for the problem of ground improvement by prefabricated vertical drains. Despite showing valuable insights into the impact of soil spatial variability on soil consolidation by prefabricated vertical drains, available stochastic works on this subject are based on a single‐drain (or unit cell) analyses. However, how the idealized unit cell solution can be a supplement to the complex multi‐drain systems for spatially variable soils has never been addressed in the literature. In this study, a rigorous stochastic finite elements modeling approach that allows the true nature of soil spatial variability to be considered in a reliable and quantifiable manner, both for the single‐drain and multi‐drain systems, is presented. The feasibility of performing an analysis based on the unit cell concept as compared with the multi‐drain analysis is assessed in a probabilistic context. It is shown that with proper input statistics representative of a particular domain of interest, both the single‐drain and multi‐drain analyses yield almost identical results. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
219.
This paper analyzes the development of environmental concern by using the three waves of the environmental modules of the International Social Survey Programme. First, we discuss the measurement of environmental concern and construct a ranking of countries according to the new 2010 results. Second, we analyze the determinants of environmental concern by employing multilevel models that take individual as well as context effects into account. Third, we explore the longitudinal aspect of the data at the macro level in order to uncover the causal relation between countries’ wealth and environmental concern. The results show that environmental concern is closely correlated with the wealth of the nations. However, environmental concern decreased in almost all nations slightly during the last two decades. The decline was lower in countries with improving economic conditions suggesting that economic growth helps to maintain higher levels of environmental concern. 相似文献
220.
Chlorite and associated minerals from the volcanogenic Taveyanne metasediment of the western Helvetic nappes, Switzerland, were investigated by electron microprobe (EMP) and transmission electron microscopy (TEM) in order to determine their textural and chemical evolution during low-temperature metamorphism. EMP analyses of chloritic material from sub-greenschist facies outcrops show a decrease of Si and Σ(Ca, Na, K) with increasing metamorphic grade. A number of conclusions may be drawn from combined TEM images and analytical electron microscopy (AEM) data. 1 In diagenetic-grade samples, chlorite crystals (observed maximum defect-free distance=80 nm) always contain some 1 nm layers (with a maximum of 29% of all layers) and less frequently some 0.7 nm berthierine-like layers. With increasing grade, the amounts of 1 and 0.7 nm layers decrease, and most chlorite from the epizone is structurally pure or contains less than 2% of 1 nm layers. 2 A positive correlation was found between the amount of 1 nm layers and the Ca+K+Na content, indicating that the 1 nm layers are saponite. 3 Observations and calculations suggest that the transformation reaction of saponite to chlorite takes place by the replacement of the interlayer cations in saponite by brucite-like layers resulting in a local volume decrease. In contrast, the destruction of berthierine has only minor influence on the local bulk volume. These results confirm recent studies which show that the change in composition measured by EMP of diagenetic-grade chloritic material are mainly the result of mixtures of chlorite and saponite. The use of chlorite ‘geothermometry’ in such systems is greatly influenced by the presence of saponite and hence is not based on reaction equilibria, even though temperatures calculated in this study agree with temperatures derived from other methods. Therefore, chlorite evolution should be treated as a kinetically controlled grade indicator and developed as a qualitative scale similar to the illite crystallinity index. 相似文献