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121.
ABSTRACTAs a tribute to the massive contribution of our friend and colleague Graeme Hugo to the population and settlement geography of Australian rural areas, this paper presents a longitudinal study from his home State. It forms part of a wider study of the long-term demographic relationships between Australia’s rapidly growing regional cities and their surrounding functional regions. Of particular interest is the question of what effect the accelerating concentration of population and economic activity into a given regional city will have for the longer term demographic sustainability of its functional region as a whole. Taking the case of Port Lincoln, regional capital of most of South Australia’s Eyre Peninsula, it examines the nature of change in the functional region over the period 1947–2011, and investigates the forces feeding, and partly counteracting, the population concentration process, informed by concepts of evolutionary economic geography. In particular it traces the demographic impact (particularly differential migration and ageing trends) of exogenous shocks to the region’s essentially primary productive economic base during the period of major change from 1981 to 2011. 相似文献
122.
Joe Weber 《The Professional geographer》2019,71(2):239-252
In the twenty-first century, there are three American Wests, which cut across cultural, political, physical, and economic boundaries. Parts of the West are booming, building homes, and adding population; others are legally off limits to such development; and much of the West has been bypassed by such development and growth. These are called here the Booming West, Protected West, and Bypassed West. Maps of climate, political boundaries, ethnic and racial identities, or presidential voting patterns do not match these three Wests. Each West has a different relationship to the others and might see them as threats or opportunities, and each West can be expected to grow in different areas at the expense of other Wests. The boundaries between the three Wests could be important locations; sharp transitions can exist between Wests, perhaps nowhere more so than where a fast growing metro area abuts a national park or forest boundary. Finally, the effects of climate change cut across the three Wests and have different implications for their future. Continued population growth will further emphasize the boundaries between each of the three Wests and raise the stakes for their control. 相似文献
123.
随着互联网的快速发展,气象部门职工作为学习者可以获得的学习资源得到极大丰富。信息超载导致检索合适的在线学习资源时遇到了困难;学习者在不同学习环境和序列访问模式上也有不同的学习需求。但是,现有的推荐系统,如基于内容的推荐和协同过滤,没有结合学习者的情境和序列访问模式,推荐结果准确度不高。本文提出了一种结合情境感知、序列模式挖掘和协同过滤算法的混合推荐算法来为学习者推荐学习资源。混合推荐算法中,情境感知被用来整合学习者的情境信息,如知识水平和学习目标;序列模式挖掘被用来对网络日志进行挖掘,发现学习者的序列访问模式;协同过滤被用来根据学习者的情境数据和序列访问模式为目标学习者计算预测并生成建议。实验和应用效果表明,该混合推荐算法推荐的质量和准确性方面优于其他推荐算法。 相似文献
124.
针对使用传统的编程方式进行空间回归分析过于繁杂的问题,本文提出将Python函数式编程引入空间回归分析方法,分析和探讨脚本语言+函数式编程方式在GIS数据分析中的推广应用前景。编程实践证明,采用Python函数式编程,结合既有的开源软件包,可以有效提高编程效率,减少代码量,将实践人员的注意力集中在问题本身。 相似文献
125.
Numerical modelling of deep sea air-lift 总被引:2,自引:0,他引:2
Deep sea air-lifting of solid particles from depth of 1600 m is simulated with a mathematical model of the three-phase flow in an upward pipe. The computations are carried out for an axisymmetric domain in a transient way. Phase distributions, pressure and velocity profiles together with flow rates for all phases are presented and analysed. The influence of the pipe diameter on the air-lift efficiency was studied for air-lift pipes of different lengths and found to be significant. The lifting efficiency increases with the increase of the pipe diameter due to the reduction of the wall friction influence on the flow. In addition, the efficiency also increases with the increase of the solid particles volume fraction at the inlet. The presented numerical model can be utilized during various stages of the design of the air-lift pumps to help answer fundamental questions on the process, and during their operation to select optimal process parameters and to address possible problems. 相似文献
126.
