As a big agricultural country,the People’s Republic of China has experienced a series of natural disasters since its founding,such as the 1959–1961 Great Famine,the 1998 floods and the 2008 snowstorm.Here we present...As a big agricultural country,the People’s Republic of China has experienced a series of natural disasters since its founding,such as the 1959–1961 Great Famine,the 1998 floods and the 2008 snowstorm.Here we present a dataset summarizing four categories of meteorological disasteraffected area at provincial level in China from 1949 to 2015:mildly-affected area,moderately-affected area,heavily-affected area,and total affected area.Based on crop-planting data and natural disaster data,grain losses are also evaluated by using a grain loss assessment model.The dataset plays an important role in the future prediction,prevention,and reduction of agrometeorological disasters.展开更多
The paper presents the change in grain-size composition of lignite under cyclic freezing-thawing (FTC) and wetting-drying (WDC). The article shows that in the spring and autumn periods the lignites can be subjected to...The paper presents the change in grain-size composition of lignite under cyclic freezing-thawing (FTC) and wetting-drying (WDC). The article shows that in the spring and autumn periods the lignites can be subjected to repeated freezing-thawing and wetting-drying, which determines the possibility of changing their grain-size composition and structure. Experimental studies in laboratory conditions on the influence of cyclic freezing-thawing (FTC) and wetting-drying (WDC) on the quality indicators of lignites have been carried out, their granulometric (fractional) composition has been studied. Freezing-thawing cycle conditions are as follows (FTC): minimum exposure temperature: -20°C;maximum: +5°C;relative humidity: 30%;number of processing cycles: 3. Wetting-drying cycles are as follows (WDC): drying temperatures are +20, +40, +60, +80°C, drying time 90 minutes, the coals are further subjected to rain (soaking) for a period of water saturation to humidity of 30% - 40% and dry again. The number of wetting-drying cycles is 3 times. The tests have revealed the destructive effects of FTC and WDC on the samples of lower metamorphic grade coal, and the cycles of wet-dry lead to the much higher yield of fine sizes (-6+0;-13+0 mm) than the cycles of freeze-thaw. Furthermore, it is found that the increase in the yield of fines depends on the heating temperature: coal disintegration proceeds more intensively at a higher temperature of drying.展开更多
China has the world’s largest planting area of paddy rice,but large quantities of paddy rice fall to the ground and are lost during harvesting with a combine harvester.Reducing grain loss is an effective way to incre...China has the world’s largest planting area of paddy rice,but large quantities of paddy rice fall to the ground and are lost during harvesting with a combine harvester.Reducing grain loss is an effective way to increase production and revenue.In this study,a monitoring system was developed to monitor the grain loss of the paddy rice and this approach was tested on the test bench for verifying the precision.The development of the monitoring system for grain loss included two stages:the first stage was to collect impact signals using a piezoelectric film,extract the four features of Root Mean Square,Peak number,Frequency and Amplitude(fundamental component),and identify the kernel impact signals using the J48(C4.5)Decision Tree algorithm.In the second stage,the precision of the monitoring system was tested for the paddy rice at three different moisture contents(10.4%,19.6%,and 30.4%)and five different grain/impurity ratios(1/0.5,1/1,1/1.5,1/2,and 1/2.5).According to the results,the highest monitoring accuracy was 99.3%(moisture content 30.8%and grain/impurity ratio 1/2.5),the average accuracy of the monitoring tests was 92.6%,and monitoring of grain/impurity ratios between 1/1 and 1/1.5(>95.4%)had higher accuracy than monitoring the other grain/impurity ratios.Monitoring accuracy decreased as impurities increased.The lowest accuracy for grain loss monitoring was obtained when the grain/impurity ratio was 1/2.5,with monitoring accuracies of 88.2%,75.7%and 78.8%at moisture contents of 10.4%,19.6%and 30.4%.展开更多
CW-CO2 laser nitriding technique was applied to improve the properties （such as aging property and the core loss） of grain oriented silicon steel. The samples were nitrided with regular space. Laser power density an...CW-CO2 laser nitriding technique was applied to improve the properties （such as aging property and the core loss） of grain oriented silicon steel. The samples were nitrided with regular space. Laser power density and scanning speed were chosen as 7.8×10^5W·cm^-2 and 100mm·min^-1. By some laser irradiation, Fe4N and Fe3N were formed in the nitrided zone. The nitrided samples were annealed at the temperatures ranged from 100 to 90℃. The core loss of some interested samples was tested. The results show that the core loss of the nitrided samples with different thickness of 0.23 and 0.30mm decreased by 14.9% and 9.4% respectively, and the aging property were improved up to 800℃. The mechanism of laser nitriding to improve the properties of grain oriented silicon steel is discussed.展开更多
Power loss of Fe-3%Sigrain-oriented silicon steelwas measured after ballscribing with different spacing using a self-designed tool.Three different sections of power loss,including hysteresis loss,abnormalloss,and eddy...Power loss of Fe-3%Sigrain-oriented silicon steelwas measured after ballscribing with different spacing using a self-designed tool.Three different sections of power loss,including hysteresis loss,abnormalloss,and eddy current loss,were measured and calculated,respectively.The loss variation and ratio were analyzed based on the experimentaldata.At 1.0 T,hysteresis loss of tested steelwith scribing spacing of 8 mm descends by 8.2% compared to samples without scribing,which is similar to the totalloss variation,and abnormalloss descends by 16.8%.At 1.0 T,hysteresis loss ratio of the steelwith scribing spacing of 16 mm ascends from 55.7% to 57.9%,and eddy current loss increases from 17.4% to 24.1%,while abnormalloss descends from 26.9% to 23.7%.The experimentalresults show that the reduction of power loss after scribing is mainly due to decreasing of hysteresis loss and abnormalloss.展开更多
基金supported by the National Natural Science Foundation of China(No.41571427)the Innovation Group Program of the Chinese Academy of Agricultural Sciences(Grant No.Y2017JC33).
