Evapotranspiration, soil moisture balance and the dynamics in a gully catchment of the Loess Plateau in China were determined with 6 land use treatments including natural grassland, shrubs （Caragana rnicrophylla）, t...Evapotranspiration, soil moisture balance and the dynamics in a gully catchment of the Loess Plateau in China were determined with 6 land use treatments including natural grassland, shrubs （Caragana rnicrophylla）, two woodlands （Prunus armeniaca var. ansu and Pinus tabulaeformis）, cultivated fallow, and farmland （Triticum aestiuum L.） in order to obtain a better understanding of soil moisture balance principles and to improve vegetation restoration efficiency for ecological rebuilding on the plateau. Average runoff from cultivated fallow was very high, reaching 10.3% of the seasonal rainfall. Evapotranspiration under T. aestivurn was not significantly different from natural grasslands. Compared with natural grass, evapotranspiration was significantly greater （P 〈 0.05） in 2002 and there was an increase in soil moisture depleted in the 1-3 m soil under P. armeniaca, P. tabulaeformis and C. microphylla. During the two years of the study the average soil moisture （0-100 cm soil profile） of T. aestivurn was generally the highest, with P. armeniaca, P. tabulaeformis and C. rnicrophylla usually the lowest. Thus, according to the soil moisture balance principle for this area the planned reforestation project was not ecologically reasonable. Reducing human disturbance and restoration with grass could be more effective.展开更多
The relationship between vegetation greening and climate change remains unclear due to its complexity, especially in drylands. Against the background of global warming, arid and semi-arid areas, including mid-latitude...The relationship between vegetation greening and climate change remains unclear due to its complexity, especially in drylands. Against the background of global warming, arid and semi-arid areas, including mid-latitude deserts, are most sensitive to climate change. In recent decades, the mechanisms underlying the relationship between vegetation greening and climate change have been widely discussed in the literature. However, the influence of vegetation greening in high latitudes on regional climate has not been fully studied. In this paper, a two-dimensional energy balance model was used to study the influence of greening in high latitudes on mid-latitude deserts. The authors found that when greening occurs in high latitudes, the mid-latitude desert recedes at the south boundary, while the polar ice belt and low-latitude vegetation belt both expand. Simultaneously, greening in high latitudes can induce a negative temperature anomaly in northern latitudes and a positive temperature anomaly in southern latitudes. The mid-latitude desert expands at its north and south boundaries until the CO2 concentration reaches 600 ppm(saturated state). The greening in high latitudes could result in a lower global-mean temperature in the ‘saturated’ state, due to the stronger cooling in high latitudes.展开更多
Water quality models are important tools to support the optimization of aquatic ecosystem rehabilitation programs and assess their efficiency. Basing on the flow conditions of the Daqinghe River Mouth of the Dianchi L...Water quality models are important tools to support the optimization of aquatic ecosystem rehabilitation programs and assess their efficiency. Basing on the flow conditions of the Daqinghe River Mouth of the Dianchi Lake, China, a two-dimensional water quality model was developed in the research. The hydrodynamics module was numerically solved by the alternating direction iteration （ADI） method. The parameters of the water quality module were obtained through the in situ experiments and the laboratory analyses that were conducted from 2006 to 2007. The model was calibrated and verified by the observation data in 2007. Among the four modelled key variables, i.e., water level, COD （in CODcr）, NH4＋-N and PO43-P the minimum value of the coefficient of determination （COD） was 0.69, indicating the model performed reasonably well. The developed model was then applied to simulate the water quality changes at a downstream cross-section assuming that the designed restoration programs were implemented. According to the simulated results, the restoration programs could cut down the loads of COD and PO43-P about 15%. Such a load reduction, unfortunately, would have very little effect on the NH4^＋-N removal. Moreover, the water quality at the outlet cross-section would be still in class V （3838-02）, indicating more measures should be taken to further reduce the loads. The study demonstrated the capability of water quality models to support aquatic ecosystem restorations.展开更多
This paper presents a software application of a new method for color restoration of faded images and maps. This method is composed of two steps. The first step is to enable the recovery of the brightest point and the ...This paper presents a software application of a new method for color restoration of faded images and maps. This method is composed of two steps. The first step is to enable the recovery of the brightest point and the darkest. The second step lets build chart of integrated average luminance in （R, G, B） space. This is different from the usual chart built for each color channel separately. The algorithm focuses on adjusting the points with the average luminance and especially the point almost gray. The algorithm is programmed as a part of the data-tool software package. The data-tool software package comprises of two parts： Part I for restoration of aged photos; and Part II specifically for maps. The data-tool software is programmed in the C language, integrated with the support of a few tools in Matlap A set of the old faded maps at the Geological Museum of Vietnam is selected to test the performance of the proposed color restoration method. The time needed to process images is shorted by utilizing parallel computing tools.展开更多
为延长电池储能系统的整体寿命,需保持储能系统中各单元的荷电状态(state of charge,SOC)均衡。为此,提出一种基于二阶一致性算法的改进下垂控制策略,通过指数函数嵌套变化系数,实现不同容量储能单元快速SOC均衡。在SOC均衡的基础上设...为延长电池储能系统的整体寿命,需保持储能系统中各单元的荷电状态(state of charge,SOC)均衡。为此,提出一种基于二阶一致性算法的改进下垂控制策略,通过指数函数嵌套变化系数,实现不同容量储能单元快速SOC均衡。在SOC均衡的基础上设计二次控制策略,在一定通信时延下实现频率、电压恢复和有功、无功功率合理分配。最后,以4台储能单元组成的电池储能系统为算例进行仿真,验证了所提控制策略的有效性,SOC能够快速收敛达到均衡状态,频率、电压能够恢复到额定值,有功、无功功率能够按照相应下垂系数比例进行分配。展开更多
基金Project supported by the National Science and Technology Advanced Project of the Tenth Five-year Plan(No. 2001BA606A-03) and the National Natural Science Foundation of China (No. 40321101).
