The aim of this work was to evaluate and compare the performance of comparatively new synthetic PTW 60019 microDiamond with PTW 60017 Diode E detector in measuring the output factors (OF) of IntraOperative Radiation T...The aim of this work was to evaluate and compare the performance of comparatively new synthetic PTW 60019 microDiamond with PTW 60017 Diode E detector in measuring the output factors (OF) of IntraOperative Radiation Therapy (IORT) electron beams. For a given electron beam, OFs are defined as the ratio of the dose for any applicator size at the depth of maximum to that for a reference applicator. IORT is an innovative treatment technique that delivers a large single fraction of radiation dose to the tumor bed during surgery. The electron beams considered in this study were generated by the mobile NOVAC7 system. This device produces high-dose-per-pulse electron beams with four different energies in the range from 3 MeV to 9 MeV. We performed measurements for two higher energies, namely 7MeV and 9 MeV. The beam collimation was performed through Perspex (PMMA) cylindrical applicators with different diameters. The accurate dose delivery of IORT tightly depends on the precision of measured dose by reference applicator and the output factors of clinical applicators. The output factors were measured using microDiamond and Diode E detectors. The microDiamond detector performance was compared with a Diode E detector. Determined output factors of two detectors were in good agreement. The maximum deviations of output factors for microDiamond were found 2.74%, and 2.17% for 7 MeV and 9 MeV, respectively with respect to the PTW Diode E. The microDiamond detector was shown to exhibit excellent properties for output factor measurements and could be considered as a suitable tool for electron beam dosimetry.展开更多
Within oasis-desert ecotone regions,the normalized difference vegetation index(NDVI)is an important parameter for evaluating the growth of vegetation.An accurate quantitative study between NDVI and environmental and a...Within oasis-desert ecotone regions,the normalized difference vegetation index(NDVI)is an important parameter for evaluating the growth of vegetation.An accurate quantitative study between NDVI and environmental and anthropogenic factors is critical for understand the driving factors of vegetation growth in oasis-desert ecotone.In 2016,four periods Landsat 8 OLI_TIRS images,relevant climatological parameters data(air temperature,air relative humidity,wind velocity and accumulated temperature),land cover type data and soil data were selected as proxies.In order to quantify the explanatory power for NDVI spatial and temporal distribution in the southern edge of Dunhuang City and northern side of the Mingsha Mountain,the geographical detector model was used to explain the potential influences of factors versus the spatial distribution of NDVI,and each explanatory variable's relative importance can be calculated.The factor detector results disclose that the spatial distribution of NDVI is primarily dominated by land cover type.The risk detector results show that,high NDVI region is located within woodland.The mean value of NDVI displays an increase and then decrease trend with air temperature increase.With the increase of wind velocity and decrease of air relative humidity,the NDVI value shows a decrease trend.The interactive q values between the two factors are higher than any q value of separated factors.Results also indicate that the strongest interactive effects of NDVI are different in distinct seasons.Consequently,anthropogenic activity is more important than environmental factors on NDVI in oasis-desert ecotone.We also demonstrate that air relative humidity rather than air temperature have played a greater role in NDVI spatial distribution.展开更多
