The mesoscopic structures of β-HMX （octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine）- based PBXs （polymer bonded explosives） at room temperature were investigated using dissipative particle dynamics method. The ...The mesoscopic structures of β-HMX （octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine）- based PBXs （polymer bonded explosives） at room temperature were investigated using dissipative particle dynamics method. The parameters and repulsive parameters of dif- ferent polymers and β-HMX, the mesoscopic structures of β-HMX-based polymer-bonded explosives at different temperatures have been studied. The results showed that the compat-ibility between β-HMX and vinylidenedifluoride （VDF）,β-HMX and chlorotrifluoroethylene （CTFE）, VDF and CTFE increased with increasing temperature. The temperature and mo-lar ratio of the polymers played an important role in wrapped process. And there exists the optimum temperature and molar ratio.展开更多
A common design practice for dynamic loading assumes the frame fixed at their bases. In reality, the supporting soil medium allows movement to some extent due to its property to deform. This may decrease the overall s...A common design practice for dynamic loading assumes the frame fixed at their bases. In reality, the supporting soil medium allows movement to some extent due to its property to deform. This may decrease the overall stiffness of the structural system and may increase the natural period of the system. The effect of soil flexibility is suggested to be accounted through consideration of springs which have specified stiffness and soil half space. Results show that the dynamic response of frame structure to vibrations is due to applied dynamic load and is highly dependent on the soil type and the method of modeling soil structure interaction. The response of frame structure under dynamic load is higher in case of linear discrete independent spring as comparing with perfect bond cases. Except the response of frame in case of piles embedded in soft clay, half space are higher than frame with piles and linear elastic spring due to the interaction between the frequencies of applied load and frequencies of frame structure. Also, result showed that it is important to include the soil-structure interaction in the analysis of the system in order to correctly simulate the dynamic problem for controlling on the resonance phenomena.展开更多
Here,the interfacial synergism of discontinuous spot shaped SnO_2 and TiO_2 mesoporous nanocomposite as electron transfer layer（ETL） underlayer is presented in highly efficient mesoscopic perovskite solar cells（M-P...Here,the interfacial synergism of discontinuous spot shaped SnO_2 and TiO_2 mesoporous nanocomposite as electron transfer layer（ETL） underlayer is presented in highly efficient mesoscopic perovskite solar cells（M-PSCs）. Based on this new strategy,strong charge recombination observed in previous SnO_2-based ETLs is suppressed to a great extent as the pathways of charge recombination and energy loss are blocked effectively. Meanwhile,the internal series resistance of entire M-PSC is decreased remarkably. The new ETL is more kinetically favorable to electron transfer and thus results in significant photovoltaic improvement and alleviated hysteresis effect of M-PSCs.展开更多
This paper presents an empirical study of the acquisition of English ambiguous verb-locative prepositional phrase constructions （VLPPs） by adult Mandarin and Spanish speakers. This study assumes that the semantic pr...This paper presents an empirical study of the acquisition of English ambiguous verb-locative prepositional phrase constructions （VLPPs） by adult Mandarin and Spanish speakers. This study assumes that the semantic properties of the target VLPPs that relate to change-of-location in sentences such as The boat floated under the bridge arise from an uninterpretable syntactic feature selected by English but unselected by Mandarin Chinese and Spanish. Results obtained from an animated cartoon selection task indicate that neither the Mandarin nor the Spanish speakers at any level of English proficiency possess native-like interpretative knowledge. Tense/ Aspect effects on the interpretation of the target constructions by Spanish speakers were also found. These results are interpreted as consistent with the Representational Deficit Hypothesis view （Hawkins, 2003, 2005） of adult second language acquisition.展开更多
This paper studies the damage-viscoelastic behavior of composite solid propellants of solid rocket motors(SRM).Based on viscoelastic theories and strain equivalent hypothesis in damage mechanics,a three-dimensional(3-...This paper studies the damage-viscoelastic behavior of composite solid propellants of solid rocket motors(SRM).Based on viscoelastic theories and strain equivalent hypothesis in damage mechanics,a three-dimensional(3-D)nonlinear viscoelastic constitutive model incorporating with damage is developed.The resulting viscoelastic constitutive equations are numerically discretized by integration algorithm,and a stress-updating method is presented by solving nonlinear equations according to the Newton-Raphson method.A material subroutine of stress-updating is made up and embedded into commercial code of Abaqus.The material subroutine is validated through typical examples.Our results indicate that the finite element results are in good agreement with the analytical ones and have high accuracy,and the suggested method and designed subroutine are efficient and can be further applied to damage-coupling structural analysis of practical SRM grain.展开更多
文摘The mesoscopic structures of β-HMX （octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine）- based PBXs （polymer bonded explosives） at room temperature were investigated using dissipative particle dynamics method. The parameters and repulsive parameters of dif- ferent polymers and β-HMX, the mesoscopic structures of β-HMX-based polymer-bonded explosives at different temperatures have been studied. The results showed that the compat-ibility between β-HMX and vinylidenedifluoride （VDF）,β-HMX and chlorotrifluoroethylene （CTFE）, VDF and CTFE increased with increasing temperature. The temperature and mo-lar ratio of the polymers played an important role in wrapped process. And there exists the optimum temperature and molar ratio.
