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1.
As the world becomes increasingly urbanized, the need for fresh fruits and vegetables in urban areas grows while the difficulty of bringing these perishable products to these areas also increases. Small-scale agriculture located in urban areas is a highly effective and profitable way to provide these products to communities that are far from extensive commercial agricultural areas. Here we describe how remote sensing can be used with data mining approaches to monitor urban and peri-urban farms within cities in both developed and developing countries. Using very high resolution satellite imagery together with moderate and coarse resolution imagery and information from social media and the web, we analyze the usefulness of different methods to identify farms within urban boundaries in four countries. The analysis shows how a mixed-method approach is necessary in order to identify where urban farming is occurring and to monitor its change through time. Although remote sensing-based vegetation and water indices were useful, without ancillary data they are not effective at remotely mapping the locations of urban farms. However, remote sensing is a good way to monitor vegetation condition in locations where actively managed urban farms are known to exist. 相似文献
2.
Samuel Walker 《Urban geography》2016,37(2):163-182
Both Vancouver, British Columbia, and Detroit, Michigan, have significant and growing urban agriculture movements. In this article, I follow recent work investigating the connection between urban agriculture and neoliberalization to determine how these local governments have used urban agriculture in narratives of economic development to selectively pursue a sustainability fix. I analyze how different regimes of local governance have influenced the urban agriculture movements, leading to local, hybridized fixes that adapt to different material and discursive contexts in each place. I argue that in both cities, urban agriculture has radical potential as a grassroots response to economic and environmental injustice, but has also been enrolled as a device by the local state in which the primary goal of sustainability planning becomes enhanced economic competitiveness. Pursuing an agenda of food justice requires examining the larger context and effects of municipal involvement with food movements. 相似文献
3.
聂飞 《华东地质学院学报》1999,22(1):91-93
ＸＥＮＩＸ作为一种多用户多任务的开放性的操作系统,容易受到攻击和破坏。本文介绍的产种方法可用来提高ＸＥＮＩＸ系统的安全性。 相似文献
4.
通过构造解析的研究，确定赛马山地区中元古代所发生的阿尔金运动共有三幕变形，第一幕发生在长城纪早期，为EW向伸展机制下中部构造相的大规模顺层滑脱韧性变形，形成了赛马西山顺层滑脱韧性变形带，具超塑性流动变形特征和多层结构样式，第二幕发生在长城纪末，为主期变形，在NS向挤压机制下，在浅部构造相形成了EW向紧闭褶皱（局部倒转褶皱），并卷入早期的顺层滑脱韧性变形带，褶皱后期，由于应力的集聚，在浅表层次下，沿兴地塔格群内岩层软弱面发生剪切而形成了滑脱面，产生由南向北的逆冲，形成了具叠瓦扇结构的永红山飞来峰构，第三幕，蓟县纪末由于SN向强烈挤压后出现“松驰”引张而产生EW向挤压应力，形成NS向开阔褶皱，叠加于主期褶皱之上，形成了赛马西山－永红山穹盆构造。 相似文献
5.
The inversion of the Middle Proterozoic Belt sedimentary basin during Late Cretaceous thrusting in Montana produced a large eastwardly-convex salient, the southern boundary of which is a 200 km-long oblique to lateral ramp subtended by a detachment between the Belt rocks and Archean basement. A 10 km-long lateral ramp segment exposes the upper levels of the detachment where hanging wall Belt rocks have moved out over the Paleozoic and Mesozoic section. The hanging wall structure consists of a train of high amplitude, faulted, asymmetrical detachment folds. Initial west-east shortening produced layer parallel shortening fabrics and dominantly strike slip faulting followed by symmetrical detachment folding. “Lock-up” of movement on the detachment surface produced regional simple shear and caused the detachment folds to become asymmetrical and faulted. Folding of the detachment surface after lock-up modified the easternmost detachment folds further into a southeast-verging, overturned fold pair with a ramp-related fault along the base of the stretched mutual limb. 相似文献
6.
王丽萍 《地理与地理信息科学》2012,28(3):101-105
遗产区域思想是世界遗产领域内专门针对跨区域、综合性遗产保护提出的新理念和新方法,其关注遗产要素到环境的整体保护。该理论为滇藏茶马古道这条在我国西南地区具有重要文化意义的带状遗产区的保护提供了借鉴,是根本改变当前滇藏茶马古道遗产备受破坏现实的迫切需求。茶马古道遗产区域保护关键在于确定遗产区域保护边界、贯彻整体保护理念和构建协作保护机制,基于此,提出古道遗产区域保护策略,具体包括编制整体保护规划、细分保护层次、落实三大必备系统、组建"省部际会商小组"协作保护机构和申报世界文化遗产等,以期创新茶马古道遗产保护理念,改善古道保护现状,完善我国线状文化遗产保护体系。 相似文献
7.
