ln order to explore the effect of broadcast application of urea （BR-U） and surface concentrated-fertilization on grain yield and nitrogen agronomy efficiency of two-line super hybrid rice, this experiment was conduc...ln order to explore the effect of broadcast application of urea （BR-U） and surface concentrated-fertilization on grain yield and nitrogen agronomy efficiency of two-line super hybrid rice, this experiment was conducted with super hybrid rice Y-Liangyou 1 and Liangyou 0293 to determine til ering dynamics, SPAD, LAl and dry matter accumulation. lts total N application was 180 kg/hm2 and different application rate and topdressing methods were set respectively. The results showed that grain yield and nitrogen agronomy efficiency were significantly improved with the T3 and T4 nitrogenous fertilizer application model. The improving of grain yield and nitrogen agronomy efficiency was benefited from rational postponing N application. However, neither single application of base fertilizer （T2） nor single application of topdressing fertilizer （T5 and T6） can coordinate the relationship between source and sink. Both grain yield and nitrogen agronomy efficiency were insignificantly under the broadcast application of urea and surface concentrated fertilization.展开更多
In this paper, the artificial neural network(ANN) model was used to evaluate the degree of intensive urban land use in Nanjing City, China. The construction and application of the ANN model took into account the compr...In this paper, the artificial neural network(ANN) model was used to evaluate the degree of intensive urban land use in Nanjing City, China. The construction and application of the ANN model took into account the comprehensive, spatial and complex nature of urban land use. Through a preliminary calculation of the degree of intensive land use of the sample area, representative sample area selection and using the back propagation neural network model to train, the intensive land use level of each evaluation unit is finally determined in the study area. Results show that the method can effectively correct the errors caused by the limitations of the model itself and the determination of the ideal value and weights when the multifactor comprehensive evaluation is used alone. The ANN model can make the evaluation results more objective and practical. The evaluation results show a tendency of decreasing land use intensity from the core urban area to the periphery and the industrial functional area has relatively low land use intensity compared with other functional areas. Based on the evaluation results, some suggestions are put forward, such as transforming the mode of urban spatial expansion, strengthening the integration and potential exploitation of the land in the urban built-up area, and strengthening the control of the construction intensity of protected areas.展开更多
A district heating and hot water supply system is presented which synthetically utilizes geothermal energy,solar thermal energy and natural gas thermal energy.The multi-energy utilization system has been set at the ne...A district heating and hot water supply system is presented which synthetically utilizes geothermal energy,solar thermal energy and natural gas thermal energy.The multi-energy utilization system has been set at the new campus of Tianjin Polytechnic University(TPU),A couple of deep geothermal wells which are 2 300 m in depth were dug,Deep geothermal energy cascade utilization is achieved by two stages of plate heat exchangers(PHE) and two stages of water source heat pumps(WSHP).Shallow geothermal energy is used in assistant heating by two ground coupled heat pumps(GCHPs) with 580 vertical ground wells which are 120 m in depth.Solar thermal energy collected by vacuum tube arrays(VTAs) and geothermal energy are complementarily utilized to make domestic hot water.Superfluous solar energy can be stored in shallow soil for the GCHP utilization.The system can use fossil fuel thermal energy by two natural gas boilers(NGB) to assist in heating and making hot water.The heating energy efficiency was measured in the winter of 2010-2011.The coefficients of performance(COP) under different heating conditions are discussed.The performance of hot water production is tested in a local typical winter day and the solar thermal energy utilization factor is presented.The rusults show that the average system COP is 5.75 or 4.96 under different working conditions,and the typical solar energy utilization factor is 0.324.展开更多
Because of global climate change,the natural environment is rapidly changing in the Arctic.The large amount of sea ice melting in the Arctic can lead to a great increase in the use of the world’s natural resources.Th...Because of global climate change,the natural environment is rapidly changing in the Arctic.The large amount of sea ice melting in the Arctic can lead to a great increase in the use of the world’s natural resources.This thesis focuses on the exploration and utilization of public waters in the Arctic region based on the economic theory of the Tragedy of the Commons,analyzes the current situation of Arctic governance,and predicts potential problems in the Arctic region,mainly including overfishing and environmental problems caused by coal and natural gas exploitation.Additionally,it makes an in-depth analysis on the current Arctic governance model based on the Arctic Council,and finally proposes some countermeasures and suggestions for Arctic governance.展开更多
A technically transparent and freely available reference sample set for validation of global land cover mapping was recently established to assess the accuracies of land cover maps with multiple resolutions.This sampl...A technically transparent and freely available reference sample set for validation of global land cover mapping was recently established to assess the accuracies of land cover maps with multiple resolutions.This sample set can be used to estimate areas because of its equal-area hexagon-based sampling design.The capabilities of these sample set-based area estimates for cropland were investigated in this paper.A 30-m cropland map for China was consolidated using three thematic maps(cropland,forest and wetland maps)to reduce confusion between cropland and forest/wetland.We compared three area estimation methods using the sample set and the 30 m cropland map.The methods investigated were:(1)pixel counting from a complete coverage map,(2)direct estimation from reference samples,and(3)model-assisted estimation combining the map with samples.Our results indicated that all three methods produced generally consistent estimates which agreed with cropland area measured from an independent national land use dataset.Areas estimated from the reference sample set were less biased by comparing with a National Land Use Dataset of China(NLUD-C).This study indicates that the reference sample set can be used as an alternative source to estimate areas over large regions.展开更多
基金Supported by Nation Key technology R&D Program(2012BAD07B02)National Innovation Experiment Program for University Students(104892013032)Hubei Provincial Key Discipline of Crop Science in Yangtze University~~
文摘ln order to explore the effect of broadcast application of urea （BR-U） and surface concentrated-fertilization on grain yield and nitrogen agronomy efficiency of two-line super hybrid rice, this experiment was conducted with super hybrid rice Y-Liangyou 1 and Liangyou 0293 to determine til ering dynamics, SPAD, LAl and dry matter accumulation. lts total N application was 180 kg/hm2 and different application rate and topdressing methods were set respectively. The results showed that grain yield and nitrogen agronomy efficiency were significantly improved with the T3 and T4 nitrogenous fertilizer application model. The improving of grain yield and nitrogen agronomy efficiency was benefited from rational postponing N application. However, neither single application of base fertilizer （T2） nor single application of topdressing fertilizer （T5 and T6） can coordinate the relationship between source and sink. Both grain yield and nitrogen agronomy efficiency were insignificantly under the broadcast application of urea and surface concentrated fertilization.
