This paper uses a Modified Soil-Plant-Atmosphere Scheme (MSPAS) to study the interaction between land surface and atmospheric boundary layer processes. The scheme is composed of two main parts: atmospheric boundary la...This paper uses a Modified Soil-Plant-Atmosphere Scheme (MSPAS) to study the interaction between land surface and atmospheric boundary layer processes. The scheme is composed of two main parts: atmospheric boundary layer processes and land surface processes. Compared with SiB and BATS, which are famous for their detailed parameterizations of physical variables, this simplified model is more convenient and saves much more computation time. Though simple, the feasibility of the model is well proved in this paper. The numerical simulation results from MSPAS show good agreement with reality. The scheme is used to obtain reasonable simulations for diurnal variations of heat balance, potential temperature of boundary layer, and wind field, and spatial distributions of temperature, specific humidity, vertical velocity, turbulence kinetic energy, and turbulence exchange coefficient over desert and oasis. In addition, MSPAS is used to simulate the interaction between desert and oasis at night, and again it obtains reasonable results. This indicates that MSPAS can be used to study the interaction between land surface processes and the atmospheric boundary layer over various underlying surfaces and can be extended for regional climate and numerical weather prediction study.展开更多
随着第五代移动通信(5th generation mobile communication,5G)基站建设数量的剧增,5G基站的备用电池将是一个具有巨大潜能的储能资源。我国电力市场化改革正不断推进,研究5G基站的备用储能参与电力市场交易是实现电网和通信运营商互利...随着第五代移动通信(5th generation mobile communication,5G)基站建设数量的剧增,5G基站的备用电池将是一个具有巨大潜能的储能资源。我国电力市场化改革正不断推进,研究5G基站的备用储能参与电力市场交易是实现电网和通信运营商互利共赢的有效途径。考虑到5G基站备用储能参与电力市场的特殊性,建立了计及退化成本和可调度容量的基站储能电池模型,并将零散的基站聚合成5G基站虚拟电厂(virtual power plant,VPP)。然后,将5G基站VPP作为独立的竞价主体,构建双层的电能量-调频辅助服务市场交易决策模型,并利用KKT(Karush-Kuhn-Tucker)条件和对偶理论将双层模型转化为可解的混合整数规划问题。最后,通过算例评估了5G基站备用储能的可调度容量以及所提交易决策模型的有效性。展开更多
Area Sampling Frames （ASFs） are the basis of many statistical programs around the world. To improve the accuracy, objectivity and efficiency of crop survey estimates, an automated stratification method based on geos...Area Sampling Frames （ASFs） are the basis of many statistical programs around the world. To improve the accuracy, objectivity and efficiency of crop survey estimates, an automated stratification method based on geospatial crop planting frequency and cultivation data is proposed. This paper investigates using 2008-2013 geospatial corn, soybean and wheat planting frequency data layers to create three corresponding single crop specific and one multi-crop specific South Dakota （SD） U.S. ASF stratifications. Corn, soybeans and wheat are three major crops in South Dakota. The crop specific ASF stratifications are developed based on crop frequency statistics derived at the primary sampling unit （PSU） level based on the Crop Frequency Data Layers. The SD corn, soybean and wheat mean planting frequency strata of the single crop stratifications are substratified by percent cultivation based on the 2013 Cultivation Layer. The three newly derived ASF stratifications provide more crop specific information when compared to the current National Agricultural Statistics Service （NASS） ASF based on percent cultivation alone. Further, a multi-crop stratification is developed based on the individual corn, soybean and wheat planting frequency data layers. It is observed that all four crop frequency based ASF stratifications consistently predict corn, soybean and wheat planting patterns well as verified by the 2014 Farm Service Agency （FSA） Common Land Unit （CLU） and 578 administrative data. This demonstrates that the new stratifications based on crop planting frequency and cultivation are crop type independent and applicable to all major crops. Further, these results indicate that the new crop specific ASF stratifications have great potential to improve ASF accuracy, efficiency and crop estimates.展开更多
