The Taihu Region in eastern China is one of China's most intensive agricultural regions and also one of the economically most developed areas. High nitrogen balance surpluses in the summer rice-winter wheat double...The Taihu Region in eastern China is one of China's most intensive agricultural regions and also one of the economically most developed areas. High nitrogen balance surpluses in the summer rice-winter wheat double-cropping systems are leading to large-scale non-point source pollution of aquifers. In an interdisciplinary approach, four-year (1995-1998) field trials were carried out in two representative areas (Jurong County and Wuxi City) of the Taihu Region. Five farmers' field sites were chosen in each of the 2 locations, with each site divided into 'standard' (farmers' practice) and 'reduced' (by 30%-40%) N fertilization. For both fertilization intensities, N balance surpluses and monetary returns from grain sales minus fertilizer expenditures were calculated in an economic assessment. Based on the field trials, the mineral N fertilizer application rates reduced by about 10% for rice and 20%-30% for wheat were recommended in 1999. Since 1999, the research focused on the trends in N fertilizer application rates and changes in grain and agricultural commodities prices.Summer rice N fertilizer use, in Wuxi City as of 2001, dropped by roughly 25%, while for winter wheat it decreased by 10%-20%, compared to the 1995-1998 period. This has been achieved not only by grain policy and price changes, but also by an increased environmental awareness from government officials. Nitrogen balance surpluses in Anzhen Town (of Wuxi City) have consequently diminished by 50%-75% in rice and by up to 40% in wheat, with reductions being achieved without concomitant decreases in physical grain yields or returns from sales minus fertilizer costs.展开更多
The composition of gases trapped in olivine, orthopyroxene and clinopyroxene in Iherzolite xenoliths collected from different locations in eastern China has been measured by the vacuum stepped-heating mass spectrometr...The composition of gases trapped in olivine, orthopyroxene and clinopyroxene in Iherzolite xenoliths collected from different locations in eastern China has been measured by the vacuum stepped-heating mass spectrometry. These xenoliths are hosted in alkali basalts and considered as residues of partial melting of the upper mantle, and may contain evidence of mantle evolution. The results show that various kinds of fluid inclusions in Iherzolite xenoliths have been released at distinct times, which could be related to different stages of mantle evolution. In general, primitive fluids of the upper mantle (PFUM) beneath eastern China are dominated by H2, CO2 and CO, and are characterized by high contents of H2 and reduced gases. The compositions of PFUM are highly variable and related to tectonic settings. CO, CO2 and H2 are the main components of the PFUM beneath cratons; the PFUM in the mantle enriched in potassic metasomatism in the northern part of northeastern China has a high content of H2, while CO2 and SO2 are the dominant components of the PFUM in the Su-Lu-Wan (Jiangsu-Shandong-Anhui) region, where recycled crustal fluids were mixed with deeper mantle components. There are several fluids with distinct compositions beneath eastern China, such as primitive fluids of upper mantle (CO, CO2 and H2), partial melting fluids (CO2 and CO) and metasomatic fluids mixed with recycled crustal fluids (CO2, N2, SO2 and CH4) etc. Fluids of the upper mantle beneath the North China craton are different from that of the South China craton in total gases and chemical compositions: the contents of the reduced gases of the PFUM in the NCC are higher than those in the SCC.展开更多
This paper focuses on the image segmentation with probabilistic neural networks (PNNs). Back propagation neural networks (BpNNs) and multi perceptron neural networks (MLPs) are also considered in this study. Especiall...This paper focuses on the image segmentation with probabilistic neural networks (PNNs). Back propagation neural networks (BpNNs) and multi perceptron neural networks (MLPs) are also considered in this study. Especially, this paper investigates the implementation of PNNs in image segmentation and optimal processing of image segmentation with a PNN. The comparison between image segmentations with PNNs and with other neural networks is given. The experimental results show that PNNs can be successfully applied to image segmentation for good results.展开更多
