基于地理探测器的大熊猫生境适宜度评价模型及验证

动物生境适宜度评价对于野生动物生境保护十分重要。基于物种活动点来建模的生态位模型是目前应用最广泛的动物生境评价方法,但该方法不能直接表达生境适宜度与环境因子间具有生态学意义的数量关系。本文以雅安地区为例,提出一种新的大熊猫（Ailuropoda melanoleuca）生境适宜度评价方法,选取海拔、坡度、坡向、地形指数、距水源距离、植被类型、主食竹及距公路距离8个环境因子,引入地理探测器,在分别基于MAXENT模型和层次分析法（The Analytic Hierarchy Process,AHP）所构建生境适宜度模型的基础上,通过4个地理探测器（风险探测器、因子探测器、生态探测器和交互作用探测器）探寻大熊猫生境与各环境因子间的关系以及环境因子对大熊猫生境的影响机理,并将其预测结果与单一MAXENT模型和AHP法进行对比。结果表明：（1）AHP、AHP-Geogdetector、MAXENT和MAXENT-Geogdetector模型总体评价精度分别为85.6%、86.5%、91.3%和94.2%,kappa系数分别为0.699、0.718、0.821和0.882,AUC值分别为0.902、0.928、0.949和0.966,模型所预测的适宜和较适宜区与实际分布区重叠比分别为63.66%、61.30%、76.70%和90.10%,说明AHP-Geogdetector和MAXENT-Geogdetector模型精度均比相应的单一模型有所提高,且MAXENT-Geogdetector模型精度最高;（2）基于地理探测器的大熊猫生境适宜度评价模型能以“生境适宜度和环境因子间具有生态学意义的数量关系”的形式直接体现环境因子对动物生境利用的生态学作用,具有较好的生态学可解释性。因此,用地理探测器进行大熊猫生境适宜度评价具有较好的可行性。     

一种变形监测中中长基线的单历元模糊度解算算法

针对已有单历元模糊度解算算法只适用于短基线的情形,根据误差传播率确定模糊度精度,依据误差确定模糊度搜索空间,提出一种利用GPS双频观测信息实现中长基线下单历元模糊度固定的算法。首先,利用电离层约束法得到双差模糊度之间的线性约束条件;其次,利用变形监测中监测站点坐标近似已知的条件进行约束,反算获得近似模糊度;最后,根据监测站点已有的观测数据精度给出搜索空间,搜索固定模糊度。结果表明,该方法可以实现中长基线下单历元的模糊度固定,对实时变形监测有一定的参考价值。     

GNSS多天线基线网单历元模糊度同步解算法

提出多天线基线网单历元模糊度同步解算法,其具体实现步骤为:1)根据宽巷组合模糊度易于固定的优点,采用附加已知基线长度约束法同步解算各基线的宽巷模糊度,得到dm～cm级精度的近似基线分量;2)将解算得到的各近似基线分量作为约束,同步解算各基线的基频模糊度,以获取mm级精度的基线矢量。该方法的关键在于检验各历元宽巷模糊度解算的正确性,以获取可靠的近似基线分量,为解算各基线的基频模糊度提供准确的基线先验信息。由于动态情况下各历元观测信息比较少,单纯依赖ratio检验不可靠,提出结合基线误差、单位权中误差、基线网模糊度闭合环及ratio值等对多组宽巷模糊度进行检验,避免ratio值设置不当导致模糊度检验中发生纳伪和弃真问题。实测数据结果证明,该处理方法使得模糊度解算的成功率提高1%～2%,可以获取移动平台更丰富的导航信息,提高其服务能力。     

地表组合粗糙度不确定性引起的SAR反演土壤水分的不确定性分析

地表粗糙度的不确定性是引起SAR土壤水分反演结果不确定性的主要因素,现有研究大多着重于研究单个粗糙度参数（主要是相关长度）的不确定性,直接研究地表组合粗糙度不确定性的较少。本文使用偏度、峰度和四分位距3个指标来量化不确定性,通过在组合粗糙度中加入不同量级高斯噪声进行随机扰动的方法,研究组合粗糙度不确定性在反演过程中的传递,并对反演土壤水分的不确定性进行定量分析。进一步研究反演土壤水分的均方根误差对组合粗糙度不同比例误差范围的响应特征,得到满足反演精度要求的组合粗糙度误差控制范围。样区的实验分析结果表明：组合粗糙度高斯噪声标准差在0-0.045之间时,峰度取值从-0.1984到1.2501,偏度取值从0.0191到0.6791,四分位距取值从0.0018到0.0167,3个量化指标都随组合粗糙度高斯噪声量级的增大而增大,土壤水分反演值有集中在众数附近的趋势,土壤水分低估倾向比高估倾向更明显;本文提出的组合粗糙度误差控制范围可满足反演精度要求,误差控制范围与入射角负相关。     

北部湾经济区土地利用总体规划实施状况差异分析

文章以北部湾经济区六市县土地利用总体规划实施为研究对象,通过用地状态偏离度计算分析六市县主要规划指标偏离总体规划的情况,及时进行纠偏,保证规划实施质量。     

空间面群目标几何相似度计算模型

本文针对空间面群目标提出了一种几何相似度计算模型。首先,利用拓扑关系概念领域图定义了面群之间的拓扑关系相似度;然后,对不同类型的面状目标选用合适的"降维"方法处理为"线群"目标,利用方向均值定义线群之间的方向关系即面群目标的方向相似度,以及利用"环形方差"定义线群目标之间的距离关系即面群目标的距离相似度。最后,结合面群的长度和平均长度、面积和平均面积,面密度及紧致度,建立了面群目标几何相似度计算模型,以对面群目标相似度进行整体度量。该模型综合考虑了空间面群目标的几何特征和空间关系特征,并对其作了适当的权重分配。从时间邻近度和尺度邻近度角度,本文设计了2个实验,结果表明,相似度计算结果与地物特征比较一致,符合人们的直观空间认知。     

