Individual tree detection (ITD) and the area-based approach (ABA) are combined to generate tree-lists using airborne LiDAR data. ITD based on the Canopy Height Model (CHM) was applied for overstory trees, while ABA ba...Individual tree detection (ITD) and the area-based approach (ABA) are combined to generate tree-lists using airborne LiDAR data. ITD based on the Canopy Height Model (CHM) was applied for overstory trees, while ABA based on nearest neighbor (NN) imputation was applied for understory trees. Our approach is intended to compensate for the weakness of LiDAR data and ITD in estimating understory trees, keeping the strength of ITD in estimating overstory trees in tree-level. We investigated the effects of three parameters on the performance of our proposed approach: smoothing of CHM, resolution of CHM, and height cutoff (a specific height that classifies trees into overstory and understory). There was no single combination of those parameters that produced the best performance for estimating stems per ha, mean tree height, basal area, diameter distribution and height distribution. The trees in the lowest LiDAR height class yielded the largest relative bias and relative root mean squared error. Although ITD and ABA showed limited explanatory powers to estimate stems per hectare and basal area, there could be improvements from methods such as using LiDAR data with higher density, applying better algorithms for ITD and decreasing distortion of the structure of LiDAR data. Automating the procedure of finding optimal combinations of those parameters is essential to expedite forest management decisions across forest landscapes using remote sensing data.展开更多
目的基于决策树模型评价玉屏风胶囊治疗慢性阻塞性肺疾病(COPD)稳定期的成本-效果。方法从医疗卫生体系角度出发,采用TreeAge Pro 2018.2.1软件构建决策树模型,模拟玉屏风胶囊联合西医常规疗法相比于西医常规疗法治疗COPD的总成本和临...目的基于决策树模型评价玉屏风胶囊治疗慢性阻塞性肺疾病(COPD)稳定期的成本-效果。方法从医疗卫生体系角度出发,采用TreeAge Pro 2018.2.1软件构建决策树模型,模拟玉屏风胶囊联合西医常规疗法相比于西医常规疗法治疗COPD的总成本和临床产出,并进行增量分析和敏感性分析。其中成本数据来源于相关价格网站,疗效数据来源于Meta分析。结果与对照组比较,玉屏风胶囊组的增量成本和增量效果分别为1069.2元和1.3次,增量成本-效果比(ICER)为822.46元,也就是说,用玉屏风胶囊联合西医常规疗法治疗COPD稳定期患者,每少发生1次急性加重次数,要多支出822.46元。以2020年人均可支配收入(32189元,国家统计局)作为基础分析的参考标准,ICER占人均可支配收入的2.56%。因此,在假设2020年人均可支配收入是患者的意愿支付阈值的情况下,玉屏风胶囊联合常规疗法比单用常规疗法更经济。敏感性分析结果表明基础分析结果较稳健。结论玉屏风胶囊联合西医常规疗法较单用西医常规疗法在减少急性加重次数方面的经济性更优。展开更多
文摘Individual tree detection (ITD) and the area-based approach (ABA) are combined to generate tree-lists using airborne LiDAR data. ITD based on the Canopy Height Model (CHM) was applied for overstory trees, while ABA based on nearest neighbor (NN) imputation was applied for understory trees. Our approach is intended to compensate for the weakness of LiDAR data and ITD in estimating understory trees, keeping the strength of ITD in estimating overstory trees in tree-level. We investigated the effects of three parameters on the performance of our proposed approach: smoothing of CHM, resolution of CHM, and height cutoff (a specific height that classifies trees into overstory and understory). There was no single combination of those parameters that produced the best performance for estimating stems per ha, mean tree height, basal area, diameter distribution and height distribution. The trees in the lowest LiDAR height class yielded the largest relative bias and relative root mean squared error. Although ITD and ABA showed limited explanatory powers to estimate stems per hectare and basal area, there could be improvements from methods such as using LiDAR data with higher density, applying better algorithms for ITD and decreasing distortion of the structure of LiDAR data. Automating the procedure of finding optimal combinations of those parameters is essential to expedite forest management decisions across forest landscapes using remote sensing data.
文摘目的基于决策树模型评价玉屏风胶囊治疗慢性阻塞性肺疾病(COPD)稳定期的成本-效果。方法从医疗卫生体系角度出发,采用TreeAge Pro 2018.2.1软件构建决策树模型,模拟玉屏风胶囊联合西医常规疗法相比于西医常规疗法治疗COPD的总成本和临床产出,并进行增量分析和敏感性分析。其中成本数据来源于相关价格网站,疗效数据来源于Meta分析。结果与对照组比较,玉屏风胶囊组的增量成本和增量效果分别为1069.2元和1.3次,增量成本-效果比(ICER)为822.46元,也就是说,用玉屏风胶囊联合西医常规疗法治疗COPD稳定期患者,每少发生1次急性加重次数,要多支出822.46元。以2020年人均可支配收入(32189元,国家统计局)作为基础分析的参考标准,ICER占人均可支配收入的2.56%。因此,在假设2020年人均可支配收入是患者的意愿支付阈值的情况下,玉屏风胶囊联合常规疗法比单用常规疗法更经济。敏感性分析结果表明基础分析结果较稳健。结论玉屏风胶囊联合西医常规疗法较单用西医常规疗法在减少急性加重次数方面的经济性更优。
