A field experiment using a split-plot randomized complete block design with three replications was carried out to determine relationships between spectral indices and wheat grain yield （GY）, to compare the performan...A field experiment using a split-plot randomized complete block design with three replications was carried out to determine relationships between spectral indices and wheat grain yield （GY）, to compare the performance of four vegetation indices （VIs） for GY prediction, and to study the feasibility of VI to estimate grain protein content （GPC） in winter wheat. Two typical winter wheat （Triticum aestivum L.） cultivars ＇Xuzhou 26＇ （high protein content） and ＇Huaimai 18＇ （low protein content） were used as the main plot treatments and four N rates, i.e., 0, 120, 210, and 300 kg N ha^-1, as the sub-plot treatments. Increasing soil N supply significantly increased GY and GPC （P ≤ 0.05）. For the two cultivars combined, significant and positive correlations were found between four VIs and GY, with the strongest relationship observed when using the green ratio vegetation index （GRVI） at mid-filling. Cumulative VI estimates improved yield predictions substantially, with the best interval being heading to maturity stage. Similar results were found between VI and grain protein yield. However, when using cumulative VI, GPC showed no significant improvement. The strong relationship between leaf N status and GPC （R2 =0.9144 for ＇Xuzhou 26＇ and R2 = 0.8285 for ＇Huaimai 18＇） indicated that canopy spectra could be used to predict GPC. The strong fit between estimated and observed GPC （R2 = 0.7939） indicated that remote sensing techniques were potentially useful predictors of grain protein content and quality in wheat.展开更多
The investment opportunities created by economic policies and increasing urbanization have enhanced demand for urban and peri-urban land. Fertile agricultural land is being converted to other uses. Around 1/3 more of ...The investment opportunities created by economic policies and increasing urbanization have enhanced demand for urban and peri-urban land. Fertile agricultural land is being converted to other uses. Around 1/3 more of the existing area under forests is needed to meet the targets of national forest policy. In the last two decades, 9% pastures have disappeared. The hills being removed cause threat to environment. The farmers seem to overuse land and other inputs. In the peri-urban areas agricultural fertile lands are many times forcefully acquired for non-agricultural uses, which result in violent protests and judicial interventions. A few cases of vast land use change, motive forces for such change, effect of change in land use on livelihood and on quality and costs of fresh vegetable supply are discussed in this paper. The partially used and unused data collected for earlier studies and some data collected for this paper have been used. The increase in land prices due to enhanced income of some sections, future need of prime land and returns from other than agricultural uses seem to be the driving force for change in land use, affecting the livelihood of people dependent upon farming who are migrating to nearby areas. Each shift of peri-urban agriculture will result in loss of quality, increase wastage by 6% and enhance costs of leafy vegetables by more than 5.5%. For an ideal urban land use, a balanced multi land use policy emphasizing peri-urban agriculture and forestry is suggested.展开更多
The results from comparative study of the EUF-K values of four different soils and of their varions particlefractions (<2μm, 2-10μm and 10 50μm) showed that the EUF-K values were related to the composition ofcl...The results from comparative study of the EUF-K values of four different soils and of their varions particlefractions (<2μm, 2-10μm and 10 50μm) showed that the EUF-K values were related to the composition ofclay minerals and the soil particle size. The EUF-K values (0-35 min) were closely related to the amountof rapidly available K and part of non-exchangeable K of soils. Biological experiments proved that EUFtechnique was an effective method for evaluating soil K-supplying power.展开更多
In order to explore the influence of soil resistivity on stray current in power supply system of urban rail transit,we establish an equivalent circuit model of the rail-to-ground structure based on resistance network ...In order to explore the influence of soil resistivity on stray current in power supply system of urban rail transit,we establish an equivalent circuit model of the rail-to-ground structure based on resistance network method first.After measuring the soil resistivity of a real subway system,a simulation model is established in Matlab to obtain the stray currents at different soil resistivities.Then the influence of soil resistivity on stray current is analyzed.Afterwards,to verify the rationality and reliability of the simulation model,we design a test circuit to measure the stray current and rail-to-ground voltage in a real subway system,and a comparison of the experimentally measured results and simulation results is presented.The results show that the stray current is the maximum when the soil resistivity is 211.57Ω·m;when the soil resistivity is 768.47Ω·m,the stray current is the minimum,that is,the smaller the soil resistivity,the greater the stray current.Therefore,the resistivity should be increased as much as possible when ramming the track foundation in urban rail transit system.展开更多