Veerle Vandeginste Rudy Swennen Sarah A. Gleeson Rob M. Ellam Kirk Osadetz François Roure 《Mineralium Deposita》2007,42(8):913-935
Two Mississippi Valley-type (MVT) ore deposits, Kicking Horse and Monarch, have been studied with the aim of comparing the
ores at the two localities and to characterize the origin of the mineralizing fluids and the ore formation process(es). Both
deposits are hosted by the Middle Cambrian Cathedral Formation carbonate host rocks, Kicking Horse on the north and Monarch
on the south flank of the Kicking Horse valley near Field (SE British Columbia). The ore bodies are situated at the transition
of (western) basinal to (eastern) shallow-water strata of the paleo-Pacific passive margin succession in the Cordilleran Foreland
Province of the Western Canada Sedimentary Basin. Both deposits are related spatially to normal faults. In both localities,
the ore minerals are dominated by pyrite, sphalerite, and galena. Dolomite, minor quartz, and calcite are also present in
close association with the ores. The salinity (21–30 wt% NaCl eq.) and homogenization temperatures (63–182°C) measured in
fluid inclusions in carbonate, quartz, and sphalerite lie within the typical range of MVT fluid conditions. The good stoichiometry
(50–53 mol% CaCO3), low δ18O values (−21 to −14‰ Vienna Peedee belemnite) and relatively high homogenization temperatures (>95°C) of the dolomite suggest
the dolomites were formed under burial diagenesis. The ore-forming fluids probably interacted with siliciclastic units, based
on elevated Li contents and 87Sr/86Sr ratios, which are highest in the dolomite type after the main ore stage. We propose that the ores formed from the mixing
of a downward-infiltrating, sulfur-bearing halite-dissolution fluid with an upward-migrating, metal-rich evaporated seawater
fluid, which had already undergone minor mixing with a dilute fluid. 相似文献
8.
George C. Bentley Priscilla McCutcheon Robert G. Cromley Dean M. Hanink 《The Professional geographer》2016,68(3):414-426
William Bunge's Fitzgerald: Portrait of a Revolution, initially published in 1971, is an enthralling verbal and visual account of the historical and geographical development of a one-square-mile neighborhood in Detroit. The original analysis of the Fitzgerald neighborhood was based on intensive field-based research conducted in a theoretical context of race and racism. The research reported here maintains that context but updates Fitzgerald's account of the neighborhood's built environment through a spatial analysis that uses parcel-by-parcel data generated in Google Earth and Google Street View instead of data collected in the field. Current spatial patterns of deterioration in the built environment are similar to those described in Fitzgerald, but positive sites are also apparent and often colocated with negative ones. 相似文献
9.
This paper investigates the impact of the Hungry Horse Dam on streamflow dynamics in the South Fork of the Flathead River, Montana, USA. To this end, pre- and post-dam periods of raw and naturalized streamflow data were analysed. Pettitt’s change point analysis indicated a significant change point in streamflow dynamics due to dam construction. Complexities in the pre- and post-dam periods were evaluated by sample and multi-scale entropy analyses, and the entropies of the post-dam period were found to be higher than those of the pre-dam period. Possible reasons for this, unrelated to the natural hydrological cycle caused by the dam, were analysed using wavelet analyses. The wavelet analyses showed a clear change in the phase relationship between precipitation and streamflow. Finally, weak positive trends found in the hydrological variables indicated the effects of human activities (e.g. dam construction). The results also revealed distorted lead times, which can improve the streamflow forecasts for different lead times. 相似文献
10.
随着世界进入全球化时代以及信息技术的广泛应用,工业发展的自身特点和外部环境都发生了变化,转型升级成为新的主题。底特律是美国重要的工业城市,本文通过研究其汽车产业发展从辉煌走向衰落的过程,认为底特律自然条件和区位环境都非常优越,在福特制生产方式主导的时期,曾拥有"全球汽车制造中心"的辉煌。当面对外部竞争激烈、要素成本领先的区位条件吸引力减弱、生产和消费市场环境改变等因素下,由于地方文化强烈的优越感而自我封闭和路径依赖过度导致创新锁定,最终产业转型失败而衰落成无人问津的城市。底特律产业转型失败的教训对于我国城市的产业升级具有良好的警示作用。 相似文献