中碳硫系易切削钢SAE1144(/%:0.42~0.47C,0.15~0.30Si,1.45~1.65Mn,0.24~0.30S,≤0.025P)采用100 t DC EAF-LF-VD-280 mm×320 mm坯连铸工艺流程生产。通过控制出钢钢包温度≥1000℃,出钢时加入200 kg硅铁,钢包底吹氩搅拌;LF采用专...中碳硫系易切削钢SAE1144(/%:0.42~0.47C,0.15~0.30Si,1.45~1.65Mn,0.24~0.30S,≤0.025P)采用100 t DC EAF-LF-VD-280 mm×320 mm坯连铸工艺流程生产。通过控制出钢钢包温度≥1000℃,出钢时加入200 kg硅铁,钢包底吹氩搅拌;LF采用专用精炼渣系(/%:45~55CaO,15~25Al_2O_3,15~25SiO_2),喂硫线,≥15 min VD处理后控制钢水过热度20~35℃,二冷比水量0.18 L/kg,拉速0.45~0.55 m/min等工艺措施,可稳定控制钢水硫含量和钢水的可浇性,铸坯中心疏松和缩孔级别≤1.5;[O]为14×10^(-6)~15×10^(-6),[H]1.3×10^(-6)~1.5×10^(-6),非金属夹杂物满足质量要求。展开更多
The history of natural fire and its relationship to climate during the last three gla-cial-interglacial cycles in the Southern coast areas of China and the northern continental shelf of the South China Sea (SCS) are d...The history of natural fire and its relationship to climate during the last three gla-cial-interglacial cycles in the Southern coast areas of China and the northern continental shelf of the South China Sea (SCS) are discussed based on the statistic study of charcoal particles and associated pollen data from ODP 1144 Site (20° 3'N, 117° 25'E, 2037 m in water depth). According to the results of the charcoal and pollen study, the sediments from the upper 225 m are divided into 8 zones (C1-C8), which might be correlated with the Marine Isotope Stage 1-8 (MIS1-8) respectively. Our study indicates that during the last glacial period (MIS2, 4), the influx of charcoal particle was much higher than that from the interglacial period, suggesting strong occurrence of natural fire and dry climate. During MIS 6 and MIS 8 (C6, C8), although the influx of fine charcoal particles was quite high, the influx of the coarse and medium charcoal particle were much low, which might be due to the smaller source area of fire probably resulting from the limited exposure of the continental shelf before MISS. During the interglacial period (MIS1, 5, 7), the influxes of charcoal particles were much lower, implying dropping of intensity of the natural fire and then a humid climate. Another reason is that the continental shelf was submerged into the sea during the interglacial periods, and the source areas of fire were reduced then. Although the influx of the fine charcoal particles was much lower during MIS3, the influx of the coarse and medium charcoal particles were almost equal to those of MIS4 (C4), which suggests that the intensity of the natural fire remained quite high and the climate was considerably dry during that period.展开更多
This paper presents the pollen record from the lower section of ODP1144 (depth 501.3-225.7 m, ca. 1.05-0.36 Ma). Two pollen zones (PA and PB) and eleven pollen subzones are recognized. Within zone PB, the 11 pollen su...This paper presents the pollen record from the lower section of ODP1144 (depth 501.3-225.7 m, ca. 1.05-0.36 Ma). Two pollen zones (PA and PB) and eleven pollen subzones are recognized. Within zone PB, the 11 pollen subzones (PB21-11) are defined according to the pine, fern and herb variations, and are equivalent to the marine isotope stages 21-11 (MISs 21-11). The interglacial periods are typified by an increase in pine pollen and fern spores, and a decrease in herbaceous pollen, while the patterning during the glacial periods is just the opposite. During the interglacial periods, pollen assemblages were dominated by pine similar to those of the present day, suggesting that the paleoenvironment of the interglacial periods was similar to that of the present day, whereas the glacial periods are marked by an increase in herbaceous pollen, mainly Gramineae and Cyperaceae, indicating that grassland covered the exposed continental shelf when sea level declined. Increased Artemisia percentages and the highest pine influx during MIS12 may result from a stronger winter monsoon.展开更多