文章以广西南宁横州市52处古建筑为研究对象,旨在揭示西南县域古建筑空间布局特征及自然—人文因子的协同驱动机制,为同类区域古建筑的整体性保护与文化传承提供科学支撑。研究整合古建筑POI(Point of Interest)、地形地貌、水系道路及...文章以广西南宁横州市52处古建筑为研究对象,旨在揭示西南县域古建筑空间布局特征及自然—人文因子的协同驱动机制,为同类区域古建筑的整体性保护与文化传承提供科学支撑。研究整合古建筑POI(Point of Interest)、地形地貌、水系道路及社会经济等多源数据,综合运用标准差椭圆、核密度分析、地理集中指数、不平衡指数及地理探测器等方法开展系统研究。结果表明:横州市古建筑总体呈西北—东南向狭长分布,中心位于校椅镇,形成“双核引领”集聚格局,整体呈现“东西密、南北疏”的分布态势;地理集中指数为39.411、不平衡指数为0.593,其中横州镇等3个镇的古建筑占比达63.46%,均衡度显著偏低。自然因素中,94.23%的古建筑分布于海拔[31,200)m平原,82.69%位于坡度小于5°的区域,36.54%分布于[750,1500)m河流缓冲区;人文因素中,人口密度为核心驱动因素,[0,2700)m道路缓冲区内集聚75.00%的古建筑。自然与人文因子交互呈非线性增强。研究表明,县域古建筑布局受自然基底与人文脉络协同约束,据此提出分级分区保护、平衡开发与保护、构建“生态—文化廊道”等策略,可为横州市及西南同类县域协调城镇化与文化遗产保护提供借鉴。展开更多
以长三角区域3A级及以上高等级旅游景区为研究对象,采用地理信息系统(Geographic Information System,GIS)空间分析技术和地理探测器工具,对其空间分布特征和影响因素进行分析。结果表明:①长三角区域高等级旅游景区的整体空间分布状态...以长三角区域3A级及以上高等级旅游景区为研究对象,采用地理信息系统(Geographic Information System,GIS)空间分析技术和地理探测器工具,对其空间分布特征和影响因素进行分析。结果表明:①长三角区域高等级旅游景区的整体空间分布状态为集聚型,呈现出“大分散、小集聚”的空间分布特征。②建筑设施类和水域景观类旅游景区分布状态最为分散;长三角区域41个城市可按吸引物属性组合情况划分为“自然人文双优型”“自然优势型”“人文优势型”“自然人文景观双低型”4类旅游地。③通过地理探测器分析得知,长三角区域高等级旅游景区空间分异特征是自然、经济、社会三大因素互相交织、共同作用的结果;地文景观类和水域景观类旅游景区分布主要受自然维度因素影响,生物景观类旅游景区分布主要受“社会自然”维度因素影响,建筑设施类和历史古迹类旅游景区分布主要受“社会经济”维度因素影响,娱乐购物类旅游景区分布则呈现出“经济社会”维度的交织主导作用。基于上述分析结果,从推进区域旅游一体化、差异化协调发展的视角提出了优化建议。展开更多
文摘The aim of this work was to evaluate and compare the performance of comparatively new synthetic PTW 60019 microDiamond with PTW 60017 Diode E detector in measuring the output factors (OF) of IntraOperative Radiation Therapy (IORT) electron beams. For a given electron beam, OFs are defined as the ratio of the dose for any applicator size at the depth of maximum to that for a reference applicator. IORT is an innovative treatment technique that delivers a large single fraction of radiation dose to the tumor bed during surgery. The electron beams considered in this study were generated by the mobile NOVAC7 system. This device produces high-dose-per-pulse electron beams with four different energies in the range from 3 MeV to 9 MeV. We performed measurements for two higher energies, namely 7MeV and 9 MeV. The beam collimation was performed through Perspex (PMMA) cylindrical applicators with different diameters. The accurate dose delivery of IORT tightly depends on the precision of measured dose by reference applicator and the output factors of clinical applicators. The output factors were measured using microDiamond and Diode E detectors. The microDiamond detector performance was compared with a Diode E detector. Determined output factors of two detectors were in good agreement. The maximum deviations of output factors for microDiamond were found 2.74%, and 2.17% for 7 MeV and 9 MeV, respectively with respect to the PTW Diode E. The microDiamond detector was shown to exhibit excellent properties for output factor measurements and could be considered as a suitable tool for electron beam dosimetry.