基金Under the auspices of Special Financial Grant and General Financial Grant from the China Postdoctoral Science Foundation(No.2015T80127,2014M561040)National Natural Science Foundation of China(No.41371172,41401171,41471143)A Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions(No.164320H101)
文摘In this paper, the artificial neural network(ANN) model was used to evaluate the degree of intensive urban land use in Nanjing City, China. The construction and application of the ANN model took into account the comprehensive, spatial and complex nature of urban land use. Through a preliminary calculation of the degree of intensive land use of the sample area, representative sample area selection and using the back propagation neural network model to train, the intensive land use level of each evaluation unit is finally determined in the study area. Results show that the method can effectively correct the errors caused by the limitations of the model itself and the determination of the ideal value and weights when the multifactor comprehensive evaluation is used alone. The ANN model can make the evaluation results more objective and practical. The evaluation results show a tendency of decreasing land use intensity from the core urban area to the periphery and the industrial functional area has relatively low land use intensity compared with other functional areas. Based on the evaluation results, some suggestions are put forward, such as transforming the mode of urban spatial expansion, strengthening the integration and potential exploitation of the land in the urban built-up area, and strengthening the control of the construction intensity of protected areas.
基金Project(2010DFA72740-06) supported by International Science & Technology Cooperation Program of China
文摘A district heating and hot water supply system is presented which synthetically utilizes geothermal energy,solar thermal energy and natural gas thermal energy.The multi-energy utilization system has been set at the new campus of Tianjin Polytechnic University(TPU),A couple of deep geothermal wells which are 2 300 m in depth were dug,Deep geothermal energy cascade utilization is achieved by two stages of plate heat exchangers(PHE) and two stages of water source heat pumps(WSHP).Shallow geothermal energy is used in assistant heating by two ground coupled heat pumps(GCHPs) with 580 vertical ground wells which are 120 m in depth.Solar thermal energy collected by vacuum tube arrays(VTAs) and geothermal energy are complementarily utilized to make domestic hot water.Superfluous solar energy can be stored in shallow soil for the GCHP utilization.The system can use fossil fuel thermal energy by two natural gas boilers(NGB) to assist in heating and making hot water.The heating energy efficiency was measured in the winter of 2010-2011.The coefficients of performance(COP) under different heating conditions are discussed.The performance of hot water production is tested in a local typical winter day and the solar thermal energy utilization factor is presented.The rusults show that the average system COP is 5.75 or 4.96 under different working conditions,and the typical solar energy utilization factor is 0.324.
基金supported by the“Fundamental Research Funds for the Central Universities”
文摘Because of global climate change,the natural environment is rapidly changing in the Arctic.The large amount of sea ice melting in the Arctic can lead to a great increase in the use of the world’s natural resources.This thesis focuses on the exploration and utilization of public waters in the Arctic region based on the economic theory of the Tragedy of the Commons,analyzes the current situation of Arctic governance,and predicts potential problems in the Arctic region,mainly including overfishing and environmental problems caused by coal and natural gas exploitation.Additionally,it makes an in-depth analysis on the current Arctic governance model based on the Arctic Council,and finally proposes some countermeasures and suggestions for Arctic governance.
基金supported by the National Natural Science Foundation of China(Grant No.41301445)a research grant from Tsinghua University(Grant No.20151080351)
文摘A technically transparent and freely available reference sample set for validation of global land cover mapping was recently established to assess the accuracies of land cover maps with multiple resolutions.This sample set can be used to estimate areas because of its equal-area hexagon-based sampling design.The capabilities of these sample set-based area estimates for cropland were investigated in this paper.A 30-m cropland map for China was consolidated using three thematic maps(cropland,forest and wetland maps)to reduce confusion between cropland and forest/wetland.We compared three area estimation methods using the sample set and the 30 m cropland map.The methods investigated were:(1)pixel counting from a complete coverage map,(2)direct estimation from reference samples,and(3)model-assisted estimation combining the map with samples.Our results indicated that all three methods produced generally consistent estimates which agreed with cropland area measured from an independent national land use dataset.Areas estimated from the reference sample set were less biased by comparing with a National Land Use Dataset of China(NLUD-C).This study indicates that the reference sample set can be used as an alternative source to estimate areas over large regions.
