Nano-sized γ-alumina (γ-Al2O3) was first prepared by a precipitation method. Then, active component of cobalt and a series of alkaline- earth metal promoters or nickel (Ni) with different contents were loaded on the...Nano-sized γ-alumina (γ-Al2O3) was first prepared by a precipitation method. Then, active component of cobalt and a series of alkaline- earth metal promoters or nickel (Ni) with different contents were loaded on the γ-Al2O3 support. The catalysts were characterized by N2 adsorption-desorption, X-ray diffraction (XRD) and thermogravimetry analysis (TGA). The activity and selectivity of the catalysts in catalytic partial oxidation (CPO) of methane have been compared with Co/γ-Al2O3, and it is found that the catalytic activity, selectivity, and stability are enhanced by the addition of alkaline-earth metals and nickel. The optimal loadings of strontium (Sr) and Ni were 6 and 4 wt%, respectively. This finding will be helpful in designing the trimetallic Co-Ni-Sr/γ-Al2O3 catalysts with high performance in CPO of methane.展开更多
Diverse and abundant microfossils,such as palynomorphs,algae and Ostracoda,were collected from lower Cretaceous strata of Lishu depression,located in southeastern Songliao basin,and were identified and classified in o...Diverse and abundant microfossils,such as palynomorphs,algae and Ostracoda,were collected from lower Cretaceous strata of Lishu depression,located in southeastern Songliao basin,and were identified and classified in order to provide relevant,detailed records for paleoclimate research.The early Cretaceous vegetation and climate of southeastern Songliao basin have been inferred from the analysis of palynomorph genera,algae and Ostracoda of the LS1 and SW110 wells.The lower Cretaceous strata include,in ascending stratigraphic order,the Shahezi,Yingcheng and Denglouku formations.Palynological assemblages for each formation,based on biostratigraphic and statistical analyses,provide an assessment of their longitudinal variations.During deposition of the Shahezi Formation,the climate was mid-subtropical.Vegetation consisted of coniferous forest and herbage.During deposition of the Yingcheng Formation,the climate was south Asian tropical.Vegetation consisted mainly of coniferous forest and herbal shrub.In addition,fresh and saline non-marine water dominated the lacustrine setting during deposition of these formations.Deposition of the Denglouku Formation,however,occurred under a hot and dry tropical climate.The vegetation was mostly coniferous forest and lake waters became saline.Palaeoclimate variation is correlated by the lake level change and the development of sedimentary facies.Palaeoclimate contribute to the formation of hydrocarbon source rocks and reservoir.展开更多
Over the last few years,waterborne polyurethane(WPU) was applied to various fibers,adhesives,primers for metals,caulking materials,emulsion polymerization media,paint additives,defoamers,associate thickeners,pigment p...Over the last few years,waterborne polyurethane(WPU) was applied to various fibers,adhesives,primers for metals,caulking materials,emulsion polymerization media,paint additives,defoamers,associate thickeners,pigment pastes,textile dyes and biomaterials,resulting in the increasing enthusiasm of researchers to design and synthesize novel WPU with unique properties.Thus,various processes and raw materials have been developed to prepare WPU.This review gives an overview on the developments of WPU mainly derived from novel polyols,analyzes the potential application in water-based inks and presents the probable future research area about water-based inks.Notably,the poly(ε-caprolactone) and poly(lactic acid) are the versatile materials used in WPU synthesis and supply the potential special performance for preparing WPU.Meanwhile,addition-fragmentation chain transfer(RAFT) polymerization and atom transfer radical polymerization(ATRP) processes provide an opportunity to control the chain sequence of WPU and obtain products with the desired performance.展开更多
The performances of semisupervised clustering for unlabeled data are often superior to those of unsupervised learning,which indicates that semantic information attached to clusters can significantly improve feature re...The performances of semisupervised clustering for unlabeled data are often superior to those of unsupervised learning,which indicates that semantic information attached to clusters can significantly improve feature representation capability.In a graph convolutional network(GCN),each node contains information about itself and its neighbors that is beneficial to common and unique features among samples.Combining these findings,we propose a deep clustering method based on GCN and semantic feature guidance(GFDC) in which a deep convolutional network is used as a feature generator,and a GCN with a softmax layer performs clustering assignment.First,the diversity and amount of input information are enhanced to generate highly useful representations for downstream tasks.Subsequently,the topological graph is constructed to express the spatial relationship of features.For a pair of datasets,feature correspondence constraints are used to regularize clustering loss,and clustering outputs are iteratively optimized.Three external evaluation indicators,i.e.,clustering accuracy,normalized mutual information,and the adjusted Rand index,and an internal indicator,i.e., the Davidson-Bouldin index(DBI),are employed to evaluate clustering performances.Experimental results on eight public datasets show that the GFDC algorithm is significantly better than the majority of competitive clustering methods,i.e.,its clustering accuracy is20% higher than the best clustering method on the United States Postal Service dataset.The GFDC algorithm also has the highest accuracy on the smaller Amazon and Caltech datasets.Moreover,DBI indicates the dispersion of cluster distribution and compactness within the cluster.展开更多
基金supported by the Open Foundation of State Key Laboratory of Physical Chemistry of Solid Surfaces, Xiamen University (No.200906)the Natural Science Foundation of Jiangxi Province (No.2010GZH0048)+1 种基金the National Natural Science Foundation of China (No. 21067004)the Young Science Foundation of Jiangxi Province Education Office (No. GJJ10150)
文摘Nano-sized γ-alumina (γ-Al2O3) was first prepared by a precipitation method. Then, active component of cobalt and a series of alkaline- earth metal promoters or nickel (Ni) with different contents were loaded on the γ-Al2O3 support. The catalysts were characterized by N2 adsorption-desorption, X-ray diffraction (XRD) and thermogravimetry analysis (TGA). The activity and selectivity of the catalysts in catalytic partial oxidation (CPO) of methane have been compared with Co/γ-Al2O3, and it is found that the catalytic activity, selectivity, and stability are enhanced by the addition of alkaline-earth metals and nickel. The optimal loadings of strontium (Sr) and Ni were 6 and 4 wt%, respectively. This finding will be helpful in designing the trimetallic Co-Ni-Sr/γ-Al2O3 catalysts with high performance in CPO of methane.