Three typical hybrid rice cultivars, together with three artificially modified plant types by the application of N fertilizer during the elongation of the two uppermost leaves were used to analyze how the plant type a...Three typical hybrid rice cultivars, together with three artificially modified plant types by the application of N fertilizer during the elongation of the two uppermost leaves were used to analyze how the plant type affected the layered leaf area and radiation transmission. Plant type factors, layered leaf area and radiation distribution were measured at the full heading, 10 d and 25 d after full heading stages, respectively. A model for calculating the layered leaf area from plant type factors was established and validated to determine the effects of plant type factors on the layered leaf area for the three hybrids. Furthermore, the relationship between layered leaf area and radiation transmission was established by using the radiation transmission model. The effects of the plant type factors on the radiation transmission for the three hybrids were evaluated by using this model. Finally, a method was established to describe the canopy structure, such as the layered leaf area index and the radiation distribution in the rice canopy.展开更多
Soil-plant systems play an important role in sand fixing and surface protection in the arid desert of China. This study examines the ecohydrological responses after a soil-plant system change for mobile dune stabiliza...Soil-plant systems play an important role in sand fixing and surface protection in the arid desert of China. This study examines the ecohydrological responses after a soil-plant system change for mobile dune stabilization by using a series of soil hydrological experiments and ecological investigation. The study results showed that decades of succession of soil-plant system has endangered the stability of the protection system. With the accumulated water and nutrient, a bio-logical system develops in a thinner and thinner surface soil. Redistribution of precipitation has changed completely in the ecosystem. In 3–15 mm of soil, a high capacity of crust water retention ultimately limits most rainfall from infiltrating below 10–20 cm deep. When that takes place, lower plants begin to compete for water with grasses and shrubs. A drought horizon forms in 20–500 cm depth with shrub transpiration. Artificial shrubs with deep roots obtain hardly rainfall supply and are gradually eliminated from the protection system. All changes in water environment affect the structure and func-tion and stabilization of whole protection systems. It is necessary to establish a relatively stable water environment by managing the soil-plant system for constructing a sustainable protective system in arid desert.展开更多
基金supported by the National Natural Science Foundation of China (Grant No.40275004)the State Key Laboratory of Atmosphere Physics and Chemistry,and the City University of Hong Kong(Grant No.8780046)the City University of Hong Kong Strategic Research(Grant No.7001038)
文摘This paper uses a Modified Soil-Plant-Atmosphere Scheme (MSPAS) to study the interaction between land surface and atmospheric boundary layer processes. The scheme is composed of two main parts: atmospheric boundary layer processes and land surface processes. Compared with SiB and BATS, which are famous for their detailed parameterizations of physical variables, this simplified model is more convenient and saves much more computation time. Though simple, the feasibility of the model is well proved in this paper. The numerical simulation results from MSPAS show good agreement with reality. The scheme is used to obtain reasonable simulations for diurnal variations of heat balance, potential temperature of boundary layer, and wind field, and spatial distributions of temperature, specific humidity, vertical velocity, turbulence kinetic energy, and turbulence exchange coefficient over desert and oasis. In addition, MSPAS is used to simulate the interaction between desert and oasis at night, and again it obtains reasonable results. This indicates that MSPAS can be used to study the interaction between land surface processes and the atmospheric boundary layer over various underlying surfaces and can be extended for regional climate and numerical weather prediction study.