The surface mechanical attrition treatment (SMAT) technique was developed to synthesize a nanocrystalline (NC) layer on the surface of metallic materials for upgrading their overall properties and performance. In this...The surface mechanical attrition treatment (SMAT) technique was developed to synthesize a nanocrystalline (NC) layer on the surface of metallic materials for upgrading their overall properties and performance. In this paper, by means of SMAT to a pure zirconium plate at the room temperature, repetitive multidirectional peening of steel shots (composition (wt%): 1C, l.SCr, base Fe) severely deformed the surface layer. A NC surface layer consisting of the intermetallic compound FeCr was fabricated on the surface of the zirconium. The microstructure characterization of the surface layer was performed by using X-ray diffraction analysis, optical microscopy, scanning and transmission electron microscopy observations. The NC surface layer was about 25 urn thick and consisted of the intermetallic compound FeCr with an average grain size of 25±10 nm. The deformation-induced fast diffusion of Fe and Cr from the steel shots into Zr occurred during SMAT, leading to the formation of intermetallic compound. In addition, the NC surface layer exhibited an ultrahigh nanohardness of 10.2 GPa.展开更多
It is shown that the 3d5(4X) 4s(5X)of 4s satellites ,except to the coupling between 3d54s(7,5S) and 3p→ 3d transition ,plays a key role on the magnitude of photoionization of 4s cross section .The coupled equation me...It is shown that the 3d5(4X) 4s(5X)of 4s satellites ,except to the coupling between 3d54s(7,5S) and 3p→ 3d transition ,plays a key role on the magnitude of photoionization of 4s cross section .The coupled equation methodis improvedto calculate this resonance by including these channels .The results of calculations are compared with the experimental data from 4 6eV to 5 6eV photon energies,which are in good agreement with the experiment.展开更多
LANZHOU,the capital of Gansu Province,is the largest and also an important industrial,scientific and technological and trade base in the upper reaches of the Yellow River.It is situated at the intersection of China’s...LANZHOU,the capital of Gansu Province,is the largest and also an important industrial,scientific and technological and trade base in the upper reaches of the Yellow River.It is situated at the intersection of China’s Qingzang,Inner Mongolian and Loess plateaus.It si narrow from north to south and extends broadly from east to west.In its north and south two mountains stand facing each other,and the Yollow River flows through the city.This riverside city is located in the very center of China’s territory.As early as over 100 years ago,Dr.Sun Yetsen imagined Lanzhou as the"terrestrial capital"after the success of the revolution.展开更多
To slove the problem that the implementation of Transmission Control Protocol (TCP) Vegas does not consider the impact of TCP's segment size on Round-Trip Time (RTT) while calculating RTT and the smallest RTT (bas...To slove the problem that the implementation of Transmission Control Protocol (TCP) Vegas does not consider the impact of TCP's segment size on Round-Trip Time (RTT) while calculating RTT and the smallest RTT (base _rtt), this paper proposes a modified congestion control mechanism for TCP Vegas. It first groups segments on the basis of segments size and updates base _rtt based on groups. In congestion avoidance phase, TCP Vegas changes its window size according to the measured RTT of the segment corresponding to the latest received ACK and the base _rtt retrieved from the group that the segment belongs to. Simulations illustrate that the enhanced TCP Vegas can achieve higher throughput up to 40 percent.展开更多
基金Project supported by the Volkswagen-Foundation, Germany (No. Ⅱ/69 948) the Institute of Soil Science, Chinese Academy of Sciences.
文摘The Taihu Region in eastern China is one of China's most intensive agricultural regions and also one of the economically most developed areas. High nitrogen balance surpluses in the summer rice-winter wheat double-cropping systems are leading to large-scale non-point source pollution of aquifers. In an interdisciplinary approach, four-year (1995-1998) field trials were carried out in two representative areas (Jurong County and Wuxi City) of the Taihu Region. Five farmers' field sites were chosen in each of the 2 locations, with each site divided into 'standard' (farmers' practice) and 'reduced' (by 30%-40%) N fertilization. For both fertilization intensities, N balance surpluses and monetary returns from grain sales minus fertilizer expenditures were calculated in an economic assessment. Based on the field trials, the mineral N fertilizer application rates reduced by about 10% for rice and 20%-30% for wheat were recommended in 1999. Since 1999, the research focused on the trends in N fertilizer application rates and changes in grain and agricultural commodities prices.Summer rice N fertilizer use, in Wuxi City as of 2001, dropped by roughly 25%, while for winter wheat it decreased by 10%-20%, compared to the 1995-1998 period. This has been achieved not only by grain policy and price changes, but also by an increased environmental awareness from government officials. Nitrogen balance surpluses in Anzhen Town (of Wuxi City) have consequently diminished by 50%-75% in rice and by up to 40% in wheat, with reductions being achieved without concomitant decreases in physical grain yields or returns from sales minus fertilizer costs.
基金the Natural Science Foundation of China(grant 40273009).
