A new multi-mesh contact algorithm for three-dimensional material point method is presented. The contact algorithm faithfully recovers the opposite acting forces between colliding bodies. Collision procedures between ...A new multi-mesh contact algorithm for three-dimensional material point method is presented. The contact algorithm faithfully recovers the opposite acting forces between colliding bodies. Collision procedures between regular bodies and/or rigid bodies are treated within the same framework. Multi-value of momentum and mass are defined on every node to describe the contact/sliding/separation procedure. Both normal and tangential velocities of each particle at the contact surface are calculated in respective individual mesh. A Coulomb friction is applied to describe the sliding or slipping between the contacting bodies. The efficiency of the contact algorithm is linearly related to the number of the contacting bodies because the overlapped nodes are labeled by sweeping the material particles of all bodies when the nodal momentum and mass are formed at every time step. Numerical simulation shows that our contact algorithm possesses high accuracy and low numerical energy dissipation, which is very important for solving collision problems.展开更多
Dealloyed ribbons with a layer of networked nanoporous structure of different pore sizes were fabricated by dealloying the as-spun Mg_(65)Cu_(25-x)Ag_(x)Y_(10)(x=0,5,10,at.%)ribbons in dilute H_(2)SO_(4) solution in o...Dealloyed ribbons with a layer of networked nanoporous structure of different pore sizes were fabricated by dealloying the as-spun Mg_(65)Cu_(25-x)Ag_(x)Y_(10)(x=0,5,10,at.%)ribbons in dilute H_(2)SO_(4) solution in order to enhance the degradation efficiency of pesticide wastewater.Compared to the as-spun ribbons,it is found that the dealloyed ribbons with the networked nanoporous structure exhibit higher degradation efficiency due to their large specific surface areas and enough active sites for the degradation process.Both the average pore sizes of the nanoporous structure and the degradation efficiency of the pesticide wastewater increase with the increase of Ag addition in the dealloyed ribbons.The maximum degradation efficiency up to 95.8%is obtained for the Mg_(65)Cu_(15)Ag_(10)Y_(10)dealloyed ribbon under the optimal conditions of pH being 3,the initial cis-cypermethrin concentration being 500 mg/L,and the dosage of dealloyed ribbon being 1.33 g/L.展开更多
According to the simulation of nitrogen sorption process in porous media with three-dimensional network model, and the analysis for such a process with percolation theory, a new method is proposed to determine a pore ...According to the simulation of nitrogen sorption process in porous media with three-dimensional network model, and the analysis for such a process with percolation theory, a new method is proposed to determine a pore structure parameter--mean coordination number of pore network, which represents the connectivity among a great number of pores. Here the 'chamber-throat' model and the Weibull distribution are used to describe the pore geometry and the pore size distribution respectively. This method is based on the scaling law of percolation theory after both effects of sorption thermodynamics and pore size on the sorption hysteresis loops are considered. The results show that it is an effective procedure to calculate the mean coordination number for micro- and meso-porous media.展开更多
Shape skeletonization （i.e., medial axis extraction） is powerful in many visual computing applications, such as pattern recognition, object segmentation, registration, and animation. In this paper, the authors expan...Shape skeletonization （i.e., medial axis extraction） is powerful in many visual computing applications, such as pattern recognition, object segmentation, registration, and animation. In this paper, the authors expand the use of diffusion equations combined with distance field information to approximate medial axes of arbitrary 3D differential properties. It offers an alternative solids represented by polygonal meshes based on their but natural way for medial axis extraction for commonly used 3D polygonal models. By solving the PDE along time axis, this system can not only quickly extract diffusion-based medial axes of input meshes, but also allow users to visualize the extraction process at each time step. In addition, the proposed model provides users a set of manipulation toolkits to sculpt extracted medial axes, then use diffusion-based techniques to recover corresponding deformed shapes according to the original input datasets. This skeleton-based shape manipulation offers a fast and easy way for animation and deformation of complicated mesh objects.展开更多
In this review a series of organic-based open porous networks are discussed, in which hydrogen bonds play an important role in network formation. Using these open networks as molecular templates: 1) a wealth of functi...In this review a series of organic-based open porous networks are discussed, in which hydrogen bonds play an important role in network formation. Using these open networks as molecular templates: 1) a wealth of functional guest species can be immo- bilized; 2) fullerene molecules can be separated and recognized; 3) photoisomerization reactions can be observed by STM; 4) 1D molecular arrays can be constructed; and 5) heterogeneous bilayer structures can be formed. It is envisioned that these su- pramolecular networks might be developed into a new family of useful soft frameworks for studies toward shape-selective ca- talysis, molecular recognition and host-guest supramolecular chemistry.展开更多
Novel hierarchical carbon nanocages （hCNCs） are proposed as high-rate anodes for Li- and Na-ion batteries. The unique structure of the porous network for hCNCs greatly favors electrolyte penetration, ion diffusion, ...Novel hierarchical carbon nanocages （hCNCs） are proposed as high-rate anodes for Li- and Na-ion batteries. The unique structure of the porous network for hCNCs greatly favors electrolyte penetration, ion diffusion, electron conduction, and structural stability, resulting in high rate capability and excellent cyclability. For lithium storage, the corresponding electrode stores a steady reversible capacity of 970 mAh·g^-1 at a rate of 0.1 A·g^-1 after 10 cycles, and stabilizes at 229 mAh·g^-1 after 10,000 cycles at a high rate of 25 A·g^-1（33 s for full-charging） while delivering a large specific power of 37 kW·kgelectrode^-1 and specific energy of 339 Wh·kgelectrode^-1. For sodium storage, the hCNC reaches a high discharge capacity of -50 mAh·g^-1 even at a high rate of 10 A·g^-1.展开更多
