A new method for solving the tiling problem of surface reconstruction is proposed. The proposed method uses a snake algorithm to segment the original images, the contours are then transformed into strings by Freeman＇...A new method for solving the tiling problem of surface reconstruction is proposed. The proposed method uses a snake algorithm to segment the original images, the contours are then transformed into strings by Freeman＇ s code. Symbolic string matching technique is applied to establish a correspondence between the two consecutive contours. The surface is composed of the pieces reconstructed from the correspondence points. Experimental results show that the proposed method exhibits a good behavior for the quality of surface reconstruction and its time complexity is proportional to mn where m and n are the numbers of vertices of the two consecutive slices, respectively.展开更多
The chemical structure of heavy oil fractions obtained by liquid-solid adsorption chromatography was character-ized by 1 H nuclear magnetic resonance and X-ray diffraction.The molecular weight and molecular formula of...The chemical structure of heavy oil fractions obtained by liquid-solid adsorption chromatography was character-ized by 1 H nuclear magnetic resonance and X-ray diffraction.The molecular weight and molecular formula of asphaltene molecules were estimated by combining 1 H nuclear magnetic resonance and X-ray diffraction analyses,and were also ob-tained from vapor pressure osmometry and elemental analysis.Heteroatoms,such as S,N,and O atoms,were considered in the construction of average molecular structure of heavy oils.Two important structural parameters were proposed,including the number of alkyl chain substituents to aromatic rings and the number of total rings with heteroatoms.Ultimately,the av-erage molecular structures of polycyclic aromatics,heavy resins and asphaltene molecules were constructed.The number of α-,β-,γ-,and aromatic hydrogen atoms of the constructed average molecular structures fits well with the number of hydro-gen atoms derived from the experimental spectral data.展开更多
The reaction of the alkyl alkylidyne W（CH2CMe3）3（=CSiMe3） （1） with H20 in THF and with D20 in benzene-d6 gave two new trimeric oxo complexes： W3O3（μ=O）3（CH2CMe3）6（THF）3 （2） and [W303（μ=O）3（Ch2CMe3...The reaction of the alkyl alkylidyne W（CH2CMe3）3（=CSiMe3） （1） with H20 in THF and with D20 in benzene-d6 gave two new trimeric oxo complexes： W3O3（μ=O）3（CH2CMe3）6（THF）3 （2） and [W303（μ=O）3（Ch2CMe3）6（D2O）3] 2benzene-d6 （3.2benzened6）, respectively, each containing two alkyl ligands per W atom. This is in contrast to the dimer W2o（β-O）（CH2CMe3）6, containing three alkyl ligands per W atom, from the previously reported reaction of the alkyl alkylidyne analog W（CH2CMe3）3- （=-CCMe3） with H2O. In the reaction of 1 with D20 in THF, an unstable intermediate W2O2（μ-O）（CD2SiMe3）2（CH2CMe3）4 （4-d4） was identified. Kinetic studies of the reactions of 1 with excess H2O and D2O in THF-ds, yielding 4 and 4-d4, respectively, give a kinetic isotope effect （KIE） of 3.46（3） at 298（1） K, suggesting that the disappearance of 1 is a rate-determining step.展开更多
文摘A new method for solving the tiling problem of surface reconstruction is proposed. The proposed method uses a snake algorithm to segment the original images, the contours are then transformed into strings by Freeman＇ s code. Symbolic string matching technique is applied to establish a correspondence between the two consecutive contours. The surface is composed of the pieces reconstructed from the correspondence points. Experimental results show that the proposed method exhibits a good behavior for the quality of surface reconstruction and its time complexity is proportional to mn where m and n are the numbers of vertices of the two consecutive slices, respectively.
基金the funding of the National Basic Research Program of China (Grant No.2006CB202505)
文摘The chemical structure of heavy oil fractions obtained by liquid-solid adsorption chromatography was character-ized by 1 H nuclear magnetic resonance and X-ray diffraction.The molecular weight and molecular formula of asphaltene molecules were estimated by combining 1 H nuclear magnetic resonance and X-ray diffraction analyses,and were also ob-tained from vapor pressure osmometry and elemental analysis.Heteroatoms,such as S,N,and O atoms,were considered in the construction of average molecular structure of heavy oils.Two important structural parameters were proposed,including the number of alkyl chain substituents to aromatic rings and the number of total rings with heteroatoms.Ultimately,the av-erage molecular structures of polycyclic aromatics,heavy resins and asphaltene molecules were constructed.The number of α-,β-,γ-,and aromatic hydrogen atoms of the constructed average molecular structures fits well with the number of hydro-gen atoms derived from the experimental spectral data.
基金supported by the US National Science Foundation(CHE-0749651 & CHE-1012173)
文摘The reaction of the alkyl alkylidyne W（CH2CMe3）3（=CSiMe3） （1） with H20 in THF and with D20 in benzene-d6 gave two new trimeric oxo complexes： W3O3（μ=O）3（CH2CMe3）6（THF）3 （2） and [W303（μ=O）3（Ch2CMe3）6（D2O）3] 2benzene-d6 （3.2benzened6）, respectively, each containing two alkyl ligands per W atom. This is in contrast to the dimer W2o（β-O）（CH2CMe3）6, containing three alkyl ligands per W atom, from the previously reported reaction of the alkyl alkylidyne analog W（CH2CMe3）3- （=-CCMe3） with H2O. In the reaction of 1 with D20 in THF, an unstable intermediate W2O2（μ-O）（CD2SiMe3）2（CH2CMe3）4 （4-d4） was identified. Kinetic studies of the reactions of 1 with excess H2O and D2O in THF-ds, yielding 4 and 4-d4, respectively, give a kinetic isotope effect （KIE） of 3.46（3） at 298（1） K, suggesting that the disappearance of 1 is a rate-determining step.
