Not a “forever model”: the curious case of graduation in Housing First     

Jalene T. Anderson-Baron 《Urban geography》2018,39(4):587-605

This article investigates how Housing First (HF) is practiced in Alberta, Canada, with a focus on the concept of graduation. The dominant HF model, Pathways, holds that client support should be time-unlimited. However, HF is highly mobile and increasingly characterized by ambiguity and drift away from Pathways principles. In Alberta, one prominent example of drift is the notion that clients can and should graduate – that is, “exit” HF programs after a certain time. Interviews conducted with 45 participants in three Alberta cities in 2014–15 revealed commonplace, but contested, graduation practices. Interviewees noted that graduation can be necessary to make room for new clients, and may be expected and encouraged by coordinating organizations. They expressed varied concerns about graduation, and the negative influence it could have on client relationships and housing stability. In particular, they emphasized clients’ ongoing dependence on rental subsidies, and the risk of relapse into homelessness.  相似文献   

中国大陆地区TanDEM-X 90 m DEM误差空间分布特征     

李文梁  汪驰升  朱武 《地球信息科学学报》2020,22(12):2277-2288

TanDEM-X 90 m 数字高程模型（DEM）在其原始雷达影像的采集与DEM产品生产过程中,坡度、坡向和地表覆盖物等 因素都会对误差产生一定的影响。为了便于该数据更好地为各领域的研究提供服务,本文以整个中国大陆为研究区域,运用ICESat/GLA14数据对该区域的TanDEM-X 90 m DEM对应位置的高程数据进行提取统计,对比分析了我国陆地区域 TanDEM-X DEM数据与GLA14高程点数据的整体误差精度,并提取坡度、坡向地形因子,研究TanDEM-X 90 m DEM误差在不同坡度、不同坡向以及不同地表覆盖物影响下的分布规律。结果表明：① TanDEM-X 90 m DEM在中国区域整体的绝对误差均值为3.89 m,中误差为9.03 m,标准差为8.85 m; ② 受地形因子的影响,在坡度<3°时,绝对误差均值仅为1.29 m,标准差为2.84 m; 在坡度>25°时,绝对误差均值20 m以上,标准差也达到30 m左右,即误差随着坡度的上升逐渐增大;③ 坡向对误差也有一定影响,在南北方向的绝对误差均值明显比东西方向小;④ 受地表覆盖物影响较大,在荒地误差最小,绝对误差均值仅为 1.85 m,但在冰川积雪区绝对误差均值达到12.68 m。通过与无人机获取的等高线及剖面图对比分析发现,TanDEM-X 90 m DEM能较好地反映真实地形情况。最后,根据不同影响因素的权值,绘制全国范围的TanDEM-X 90 m DEM误差绝对值分布图,且验证了可靠性。  相似文献   

水力反循环连续取心(样)钻探在浅海砂矿勘查中的应用   总被引：1，自引：1，他引：0  

张永勤  孙建华  刘秀美  王汉宝  郑志昌  梁开 《探矿工程》2008,35(6):15-18

概述了水力反循环(HRC—Hydraulic Reverse Circulation)连续取心钻探技术首次在我国海南砂矿勘查取心(样)钻探施工过程及取得的效果;总结了海上砂矿取心(样)钻探施工的经验。该技术的成功应用,为国内外开展海洋区域地质、海洋环境地质、海洋工程地质调查等钻探取心(样)施工提供了一种全新、高效实用的技术方法。  相似文献   

遥感影像预分类精度对地物面积空间抽样估算的敏感性分析   总被引：3，自引：1，他引：2  

贾斌  朱文泉  潘耀忠  宋国宝  胡潭高 《遥感学报》2008,12(6)

传统的地物面积测量受精度和效率制约,为此引入了结合遥感影像的空间分层抽样方法.首先以遥感影像的预分类结果作为模拟地物的真实分布,在地物外沿等概率随机添加不同比例的错分像元,从而获得准真实地物区的摸拟预分类结果,并依此设定各层等比例取样的样本人层标志,指导地物样本的选取,然后以抽中样本地物的准真实值之和按比例推算出总量.通过比较分析各水平含量的地物类别、不同预分类精度、层内随机和系统抽样下的多次总量估计精度及其稳定性变化情况,结果表明:该方法不需要背景数据库等先验知识,在预分类达到一定精度之上时,依分类区域设立层标志的分层抽样方法所获得的总量估计精度及标准差均好于无分类支持的随机和系统抽样;当预分类精度达到50%以上时,具有较高的成本效率比,其中在60%时,各类地物在0.5%抽样率、95%的置信度下可以保证估计量精度在92%以上.  相似文献   

基于局部约束的建筑物屋顶点云平面分割方法     

张宏伟  姜超  张保明  郭海涛 《测绘科学技术学报》2017,34(3)

建筑物屋顶面点云分割结果的好坏对建筑物三维模型重建起着重要的作用。针对传统RANSAC算法建筑物屋顶面点云的分割问题,提出了一种基于局部约束的建筑物点云平面分割方法。利用点云局部曲面法向约束构建法向准则,利用半径约束的点云空间聚类的方法对共面屋顶面点云进行分解,从而抑制"伪屋顶面"的产生;利用局部抽样策略降低算法的迭代次数,减少运算量。实验表明该方法能够获得稳定可靠的建筑物屋顶点云分割结果,将有利于后续的建筑物三维模型重建。  相似文献   