现行业务湿度传感器测量不确定度研究

依据JJF1059.1-2012《测量不确定度评定与表示》,针对自动气象站各要素传感器的测量误差会随时间、温度等环境因素的变化而发生漂移.为确保观测数据的准确、可靠,以CP340恒温恒湿箱为湿度发生环境、采用英国michell公司的Optidew Vision精密露点仪为标准器,介绍了利用HMP155A温湿度传感器进行湿度测量不确定度评定的一般方法和详细步骤.最后给出一个评定实例,在温度为22℃和40℃,相对湿度为30％ RH～75％RH时,通过对测量不确定度的各分量进行分析和计算,得到HMP155A温湿度传感器测量结果的扩展不确定度分别为1.50％和1.46％.     

Biodiversity and invasibility: Distribution patterns of invasive plant species in the Himalayas,Nepal

Invasive plant species are exerting a serious threat to biological diversity in many regions of the world. To understand plant invasions this study aims to test which of the two plant invasiveness hypotheses; ‘low native diversity' vs. ‘high native diversity', is supported by the regional distribution patterns of invasive plant species in the Himalayas,Nepal. This study is based on data retrieved from published literatures and herbarium specimens. The relationship between invasive plant species distribution patterns and that of native plant species is elucidated by scatter plots, as well as by generalized linear models. The native plant species and invasive plant species have similar distribution patterns and the maximum number of invasive plant species is found in the same altitudinal range where the highest richness for native tree species is found. There is a clear trend of higher invasive plant richness in regions where native tree species richness is relatively high.Consequently, the native plant richness is highest in the central phytogeographic region, followed by the eastern and the western regions, respectively. The invasive plant species also follows a similar trend.Additionally, the invasive plant species richness was positively correlated with anthropogenic factors such as human population density and the number of visiting tourists. This study supports the hypothesis that ‘high native diversity' supports or facilitates invasive plant species. Further, it indicates that nativeand invasive plant species may require similar natural conditions, but that the invasive plant species seem more dependent and influenced by anthropogenic disturbance factors.     

Species richness,diversity and density of understory vegetation along disturbance gradients in the Himalayan conifer forest

We investigated whether species richness, diversity and density of understory herbaceous plants differed along logging(gap) and grazing(primarily by cattle) disturbance gradients, and sought to identify drivers of richness, diversity and density of understory vegetation of logged sites. A factorial experiment was conducted in the mixed conifer forest of Gidakom in Western Bhutan. Levels of the logging treatment included small(0.15 – 0.24 ha), medium(0.25 – 0.35 ha) and large(0.36 – 1.31 ha) gaps. The grazing treatment included grazed(primarily by cattle) and ungrazed(where herbivores were excluded by a fence) plots nested within each gap. Data were collected from 12 gaps(4 replicates at each level of logging) using the point intercept method. Shannon Weaver Diversity and Margalef's indices were used to estimate species diversity and describe species richness, respectively. Soil samples were analyzed for pH and nutrients. The interaction effect of logging and grazing was significant(p≤0.001) only on species diversity. Relative to ungrazed areas, species diversity was significantly higher(0.01≤p≤0.05) in medium grazed gaps. Under grazed conditions, soil P was negatively correlated with gap size and species diversity. While species diversity was positivelycorrelated(0.01≤p≤0.05) with soil N in grazed plots species richness was positively correlated(0.001≤p≤0.01) with soil N in ungrazed plots. Relative density of Yushania microphylla and Carex nubigena were higher under ungrazed conditions. Our study suggests that the combined effect of cattle grazing and logging results in higher species diversity of understory vegetation in medium and grazed gaps in mixed conifer forests of Bhutan,whereas increase or decrease in relative density of major species is determined primarily by the independent effects of grazing and logging. From management perspective, forest managers must refrain from creating large gaps to avoid loss of nutrients(mainly P and N), which may eventually affect tree regeneration. Managers intending to maintain understory vegetation diversity must consider the combined effects of grazing and logging, ensuring low to moderate grazing pressure.     

Mineral occurrence for Dachang gold deposit and its impact on gold recovery rate in Qumarleb County,Qinghai

Based on X-ray diffraction, optical microscopy and scanning electron microscopy analysis of the Dachang gold ore, it is showed that the sulfide of ore is the main carrier minerals of gold. A majority of gold is embedded in pyrite and tetrahedrite as the form of inclusion and a small amount intergrowth with pyrite and gangue mineral, occasionally the presence is in form of monomer natural gold. The main factors which influence the recovery rate are sulfide mineral particle size, and the fine grained sulfide is beneficial for the dissociation and flotation of gold bearing minerals. The monomer dissociation degree of gold bearing minerals can reach 91.3% , when the grinding fineness is less than 0. 074 mm and grain level accounts as 80%. It is not conducive to the flotation of sulfide if the grinding fineness is low or high. It is difficult to completely dissociate the monomer if there is a small amount of pyrite and arsenopyrite in the ore. Therefore, before leaching the gold, it must conduct pretreatment to reach the ideal recovery rate of the gold, like roasting oxidation, pressure oxidation and biological oxidation. The fine microscopic gold has little influence on the gold recovery rate.