Iron based superconducting wires(IBSCs)produced by the Powder in Tube(PIT)method rely on the use of silver sheaths as chemical buffer between the outer metal and the superconducting core.The adoption of silver entails...Iron based superconducting wires(IBSCs)produced by the Powder in Tube(PIT)method rely on the use of silver sheaths as chemical buffer between the outer metal and the superconducting core.The adoption of silver entails however some limitations,such as the viable temperature range when coupled with copper,and the incompatibility with calcium-based IBSCs already at 600℃,driving the research towards other wires architecture.Taking inspiration from the low temperature superconductors field,we decided to evaluate the adoption of tantalum as diffusion barrier in a layered Cu/Ta architecture,choosing a Ca/K-1144 IBSC as case study considering the high reactivity issues already reported in the case of silver sheaths for this compound.Squared wires were produced through a groove rolling lamination process coupled with a thermal treatment at 800℃.The microstructural analyses show the absence of interdiffusion between the different parts of the wire,and the magnetic characterization shows performance in line with similar polycrystalline manufacts,with margin of enhancement to be pursued via the optimization of the mechanical process and other experimental variables.The reported results suggest thus the effectiveness of tantalum as diffusion barrier for Ca/K-1144 PIT wires.展开更多
New XMM-Newton data of seven Seyfert 2 galaxies with optical spectropolarimetric observations are presented. An analysis of the 0.5 - 10 keV spectra shows that four Seyfert 2 galaxies with polarized broad lines （PBLs...New XMM-Newton data of seven Seyfert 2 galaxies with optical spectropolarimetric observations are presented. An analysis of the 0.5 - 10 keV spectra shows that four Seyfert 2 galaxies with polarized broad lines （PBLs） are absorbed by NH 〈 1024 cm^-2, while two of three Seyfert 2 galaxies without PBLs show evidence of Compton-thick obscuration, supporting the conclusion that Seyfert 2 galaxies without PBLs are more obscured than those with PBLs, Adding the measured obscuration indicators （NH, T ratio, and Fe Kα line EW） of six luminous AGNs to our previous sample improves the significance level of the difference in absorption from 92.3% to 96.3% for NH, 99.1% to 99.4% for T ratio, and 95.3% to 97.4% for Fe Kα line EW. The present results support and enhance the suggestions that the absence of PBLs in Seyfert 2 galaxies can be explained by larger viewing angles of the line of sight to the putative dusty toms, which leads to the obscuration of the broad-line scattering screen, as expected in the unification model.展开更多
文摘中碳硫系易切削钢SAE1144(/%:0.42~0.47C,0.15~0.30Si,1.45~1.65Mn,0.24~0.30S,≤0.025P)采用100 t DC EAF-LF-VD-280 mm×320 mm坯连铸工艺流程生产。通过控制出钢钢包温度≥1000℃,出钢时加入200 kg硅铁,钢包底吹氩搅拌;LF采用专用精炼渣系(/%:45~55CaO,15~25Al_2O_3,15~25SiO_2),喂硫线,≥15 min VD处理后控制钢水过热度20~35℃,二冷比水量0.18 L/kg,拉速0.45~0.55 m/min等工艺措施,可稳定控制钢水硫含量和钢水的可浇性,铸坯中心疏松和缩孔级别≤1.5;[O]为14×10^(-6)~15×10^(-6),[H]1.3×10^(-6)~1.5×10^(-6),非金属夹杂物满足质量要求。
基金key grand of the National Natural Science Foundation of China (Grant Nos. 49999560,49894170) and grand of the National Natural Science Foundation of China (Grant No. 49871077).