收缩城市建设用地利用效率时空分异及影响机制——以黑龙江省伊春市为例 总被引:1,自引:1,他引:0
建设用地是城镇经济社会活动的空间载体,其利用效率是调控建设用地扩张和配置的重要基础.论文以收缩型城市——黑龙江省伊春市为例,利用DEA模型测算了1995-2015年伊春市建设用地利用效率分析其时空演变规律,并运用地理探测器模型探究伊春市建设用地利用效率空间分异的影响机制,结论如下:①1995-2015年伊春市建设用地利... 相似文献
127.
论述了兖州矿区18上煤底板煤系高岭岩(土)的地质特征、赋存状态、矿石性质,并在产品研制的基础上,提出了矿石合理的利用途径,为资源的开发利用方向提供了科学依据,为衰老矿井资源综合开采和开发提供了新的出路。 相似文献
128.
Rio Tinto estuary (Spain): 5000 years of pollution 总被引:6,自引:0,他引:6
R.A. Davis Jr. A. T. Welty J. Borrego J. A. Morales J. G. Pendon J. G. Ryan 《Environmental Geology》2000,39(10):1107-1116
Mining of massive sulfide deposits in southwestern Spain extending back to the Copper and Bronze Ages has resulted in the
pollution of the Rio Tinto fluvial-estuarine complex, the site of Columbus' departure for the New World in 1492. Additional
sources of potential pollution include the large industrial complex at Huelva near the lower portion of the estuary. Extensive
analysis of surface sediment samples and cores has established that there are no geographic trends in the distribution of
the pollutants, which include Cu, Fe, Pb, Zn, Ti, Ba, Cr, V and Co. These data have, however, demonstrated that tidal flux
within the estuary carries phosphorus and perhaps other elements from the industrial complex at Huelva to the tidal limit
of the system, several kilometers upstream from the discharge site. Radiometric analysis of short cores shows that sedimentation
rates over at least the past couple of centuries have been about 0.3 cm/year. These data and that from a single deep core
demonstrate that the estuary was polluted from mining activity long before the large-scale operations began in the late nineteenth
century.
Received: 3 May 1999 · Accepted: 18 October 1999 相似文献
129.
以云南磷化集团有限公司晋宁磷矿为依托背景,借助数字照相量测技术,通过相似材料模拟试验,对20与50两种矿体倾角赋存下,露转井工后,井下采场及其上覆岩层的位移与应力响应特征及动态演化过程进行了系统研究。结果表明:(1)地下采场围岩及覆岩的变形演化过程可划分为局部小范围微动、线性持续增大以及整体非线性剧烈垮塌3个阶段;(2)矿体倾角由20增至50后,边坡与地下采场围岩及覆岩的变形整体趋缓,采动影响范围小幅度缩减,沉降曲线则由非对称槽型变为碗型;(3)采场矿柱回收过程中,地下采场围岩及覆岩发生突发性失稳,呈现出明显的多米诺骨牌效应。相关研究结论可为矿山露天转地下开采后地压管理与边坡维护提供一定的理论参考。 相似文献
130.
高硫煤矿闭坑后成为埋藏在地表以下深部的产酸污染场,对相邻含水层和周边环境造成了潜在危害,且因采动效应影响和矿井空间分布复杂导致相邻含水层的污染过程与污染程度评价困难。以某闭坑矿区为研究对象,选取SO4 2−作为特征污染物,考虑多煤层采动裂隙对含水层结构的破坏影响,运用数值模拟技术对闭坑矿区酸性矿井水中SO4 2−污染迁移特征进行研究,并分析流体扩散系数对含水层污染物运移的影响。结果表明:SO4 2−在二叠系童子岩组砂岩含水层中水平迁移面积随时间增大而增大,增大速率逐渐减小,垂向渗透系数扩大10倍,空间变异性增强;闭坑5、10、15 a后,最大水平迁移距离分别为215、414、612 m,最大垂向迁移距离分别达到50、65、70 m;而扩散系数越大,产酸时间越长,SO4 2−迁移距离和污染范围将随之增大,相较于水平方向,垂向上SO4 2−浓度变化对扩散系数的敏感度更高。基于模拟结果,结合闭坑矿区实际条件,针对性提出了“源头减量−过程阻断−末端治理”的综合防控与治理方案。研究结果将为该闭坑煤矿酸性矿井水污染治理与防控提供理论基础,也为其他同类矿井提供科学借鉴。
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