Natural gas is one of the key energy resources for Turkey due to fact that 32% of annual primary energy supply and 45% of annual electricity production is obtained from natural gas with also common usage of residentia...Natural gas is one of the key energy resources for Turkey due to fact that 32% of annual primary energy supply and 45% of annual electricity production is obtained from natural gas with also common usage of residential and industrial zones. In this study, the supply security of natural gas was taken into consideration with strategic criteria of energy policy with the SWOT （strengths, weaknesses, opportunities and threats） analysis and the future projection for Turkey. It has been concluded on geopolitics criteria, domestic production and research for resources must be stimulated as high as possible and participation to abroad resources must be implemented.展开更多
A building model with radiant cooling system was established and the cooling load, indoor temperature, surface temperature of the wails and other parameters in non-cooling and radiant cooling room were calculated by T...A building model with radiant cooling system was established and the cooling load, indoor temperature, surface temperature of the wails and other parameters in non-cooling and radiant cooling room were calculated by TRNSYS. The comparative analysis of the characteristics of attenuation and delay proves that the operation of radiant cooling system increases the degree of temperature attenuation of the room and reduces the inner surface temperature of the wall significantly, but has little effect on the attenuation coefficient and delay time of wall heat transfer. The simulation results also show that the inner surface temperature of the walls in the radiant cooling room is much lower than that in non-cooling room in the day with the maximum cooling load, which reduces the indoor operation temperature largely, and improves the thermal comfort. Finally, according to the analysis of indoor temperature of the rooms with different operation schedules of cooling system, it can be derived that the indoor mean temperature changes with the working time of radiant cooling system, and the operation schedule can be adjusted in practice according to the actual indoor temperature to achieve the integration of energy efficiency and thermal comfort.展开更多
Fifteen upland soils collected from the major arable areas in North China were used to assess the availability of soil sulfur (S) to plants in a pot experiment. Soils were extracted with various reagents and the extra...Fifteen upland soils collected from the major arable areas in North China were used to assess the availability of soil sulfur (S) to plants in a pot experiment. Soils were extracted with various reagents and the extractable S was determined using turbidimetric method or inductively coupled plasma atomic emission spectrometry (ICP-AES), respectively. In addition, mineralizable organic S, organic S, N/S ratio, sulfur availability index (SAI) and available sulfur correction value (ASC) in soils were also determined. The S amount extracted by 1.5 g L-1 CaCl2 was nearly equivalent to that by 0.25 mol L-1 KCl (40 ℃), and both of them were slightly smaller than that by 0.01 mol L-1 Ca(H2PO4)2 solution, as measured by turbidimetric method or ICP-AES. The extractable S measured by turbidimetric method was consistently smaller than that by ICP-AES. All methods tested except that for organic S and N/S ratio produced satisfactory results in the regression analyses of the relationships between the amounts of S extracted and plant dry matter weight and S uptake in the pot experiment. In general, 0.01 mol L-1 Ca (H2PO4) 2-extracted S determined by ICP-AES or turbidimetric method and 0.25 mol L-1 KCl(40℃)-extracted S determined by ICP-AES appeared to be the best indicators for evaluation of soil available S.展开更多
基金Project supported by the National Natural Science Foundation of China (No.30400278)National High Technology Research and Development Program (863 Program) of China (No.2006AA10Z129)
文摘A field experiment using a split-plot randomized complete block design with three replications was carried out to determine relationships between spectral indices and wheat grain yield （GY）, to compare the performance of four vegetation indices （VIs） for GY prediction, and to study the feasibility of VI to estimate grain protein content （GPC） in winter wheat. Two typical winter wheat （Triticum aestivum L.） cultivars ＇Xuzhou 26＇ （high protein content） and ＇Huaimai 18＇ （low protein content） were used as the main plot treatments and four N rates, i.e., 0, 120, 210, and 300 kg N ha^-1, as the sub-plot treatments. Increasing soil N supply significantly increased GY and GPC （P ≤ 0.05）. For the two cultivars combined, significant and positive correlations were found between four VIs and GY, with the strongest relationship observed when using the green ratio vegetation index （GRVI） at mid-filling. Cumulative VI estimates improved yield predictions substantially, with the best interval being heading to maturity stage. Similar results were found between VI and grain protein yield. However, when using cumulative VI, GPC showed no significant improvement. The strong relationship between leaf N status and GPC （R2 =0.9144 for ＇Xuzhou 26＇ and R2 = 0.8285 for ＇Huaimai 18＇） indicated that canopy spectra could be used to predict GPC. The strong fit between estimated and observed GPC （R2 = 0.7939） indicated that remote sensing techniques were potentially useful predictors of grain protein content and quality in wheat.
