We have reported previously the ultrafast energy transfer process with a time constant of 0.8 ps from a monomeric to a dimeric subunit within a perylenetetracarboxylic diimide trimer, which was derived indirectly from...We have reported previously the ultrafast energy transfer process with a time constant of 0.8 ps from a monomeric to a dimeric subunit within a perylenetetracarboxylic diimide trimer, which was derived indirectly from a model fitting into the transient absorption experimental data. Here we present a direct ultrafast fluorescence quenching measurement by employing fs time-resolved transient fluorescence spectroscopy based on noncollinear optical parametric amplification technique. The rapid decay of the monomer＇s emission due to energy transfer was observed directly with a time constant of about 0.82 ps, in good agreement with the previous result.展开更多
Based on use of multi-dimensional models,this investigation simulates the performance of a proton exchange membrane fuel cell by varying the channel pattern.In the one-dimensional model,the porosity of the gas diffusi...Based on use of multi-dimensional models,this investigation simulates the performance of a proton exchange membrane fuel cell by varying the channel pattern.In the one-dimensional model,the porosity of the gas diffusion layer is 0.3.The model reveals the water vapor distribution of the fuel cell and demonstrates that the amount of water vapor increases linearly with the reduction reaction adjacent to the gas channel and the gas diffusion layer.Secondly,four novel tapered gas channels are simulated by a two-dimensional model.The model considers the distributions of oxygen,the pressure drop,the amount of water vapor distribution and the polarization curves.The results indicate that as the channel depth decreases,the oxygen in the tapered gas channel can be accel-erated and forced into the gas diffusion layer to improve the cell performance.The three-dimensional model is employed to simulate the phenomenon associated with four novel tapered gas channels.The results also show that the best performance is realized in the least tapered gas channel.Finally,an experimentally determined mechanism is found to be consistent with the results of the simulation.展开更多
This paper explores the key vocabularies, themes, ideas, artistic movements, and technological innovations contributing to the development of the digital arts over time. As new media theorists have argued, one of the ...This paper explores the key vocabularies, themes, ideas, artistic movements, and technological innovations contributing to the development of the digital arts over time. As new media theorists have argued, one of the defining features of the digital arts is the break-down of divisions between art forms, and between art and society （for example, Manovich 2001, 2005）. This paper outlines how digital processes intersect with aesthetic and conceptual forms. Relevant frameworks, such as materiality, embodiment, hybridity, interactivity, and narrativity, form the origins of the genre. Digital artworks, like digital media, are interactive, participatory, dynamic, and customizable, incorporating shifting data flows and real-time user inputs （Paul 2003, 67）. The customization of content and technology, as well as the recontextualization of information, characterize projects of digital art.展开更多
By considering the fluctuation of grand potential f~ around equilibrium with respect to small one-particle density fluctuations δpα（r→）, the phase instability of restricted primitive model （RPM） of ionic system...By considering the fluctuation of grand potential f~ around equilibrium with respect to small one-particle density fluctuations δpα（r→）, the phase instability of restricted primitive model （RPM） of ionic systems is investigated. We use the integral equation theory to calculate the direct correlation functions in the reference hypernetted chain approximation and obtain the spinodai line of RPM. Our anaiysis explicitly indicates that the gas-fluid phase instability is induced by k = 0 fluctuation mode, while the fluid-solid phase instability is related to k ≠ 0 fluctuation modes. The spinodai line is qualitatively consistent with the result of computer simulations by others.展开更多
Nano-rod and bow-tie antennas that are gold nano-antennas on dielectric material and the nano-rod antenna arrays are numerically studied by the finite difference time domain method in three dimensions. The light field...Nano-rod and bow-tie antennas that are gold nano-antennas on dielectric material and the nano-rod antenna arrays are numerically studied by the finite difference time domain method in three dimensions. The light field that project on the antennas can be confined to a spot with subwavelength width （-λ/11）,and the light intensity can be enhanced to 91 times the incident light in the near-field with the bow-tie antenna. The enhancement also exists in the antenna arrays. The highest enhancement of the light intensity at the bow-tie antenna gap can reach about 28000 times,and the localized field can be coupled to a nano-particle near the antenna gap.展开更多
ZEUS is a magnetohydrodynamics simulation code widely used in astrophysical research.However,it was recently found that the code may produce artificial shocks in the rarefaction region in some numerical tests since it...ZEUS is a magnetohydrodynamics simulation code widely used in astrophysical research.However,it was recently found that the code may produce artificial shocks in the rarefaction region in some numerical tests since it is not upwinded in fast and slow waves.We propose a method of magnetosonic characteristics to evolve compressional waves.The tests indicate that this method cures the "rarefaction shocks" problem to a large extent and it also greatly reduces some post shock oscillations.展开更多
基金This work was supported by the National Natural Science Foundation of China （No.20925313 and No.60438020）, the National Basic Research Program of China （No.2009CB929404）, and the Chinese Academy of Sciences Innovation Program （KJCX2-YW-W25）.