地质勘探空气反循环钻进技术找矿效果示范应用研究          下载免费PDF全文

黄晟辉  陆生林  殷琨  邓梦春 《探矿工程》2013,40(3):1-6

2011年,“地质勘探空气反循环钻进技术找矿效果示范应用研究”项目在云南省大理州北衙金矿进行了对比试验。介绍了设备的选择、钻孔结构、钻进工艺、试验的技术指标、地质找矿效果和需要进一步研究的主要问题。  相似文献   

空气反循环取样钻探的岩样收集和缩分技术   总被引：1，自引：1，他引：0       下载免费PDF全文

邓梦春  黄晟辉  殷琨  陆生林 《探矿工程》2013,40(7):73-76,80

简要介绍了国内外空气反循环取样钻探的岩样收集和缩分技术。主要包括美国和澳大利亚的岩样收集缩分设备和技术,以及国内吉林大学、中国地质科学院勘探技术研究所和探矿工艺研究所在岩样收集和缩分技术方面所开展的工作和成果。  相似文献   

Effect of sampling plan and trend removal on residual uncertainty     

《Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards》2013,7(4):253-264

ABSTRACT

The ground is one of the most highly variable of all engineering materials. As a result, geotechnical designs depend upon a site investigation to estimate the ability of the ground to perform acceptably. For example, when a shallow foundation is being proportioned to avoid a bearing capacity failure under a certain applied load, the frictional and cohesive properties of the ground under the foundation must first be estimated through a site investigation. Questions which arise are: How does the quality and intensity of the site investigation affect the design? Is more investigation cost effective? If the site is sampled at one location and the foundation placed at a different location, how does this mismatch affect the target design and the reliability of the final foundation? By modelling the ground as a spatially variable material, questions such as the above can be investigated through Monte Carlo simulation and sometimes theoretical probabilistic models. Using such tools, this paper looks specifically at how the intensity (frequency and spatial distribution) of a site sampling plan, and how the samples are used, affects the understanding of the ground properties under a foundation. Interestingly, it is found that removing the sample mean outperforms removing the best linear unbiased estimate (BLUE) when the actual field correlation length is small but the BLUE correlation length is assumed equal to the field size. Recommendations are made regarding number of samples and the type of trend to best characterise the field.

Abbreviations: BLUE: best linear unbiased estimate; MCS: Monte Carlo simulation; LAS: local average subdivision  相似文献   

Integration of European habitat monitoring based on plant life form composition as an indicator of environmental change and change in biodiversity     

Margit Bloch-Petersen  Jesper Brandt  Martin Olsen 《Geografisk tidskrift / udgivet af Bestyrelsen for Det Kongelige danske geografiske selskab》2013,113(2):61-74

Geografisk Tidsskrift, Danish Journal of Geography 106(2): 61–74, 2006

During the last 25 years a number of European countries have developed general landscape monitoring systems. In the agricultural landscapes of Denmark the Small Biotope Monitoring Program (SBMP). which focuses on the dynamics of small biotopes and their relation to changes in agricultural technology and structural characteristics, has been developed since 1981. Erom 2007, the SBMP will continue as part of the Danish nature monitoring program, NOVANA.

In Europe, during the last 10 years, several national landscape surveys have cooperated to develop a European platform for consistent landscape related habitat monitoring. This has been through the BioHab Concerted Action Framework Programme of the EU (2002–2005), and the resulting publication of a handbook for recording and monitoring habitats (Bunce et al., 2005). The focus on environmentally conditioned habitat changes at a landscape level has led to the re-introduction of Raunkiaer's plant life form concept. This approach enables the indication of changes in biodiversity based on alterations in general habitat composition and quality.

Although the objectives of the SBMP and the BioHab projects have been somewhat different, the methodologies have much in common. In this paper the background and perspectives of the two approaches are discussed, and a test of the BioHab field methodology in an area previously monitored by the SBMP is presented. It was found not to be difficult to integrate the BioHab field recording methodology with the existing SBMP methods, thus permitting the SBMP to deliver an additional European perspective, with relatively little additional effort.  相似文献   

High-Resolution Measurement and Analysis of Visitor Experiences in Time and Space: The Case of Aalborg Zoo in Denmark     

Amit Birenboim  Kristian Hegner Reinau  Noam Shoval  Henrik Harder 《The Professional geographer》2013,65(4):620-629

The notion of consumer and user experience has become dominant in our society in recent years, especially in relation to leisure activities. In this study we used the experience sampling method (ESM) data collection technique in Aalborg Zoo, Denmark, to understand the distribution of subjective experiences within this site. Visitors to the zoo were asked to send phone messages (SMS) about their subjective feelings in real time and to carry with them Global Positioning System (GPS) devices that recorded their movement. This method allowed us to geotag experiences of visitors throughout the zoo compound. The results indicate that the quality of experience of visitors varies both in time and in space. We conclude that there is a need to further explore the effect of place on experiences using repeat, high-resolution measurements. In this regard we believe that geographers, who have a long tradition of studying human–environment relations, have the tools to lead this type of exploration.  相似文献