文摘The composition of gases trapped in olivine, orthopyroxene and clinopyroxene in Iherzolite xenoliths collected from different locations in eastern China has been measured by the vacuum stepped-heating mass spectrometry. These xenoliths are hosted in alkali basalts and considered as residues of partial melting of the upper mantle, and may contain evidence of mantle evolution. The results show that various kinds of fluid inclusions in Iherzolite xenoliths have been released at distinct times, which could be related to different stages of mantle evolution. In general, primitive fluids of the upper mantle (PFUM) beneath eastern China are dominated by H2, CO2 and CO, and are characterized by high contents of H2 and reduced gases. The compositions of PFUM are highly variable and related to tectonic settings. CO, CO2 and H2 are the main components of the PFUM beneath cratons; the PFUM in the mantle enriched in potassic metasomatism in the northern part of northeastern China has a high content of H2, while CO2 and SO2 are the dominant components of the PFUM in the Su-Lu-Wan (Jiangsu-Shandong-Anhui) region, where recycled crustal fluids were mixed with deeper mantle components. There are several fluids with distinct compositions beneath eastern China, such as primitive fluids of upper mantle (CO, CO2 and H2), partial melting fluids (CO2 and CO) and metasomatic fluids mixed with recycled crustal fluids (CO2, N2, SO2 and CH4) etc. Fluids of the upper mantle beneath the North China craton are different from that of the South China craton in total gases and chemical compositions: the contents of the reduced gases of the PFUM in the NCC are higher than those in the SCC.
文摘This paper focuses on the image segmentation with probabilistic neural networks (PNNs). Back propagation neural networks (BpNNs) and multi perceptron neural networks (MLPs) are also considered in this study. Especially, this paper investigates the implementation of PNNs in image segmentation and optimal processing of image segmentation with a PNN. The comparison between image segmentations with PNNs and with other neural networks is given. The experimental results show that PNNs can be successfully applied to image segmentation for good results.
基金supported by the National Natural Science Foundation of Chinathe Chinese Academy of Sciences
文摘The surface mechanical attrition treatment (SMAT) technique was developed to synthesize a nanocrystalline (NC) layer on the surface of metallic materials for upgrading their overall properties and performance. In this paper, by means of SMAT to a pure zirconium plate at the room temperature, repetitive multidirectional peening of steel shots (composition (wt%): 1C, l.SCr, base Fe) severely deformed the surface layer. A NC surface layer consisting of the intermetallic compound FeCr was fabricated on the surface of the zirconium. The microstructure characterization of the surface layer was performed by using X-ray diffraction analysis, optical microscopy, scanning and transmission electron microscopy observations. The NC surface layer was about 25 urn thick and consisted of the intermetallic compound FeCr with an average grain size of 25±10 nm. The deformation-induced fast diffusion of Fe and Cr from the steel shots into Zr occurred during SMAT, leading to the formation of intermetallic compound. In addition, the NC surface layer exhibited an ultrahigh nanohardness of 10.2 GPa.
文摘It is shown that the 3d5(4X) 4s(5X)of 4s satellites ,except to the coupling between 3d54s(7,5S) and 3p→ 3d transition ,plays a key role on the magnitude of photoionization of 4s cross section .The coupled equation methodis improvedto calculate this resonance by including these channels .The results of calculations are compared with the experimental data from 4 6eV to 5 6eV photon energies,which are in good agreement with the experiment.
文摘LANZHOU,the capital of Gansu Province,is the largest and also an important industrial,scientific and technological and trade base in the upper reaches of the Yellow River.It is situated at the intersection of China’s Qingzang,Inner Mongolian and Loess plateaus.It si narrow from north to south and extends broadly from east to west.In its north and south two mountains stand facing each other,and the Yollow River flows through the city.This riverside city is located in the very center of China’s territory.As early as over 100 years ago,Dr.Sun Yetsen imagined Lanzhou as the"terrestrial capital"after the success of the revolution.
文摘To slove the problem that the implementation of Transmission Control Protocol (TCP) Vegas does not consider the impact of TCP's segment size on Round-Trip Time (RTT) while calculating RTT and the smallest RTT (base _rtt), this paper proposes a modified congestion control mechanism for TCP Vegas. It first groups segments on the basis of segments size and updates base _rtt based on groups. In congestion avoidance phase, TCP Vegas changes its window size according to the measured RTT of the segment corresponding to the latest received ACK and the base _rtt retrieved from the group that the segment belongs to. Simulations illustrate that the enhanced TCP Vegas can achieve higher throughput up to 40 percent.
