As bifunctional oxygen evolution/reduction electrocatalysts,transition-metal-based single-atom-doped nitrogen-carbon(NC)matrices are promising successors of the corresponding noblemetal-based catalysts,offering the ad...As bifunctional oxygen evolution/reduction electrocatalysts,transition-metal-based single-atom-doped nitrogen-carbon(NC)matrices are promising successors of the corresponding noblemetal-based catalysts,offering the advantages of ultrahigh atom utilization effciency and surface active energy.However,the fabrication of such matrices(e.g.,well-dispersed single-atom-doped M-N4/NCs)often requires numerous steps and tedious processes.Herein,ultrasonic plasma engineering allows direct carbonization in a precursor solution containing metal phthalocyanine and aniline.When combining with the dispersion effect of ultrasonic waves,we successfully fabricated uniform single-atom M-N4(M=Fe,Co)carbon catalysts with a production rate as high as 10 mg min-1.The Co-N4/NC presented a bifunctional potential drop ofΔE=0.79 V,outperforming the benchmark Pt/C-Ru/C catalyst(ΔE=0.88 V)at the same catalyst loading.Theoretical calculations revealed that Co-N4 was the major active site with superior O2 adsorption-desorption mechanisms.In a practical Zn-air battery test,the air electrode coated with Co-N4/NC exhibited a specific capacity(762.8 mAh g(-1))and power density(101.62 mW cm^(-2)),exceeding those of Pt/C-Ru/C(700.8 mAh g^(-1) and 89.16 mW cm^(-2),respectively)at the same catalyst loading.Moreover,for Co-N4/NC,the potential difference increased from 1.16 to 1.47 V after 100 charge-discharge cycles.The proposed innovative and scalable strategy was concluded to be well suited for the fabrication of single-atom-doped carbons as promising bifunctional oxygen evolution/reduction electrocatalysts for metal-air batteries.展开更多
The gas-bearing reservoir in X area is mainly the tight sandstone reservoir characterized by low porosity and permeability, frequently lateral variation and poor connectivity of single sand. The previous research resu...The gas-bearing reservoir in X area is mainly the tight sandstone reservoir characterized by low porosity and permeability, frequently lateral variation and poor connectivity of single sand. The previous research results reveal that the general seismic attributes analysis cannot meet the requirement of fluid identification. This is because the relationship between seismic attributes and their implication is uncertain and ambiguous, which decreases the precision of both reservoir prediction and fluid identification. To overcome the problem, multi-attribute crossplot technology is proposed from the mathematical statistical point of view rather than the correspondence between the seismic attributes and their geological implication. In this method, the wells which have the same statistical law are classified firstly, and then all the interest wells are retained while the wells beyond the statistical law are eliminated, and the seismic attributes sensitive to the same types of eliminated wells are optimized and used to generate crossplots. The nonzero area of their crossplots results just predicts the potential distribution. The discontinuity of subsurface geological conditions results in the non-continuous shape and the seismic bin lead to the mosaic form. The optimization of sensitive attributes relative to the same types of wells is independent from each other, and thus the order of attributes in crossplots does not affect the final prediction results. This method is based on the statistical theory and suitable for the areas such as the study area abundant of lots of well data. Application to X area proves the effectiveness of this method and predicts plane distribution about different types of gas production. Due to the effect of faults and other geological factors, the partition prediction results using multi-attribute crossplots reach 95% of coincidence which is obviously and far higher than the results of the whole area. The final prediction results show that the potential areas with medium and high gas production are mainly concentrated in the northern part of the study area, where lots of development research will be strengthened.展开更多
Let A be m by n matrix, M and N be positive definite matrices of order in and n respectively. This paper presents an efficient method for computing (M-N) singular value decomposition((M-N) SVD) of A on a cube connecte...Let A be m by n matrix, M and N be positive definite matrices of order in and n respectively. This paper presents an efficient method for computing (M-N) singular value decomposition((M-N) SVD) of A on a cube connected single instruction stream-multiple data stream(SIMD) parallel computer. This method is based on a one-sided orthogonalization algorithm due to Hestenes. On the cube connected SIMD parallel computer with o(n) processors, the (M -- N) SVD of a matrix A requires a computation time of o(m3 log m/n).展开更多