文摘A common design practice for dynamic loading assumes the frame fixed at their bases. In reality, the supporting soil medium allows movement to some extent due to its property to deform. This may decrease the overall stiffness of the structural system and may increase the natural period of the system. The effect of soil flexibility is suggested to be accounted through consideration of springs which have specified stiffness and soil half space. Results show that the dynamic response of frame structure to vibrations is due to applied dynamic load and is highly dependent on the soil type and the method of modeling soil structure interaction. The response of frame structure under dynamic load is higher in case of linear discrete independent spring as comparing with perfect bond cases. Except the response of frame in case of piles embedded in soft clay, half space are higher than frame with piles and linear elastic spring due to the interaction between the frequencies of applied load and frequencies of frame structure. Also, result showed that it is important to include the soil-structure interaction in the analysis of the system in order to correctly simulate the dynamic problem for controlling on the resonance phenomena.
基金supported by the National Natural Science Foundation of China(51402036,51273104 and 91433205)the International Science&Technology Cooperation Program of China(2013DFA51000)
文摘Here,the interfacial synergism of discontinuous spot shaped SnO_2 and TiO_2 mesoporous nanocomposite as electron transfer layer（ETL） underlayer is presented in highly efficient mesoscopic perovskite solar cells（M-PSCs）. Based on this new strategy,strong charge recombination observed in previous SnO_2-based ETLs is suppressed to a great extent as the pathways of charge recombination and energy loss are blocked effectively. Meanwhile,the internal series resistance of entire M-PSC is decreased remarkably. The new ETL is more kinetically favorable to electron transfer and thus results in significant photovoltaic improvement and alleviated hysteresis effect of M-PSCs.
文摘This paper presents an empirical study of the acquisition of English ambiguous verb-locative prepositional phrase constructions （VLPPs） by adult Mandarin and Spanish speakers. This study assumes that the semantic properties of the target VLPPs that relate to change-of-location in sentences such as The boat floated under the bridge arise from an uninterpretable syntactic feature selected by English but unselected by Mandarin Chinese and Spanish. Results obtained from an animated cartoon selection task indicate that neither the Mandarin nor the Spanish speakers at any level of English proficiency possess native-like interpretative knowledge. Tense/ Aspect effects on the interpretation of the target constructions by Spanish speakers were also found. These results are interpreted as consistent with the Representational Deficit Hypothesis view （Hawkins, 2003, 2005） of adult second language acquisition.
基金supported by the National Natural Science Foundation of China(Grant No.11132012)
文摘This paper studies the damage-viscoelastic behavior of composite solid propellants of solid rocket motors(SRM).Based on viscoelastic theories and strain equivalent hypothesis in damage mechanics,a three-dimensional(3-D)nonlinear viscoelastic constitutive model incorporating with damage is developed.The resulting viscoelastic constitutive equations are numerically discretized by integration algorithm,and a stress-updating method is presented by solving nonlinear equations according to the Newton-Raphson method.A material subroutine of stress-updating is made up and embedded into commercial code of Abaqus.The material subroutine is validated through typical examples.Our results indicate that the finite element results are in good agreement with the analytical ones and have high accuracy,and the suggested method and designed subroutine are efficient and can be further applied to damage-coupling structural analysis of practical SRM grain.
