Developing acid/base-resistant and low-price microwave-absorbing materials with lighter weight is highly desired for practical applications in extreme environments.Herein,we demonstrate the successful synthesis of the...Developing acid/base-resistant and low-price microwave-absorbing materials with lighter weight is highly desired for practical applications in extreme environments.Herein,we demonstrate the successful synthesis of the N-doped porous carbon(NC)material with hierarchical pore structure by the spray pyrolysis method.The large specific surface area(SBET=707.53 m^(2)·g^(−1))of materials enables multiple scattering of incident electromagnetic waves,and N doping greatly enhances the electrical conductivity of the material.Notably,single-atom Zn can adjust the local electronic structure of adjacent sites such as carbon and nitrogen atoms,induce the center of polarization,and thus change the dielectric and electronic properties of the host material.The porous carbon coating of single-atom Zn avoids the deterioration of electromagnetic parameters caused by the accumulation of magnetic particles under high-temperature pyrolysis.At the same time,they can also be used in various complex environments,such as acidic and basic environments.Ultimately,NC-1000,with high surface area,low density,and good chemical stability,obtained a minimum reflection loss(RLmin)of−50.5 dB and an effective absorption bandwidth(EAB)exceeding 5.1 GHz at the thickness of 1.9 mm.After soaking in the strong acid and base solution,the electromagnetic wave absorption performance of the material decreased by<15%.Widely available raw materials and a simple preparation scheme are expected to expedite industrial mass production for this novel type of materials.展开更多
Hierarchical Text Classification(HTC)aims to match text to hierarchical labels.Existing methods overlook two critical issues:first,some texts cannot be fully matched to leaf node labels and need to be classified to th...Hierarchical Text Classification(HTC)aims to match text to hierarchical labels.Existing methods overlook two critical issues:first,some texts cannot be fully matched to leaf node labels and need to be classified to the correct parent node instead of treating leaf nodes as the final classification target.Second,error propagation occurs when a misclassification at a parent node propagates down the hierarchy,ultimately leading to inaccurate predictions at the leaf nodes.To address these limitations,we propose an uncertainty-guided HTC depth-aware model called DepthMatch.Specifically,we design an early stopping strategy with uncertainty to identify incomplete matching between text and labels,classifying them into the corresponding parent node labels.This approach allows us to dynamically determine the classification depth by leveraging evidence to quantify and accumulate uncertainty.Experimental results show that the proposed DepthMatch outperforms recent strong baselines on four commonly used public datasets:WOS(Web of Science),RCV1-V2(Reuters Corpus Volume I),AAPD(Arxiv Academic Paper Dataset),and BGC.Notably,on the BGC dataset,it improvesMicro-F1 andMacro-F1 scores by at least 1.09%and 1.74%,respectively.展开更多
In view of the “Node-Arc” data model of road network in the aspect of structured expressing the deficiencies, the hierarchical area partitioning of road network based on the principle of stroke, which made road netw...In view of the “Node-Arc” data model of road network in the aspect of structured expressing the deficiencies, the hierarchical area partitioning of road network based on the principle of stroke, which made road network space structure characteristics of the expression with the hierarchical feature was designed. Based on road hierarchy and connected relationship with the area domain boundaries, the road in the area was hierarchically divided. A hierarchical model was established based on “whole-part-object” data model. Finally, the model of urban road network matching is proposed, which used consistency evaluation model selected matching objects from high-grade road to the low-level road. The experiment results indicated that the method was suitable to solve the road matching problem with typical urban features.展开更多
基金B.X.thanks financial support from the National Natural Science Foundation of China(No.21801133)the Jiangsu Specially Appointed Professorship and Innovation and Entrepreneurship Talents in Jiangsu Province,the State Key Laboratory of Coordination Chemistry,the School of Chemistry and Chemical Engineering,and Collaborative Innovation Center of Advanced Microstructures,Nanjing University.
文摘Developing acid/base-resistant and low-price microwave-absorbing materials with lighter weight is highly desired for practical applications in extreme environments.Herein,we demonstrate the successful synthesis of the N-doped porous carbon(NC)material with hierarchical pore structure by the spray pyrolysis method.The large specific surface area(SBET=707.53 m^(2)·g^(−1))of materials enables multiple scattering of incident electromagnetic waves,and N doping greatly enhances the electrical conductivity of the material.Notably,single-atom Zn can adjust the local electronic structure of adjacent sites such as carbon and nitrogen atoms,induce the center of polarization,and thus change the dielectric and electronic properties of the host material.The porous carbon coating of single-atom Zn avoids the deterioration of electromagnetic parameters caused by the accumulation of magnetic particles under high-temperature pyrolysis.At the same time,they can also be used in various complex environments,such as acidic and basic environments.Ultimately,NC-1000,with high surface area,low density,and good chemical stability,obtained a minimum reflection loss(RLmin)of−50.5 dB and an effective absorption bandwidth(EAB)exceeding 5.1 GHz at the thickness of 1.9 mm.After soaking in the strong acid and base solution,the electromagnetic wave absorption performance of the material decreased by<15%.Widely available raw materials and a simple preparation scheme are expected to expedite industrial mass production for this novel type of materials.
基金sponsored by the National Key Research and Development Program of China(No.2021YFF0704100)the National Natural Science Foundation of China(No.62136002)+1 种基金the Chongqing Natural Science Foundation(No.cstc2022ycjh-bgzxm0004)the Science and Technology Commission of Chongqing Municipality(CSTB2023NSCQ-LZX0006),respectively.
文摘Hierarchical Text Classification(HTC)aims to match text to hierarchical labels.Existing methods overlook two critical issues:first,some texts cannot be fully matched to leaf node labels and need to be classified to the correct parent node instead of treating leaf nodes as the final classification target.Second,error propagation occurs when a misclassification at a parent node propagates down the hierarchy,ultimately leading to inaccurate predictions at the leaf nodes.To address these limitations,we propose an uncertainty-guided HTC depth-aware model called DepthMatch.Specifically,we design an early stopping strategy with uncertainty to identify incomplete matching between text and labels,classifying them into the corresponding parent node labels.This approach allows us to dynamically determine the classification depth by leveraging evidence to quantify and accumulate uncertainty.Experimental results show that the proposed DepthMatch outperforms recent strong baselines on four commonly used public datasets:WOS(Web of Science),RCV1-V2(Reuters Corpus Volume I),AAPD(Arxiv Academic Paper Dataset),and BGC.Notably,on the BGC dataset,it improvesMicro-F1 andMacro-F1 scores by at least 1.09%and 1.74%,respectively.
基金The National Natural Science Foundation of China (41471386).
文摘In view of the “Node-Arc” data model of road network in the aspect of structured expressing the deficiencies, the hierarchical area partitioning of road network based on the principle of stroke, which made road network space structure characteristics of the expression with the hierarchical feature was designed. Based on road hierarchy and connected relationship with the area domain boundaries, the road in the area was hierarchically divided. A hierarchical model was established based on “whole-part-object” data model. Finally, the model of urban road network matching is proposed, which used consistency evaluation model selected matching objects from high-grade road to the low-level road. The experiment results indicated that the method was suitable to solve the road matching problem with typical urban features.