文摘The investment opportunities created by economic policies and increasing urbanization have enhanced demand for urban and peri-urban land. Fertile agricultural land is being converted to other uses. Around 1/3 more of the existing area under forests is needed to meet the targets of national forest policy. In the last two decades, 9% pastures have disappeared. The hills being removed cause threat to environment. The farmers seem to overuse land and other inputs. In the peri-urban areas agricultural fertile lands are many times forcefully acquired for non-agricultural uses, which result in violent protests and judicial interventions. A few cases of vast land use change, motive forces for such change, effect of change in land use on livelihood and on quality and costs of fresh vegetable supply are discussed in this paper. The partially used and unused data collected for earlier studies and some data collected for this paper have been used. The increase in land prices due to enhanced income of some sections, future need of prime land and returns from other than agricultural uses seem to be the driving force for change in land use, affecting the livelihood of people dependent upon farming who are migrating to nearby areas. Each shift of peri-urban agriculture will result in loss of quality, increase wastage by 6% and enhance costs of leafy vegetables by more than 5.5%. For an ideal urban land use, a balanced multi land use policy emphasizing peri-urban agriculture and forestry is suggested.
文摘The results from comparative study of the EUF-K values of four different soils and of their varions particlefractions (<2μm, 2-10μm and 10 50μm) showed that the EUF-K values were related to the composition ofclay minerals and the soil particle size. The EUF-K values (0-35 min) were closely related to the amountof rapidly available K and part of non-exchangeable K of soils. Biological experiments proved that EUFtechnique was an effective method for evaluating soil K-supplying power.
基金National Natural Science Foundation of China(Nos.51476073,51266004)Natural Science Foundation of Gansu Province(No.1308RJZA199)。
文摘In order to explore the influence of soil resistivity on stray current in power supply system of urban rail transit,we establish an equivalent circuit model of the rail-to-ground structure based on resistance network method first.After measuring the soil resistivity of a real subway system,a simulation model is established in Matlab to obtain the stray currents at different soil resistivities.Then the influence of soil resistivity on stray current is analyzed.Afterwards,to verify the rationality and reliability of the simulation model,we design a test circuit to measure the stray current and rail-to-ground voltage in a real subway system,and a comparison of the experimentally measured results and simulation results is presented.The results show that the stray current is the maximum when the soil resistivity is 211.57Ω·m;when the soil resistivity is 768.47Ω·m,the stray current is the minimum,that is,the smaller the soil resistivity,the greater the stray current.Therefore,the resistivity should be increased as much as possible when ramming the track foundation in urban rail transit system.
文摘Natural gas is one of the key energy resources for Turkey due to fact that 32% of annual primary energy supply and 45% of annual electricity production is obtained from natural gas with also common usage of residential and industrial zones. In this study, the supply security of natural gas was taken into consideration with strategic criteria of energy policy with the SWOT （strengths, weaknesses, opportunities and threats） analysis and the future projection for Turkey. It has been concluded on geopolitics criteria, domestic production and research for resources must be stimulated as high as possible and participation to abroad resources must be implemented.
基金Project(2010DFA72740) supported by the International Science & Technology Cooperation Program of China
文摘A building model with radiant cooling system was established and the cooling load, indoor temperature, surface temperature of the wails and other parameters in non-cooling and radiant cooling room were calculated by TRNSYS. The comparative analysis of the characteristics of attenuation and delay proves that the operation of radiant cooling system increases the degree of temperature attenuation of the room and reduces the inner surface temperature of the wall significantly, but has little effect on the attenuation coefficient and delay time of wall heat transfer. The simulation results also show that the inner surface temperature of the walls in the radiant cooling room is much lower than that in non-cooling room in the day with the maximum cooling load, which reduces the indoor operation temperature largely, and improves the thermal comfort. Finally, according to the analysis of indoor temperature of the rooms with different operation schedules of cooling system, it can be derived that the indoor mean temperature changes with the working time of radiant cooling system, and the operation schedule can be adjusted in practice according to the actual indoor temperature to achieve the integration of energy efficiency and thermal comfort.
文摘Fifteen upland soils collected from the major arable areas in North China were used to assess the availability of soil sulfur (S) to plants in a pot experiment. Soils were extracted with various reagents and the extractable S was determined using turbidimetric method or inductively coupled plasma atomic emission spectrometry (ICP-AES), respectively. In addition, mineralizable organic S, organic S, N/S ratio, sulfur availability index (SAI) and available sulfur correction value (ASC) in soils were also determined. The S amount extracted by 1.5 g L-1 CaCl2 was nearly equivalent to that by 0.25 mol L-1 KCl (40 ℃), and both of them were slightly smaller than that by 0.01 mol L-1 Ca(H2PO4)2 solution, as measured by turbidimetric method or ICP-AES. The extractable S measured by turbidimetric method was consistently smaller than that by ICP-AES. All methods tested except that for organic S and N/S ratio produced satisfactory results in the regression analyses of the relationships between the amounts of S extracted and plant dry matter weight and S uptake in the pot experiment. In general, 0.01 mol L-1 Ca (H2PO4) 2-extracted S determined by ICP-AES or turbidimetric method and 0.25 mol L-1 KCl(40℃)-extracted S determined by ICP-AES appeared to be the best indicators for evaluation of soil available S.