Reaction of Zn(NO3)2.6H2O with 5-(isonicotinamido) isophthalic acid(H2INAIP) in N,N-dimethylformamide(DMF) affords a new three-dimensional(3D) coordination polymer {[Zn(INAIP)(DMF)].0.5DMF.4H2O}n(1).The X-ray crystall...Reaction of Zn(NO3)2.6H2O with 5-(isonicotinamido) isophthalic acid(H2INAIP) in N,N-dimethylformamide(DMF) affords a new three-dimensional(3D) coordination polymer {[Zn(INAIP)(DMF)].0.5DMF.4H2O}n(1).The X-ray crystallographic structural analysis reveals that complex 1 is a 3D porous framework containing a potential open metal site inside the pores.Topology analysis confirms that complex 1 is a two-fold interpenetrated(10,3)-b net with both metal ion and ligand acting as 3-connecting nodes.The thermal stability,variable temperature X-ray diffraction pattern and N2 adsorption property of the complex are investigated.展开更多
The understanding and prediction of preferential fluid flow in porous media have attracted considerable attention in various engineering fields because of the implications of such flows in leading to a non-equilibrium...The understanding and prediction of preferential fluid flow in porous media have attracted considerable attention in various engineering fields because of the implications of such flows in leading to a non-equilibrium fluid flow in the subsurface. In this study, a novel algorithm is proposed to predict preferential flow paths based on the topologically equivalent network of a porous structure and the flow resistance of flow paths. The equivalent flow network was constructed using Poiseuille's law and the maximal inscribed sphere algorithm. The flow resistance of each path was then determined based on Darcy's law. It was determined that fluid tends to follow paths with lower flow resistance. A computer program was developed and applied to an actual porous structure. To validate the algorithm and program, we tested and recorded two-dimensional(2 D) water flow using an ablated Perspex sheet featuring the same porous structure investigated using the analytical calculations. The results show that the measured preferential flow paths are consistent with the predictions.展开更多
Conventional carbon materials cannot combine high density and high porosity,which are required in many applications,typically for energy storage under a limited space.A novel highly dense yet porous carbon has previou...Conventional carbon materials cannot combine high density and high porosity,which are required in many applications,typically for energy storage under a limited space.A novel highly dense yet porous carbon has previously been produced from a three-dimensional(3D)reduced graphene oxide(r-GO)hydrogel by evaporation-induced drying.Here the mechanism of such a network shrinkage in r-GO hydrogel is specifically illustrated by the use of water and 1,4-dioxane,which have a sole difference in surface tension.As a result,the surface tension of the evaporating solvent determines the capillary forces in the nanochannels,which causes shrinkage of the r-GO network.More promisingly,the selection of a solvent with a known surface tension can precisely tune the microstructure associated with the density and porosity of the resulting porous carbon,rendering the porous carbon materials great potential in practical devices with high volumetric performance.展开更多
Construction of functional porous titanium scaffold is drawing ever growing attention, due to its effectiveness in solving the mechanical mismatch between titanium implant and bone tissue. However, the poor water perm...Construction of functional porous titanium scaffold is drawing ever growing attention, due to its effectiveness in solving the mechanical mismatch between titanium implant and bone tissue. However, the poor water permeability as well as the problem in achieving uniform surface modification inside scaffold hinders the further biomedical application of porous titanium scaffold. In this study, largescale functional Ti O2 nanostructures（nanonetwork, nanoplate and nanowire） were constructed on three-dimensional porous titanium scaffolds surface via an effective hydrothermal treatment method. These nanostructures increase the hydrophilicity of the titanium scaffold surface, facilitating the cell culture medium to penetrate into the inner pore of the scaffold. Zeta potential analyses indicate that the surface electrical properties depend on the nanostructure, with nanowire exhibiting the lowest potential at p H 7.4. The influence of the nano-functionalized scaffold on protein adsorption and cell adhesion was examined. The results indicate that the nano-functionalized surface could modulate protein adsorption and bone marrow derived mesenchymal stem cells（BMSCs） adhesion, with the nanowire functionalized porous scaffold homogeneously promoting protein adsorption and BMSCs adhesion. Our research will facilitate future research on the development of novel functional porous scaffold.展开更多
基金The project supported by the Science Foundation of Laboratory of Computational Physics,Science Foundation of China Academy of Engineering Physics,and National Natural Science Foundation of China under Grant Nos.10702010,10775018,10472052,and 10604010
文摘A new multi-mesh contact algorithm for three-dimensional material point method is presented. The contact algorithm faithfully recovers the opposite acting forces between colliding bodies. Collision procedures between regular bodies and/or rigid bodies are treated within the same framework. Multi-value of momentum and mass are defined on every node to describe the contact/sliding/separation procedure. Both normal and tangential velocities of each particle at the contact surface are calculated in respective individual mesh. A Coulomb friction is applied to describe the sliding or slipping between the contacting bodies. The efficiency of the contact algorithm is linearly related to the number of the contacting bodies because the overlapped nodes are labeled by sweeping the material particles of all bodies when the nodal momentum and mass are formed at every time step. Numerical simulation shows that our contact algorithm possesses high accuracy and low numerical energy dissipation, which is very important for solving collision problems.
