In this paper, a novel component-based scene graph is proposed, in which all objects in the scene are classified to different entities, and a scene can be represented as a hierarchical graph composed of the instances ...In this paper, a novel component-based scene graph is proposed, in which all objects in the scene are classified to different entities, and a scene can be represented as a hierarchical graph composed of the instances of entities. Each entity contains basic data and its operations which are encapsulated into the entity component. The entity possesses certain behaviours which are responses to rules and interaction defined by the high-level application. Such behaviours can be described by script or behaviours model. The component-based scene graph in the paper is more abstractive and high-level than traditional scene graphs. The contents of a scene could be extended flexibly by adding new entities and new entity components, and behaviour modification can be obtained by modifying the model components or behaviour scripts. Its robustness and efficiency are verified by many examples implemented in the Virtual Scenario developed by Peking University.展开更多
In this study, a modelization of the viscoplastic behaviour of amorphous polymers is proposed, from an approach originally developed for metals behaviour at high temperature, in which state variable constitutive equat...In this study, a modelization of the viscoplastic behaviour of amorphous polymers is proposed, from an approach originally developed for metals behaviour at high temperature, in which state variable constitutive equations have been modified. The model includes the effect of strain rate sensitivity, strain softening and strain hardening. A procedure for the identification of model parameters is developed through the use of experimental data from uniaxial tests extracted from the literature, across a variety of strain rates and below the glass transition temperature ( Tg). The numerical algorithm shows that the predictions of this model well describe the intrinsic softening upon yield threshold and the subsequent progressive orientational hardening typical for amorphous glassy polymers.展开更多
Four double-stranded DNA films with different chain lengths were prepared on 3-aminopropyltriethoxysilane(APS)-modified mica surfaces in the NaCl solution with concentration ranging from 0.001 to 0.1 M.By using an ato...Four double-stranded DNA films with different chain lengths were prepared on 3-aminopropyltriethoxysilane(APS)-modified mica surfaces in the NaCl solution with concentration ranging from 0.001 to 0.1 M.By using an atomic force microscope,the force-distance curves and friction behaviour of each DNA film were studied in the NaCl solution that was used in the sample preparation.When adsorbed on mica as films in salt solution,the conformation of DNA molecules would be a combination of loops and"train-like".As the chain length increased from 50 to 20000 bp,the extension rate of DNA film increased from 7.1to 11.5 in 0.001 mol/L NaCl solution,which suggested that the DNA molecule with long chain likely resulted in more extended conformation.In addition,under low normal load,low NaCl concentration could increase the friction of DNA film and the chain length revealed insignificant effect on the friction force of DNA film.Therefore,long chain DNA with low salt concentration is more conducive to the nanopore sequencing process,since extended conformation can make DNA molecules easier to reach into nanopore and the high friction can reduce the translocation speed.These results may benefit the development of the third-generation sequencing technique based on nanopore.展开更多
基金Project supported by the National Basic Research Program (973) of China (No. 2004CB719403), and the National Natural Science Foun-dation of China (Nos. 60573151 and 60473100)
文摘In this paper, a novel component-based scene graph is proposed, in which all objects in the scene are classified to different entities, and a scene can be represented as a hierarchical graph composed of the instances of entities. Each entity contains basic data and its operations which are encapsulated into the entity component. The entity possesses certain behaviours which are responses to rules and interaction defined by the high-level application. Such behaviours can be described by script or behaviours model. The component-based scene graph in the paper is more abstractive and high-level than traditional scene graphs. The contents of a scene could be extended flexibly by adding new entities and new entity components, and behaviour modification can be obtained by modifying the model components or behaviour scripts. Its robustness and efficiency are verified by many examples implemented in the Virtual Scenario developed by Peking University.
文摘In this study, a modelization of the viscoplastic behaviour of amorphous polymers is proposed, from an approach originally developed for metals behaviour at high temperature, in which state variable constitutive equations have been modified. The model includes the effect of strain rate sensitivity, strain softening and strain hardening. A procedure for the identification of model parameters is developed through the use of experimental data from uniaxial tests extracted from the literature, across a variety of strain rates and below the glass transition temperature ( Tg). The numerical algorithm shows that the predictions of this model well describe the intrinsic softening upon yield threshold and the subsequent progressive orientational hardening typical for amorphous glassy polymers.
基金supported by the National Basic Research Program("973" Project)(Grant No.2011CB707604)the Natural Science Foundation of China(Grant Nos.91323103,51375409,21222401)
文摘Four double-stranded DNA films with different chain lengths were prepared on 3-aminopropyltriethoxysilane(APS)-modified mica surfaces in the NaCl solution with concentration ranging from 0.001 to 0.1 M.By using an atomic force microscope,the force-distance curves and friction behaviour of each DNA film were studied in the NaCl solution that was used in the sample preparation.When adsorbed on mica as films in salt solution,the conformation of DNA molecules would be a combination of loops and"train-like".As the chain length increased from 50 to 20000 bp,the extension rate of DNA film increased from 7.1to 11.5 in 0.001 mol/L NaCl solution,which suggested that the DNA molecule with long chain likely resulted in more extended conformation.In addition,under low normal load,low NaCl concentration could increase the friction of DNA film and the chain length revealed insignificant effect on the friction force of DNA film.Therefore,long chain DNA with low salt concentration is more conducive to the nanopore sequencing process,since extended conformation can make DNA molecules easier to reach into nanopore and the high friction can reduce the translocation speed.These results may benefit the development of the third-generation sequencing technique based on nanopore.
