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Overabundance of white-tailed deer is a pervasive problem across the United States. Deer are blamed for increased risk of auto accidents, tick-borne diseases, and overbrowsing of native species. Lethal management techniques, cited as cost-effective and humane, are commonly employed for herd management. However, the approach frequently sparks outrage among various stakeholders who feel killing of animals is unjustified and prefer nonlethal measures. Wildlife managers then face the challenge of communicating with the public to build policy support for lethal management. The Narrative Policy Framework was used to test the effects of differing narratives on public opinion for lethal deer management. Results indicated narratives were influential in shifting attitudes toward and support for a proposed sharpshooting policy even in some cases where respondents were already familiar with the issue and held a previous opinion. This study also supported the utility of the Narrative Policy Framework for examining human dimensions of wildlife issues. 相似文献
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近20a来巢湖流域生态服务价值空间分异机制的地理探测 总被引:3,自引:0,他引:3
生态系统服务功能是生态系统和生态过程形成和维持的自然环境条件及作用。基于1995—2017年遥感分类数据,对研究区按3 km×3 km幅度网格化2019个样方,利用空间统计和缓冲区等方法进行巢湖流域生态服务价值时空演变特征分析,应用地理探测器工具揭示生态服务价值空间分异的主导因子及因子交互作用机制,并提出生态服务价值空间优化策略。结果表明:① 巢湖流域生态服务价值量由1995年的303.17亿元分别下降为2005年300.95亿元和2017年287.70亿元,近20a来减少约5.11%,年均下降率0.23%,其中合肥市区、巢湖南部和东部地区降速明显;② 生态服务价值等级空间转移分析表明,巢湖流域低级别生态服务价值区域在扩展,中等及高级别区域在缩小。以巢湖为核心的缓冲区分析表明,20a来缓冲区核心环带内生态服务价值量下降18.55%,巢湖流域水环境保护核心区的生态系统功能变化值得关注;③ 地理探测分析表明,人为影响综合指数是生态服务价值空间分异的主导因子;地形、气象因素是重要影响因子;人为影响指数因子、自然因子及社会经济因子的交互协同增强效应共同影响了流域生态服务价值在空间上的分异效果。研究结果在一定程度上可为巢湖流域生态系统调控与优化提供理论依据。 相似文献
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In this Mini-Volume, seven papers written on the basis of talks selected from those presented at the scientific conference "Modern studies of variable stars," commemorating Prof. M. A. Svechnikov(1933–2011), are published. The conference covered a variety of variable-star topics; the papers in this Mini-Volume deal with close, mainly eclipsing, binaries, Herbig Be stars and stellar molecular masers, with an accent on stellar catalogs of different kinds. We briefly review the contents of these papers. 相似文献
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机载多光谱LiDAR的随机森林地物分类 总被引:1,自引:0,他引:1
机载多光谱LiDAR技术利用激光进行探测和测距,不仅可以快速获取地面物体的三维坐标,还可以获得多个波段的地物光谱信息,可广泛用于地形测绘、土地覆盖分类、环境建模、森林资源调查等。本文提出了多光谱LiDAR的随机森林地物分类方法。该方法通过对LiDAR强度数据和高程数据提取分类特征,完成多光谱LiDAR的随机森林地物分类;并分析随机森林的特征贡献度特性,采用后向特征选择方法实现分类特征选择。通过对加拿大Optech Titan多光谱LiDAR数据的试验表明:随机森林方法可以获得较好的地物分类精度,而且可以适当地去除部分冗余和相关的特征,从而有效提高分类精度。 相似文献
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苹果手机零部件全球价值链的价值分配与中国角色演变 总被引:3,自引:2,他引:1
产品内分工已成为支配当代企业分工与产品生产的重要模式。研究智能手机生产网络价值分配格局,对辨析中国大陆企业在移动通讯产业价值链中所处地位与演进具有重要意义。论文利用2012—2017年苹果公司供应商数据,以其零部件价值含量与技术要求为测度标准,分析了苹果手机零部件全球价值链的分配特征以及中国大陆企业在其中的地位变化。发现:高价值环节的供应商主要以美国、日本、韩国为主,而中低价值环节则以中国台湾、日本和中国大陆供应商为主,且中国大陆与中国台湾在中间环节占据重要地位。处于价值链高端的供应商分支数量在中国大陆和美国缩减明显,日本、韩国较为稳定,中国台湾增加明显。在价值链的中低端环节,供应商分支趋向中国大陆集中。印度、巴西以及越南等地成为新的中低端价值环节转移承接地。近年来,中国大陆在苹果手机价值链的高端环节得到了提升,长三角、珠三角、京津冀、成渝、中原地区等地逐渐形成了苹果供应商分支的集聚区域,呈现出零部件生产的区域分工特征。长三角(上海-苏州为核心)与珠三角(深圳-东莞为核心),承接了价值链多个生产环节,是中国大陆嵌入苹果手机生产网络的主要阵地。成渝地区既承接了芯片类企业布局,也承接了价值链低端的组装代工和包装服务环节,呈现出在价值链两端双向承接的特征。环渤海、福建及湖南等地主要承接苹果手机价值链的中间环节,而中原地区主要以苹果手机组装与包装服务为主,承接价值链的低端环节。最后,论文从创新驱动、政府作用与外资等方面探讨了影响中国大陆地位提升的因素。 相似文献
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Floating wind turbine has been the highlight in offshore wind industry lately. There has been great effort on developing highly sophisticated numerical model to better understand its hydrodynamic behaviour. A engineering-practical method to study the nonlinear wave effects on floating wind turbine has been recently developed. Based on the method established, the focus of this paper is to quantify the wave nonlinearity effect due to nonlinear wave kinematics by comparing the structural responses of floating wind turbine when exposed to irregular linear Airy wave and fully nonlinear wave. Critical responses and fatigue damage are studied in operational conditions and short-term extreme values are predicted in extreme conditions respectively. In the operational condition, wind effects are dominating the mean value and standard deviation of most responses except floater heave motion. The fatigue damage at the tower base is dominated by wind effects. The fatigue damage for the mooring line is more influenced by wind effects for conditions with small wave and wave effects for conditions with large wave. The wave nonlinearity effect becomes significant for surge and mooring line tension for large waves while floater heave, pitch motion, tower base bending moment and pontoon axial force are less sensitive to the nonlinear wave effect. In the extreme condition, linear wave theory underestimates wave elevation, floater surge motion and mooring line tension compared with fully nonlinear wave theory while quite close results are predicted for other responses. 相似文献
120.
The aim of this study is to develop a two-dimensional hydrodynamic tidal model for the Persian Gulf (PG2017) using 2D-MIKE21 software. The advantages of present study is accounting for the spatial variation of bed friction coefficient besides a precise bathymetry together with a 23-year of combined records of satellite altimetry data. We found that the bed friction coefficient has a significant effect on sea level changes in the region under our modeling consideration. Since the tidal behavior in the northern part of the Qeshm Island is significantly different from the other parts of the Persian Gulf, to present a more accurate hydrodynamic tidal model, the Gulf is divided into two regions where the bed friction coefficient is modeled separately for each region. The root mean square value of the differences between the amplitude of dominant constituents; M2, S2, K1, and O1 derived from the PG2017 model and that of 98 altimetry and coastal tide gauge stations are respectively equal to 1.6, 1.9, 2.8, and 1.3?cm. Moreover, comparing the PG2017 model efficiency with the FES2014, OSU12, EOT11a, DTU10, and Admiralty models shows that the PG2017 model has an improvement of 22.1%, 47.2%, 43.2%, 44.2%, and 57.6% in terms of relative error, respectively. 相似文献