文摘Evapotranspiration, soil moisture balance and the dynamics in a gully catchment of the Loess Plateau in China were determined with 6 land use treatments including natural grassland, shrubs （Caragana rnicrophylla）, two woodlands （Prunus armeniaca var. ansu and Pinus tabulaeformis）, cultivated fallow, and farmland （Triticum aestiuum L.） in order to obtain a better understanding of soil moisture balance principles and to improve vegetation restoration efficiency for ecological rebuilding on the plateau. Average runoff from cultivated fallow was very high, reaching 10.3% of the seasonal rainfall. Evapotranspiration under T. aestivurn was not significantly different from natural grasslands. Compared with natural grass, evapotranspiration was significantly greater （P 〈 0.05） in 2002 and there was an increase in soil moisture depleted in the 1-3 m soil under P. armeniaca, P. tabulaeformis and C. microphylla. During the two years of the study the average soil moisture （0-100 cm soil profile） of T. aestivurn was generally the highest, with P. armeniaca, P. tabulaeformis and C. rnicrophylla usually the lowest. Thus, according to the soil moisture balance principle for this area the planned reforestation project was not ecologically reasonable. Reducing human disturbance and restoration with grass could be more effective.
基金This work was jointly supported by the Strategic Priority Research Program of the Chinese Academy of Sciences[grant number XDA2006010301]the National Natural Science Foundation of China[grant numbers 41521004,41705047,and 41875083]+1 种基金the Foundation of the Key Laboratory for Semi-Arid Climate Change of the Ministry of Education in Lanzhou University from the Fundamental Research Funds for the Central Universities[grant numbers lzujbky-2017-bt04 and lzujbky-2017-70]the China 111 Project[grant number B13045].
文摘The relationship between vegetation greening and climate change remains unclear due to its complexity, especially in drylands. Against the background of global warming, arid and semi-arid areas, including mid-latitude deserts, are most sensitive to climate change. In recent decades, the mechanisms underlying the relationship between vegetation greening and climate change have been widely discussed in the literature. However, the influence of vegetation greening in high latitudes on regional climate has not been fully studied. In this paper, a two-dimensional energy balance model was used to study the influence of greening in high latitudes on mid-latitude deserts. The authors found that when greening occurs in high latitudes, the mid-latitude desert recedes at the south boundary, while the polar ice belt and low-latitude vegetation belt both expand. Simultaneously, greening in high latitudes can induce a negative temperature anomaly in northern latitudes and a positive temperature anomaly in southern latitudes. The mid-latitude desert expands at its north and south boundaries until the CO2 concentration reaches 600 ppm(saturated state). The greening in high latitudes could result in a lower global-mean temperature in the ‘saturated’ state, due to the stronger cooling in high latitudes.
基金supported by the National Hi-Tech Research and Development Program (863) of China (No.2007AA06A405, 2005AA6010100401)
文摘Water quality models are important tools to support the optimization of aquatic ecosystem rehabilitation programs and assess their efficiency. Basing on the flow conditions of the Daqinghe River Mouth of the Dianchi Lake, China, a two-dimensional water quality model was developed in the research. The hydrodynamics module was numerically solved by the alternating direction iteration （ADI） method. The parameters of the water quality module were obtained through the in situ experiments and the laboratory analyses that were conducted from 2006 to 2007. The model was calibrated and verified by the observation data in 2007. Among the four modelled key variables, i.e., water level, COD （in CODcr）, NH4＋-N and PO43-P the minimum value of the coefficient of determination （COD） was 0.69, indicating the model performed reasonably well. The developed model was then applied to simulate the water quality changes at a downstream cross-section assuming that the designed restoration programs were implemented. According to the simulated results, the restoration programs could cut down the loads of COD and PO43-P about 15%. Such a load reduction, unfortunately, would have very little effect on the NH4^＋-N removal. Moreover, the water quality at the outlet cross-section would be still in class V （3838-02）, indicating more measures should be taken to further reduce the loads. The study demonstrated the capability of water quality models to support aquatic ecosystem restorations.
文摘This paper presents a software application of a new method for color restoration of faded images and maps. This method is composed of two steps. The first step is to enable the recovery of the brightest point and the darkest. The second step lets build chart of integrated average luminance in （R, G, B） space. This is different from the usual chart built for each color channel separately. The algorithm focuses on adjusting the points with the average luminance and especially the point almost gray. The algorithm is programmed as a part of the data-tool software package. The data-tool software package comprises of two parts： Part I for restoration of aged photos; and Part II specifically for maps. The data-tool software is programmed in the C language, integrated with the support of a few tools in Matlap A set of the old faded maps at the Geological Museum of Vietnam is selected to test the performance of the proposed color restoration method. The time needed to process images is shorted by utilizing parallel computing tools.
文摘为延长电池储能系统的整体寿命,需保持储能系统中各单元的荷电状态(state of charge,SOC)均衡。为此,提出一种基于二阶一致性算法的改进下垂控制策略,通过指数函数嵌套变化系数,实现不同容量储能单元快速SOC均衡。在SOC均衡的基础上设计二次控制策略,在一定通信时延下实现频率、电压恢复和有功、无功功率合理分配。最后,以4台储能单元组成的电池储能系统为算例进行仿真,验证了所提控制策略的有效性,SOC能够快速收敛达到均衡状态,频率、电压能够恢复到额定值,有功、无功功率能够按照相应下垂系数比例进行分配。
