Rice growth requires a large amount of water,and planting rice will increase the contradiction between supply and demand of water resources.Paddy field fllowing is important for the sustainable development of an agric...Rice growth requires a large amount of water,and planting rice will increase the contradiction between supply and demand of water resources.Paddy field fllowing is important for the sustainable development of an agricultural region,but it remains a great challenge to accurately and quickly monitor the extent and area of fallowed paddy fields.Paddy fields have unique physical features associated with paddy rice during the flooding and transplanting phases.By comparing the differences in phenology before and after paddy field fllowing,we proposed a phenology-based fallowed paddy field mapping algorithm.We used the Google Earth Engine(GEE)cloud computing platform and Landsat 8 images to extract the fllowed paddy field area on Sanjiang Plain of China in 2018.The results indicated that the Landsat8,GEE,and phenology-based fllowed paddy field mapping algorithm can effectively support the mapping of fallowed paddy fields on Sanjiang Plain of China.Based on remote sensing monitoring,the total fallowed paddy field area of Sanjiang Plain is 91543 ha.The resultant fallowed paddy field map is of high accuracy,with a producer(user)accuracy of 83%(81%),based on validation using ground-truth samples.The Landsat-based map also exhibits high consistency with the agricultural statistical data.We estimated that paddy field fallowing reduced irigation water by 384-521 million cubic meters on Sanjiang Plain in 2018.The research results can support subsidization grants for fallowed paddy fields,the evaluation of fallowed paddy field effects and improvement in subsequent fallowed paddy field policy in the future.展开更多
为了深入研究变电站内工频电场在有无考虑站内电气设备接地体影响时的分布情况,推导了计算开关场内工频电场的三维模拟电荷法,以500 k V变电站为例,对变电站500 k V开关场及各类电气设备的接地体进行模型建立与工频电场分布的计算分析...为了深入研究变电站内工频电场在有无考虑站内电气设备接地体影响时的分布情况,推导了计算开关场内工频电场的三维模拟电荷法,以500 k V变电站为例,对变电站500 k V开关场及各类电气设备的接地体进行模型建立与工频电场分布的计算分析。首先,通过仿真结果与实测结果的对比,验证所建模型的正确性;然后分析了变电站站内有无电气设备接地体影响时的工频电场分布情况。文章方法为考虑接地体影响时站内工频电场的计算与分析提供了一种有效、快捷的途径。展开更多
In this study,the soil-air generator of the thermoelectric safety system working with soil heat was investigated.For this,a special electronic safety device was made and the output parameters of the device were invest...In this study,the soil-air generator of the thermoelectric safety system working with soil heat was investigated.For this,a special electronic safety device was made and the output parameters of the device were investigated.In order to investigate the operation of the thermoelectric“earth-air”generator safety system in real nature conditions,temperatures at the soil depth and soil surface equal to the length of the generator in four different regions of Ankara in four seasons were measured and modeled.Afterwards,physical parameters such as power P(W),voltage U(V)and current I(A)produced by the generator according toΔT were examined by using all this scientific information with a special test setup.According to the results obtained,it has been determined that the Intelligent thermoelectric earth-air generator safety system(ATES)has the feature of notifying the security units in case of area violation by generating its own electricity with the help of the heat in the soil without the need for any electrical cable.In addition,the environmentally friendly ATES system is an innovative product and it has been seen that it will be used in various fields,especially in military applications.展开更多
基金supported by the National Key Research and Development Program of China (2016YFD0300604-4)the Academic Backbone Project of Northeast Agricultural University,Chinathe Jilin Scientific and Technological Development Program,China (20170301001NY)。
文摘Rice growth requires a large amount of water,and planting rice will increase the contradiction between supply and demand of water resources.Paddy field fllowing is important for the sustainable development of an agricultural region,but it remains a great challenge to accurately and quickly monitor the extent and area of fallowed paddy fields.Paddy fields have unique physical features associated with paddy rice during the flooding and transplanting phases.By comparing the differences in phenology before and after paddy field fllowing,we proposed a phenology-based fallowed paddy field mapping algorithm.We used the Google Earth Engine(GEE)cloud computing platform and Landsat 8 images to extract the fllowed paddy field area on Sanjiang Plain of China in 2018.The results indicated that the Landsat8,GEE,and phenology-based fllowed paddy field mapping algorithm can effectively support the mapping of fallowed paddy fields on Sanjiang Plain of China.Based on remote sensing monitoring,the total fallowed paddy field area of Sanjiang Plain is 91543 ha.The resultant fallowed paddy field map is of high accuracy,with a producer(user)accuracy of 83%(81%),based on validation using ground-truth samples.The Landsat-based map also exhibits high consistency with the agricultural statistical data.We estimated that paddy field fallowing reduced irigation water by 384-521 million cubic meters on Sanjiang Plain in 2018.The research results can support subsidization grants for fallowed paddy fields,the evaluation of fallowed paddy field effects and improvement in subsequent fallowed paddy field policy in the future.
文摘为了深入研究变电站内工频电场在有无考虑站内电气设备接地体影响时的分布情况,推导了计算开关场内工频电场的三维模拟电荷法,以500 k V变电站为例,对变电站500 k V开关场及各类电气设备的接地体进行模型建立与工频电场分布的计算分析。首先,通过仿真结果与实测结果的对比,验证所建模型的正确性;然后分析了变电站站内有无电气设备接地体影响时的工频电场分布情况。文章方法为考虑接地体影响时站内工频电场的计算与分析提供了一种有效、快捷的途径。
文摘In this study,the soil-air generator of the thermoelectric safety system working with soil heat was investigated.For this,a special electronic safety device was made and the output parameters of the device were investigated.In order to investigate the operation of the thermoelectric“earth-air”generator safety system in real nature conditions,temperatures at the soil depth and soil surface equal to the length of the generator in four different regions of Ankara in four seasons were measured and modeled.Afterwards,physical parameters such as power P(W),voltage U(V)and current I(A)produced by the generator according toΔT were examined by using all this scientific information with a special test setup.According to the results obtained,it has been determined that the Intelligent thermoelectric earth-air generator safety system(ATES)has the feature of notifying the security units in case of area violation by generating its own electricity with the help of the heat in the soil without the need for any electrical cable.In addition,the environmentally friendly ATES system is an innovative product and it has been seen that it will be used in various fields,especially in military applications.
基金supported by National Natural Science Foundation of China(51277189)Program of Introducing Talents of Discipline to Universities(B08036)Fundamental Research Funds for the Central Universities(CDJXS12151108)