基金supported by a grant from the Key Project of the National Science and Technology(2011ZX05009-02)
文摘Diverse and abundant microfossils,such as palynomorphs,algae and Ostracoda,were collected from lower Cretaceous strata of Lishu depression,located in southeastern Songliao basin,and were identified and classified in order to provide relevant,detailed records for paleoclimate research.The early Cretaceous vegetation and climate of southeastern Songliao basin have been inferred from the analysis of palynomorph genera,algae and Ostracoda of the LS1 and SW110 wells.The lower Cretaceous strata include,in ascending stratigraphic order,the Shahezi,Yingcheng and Denglouku formations.Palynological assemblages for each formation,based on biostratigraphic and statistical analyses,provide an assessment of their longitudinal variations.During deposition of the Shahezi Formation,the climate was mid-subtropical.Vegetation consisted of coniferous forest and herbage.During deposition of the Yingcheng Formation,the climate was south Asian tropical.Vegetation consisted mainly of coniferous forest and herbal shrub.In addition,fresh and saline non-marine water dominated the lacustrine setting during deposition of these formations.Deposition of the Denglouku Formation,however,occurred under a hot and dry tropical climate.The vegetation was mostly coniferous forest and lake waters became saline.Palaeoclimate variation is correlated by the lake level change and the development of sedimentary facies.Palaeoclimate contribute to the formation of hydrocarbon source rocks and reservoir.
基金financial support provided by Programs for New Century Excellent Talents in University of Ministry of Education of China(Grant No.:NCET-12-1045)Shaanxi Programs for Science and Technology Development(No.2010K01-096)+1 种基金Shaanxi Special Programs for Patent Industrialization Hatch(No.2011-02-15)Xi'an Programs for Science and Technology Plan(No.CXY1433(6))
文摘Over the last few years,waterborne polyurethane(WPU) was applied to various fibers,adhesives,primers for metals,caulking materials,emulsion polymerization media,paint additives,defoamers,associate thickeners,pigment pastes,textile dyes and biomaterials,resulting in the increasing enthusiasm of researchers to design and synthesize novel WPU with unique properties.Thus,various processes and raw materials have been developed to prepare WPU.This review gives an overview on the developments of WPU mainly derived from novel polyols,analyzes the potential application in water-based inks and presents the probable future research area about water-based inks.Notably,the poly(ε-caprolactone) and poly(lactic acid) are the versatile materials used in WPU synthesis and supply the potential special performance for preparing WPU.Meanwhile,addition-fragmentation chain transfer(RAFT) polymerization and atom transfer radical polymerization(ATRP) processes provide an opportunity to control the chain sequence of WPU and obtain products with the desired performance.
基金supported by the Hebei Province Introduction of Studying Abroad Talent Funded Project (No. C20200302)the Opening Fund of Hebei Key Laboratory of Machine Learning and Computational Intelligence (Nos. 2019-2021-A and ZZ201909-202109-1)+1 种基金the National Natural Science Foundation of China (No. 61976141)the Social Science Foundation of Hebei Province (No. HB20TQ005)。
文摘The performances of semisupervised clustering for unlabeled data are often superior to those of unsupervised learning,which indicates that semantic information attached to clusters can significantly improve feature representation capability.In a graph convolutional network(GCN),each node contains information about itself and its neighbors that is beneficial to common and unique features among samples.Combining these findings,we propose a deep clustering method based on GCN and semantic feature guidance(GFDC) in which a deep convolutional network is used as a feature generator,and a GCN with a softmax layer performs clustering assignment.First,the diversity and amount of input information are enhanced to generate highly useful representations for downstream tasks.Subsequently,the topological graph is constructed to express the spatial relationship of features.For a pair of datasets,feature correspondence constraints are used to regularize clustering loss,and clustering outputs are iteratively optimized.Three external evaluation indicators,i.e.,clustering accuracy,normalized mutual information,and the adjusted Rand index,and an internal indicator,i.e., the Davidson-Bouldin index(DBI),are employed to evaluate clustering performances.Experimental results on eight public datasets show that the GFDC algorithm is significantly better than the majority of competitive clustering methods,i.e.,its clustering accuracy is20% higher than the best clustering method on the United States Postal Service dataset.The GFDC algorithm also has the highest accuracy on the smaller Amazon and Caltech datasets.Moreover,DBI indicates the dispersion of cluster distribution and compactness within the cluster.