文摘We have reported previously the ultrafast energy transfer process with a time constant of 0.8 ps from a monomeric to a dimeric subunit within a perylenetetracarboxylic diimide trimer, which was derived indirectly from a model fitting into the transient absorption experimental data. Here we present a direct ultrafast fluorescence quenching measurement by employing fs time-resolved transient fluorescence spectroscopy based on noncollinear optical parametric amplification technique. The rapid decay of the monomer＇s emission due to energy transfer was observed directly with a time constant of about 0.82 ps, in good agreement with the previous result.
基金Supported by the National Science Council (NSC 97-222-E-009-067)
文摘Based on use of multi-dimensional models,this investigation simulates the performance of a proton exchange membrane fuel cell by varying the channel pattern.In the one-dimensional model,the porosity of the gas diffusion layer is 0.3.The model reveals the water vapor distribution of the fuel cell and demonstrates that the amount of water vapor increases linearly with the reduction reaction adjacent to the gas channel and the gas diffusion layer.Secondly,four novel tapered gas channels are simulated by a two-dimensional model.The model considers the distributions of oxygen,the pressure drop,the amount of water vapor distribution and the polarization curves.The results indicate that as the channel depth decreases,the oxygen in the tapered gas channel can be accel-erated and forced into the gas diffusion layer to improve the cell performance.The three-dimensional model is employed to simulate the phenomenon associated with four novel tapered gas channels.The results also show that the best performance is realized in the least tapered gas channel.Finally,an experimentally determined mechanism is found to be consistent with the results of the simulation.
文摘This paper explores the key vocabularies, themes, ideas, artistic movements, and technological innovations contributing to the development of the digital arts over time. As new media theorists have argued, one of the defining features of the digital arts is the break-down of divisions between art forms, and between art and society （for example, Manovich 2001, 2005）. This paper outlines how digital processes intersect with aesthetic and conceptual forms. Relevant frameworks, such as materiality, embodiment, hybridity, interactivity, and narrativity, form the origins of the genre. Digital artworks, like digital media, are interactive, participatory, dynamic, and customizable, incorporating shifting data flows and real-time user inputs （Paul 2003, 67）. The customization of content and technology, as well as the recontextualization of information, characterize projects of digital art.
基金Supported by National Natural Science Foundation of China under Grant No.10325418
文摘By considering the fluctuation of grand potential f~ around equilibrium with respect to small one-particle density fluctuations δpα（r→）, the phase instability of restricted primitive model （RPM） of ionic systems is investigated. We use the integral equation theory to calculate the direct correlation functions in the reference hypernetted chain approximation and obtain the spinodai line of RPM. Our anaiysis explicitly indicates that the gas-fluid phase instability is induced by k = 0 fluctuation mode, while the fluid-solid phase instability is related to k ≠ 0 fluctuation modes. The spinodai line is qualitatively consistent with the result of computer simulations by others.
文摘Nano-rod and bow-tie antennas that are gold nano-antennas on dielectric material and the nano-rod antenna arrays are numerically studied by the finite difference time domain method in three dimensions. The light field that project on the antennas can be confined to a spot with subwavelength width （-λ/11）,and the light intensity can be enhanced to 91 times the incident light in the near-field with the bow-tie antenna. The enhancement also exists in the antenna arrays. The highest enhancement of the light intensity at the bow-tie antenna gap can reach about 28000 times,and the localized field can be coupled to a nano-particle near the antenna gap.
基金supported by the National Basic Research Program of China(Grant No. 2011CB811406)the National Natural Science Foundation of China (Grant Nos. 10921303,10733020,10803011,40890161 and10973020)
文摘ZEUS is a magnetohydrodynamics simulation code widely used in astrophysical research.However,it was recently found that the code may produce artificial shocks in the rarefaction region in some numerical tests since it is not upwinded in fast and slow waves.We propose a method of magnetosonic characteristics to evolve compressional waves.The tests indicate that this method cures the "rarefaction shocks" problem to a large extent and it also greatly reduces some post shock oscillations.
