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341.
Lorraine Moore 《Geoforum》2011,42(1):51-60
This paper uses a case study that explores the impacts of the ivory trade ban on elephant management in Namibia to illuminate the processes and complexities associated with the commodification and neoliberalisation of nature. The paper demonstrates that the ivory trade ban neither prevents the commodification of elephants, nor hampers the neoliberalisation of nature. By tracing Namibia’s experience associated with applying market based approaches to elephant conservation, this paper highlights that the ivory trade ban is only one obstacle among many which prevent the commodification of the ‘living’ elephant. Analysing Namibia’s experiences alongside the wider debates informing elephant conservation reveals that actors of preservation and sustainable utilisation produce elephants. In particular, during the events leading up to the 1989 ivory trade ban, advocates of preservation produced a very lucrative representation of the elephant that relies on market mechanisms. This image has become a powerful commodity that competes with parts of the biophysical elephant (particularly its ivory) and therefore creates new and contesting ways in which elephants can be commodified. 相似文献
342.
Brittle and ductile deformation of alternating layers of Devonian sandstone and mudstone at Cape Liptrap, Victoria, Australia, resulted in upright folds with associated fold accommodation faults and multiple fracture sets. Structures were mapped at the Fold Stack locality at Cape Liptrap using high-resolution aerial photographs acquired by a digital camera mounted on an unmanned aerial vehicle (UAV). Subsequent photogrammetric modelling resulted in georeferenced spatial datasets (point cloud, digital elevation model and orthophotograph) with sub-cm resolution and cm accuracy, which were used to extract brittle and ductile structure orientation data. An extensive dataset of bedding measurements derived from the dense point cloud was used to compute a 3D implicit structural trend model to visualise along-strike changes of Devonian (Tabberabberan) folds at the Fold Stack locality and to estimate bulk shortening strain. This model and newly collected data indicate that first generation shallowly south-southwest plunging upright folds were gently refolded about a steeply plunging/subvertical fold axis during a Devonian low-strain north–south shortening event. This also led to the local tightening of first generation folds and possibly strike-slip movement along regional scale faults. In order to distinguish fractures associated with Devonian compression from those that formed during Cretaceous extension and later inversion, we compared the five fracture sets defined at Cape Liptrap to previously mapped joints and faults within the overlying sedimentary cover rocks of the Cretaceous Strzelecki Group (Gippsland Basin), which crop out nearby. An east-southeast trending fracture set that is not evident in the Strzelecki Group can be linked to the formation of Devonian folds. Additionally, hinge line traces extracted from the Fold Stack dataset are aligned parallel to a dominant fracture set within the overlying cover sediments. This suggests that basement structures (folds and coeval parallel faults) have an important influence on fault and joint orientations within Cretaceous cover rocks. 相似文献
343.
在现有的精密轨道和钟差条件下,选取8个MGEX跟踪站2014年6—9月的观测数据,详细分析利用BDS/GPS组合PPP法在未固定跟踪站坐标和固定跟踪站坐标情况下估计ZTD的效果,并与IGS提供的对流层产品对比分析。实验分析表明,利用PPP法估计ZTD,BDS ZTD现阶段的STD优于34mm,GPS ZTD与BDS/GPS组合现阶段的STD相当,均优于14mm。与未固定跟踪站情形下估计的BDS ZTD相比,固定跟踪站坐标的方式虽然可以提高利用BDS估计ZTD的稳定性,但不能提高精度。 相似文献
344.
Kevin Leahy 《Bulletin of Volcanology》1997,59(1):65-71
Reworked volcaniclastics are traditionally discriminated from primary tephra-fall pyroclastics by an absence of features
such as blanketing, juvenile lapilli, grain welding and poor sorting. Frequently, these features are difficult to identify,
especially in small outcrops, ancient or altered successions, debris flows and surge deposits. Crystal-rich volcaniclastics,
such as kimberlites, have a large proportion of coarse euhedral crystals, and abrasion leading to rounding can be recognised
and classified with relative ease. A petrographic method of discriminating reworked material has been devised, based on the
degree of grain roundness, and is illustrated using volcaniclastic kimberlite from Fort a la Corne, Saskatchewan, Canada.
Petrographic thin sections of samples at regular intervals throughout the borehole core, and from a nearby crater-facies kimberlite,
show that the percentages of rounded, subrounded and euhedral grains define two distinct groupings. The first group contains
a higher percentage of euhedral grains and includes all the samples from the basal 4.8 m of the 14.1-m-thick kimberlite section
in borehole 004, and all of the crater facies tephra-fall tuffs. A second group contains more rounded, subrounded and fragmental
grains and includes all the data from the upper 6.3 m, which are interpreted as reworked strata. Thus, point counting concurs
with hand-sample interpretation and may be used as a verification tool in discriminating reworked pyroclastic sands from primary
tephra-fall tuffs.
Received: 27 August 1996 / Accepted: 31 May 1997 相似文献
345.