文摘随着第五代移动通信(5th generation mobile communication,5G)基站建设数量的剧增,5G基站的备用电池将是一个具有巨大潜能的储能资源。我国电力市场化改革正不断推进,研究5G基站的备用储能参与电力市场交易是实现电网和通信运营商互利共赢的有效途径。考虑到5G基站备用储能参与电力市场的特殊性,建立了计及退化成本和可调度容量的基站储能电池模型,并将零散的基站聚合成5G基站虚拟电厂(virtual power plant,VPP)。然后,将5G基站VPP作为独立的竞价主体,构建双层的电能量-调频辅助服务市场交易决策模型,并利用KKT(Karush-Kuhn-Tucker)条件和对偶理论将双层模型转化为可解的混合整数规划问题。最后,通过算例评估了5G基站备用储能的可调度容量以及所提交易决策模型的有效性。
文摘Area Sampling Frames （ASFs） are the basis of many statistical programs around the world. To improve the accuracy, objectivity and efficiency of crop survey estimates, an automated stratification method based on geospatial crop planting frequency and cultivation data is proposed. This paper investigates using 2008-2013 geospatial corn, soybean and wheat planting frequency data layers to create three corresponding single crop specific and one multi-crop specific South Dakota （SD） U.S. ASF stratifications. Corn, soybeans and wheat are three major crops in South Dakota. The crop specific ASF stratifications are developed based on crop frequency statistics derived at the primary sampling unit （PSU） level based on the Crop Frequency Data Layers. The SD corn, soybean and wheat mean planting frequency strata of the single crop stratifications are substratified by percent cultivation based on the 2013 Cultivation Layer. The three newly derived ASF stratifications provide more crop specific information when compared to the current National Agricultural Statistics Service （NASS） ASF based on percent cultivation alone. Further, a multi-crop stratification is developed based on the individual corn, soybean and wheat planting frequency data layers. It is observed that all four crop frequency based ASF stratifications consistently predict corn, soybean and wheat planting patterns well as verified by the 2014 Farm Service Agency （FSA） Common Land Unit （CLU） and 578 administrative data. This demonstrates that the new stratifications based on crop planting frequency and cultivation are crop type independent and applicable to all major crops. Further, these results indicate that the new crop specific ASF stratifications have great potential to improve ASF accuracy, efficiency and crop estimates.
基金financially supported by the National Natural Science Foundation of China(Grant No.NSFC30871479)
文摘Three typical hybrid rice cultivars, together with three artificially modified plant types by the application of N fertilizer during the elongation of the two uppermost leaves were used to analyze how the plant type affected the layered leaf area and radiation transmission. Plant type factors, layered leaf area and radiation distribution were measured at the full heading, 10 d and 25 d after full heading stages, respectively. A model for calculating the layered leaf area from plant type factors was established and validated to determine the effects of plant type factors on the layered leaf area for the three hybrids. Furthermore, the relationship between layered leaf area and radiation transmission was established by using the radiation transmission model. The effects of the plant type factors on the radiation transmission for the three hybrids were evaluated by using this model. Finally, a method was established to describe the canopy structure, such as the layered leaf area index and the radiation distribution in the rice canopy.
基金supported by the National Key Tech-nologies R&D Program in the 10th Five-year Plan (2004BA 901A 15)the Knowledge Innovation Project of The Chinese Academy of Sciences (No. KZCX1-09)by the Key Program of National Natural Science Foundation of China (Grant No. 90702001)
文摘Soil-plant systems play an important role in sand fixing and surface protection in the arid desert of China. This study examines the ecohydrological responses after a soil-plant system change for mobile dune stabilization by using a series of soil hydrological experiments and ecological investigation. The study results showed that decades of succession of soil-plant system has endangered the stability of the protection system. With the accumulated water and nutrient, a bio-logical system develops in a thinner and thinner surface soil. Redistribution of precipitation has changed completely in the ecosystem. In 3–15 mm of soil, a high capacity of crust water retention ultimately limits most rainfall from infiltrating below 10–20 cm deep. When that takes place, lower plants begin to compete for water with grasses and shrubs. A drought horizon forms in 20–500 cm depth with shrub transpiration. Artificial shrubs with deep roots obtain hardly rainfall supply and are gradually eliminated from the protection system. All changes in water environment affect the structure and func-tion and stabilization of whole protection systems. It is necessary to establish a relatively stable water environment by managing the soil-plant system for constructing a sustainable protective system in arid desert.
