面向对象的无人机影像地物分类

为了对农村用地进行有效分类,本文选取面向对象的分类方法,利用某农村的无人机航摄影像提取其土地类别信息.首先对无人机获取的原始影像进行预处理;然后对研究区反复进行分割实验,选取最优的分割尺度,在不同层次进行最优尺度地物分割;最后根据地物矢量、光谱、形状等特征差异,对最优分割尺度层上的地物进行最适宜的分类规则的建立,进而在...     

长江中游经济带土地利用转型风险评估

长江中游经济带土地利用转型过程可能导致的经济、社会及生态风险,将影响该区域甚至全国的可持续发展,研究其土地利用转型的风险评估方法至关重要。该文设计了基于“压力-状态-响应”框架的土地利用转型风险评价指标体系,利用基于熵权的逼近理想解排序法评价了土地利用转型的风险,应用障碍度分析法识别土地利用转型风险因子,分析了1990—2015年长江中游经济带土地利用转型的经济、社会与生态风险的分布状态与变化趋势,完成对各时期区域土地利用转型风险的风险因子识别,为提高长江中游经济带土地利用转型的影响研究效率,推进土地利用转型的风险评估工作提供技术支持。     

高速铁路大型临时设施土地复垦利用研究

在分析高速铁路大型临时设施土地复垦利用过程的基础上,以京沪高速铁路江阴制梁场为例,对其进行复垦工程分区、复垦规划制定与复垦方案优选。研究结果表明,根据工程布置、硬化特点及复垦难度可将江阴制梁场划分成7个亚区,结合土地利用规划要求,在复垦适宜性评价和投入-产出分析的基础上,确定待复垦区中的制梁区和存梁区最宜复垦为设施农业用地,而其他亚区最宜复垦为林地,评价结果与实际较为吻合。     

Variability of snail growing season at the Chinese Loess Plateau during the last 75 ka

Knowledge of seasonal climate change is one of the key issues facing Quaternary paleoclimatic studies and estimating seasonal climate change is difficult,especially changes such as seasonal length on glacial-interglacial timescales.The stable isotope composition from seasonal land snail shells provides the potential to reveal seasonal climatic features.Two modern land snail species,cold-aridiphilous Pupilla aeoli and thermo-humidiphilous Punctum orphana,were collected from different climatic zones in 18 localities across the Chinese Loess Plateau,spanning 11 degrees of longitude and covering a range of 1000 km2.The duration of the snail growing season(temperature ≥10℃) was shorter(202 ± 6 d) in the eastern Loess Plateau compared with in the western Loess Plateau(162 ±7 d).The δ13C of P.aeoli shells was ?9.1‰ to ?4.7‰ and ?5.0‰ to 0.3‰ for δ18O.For P.orphana,the δ13C ranged from ?9.1‰ to ?1.9‰ and ?8.9‰ to ?2.9‰ for δ18O.Both the δ13C and δ18O differences between the two snail species were reduced from the east to the western Loess Plateau(2.8‰ to 0.2 ± 1.1‰ for δ13C and 4.7‰ to 2.9 ± 1.3‰ for δ18O).These isotopic differences roughly reflect the difference in the growing season lengths between the east and west Loess Plateau indicating that the duration of the snail growing season shortens by 15 d or 19 d if the difference decreases by 1‰ in δ13C or δ18O,respectively.Thus,the difference in δ13C and δ18O between both snail species can be used to reveal the length of the snail growing season in the past.Based on our investigation,the length of the snail growing seasons from the Xifeng region during the last 75 ka was reconstructed.During the mid-Holocene(8-3 ka),the mean isotopic difference from both snail species reached maximum values of 2.6 ± 0.7‰ and 2.1 ± 1.4‰ for δ13C and δ18O,respectively.This was followed by MIS 3 that ranged from 2.5 ± 0.4‰ for δ13C and 1.6 ± 0.8‰ for δ18O.The Last Glacial Maximum changed by only 0.2‰ and 0.4‰ for δ13C and δ18O,respectively.Therefore,we estimate that the duration of the snail growing seasons to be ～200 ± 10 d during the mid-Holocene,190 ± 6 d in MIS 3 and 160 ± 3 d during the last glacial period.     

济源市土地流转现状分析

土地问题是解决“三农”问题的核心和基础,也是广大农民关心的焦点问题。本文结合济源市土地流转实际,对土地流转的方式、土地合理流转的作用及土地流转过程中的制约因素进行了分析,提出了推进土地合理流转的意见和建议。     

自然图景的天基监视雷达地杂波仿真

为了评估空-时自适应处理算法应用于天基雷达系统的效果,需要对地杂波图景进行高逼真度的仿真.首先根据特定地区的地表覆盖物数据、地形数据和雷达工作参数构建该地区的地表反射特性瞬态图景.然后根据距离重叠、地球自转效应和天基雷达的阵列模式,用反射特性图景计算杂波协方差矩阵最优值和估计值.最后根据Billingsley提出的谱模型,仿真杂波内部运动效应.仿真结果表明,所得的地表反射特性在统计意义上与实际地表反射特性差距小于5 dB,所得天基雷达杂波环境对空-时自适应算法效果影响可作定量分析.     

安徽省人口和土地城市化耦合协调过程与影响因素

人口城市化和土地城市化是衡量城市化水平的重要内容,探究两者耦合协调关系及耦合发展驱动因素对实现新型城镇化具有重要意义.以安徽省地级市辖区、县级市、县为研究单元,选取国内生产总值(gross domestic product,GDP)、人口密度、平均高程等相关指标计算人口和土地城市化速率的协调度,运用耦合协调模型和地理探...     

AERMOD模型在大气二氧化硫空间分布格局研究中的应用

整合闽清县的气象、地形、污染源等数据,综合运用分数偏差与参数估计最优化方法研究反照率、波文比及地表粗糙度3个地表参数设置对AERMOD模式预测结果的影响程度及趋势,并在地表参数率定的基础上建立县域尺度上的AERMOD模型.此外利用AERMOD模型模拟闽清县的SO_2污染现状并作出SO_2空间分布图,结合闽清县大气污染防治规划提出煤改天然气措施并进行情景模拟,以期为模型运用、大气环境评价及污染防控提供一定参考.