Transport and delivery of suspended solids, nitrogen and phosphorus from various sources to freshwaters in the UK 总被引:8,自引:0,他引:8
Sources of nutrients and suspended solids (SS) are diverse in origin and dynamic with respect to their transport pathways and delivery to surface and groundwaters. Three broad source groups can be identified based on their hydrological and compositional characteristics. Consented discharges from point sources are generally continuous and highly concentrated relative to receiving waters while non-point (diffuse) sources are generally more dilute with SS and phosphorus in particular tending to have a high transport dependence upon hydrological (storm) events. A third group with properties that are intermediate include overflows from septic systems, seepages from farmyards or road/track runoff. This grouping automatically introduces a strong temporal and spatial variability in the relative contribution individual group sources make to the total quantity of nutrients and SS delivered to freshwaters. This spatial or temporal variability in either effluent volumes or composition is generally not considered when predicting impacts, which can be highly significant in headwater streams. Complete compositional data for individual sources (especially the intermediary group) are also often lacking when apportioning source contributions in catchments, being simply lumped into average export coefficients. Better definition of intermediary sources would help to more accurately define the relative contribution of different sources and enable cost-effective river basin management planning as required under the Water Framework Directive. 相似文献
346.
从GPS基本观测模型出发,给出并推导了分离相位小数偏差求解非差整数模糊度的精密单点定位数学模型和算法.利用少量IGS跟踪站组成服务端观测网计算未检校的相位小数偏差改正信息,用于改正用户端接收机的相位观测值,实现了固定非差整数模糊度的快速精密单点定位与定轨.试验结果表明:利用30 min的地面动态或静态观测数据进行精密单点定位,非差模糊度固定成整数后,其定位结果较PPP浮点解有明显改善,水平方向提高了近一个数量级,可达到1 cm甚至毫米级的精度;高程方向与对流层延迟解算精度也改善了20%~60%.与浮点解相比,固定解能显著改善PPP的定轨精度,仅用15 min的短弧段观测数据,切向与法向的定轨精度可达到1 cm左右;径向方向为3~5 cm左右,较浮点解定轨精度改善了50%~70%.因此,固定非差整数模糊度后的PPP能够满足毫米至厘米级的快速精密定位和定轨的要求,这在GPS(准)实时应用与服务中具有很好的应用前景. 相似文献
347.
Fuzzy and Multiple Regression Modelling for Evaluation of Intact Rock Strength Based on Point Load, Schmidt Hammer and Sonic Velocity 总被引:4,自引:0,他引:4
Summary. Uniaxial Compressive Strength (UCS), considered to be one of the most useful rock properties for mining and civil engineering
applications, has been estimated from some index test results by fuzzy and multiple regression modelling. Laboratory investigations
including Uniaxial Compressive Strength (UCS), Point Load Index test (PL), Schmidt Hammer Hardness test (SHR) and Sonic velocity
(Vp) test have been carried out on nine different rock types yielding to 305 tested specimens in total. Average values along
with the standard deviations (Stdev) as well as Coefficients of variation (CoV) have been calculated for each rock type. Having
constructed the Mamdani Fuzzy algorithm, UCS of intact rock samples was then predicted using a data driven fuzzy model. The
predicted values derived from fuzzy model were compared with multi-linear statistical model. Comparison proved that the best
model predictions have been achieved by fuzzy modelling in contrast to multi-linear statistical modelling. As a result, the
developed fuzzy model based on point load, Schmidt hammer and sonic velocity can be used as a tool to predict UCS of intact
rocks. 相似文献
348.
当前国土空间规划现状细化调查尚处于外业核查与内业人工目视判读的方法探索阶段,缺乏较高效率、较高精准度的技术方法。因此,文章提出一种融合高分遥感影像图像信息和POI类别属性信息的数据特点,利用核密度分析和面向对象的信息提取方法,实现对国土空间规划现状地类的细化调查。通过对城镇中心和城镇边缘2个研究区进行建筑物提取和POI属性挂接,识别出各建筑物的使用功能类别,再与2019年第三次全国国土调查的国土利用现状图层进行空间叠加,完成对研究区的地类细化调查。结果表明,经样本误差矩阵评价建筑物提取结果具有较高分类精度,研究区的地类细化调查结果准确度达到86.2%,且大大提高了工作效率,为国土空间规划现状调查逐步走向精准化、高效化和智能化道路提供了方法和思路借鉴,具有重要的深入研究和应用推广意义。 相似文献
349.
本文初步探讨了彩色扫描地图上点状符号自动识别的方法及软件设计的模型和框架.彩色扫描地图上规则符号的主要视觉特征是颜色、形状及大小.识别符号建立在符号模式库的基础上,根据模式库中提供的颜色类型,通过颜色分层方法去寻找彩色扫描地图上的目标,然后提取其轮廓线,获取形状和大小等特征量,最后用符号特征相量与模式库中的特征相量相匹配,对符号进行判别分类,并通过坐标转换,输出符号的中心点地理坐标及符号的其他对应属性.本文最后以彩色地图上电信号强度符号的识别为实例,论述了具体应用系统的设计和开发. 相似文献
350.
介绍了长城站北斗基准站建设和运行的基本情况,并对其稳定性进行了分析。从结果可以看出,基准站观测环境和数据质量良好,站址稳定,常年连续运行和数据实时回传正常。通过设备不断维护升级可以满足北斗全球卫星导航系统建成后的跟踪观测需求,进一步优化和拓展了南极大陆的北斗卫星跟踪监测网络。 相似文献