For the problems of nonlinearity,uncertainty and low prediction accuracy in the gas outburst prediction of coal mining face,the least squares support vector machine(LSSVM)is proposed to establish the prediction model....For the problems of nonlinearity,uncertainty and low prediction accuracy in the gas outburst prediction of coal mining face,the least squares support vector machine(LSSVM)is proposed to establish the prediction model.Firstly,considering the inertia coefficients as global parameters lacks the ability to improve the solution for the traditional particle swarm optimization(PSO),an improved PSO(IPSO)algorithm is introduced to adjust different inertia weights in updating the particle swarm and solve the fitness to stagnate.Secondly,the penalty factor and kernel function parameter of LSSVM are searched automatically,and the regression accuracy and generalization performance is enhanced by applying IPSO.Finally,to verify the proposed prediction model,the model is applied for gas outburst prediction of Jiuli Hill coal mine in Jiaozuo City,and the results are compared with that of PSO-SVM model,IGA-LSSVM model and BP model.The results show that the relative errors of the proposed model are not greater than 2.7%,and the prediction accuracy is higher than other three prediction models.The IPSO-LSSVM model can be used to predict the intensity of gas outburst of coal mining face effectively.展开更多
A palladium-catalyzed cascade cyclization of allenylethylene carbonates with 1,3-indandiones was developed, providing biologically interesting tetracyclic dihydrocyclopentaindenofuranone derivatives having three conti...A palladium-catalyzed cascade cyclization of allenylethylene carbonates with 1,3-indandiones was developed, providing biologically interesting tetracyclic dihydrocyclopentaindenofuranone derivatives having three contiguous quaternary carbon centers in moderate to high yields with excellent diastereoselectivities. In this reaction, the allene moiety was fully fused into the cyclopentene ring.展开更多
A terpyridine-substituted cyanostilbene derivative(Z)-2-(4′-([2,2′:6′,2″-terpyridin]-4′-yl)-[1,1′-biphenyl]-4-yl)-3-phenylacrylonitrile(CNSTPy) was synthesized and characterized. The compound exhibits remarkable...A terpyridine-substituted cyanostilbene derivative(Z)-2-(4′-([2,2′:6′,2″-terpyridin]-4′-yl)-[1,1′-biphenyl]-4-yl)-3-phenylacrylonitrile(CNSTPy) was synthesized and characterized. The compound exhibits remarkable aggregation-induced emission phenomenon and its single crystal shows a blue emission with fluorescent efficiency as high as 45%. Based on its aggregation state behavior, multiple applications towards exploring its lasing, fluorescence switching and electroluminescence properties were realized. Amplified spontaneous emission(ASE) was observed from the crystal and verified by the variable pump strip method, with a threshold value of ～1.5 m J cm^(-2). The protonation/deprotonation processes accompanied by the formation of different molecular aggregation structure result in the distinct blue and yellow emissions. Additionally, the molecule also shows a moderate electroluminescence performance.展开更多
基金Key Project of Science and Technology of Education Department of Henan Province(19B120002)Key Laboratory of Control Engineering of Henan Province(KG2016-17).
文摘For the problems of nonlinearity,uncertainty and low prediction accuracy in the gas outburst prediction of coal mining face,the least squares support vector machine(LSSVM)is proposed to establish the prediction model.Firstly,considering the inertia coefficients as global parameters lacks the ability to improve the solution for the traditional particle swarm optimization(PSO),an improved PSO(IPSO)algorithm is introduced to adjust different inertia weights in updating the particle swarm and solve the fitness to stagnate.Secondly,the penalty factor and kernel function parameter of LSSVM are searched automatically,and the regression accuracy and generalization performance is enhanced by applying IPSO.Finally,to verify the proposed prediction model,the model is applied for gas outburst prediction of Jiuli Hill coal mine in Jiaozuo City,and the results are compared with that of PSO-SVM model,IGA-LSSVM model and BP model.The results show that the relative errors of the proposed model are not greater than 2.7%,and the prediction accuracy is higher than other three prediction models.The IPSO-LSSVM model can be used to predict the intensity of gas outburst of coal mining face effectively.
基金supported by the Natural Science Foundation of China(Nos.21871293 and 22071264)。
文摘A palladium-catalyzed cascade cyclization of allenylethylene carbonates with 1,3-indandiones was developed, providing biologically interesting tetracyclic dihydrocyclopentaindenofuranone derivatives having three contiguous quaternary carbon centers in moderate to high yields with excellent diastereoselectivities. In this reaction, the allene moiety was fully fused into the cyclopentene ring.
基金supported by the Hong Kong Research Grants Council (C6009-17G)the Areas of Excellence Scheme of HKSAR (Ao E/P-03/08)+2 种基金the Clarea Au Endowed Professorship in Energy (847S)the Hong Kong Polytechnic University (1-ZE1C)the Hong Kong Research Grants Council for the financial support
文摘A terpyridine-substituted cyanostilbene derivative(Z)-2-(4′-([2,2′:6′,2″-terpyridin]-4′-yl)-[1,1′-biphenyl]-4-yl)-3-phenylacrylonitrile(CNSTPy) was synthesized and characterized. The compound exhibits remarkable aggregation-induced emission phenomenon and its single crystal shows a blue emission with fluorescent efficiency as high as 45%. Based on its aggregation state behavior, multiple applications towards exploring its lasing, fluorescence switching and electroluminescence properties were realized. Amplified spontaneous emission(ASE) was observed from the crystal and verified by the variable pump strip method, with a threshold value of ～1.5 m J cm^(-2). The protonation/deprotonation processes accompanied by the formation of different molecular aggregation structure result in the distinct blue and yellow emissions. Additionally, the molecule also shows a moderate electroluminescence performance.
