[Objective] This paper aimed to understand the area change and distribu- tion of medium-low yield farmland, and offered basis to the improvement of mediumlow farmland and its increase of grain production in Tianjin. [...[Objective] This paper aimed to understand the area change and distribu- tion of medium-low yield farmland, and offered basis to the improvement of mediumlow farmland and its increase of grain production in Tianjin. [Method] Based on the statistical date of Tianjin and its relevant counties and districts, the yield standard was set up to classify high-yield, medium-yield and low-yield farmland in Tianjin. The author analyzed area change of medium-low yield farmland in six agricultural counties and districts （including Jixian County, Wuqing District, Baodi District, Ninghe County, Jinghai County and Dagang district of Binghai New Area） from 1980 to 2010. [Result] The results showed that the average yield of grain rose from 2 445 kg/hm^2 in 1980 to 5 130 kg/hm^2 in 2010, increasing 109.82%. The area of mediumlow yield farmland was reduced from 291 250.13 hm^2 in 1985 to 76 489.87 hm^2 in 2010, coming down 74%. In Tianjin, the area of medium-low yield farmland of 2010 accounted for 19% of the total farmland, of which the ratios of medium-low yield farmland of Jinghai County, Jixian County, Dagang district of Binghai New Area, Wuqing District, Baodi District and Ninghe County were 43.12%, 18.59%, 17.23%, 14.01%, 7.05% and 0, respectively. Low soil nutrient content, drought and water shortage, as well as soil salinization were the main yield limiting factors to mediumlow yield farmland in Tianjin in 2010. [Conclusion] The countermeasures to improve the medium-low yield farmland were proposed, involving enhancing the investment of the government, strengthening the construction of water conservancy infrastructure, further improving the soil fertility, as well as saline and alkaline land, optimizing the farming system and planting drought and salt tolerance crops, etc.展开更多
By extracting the outlet pressure data of gas regulators,this paper uses the EMD toolbox of the MATLAB software,which can perform data decomposition and the Hilbert-Huang Transform to find the rules with fault data.Ev...By extracting the outlet pressure data of gas regulators,this paper uses the EMD toolbox of the MATLAB software,which can perform data decomposition and the Hilbert-Huang Transform to find the rules with fault data.Eventually,the medium-low pressure gas regulator fault criterion can be established.展开更多
To improve microalgae biomass utilization efficiency during biofuel production process,medium-low temperature hydrothermal hydrolysis pretreatment was adopted in this study.The pretreatment kinetic characteristics of ...To improve microalgae biomass utilization efficiency during biofuel production process,medium-low temperature hydrothermal hydrolysis pretreatment was adopted in this study.The pretreatment kinetic characteristics of concentrated wet microalgae Chlorella vulgaris biomass(50 g/L)under medium-low temperature hydrolysis(100°C-200°C)were experimentally investigated.The hydrothermal hydrolysis kinetics describing the coupled effects of temperature,initial pressure and retention time then were proposed using response surface methodology(RSM).The maximum carbohydrate yield reached 327.3 mg/g dried biomass under initial pressure of 4 MPa at reaction temperature of 150°C for 120 min.The maximum protein yield(321.5 mg/g dried biomass)was obtained under initial pressure of 4 MPa at reaction temperature of 200°C for 60 min.Based on the hydrothermal hydrolysis kinetic models,it was confirmed that temperature was the most important factor affecting both carbohydrate and protein release during hydrothermal hydrolysis process.Hydrothermal initial pressure and retention time were significant to carbohydrate release,but not to protein release.While,lipid was mainly distributed in microalgae residual and almost did not exist in supernatant(about 8.03 mg/g).And with assistance of mixed hexane and methanol(the ratio of hexane to methanol was 7:3),67.69%of microalgae lipid was extracted out from hydrothermal hydrolysed microalgae residual(123.3 mg/g dried biomass).展开更多
文摘[Objective] This paper aimed to understand the area change and distribu- tion of medium-low yield farmland, and offered basis to the improvement of mediumlow farmland and its increase of grain production in Tianjin. [Method] Based on the statistical date of Tianjin and its relevant counties and districts, the yield standard was set up to classify high-yield, medium-yield and low-yield farmland in Tianjin. The author analyzed area change of medium-low yield farmland in six agricultural counties and districts （including Jixian County, Wuqing District, Baodi District, Ninghe County, Jinghai County and Dagang district of Binghai New Area） from 1980 to 2010. [Result] The results showed that the average yield of grain rose from 2 445 kg/hm^2 in 1980 to 5 130 kg/hm^2 in 2010, increasing 109.82%. The area of mediumlow yield farmland was reduced from 291 250.13 hm^2 in 1985 to 76 489.87 hm^2 in 2010, coming down 74%. In Tianjin, the area of medium-low yield farmland of 2010 accounted for 19% of the total farmland, of which the ratios of medium-low yield farmland of Jinghai County, Jixian County, Dagang district of Binghai New Area, Wuqing District, Baodi District and Ninghe County were 43.12%, 18.59%, 17.23%, 14.01%, 7.05% and 0, respectively. Low soil nutrient content, drought and water shortage, as well as soil salinization were the main yield limiting factors to mediumlow yield farmland in Tianjin in 2010. [Conclusion] The countermeasures to improve the medium-low yield farmland were proposed, involving enhancing the investment of the government, strengthening the construction of water conservancy infrastructure, further improving the soil fertility, as well as saline and alkaline land, optimizing the farming system and planting drought and salt tolerance crops, etc.
基金supported by Science and technology project of Beijing in 2015 from Beijing Municipal Science&Technology Commission
文摘By extracting the outlet pressure data of gas regulators,this paper uses the EMD toolbox of the MATLAB software,which can perform data decomposition and the Hilbert-Huang Transform to find the rules with fault data.Eventually,the medium-low pressure gas regulator fault criterion can be established.
基金the International Cooperation and Exchange of the National Natural Science Foundation of China(Grant No.51561145013)the National Science Foundation for Young Scientists of China(Grant No.51606020)the National Key Research and Development Program-China(2016YFB0601002).
文摘To improve microalgae biomass utilization efficiency during biofuel production process,medium-low temperature hydrothermal hydrolysis pretreatment was adopted in this study.The pretreatment kinetic characteristics of concentrated wet microalgae Chlorella vulgaris biomass(50 g/L)under medium-low temperature hydrolysis(100°C-200°C)were experimentally investigated.The hydrothermal hydrolysis kinetics describing the coupled effects of temperature,initial pressure and retention time then were proposed using response surface methodology(RSM).The maximum carbohydrate yield reached 327.3 mg/g dried biomass under initial pressure of 4 MPa at reaction temperature of 150°C for 120 min.The maximum protein yield(321.5 mg/g dried biomass)was obtained under initial pressure of 4 MPa at reaction temperature of 200°C for 60 min.Based on the hydrothermal hydrolysis kinetic models,it was confirmed that temperature was the most important factor affecting both carbohydrate and protein release during hydrothermal hydrolysis process.Hydrothermal initial pressure and retention time were significant to carbohydrate release,but not to protein release.While,lipid was mainly distributed in microalgae residual and almost did not exist in supernatant(about 8.03 mg/g).And with assistance of mixed hexane and methanol(the ratio of hexane to methanol was 7:3),67.69%of microalgae lipid was extracted out from hydrothermal hydrolysed microalgae residual(123.3 mg/g dried biomass).