基金supported by the National Natural Sciences Foundation of China(41871016)the National Key Research and Development Program of China(2017YFC0504801)
文摘Within oasis-desert ecotone regions,the normalized difference vegetation index(NDVI)is an important parameter for evaluating the growth of vegetation.An accurate quantitative study between NDVI and environmental and anthropogenic factors is critical for understand the driving factors of vegetation growth in oasis-desert ecotone.In 2016,four periods Landsat 8 OLI_TIRS images,relevant climatological parameters data(air temperature,air relative humidity,wind velocity and accumulated temperature),land cover type data and soil data were selected as proxies.In order to quantify the explanatory power for NDVI spatial and temporal distribution in the southern edge of Dunhuang City and northern side of the Mingsha Mountain,the geographical detector model was used to explain the potential influences of factors versus the spatial distribution of NDVI,and each explanatory variable's relative importance can be calculated.The factor detector results disclose that the spatial distribution of NDVI is primarily dominated by land cover type.The risk detector results show that,high NDVI region is located within woodland.The mean value of NDVI displays an increase and then decrease trend with air temperature increase.With the increase of wind velocity and decrease of air relative humidity,the NDVI value shows a decrease trend.The interactive q values between the two factors are higher than any q value of separated factors.Results also indicate that the strongest interactive effects of NDVI are different in distinct seasons.Consequently,anthropogenic activity is more important than environmental factors on NDVI in oasis-desert ecotone.We also demonstrate that air relative humidity rather than air temperature have played a greater role in NDVI spatial distribution.
文摘文章以广西南宁横州市52处古建筑为研究对象,旨在揭示西南县域古建筑空间布局特征及自然—人文因子的协同驱动机制,为同类区域古建筑的整体性保护与文化传承提供科学支撑。研究整合古建筑POI(Point of Interest)、地形地貌、水系道路及社会经济等多源数据,综合运用标准差椭圆、核密度分析、地理集中指数、不平衡指数及地理探测器等方法开展系统研究。结果表明:横州市古建筑总体呈西北—东南向狭长分布,中心位于校椅镇,形成“双核引领”集聚格局,整体呈现“东西密、南北疏”的分布态势;地理集中指数为39.411、不平衡指数为0.593,其中横州镇等3个镇的古建筑占比达63.46%,均衡度显著偏低。自然因素中,94.23%的古建筑分布于海拔[31,200)m平原,82.69%位于坡度小于5°的区域,36.54%分布于[750,1500)m河流缓冲区;人文因素中,人口密度为核心驱动因素,[0,2700)m道路缓冲区内集聚75.00%的古建筑。自然与人文因子交互呈非线性增强。研究表明,县域古建筑布局受自然基底与人文脉络协同约束,据此提出分级分区保护、平衡开发与保护、构建“生态—文化廊道”等策略,可为横州市及西南同类县域协调城镇化与文化遗产保护提供借鉴。
文摘以长三角区域3A级及以上高等级旅游景区为研究对象,采用地理信息系统(Geographic Information System,GIS)空间分析技术和地理探测器工具,对其空间分布特征和影响因素进行分析。结果表明:①长三角区域高等级旅游景区的整体空间分布状态为集聚型,呈现出“大分散、小集聚”的空间分布特征。②建筑设施类和水域景观类旅游景区分布状态最为分散;长三角区域41个城市可按吸引物属性组合情况划分为“自然人文双优型”“自然优势型”“人文优势型”“自然人文景观双低型”4类旅游地。③通过地理探测器分析得知,长三角区域高等级旅游景区空间分异特征是自然、经济、社会三大因素互相交织、共同作用的结果;地文景观类和水域景观类旅游景区分布主要受自然维度因素影响,生物景观类旅游景区分布主要受“社会自然”维度因素影响,建筑设施类和历史古迹类旅游景区分布主要受“社会经济”维度因素影响,娱乐购物类旅游景区分布则呈现出“经济社会”维度的交织主导作用。基于上述分析结果,从推进区域旅游一体化、差异化协调发展的视角提出了优化建议。