文摘As a big agricultural country,the People’s Republic of China has experienced a series of natural disasters since its founding,such as the 1959–1961 Great Famine,the 1998 floods and the 2008 snowstorm.Here we present a dataset summarizing four categories of meteorological disasteraffected area at provincial level in China from 1949 to 2015:mildly-affected area,moderately-affected area,heavily-affected area,and total affected area.Based on crop-planting data and natural disaster data,grain losses are also evaluated by using a grain loss assessment model.The dataset plays an important role in the future prediction,prevention,and reduction of agrometeorological disasters.
文摘The paper presents the change in grain-size composition of lignite under cyclic freezing-thawing (FTC) and wetting-drying (WDC). The article shows that in the spring and autumn periods the lignites can be subjected to repeated freezing-thawing and wetting-drying, which determines the possibility of changing their grain-size composition and structure. Experimental studies in laboratory conditions on the influence of cyclic freezing-thawing (FTC) and wetting-drying (WDC) on the quality indicators of lignites have been carried out, their granulometric (fractional) composition has been studied. Freezing-thawing cycle conditions are as follows (FTC): minimum exposure temperature: -20°C;maximum: +5°C;relative humidity: 30%;number of processing cycles: 3. Wetting-drying cycles are as follows (WDC): drying temperatures are +20, +40, +60, +80°C, drying time 90 minutes, the coals are further subjected to rain (soaking) for a period of water saturation to humidity of 30% - 40% and dry again. The number of wetting-drying cycles is 3 times. The tests have revealed the destructive effects of FTC and WDC on the samples of lower metamorphic grade coal, and the cycles of wet-dry lead to the much higher yield of fine sizes (-6+0;-13+0 mm) than the cycles of freeze-thaw. Furthermore, it is found that the increase in the yield of fines depends on the heating temperature: coal disintegration proceeds more intensively at a higher temperature of drying.
基金This work was supported by the National Key Research and Development Program of China(Grant No.2018YFD0700705)Synergistic Innovation Center of Jiangsu Modern Agricultural Equipment and Technology(Grant No.4091600002)and the Key Research&Development plan of Zhenjiang City-Modern Agriculture(Grant No.NY2019009).
文摘China has the world’s largest planting area of paddy rice,but large quantities of paddy rice fall to the ground and are lost during harvesting with a combine harvester.Reducing grain loss is an effective way to increase production and revenue.In this study,a monitoring system was developed to monitor the grain loss of the paddy rice and this approach was tested on the test bench for verifying the precision.The development of the monitoring system for grain loss included two stages:the first stage was to collect impact signals using a piezoelectric film,extract the four features of Root Mean Square,Peak number,Frequency and Amplitude(fundamental component),and identify the kernel impact signals using the J48(C4.5)Decision Tree algorithm.In the second stage,the precision of the monitoring system was tested for the paddy rice at three different moisture contents(10.4%,19.6%,and 30.4%)and five different grain/impurity ratios(1/0.5,1/1,1/1.5,1/2,and 1/2.5).According to the results,the highest monitoring accuracy was 99.3%(moisture content 30.8%and grain/impurity ratio 1/2.5),the average accuracy of the monitoring tests was 92.6%,and monitoring of grain/impurity ratios between 1/1 and 1/1.5(>95.4%)had higher accuracy than monitoring the other grain/impurity ratios.Monitoring accuracy decreased as impurities increased.The lowest accuracy for grain loss monitoring was obtained when the grain/impurity ratio was 1/2.5,with monitoring accuracies of 88.2%,75.7%and 78.8%at moisture contents of 10.4%,19.6%and 30.4%.
基金supported by the National Natural Science Foundation of China(No.50174020).
文摘CW-CO2 laser nitriding technique was applied to improve the properties （such as aging property and the core loss） of grain oriented silicon steel. The samples were nitrided with regular space. Laser power density and scanning speed were chosen as 7.8×10^5W·cm^-2 and 100mm·min^-1. By some laser irradiation, Fe4N and Fe3N were formed in the nitrided zone. The nitrided samples were annealed at the temperatures ranged from 100 to 90℃. The core loss of some interested samples was tested. The results show that the core loss of the nitrided samples with different thickness of 0.23 and 0.30mm decreased by 14.9% and 9.4% respectively, and the aging property were improved up to 800℃. The mechanism of laser nitriding to improve the properties of grain oriented silicon steel is discussed.
基金Funded by the National Natural Science Foundation of China(Nos.51174057 and 51404159)the National High Technology Research and Development Program(No.2012AA03A503)Research Fund for the Doctoral Program of Higher Education of China(No.20130042110040)
文摘Power loss of Fe-3%Sigrain-oriented silicon steelwas measured after ballscribing with different spacing using a self-designed tool.Three different sections of power loss,including hysteresis loss,abnormalloss,and eddy current loss,were measured and calculated,respectively.The loss variation and ratio were analyzed based on the experimentaldata.At 1.0 T,hysteresis loss of tested steelwith scribing spacing of 8 mm descends by 8.2% compared to samples without scribing,which is similar to the totalloss variation,and abnormalloss descends by 16.8%.At 1.0 T,hysteresis loss ratio of the steelwith scribing spacing of 16 mm ascends from 55.7% to 57.9%,and eddy current loss increases from 17.4% to 24.1%,while abnormalloss descends from 26.9% to 23.7%.The experimentalresults show that the reduction of power loss after scribing is mainly due to decreasing of hysteresis loss and abnormalloss.