基金supported by Global Frontier Program through the Global Frontier Hybrid Interface materials(GFHIM)of the National Research Foundation of Korea(NRF)funded by the ministry of science,ICT and Future Planning(2013M3A6B1078874)co-supported by Busan Innovation Institute of Industry,Science&Technology Planning(BISTEP)+1 种基金the financial support of Federal Ministry of Education and Research(BMBF)under the“Make Our Planet Great Again-German Research Initiative”(MOPGAGRI),57429784implemented by the German Academic Exchange Service Deutscher Akademischer Austauschdienst(DAAD)。
文摘As bifunctional oxygen evolution/reduction electrocatalysts,transition-metal-based single-atom-doped nitrogen-carbon(NC)matrices are promising successors of the corresponding noblemetal-based catalysts,offering the advantages of ultrahigh atom utilization effciency and surface active energy.However,the fabrication of such matrices(e.g.,well-dispersed single-atom-doped M-N4/NCs)often requires numerous steps and tedious processes.Herein,ultrasonic plasma engineering allows direct carbonization in a precursor solution containing metal phthalocyanine and aniline.When combining with the dispersion effect of ultrasonic waves,we successfully fabricated uniform single-atom M-N4(M=Fe,Co)carbon catalysts with a production rate as high as 10 mg min-1.The Co-N4/NC presented a bifunctional potential drop ofΔE=0.79 V,outperforming the benchmark Pt/C-Ru/C catalyst(ΔE=0.88 V)at the same catalyst loading.Theoretical calculations revealed that Co-N4 was the major active site with superior O2 adsorption-desorption mechanisms.In a practical Zn-air battery test,the air electrode coated with Co-N4/NC exhibited a specific capacity(762.8 mAh g(-1))and power density(101.62 mW cm^(-2)),exceeding those of Pt/C-Ru/C(700.8 mAh g^(-1) and 89.16 mW cm^(-2),respectively)at the same catalyst loading.Moreover,for Co-N4/NC,the potential difference increased from 1.16 to 1.47 V after 100 charge-discharge cycles.The proposed innovative and scalable strategy was concluded to be well suited for the fabrication of single-atom-doped carbons as promising bifunctional oxygen evolution/reduction electrocatalysts for metal-air batteries.
文摘The gas-bearing reservoir in X area is mainly the tight sandstone reservoir characterized by low porosity and permeability, frequently lateral variation and poor connectivity of single sand. The previous research results reveal that the general seismic attributes analysis cannot meet the requirement of fluid identification. This is because the relationship between seismic attributes and their implication is uncertain and ambiguous, which decreases the precision of both reservoir prediction and fluid identification. To overcome the problem, multi-attribute crossplot technology is proposed from the mathematical statistical point of view rather than the correspondence between the seismic attributes and their geological implication. In this method, the wells which have the same statistical law are classified firstly, and then all the interest wells are retained while the wells beyond the statistical law are eliminated, and the seismic attributes sensitive to the same types of eliminated wells are optimized and used to generate crossplots. The nonzero area of their crossplots results just predicts the potential distribution. The discontinuity of subsurface geological conditions results in the non-continuous shape and the seismic bin lead to the mosaic form. The optimization of sensitive attributes relative to the same types of wells is independent from each other, and thus the order of attributes in crossplots does not affect the final prediction results. This method is based on the statistical theory and suitable for the areas such as the study area abundant of lots of well data. Application to X area proves the effectiveness of this method and predicts plane distribution about different types of gas production. Due to the effect of faults and other geological factors, the partition prediction results using multi-attribute crossplots reach 95% of coincidence which is obviously and far higher than the results of the whole area. The final prediction results show that the potential areas with medium and high gas production are mainly concentrated in the northern part of the study area, where lots of development research will be strengthened.
文摘Let A be m by n matrix, M and N be positive definite matrices of order in and n respectively. This paper presents an efficient method for computing (M-N) singular value decomposition((M-N) SVD) of A on a cube connected single instruction stream-multiple data stream(SIMD) parallel computer. This method is based on a one-sided orthogonalization algorithm due to Hestenes. On the cube connected SIMD parallel computer with o(n) processors, the (M -- N) SVD of a matrix A requires a computation time of o(m3 log m/n).