文摘The history of natural fire and its relationship to climate during the last three gla-cial-interglacial cycles in the Southern coast areas of China and the northern continental shelf of the South China Sea (SCS) are discussed based on the statistic study of charcoal particles and associated pollen data from ODP 1144 Site (20° 3'N, 117° 25'E, 2037 m in water depth). According to the results of the charcoal and pollen study, the sediments from the upper 225 m are divided into 8 zones (C1-C8), which might be correlated with the Marine Isotope Stage 1-8 (MIS1-8) respectively. Our study indicates that during the last glacial period (MIS2, 4), the influx of charcoal particle was much higher than that from the interglacial period, suggesting strong occurrence of natural fire and dry climate. During MIS 6 and MIS 8 (C6, C8), although the influx of fine charcoal particles was quite high, the influx of the coarse and medium charcoal particle were much low, which might be due to the smaller source area of fire probably resulting from the limited exposure of the continental shelf before MISS. During the interglacial period (MIS1, 5, 7), the influxes of charcoal particles were much lower, implying dropping of intensity of the natural fire and then a humid climate. Another reason is that the continental shelf was submerged into the sea during the interglacial periods, and the source areas of fire were reduced then. Although the influx of the fine charcoal particles was much lower during MIS3, the influx of the coarse and medium charcoal particles were almost equal to those of MIS4 (C4), which suggests that the intensity of the natural fire remained quite high and the climate was considerably dry during that period.
基金the National Natural Science Foundation of China (Grant No. 49999560) the State Key Basic Research and Development Plan of China (Grant No. 2000078503).
文摘This paper presents the pollen record from the lower section of ODP1144 (depth 501.3-225.7 m, ca. 1.05-0.36 Ma). Two pollen zones (PA and PB) and eleven pollen subzones are recognized. Within zone PB, the 11 pollen subzones (PB21-11) are defined according to the pine, fern and herb variations, and are equivalent to the marine isotope stages 21-11 (MISs 21-11). The interglacial periods are typified by an increase in pine pollen and fern spores, and a decrease in herbaceous pollen, while the patterning during the glacial periods is just the opposite. During the interglacial periods, pollen assemblages were dominated by pine similar to those of the present day, suggesting that the paleoenvironment of the interglacial periods was similar to that of the present day, whereas the glacial periods are marked by an increase in herbaceous pollen, mainly Gramineae and Cyperaceae, indicating that grassland covered the exposed continental shelf when sea level declined. Increased Artemisia percentages and the highest pine influx during MIS12 may result from a stronger winter monsoon.
基金funded by the European Union via the Euratom Research and Training Programme(Grant Agreement No 101052200-EUROfusion).
文摘Iron based superconducting wires(IBSCs)produced by the Powder in Tube(PIT)method rely on the use of silver sheaths as chemical buffer between the outer metal and the superconducting core.The adoption of silver entails however some limitations,such as the viable temperature range when coupled with copper,and the incompatibility with calcium-based IBSCs already at 600℃,driving the research towards other wires architecture.Taking inspiration from the low temperature superconductors field,we decided to evaluate the adoption of tantalum as diffusion barrier in a layered Cu/Ta architecture,choosing a Ca/K-1144 IBSC as case study considering the high reactivity issues already reported in the case of silver sheaths for this compound.Squared wires were produced through a groove rolling lamination process coupled with a thermal treatment at 800℃.The microstructural analyses show the absence of interdiffusion between the different parts of the wire,and the magnetic characterization shows performance in line with similar polycrystalline manufacts,with margin of enhancement to be pursued via the optimization of the mechanical process and other experimental variables.The reported results suggest thus the effectiveness of tantalum as diffusion barrier for Ca/K-1144 PIT wires.
基金the National Natural Science Foundation of China
文摘New XMM-Newton data of seven Seyfert 2 galaxies with optical spectropolarimetric observations are presented. An analysis of the 0.5 - 10 keV spectra shows that four Seyfert 2 galaxies with polarized broad lines （PBLs） are absorbed by NH 〈 1024 cm^-2, while two of three Seyfert 2 galaxies without PBLs show evidence of Compton-thick obscuration, supporting the conclusion that Seyfert 2 galaxies without PBLs are more obscured than those with PBLs, Adding the measured obscuration indicators （NH, T ratio, and Fe Kα line EW） of six luminous AGNs to our previous sample improves the significance level of the difference in absorption from 92.3% to 96.3% for NH, 99.1% to 99.4% for T ratio, and 95.3% to 97.4% for Fe Kα line EW. The present results support and enhance the suggestions that the absence of PBLs in Seyfert 2 galaxies can be explained by larger viewing angles of the line of sight to the putative dusty toms, which leads to the obscuration of the broad-line scattering screen, as expected in the unification model.