基金the financial supports from State Key Laboratory of Light Alloy Casting Technology for High-end Equipmentthe Natural Science Foundation of Liaoning Province,China(No.2020-KF-14-03)the National Natural Science Foundation of China(No.51775353)。
文摘Dealloyed ribbons with a layer of networked nanoporous structure of different pore sizes were fabricated by dealloying the as-spun Mg_(65)Cu_(25-x)Ag_(x)Y_(10)(x=0,5,10,at.%)ribbons in dilute H_(2)SO_(4) solution in order to enhance the degradation efficiency of pesticide wastewater.Compared to the as-spun ribbons,it is found that the dealloyed ribbons with the networked nanoporous structure exhibit higher degradation efficiency due to their large specific surface areas and enough active sites for the degradation process.Both the average pore sizes of the nanoporous structure and the degradation efficiency of the pesticide wastewater increase with the increase of Ag addition in the dealloyed ribbons.The maximum degradation efficiency up to 95.8%is obtained for the Mg_(65)Cu_(15)Ag_(10)Y_(10)dealloyed ribbon under the optimal conditions of pH being 3,the initial cis-cypermethrin concentration being 500 mg/L,and the dosage of dealloyed ribbon being 1.33 g/L.
基金Supported by the National Natural Science Foundation of China(No.29776038).
文摘According to the simulation of nitrogen sorption process in porous media with three-dimensional network model, and the analysis for such a process with percolation theory, a new method is proposed to determine a pore structure parameter--mean coordination number of pore network, which represents the connectivity among a great number of pores. Here the 'chamber-throat' model and the Weibull distribution are used to describe the pore geometry and the pore size distribution respectively. This method is based on the scaling law of percolation theory after both effects of sorption thermodynamics and pore size on the sorption hysteresis loops are considered. The results show that it is an effective procedure to calculate the mean coordination number for micro- and meso-porous media.
基金This research was supported in part by the National Science Foundation (NSF) Information Technology Research under Grant No.IIS-0082035the NSF under Grant No.IIS-0097646+1 种基金Alfred P.Sloan Fellowship,Honda Initiation Awardan appointment of Haixia Du to the NLM Research Participation Program sponsored by the National Library of Medicine and administered by the Oak Ridge Institute for Science and Education
文摘Shape skeletonization （i.e., medial axis extraction） is powerful in many visual computing applications, such as pattern recognition, object segmentation, registration, and animation. In this paper, the authors expand the use of diffusion equations combined with distance field information to approximate medial axes of arbitrary 3D differential properties. It offers an alternative solids represented by polygonal meshes based on their but natural way for medial axis extraction for commonly used 3D polygonal models. By solving the PDE along time axis, this system can not only quickly extract diffusion-based medial axes of input meshes, but also allow users to visualize the extraction process at each time step. In addition, the proposed model provides users a set of manipulation toolkits to sculpt extracted medial axes, then use diffusion-based techniques to recover corresponding deformed shapes according to the original input datasets. This skeleton-based shape manipulation offers a fast and easy way for animation and deformation of complicated mesh objects.
文摘In this review a series of organic-based open porous networks are discussed, in which hydrogen bonds play an important role in network formation. Using these open networks as molecular templates: 1) a wealth of functional guest species can be immo- bilized; 2) fullerene molecules can be separated and recognized; 3) photoisomerization reactions can be observed by STM; 4) 1D molecular arrays can be constructed; and 5) heterogeneous bilayer structures can be formed. It is envisioned that these su- pramolecular networks might be developed into a new family of useful soft frameworks for studies toward shape-selective ca- talysis, molecular recognition and host-guest supramolecular chemistry.
基金Acknowledgements This work was jointly supported by the National Natural Science Foundation of China （Nos. 21473089, 51232003, 21373108, 21173115, and 21203092）, the National Basic Research Program of China （No. 2013CB932902）, Suzhou Program （No. ZXG2013025） and Changzhou Technology Support Program （No. CE20130032）.
文摘Novel hierarchical carbon nanocages （hCNCs） are proposed as high-rate anodes for Li- and Na-ion batteries. The unique structure of the porous network for hCNCs greatly favors electrolyte penetration, ion diffusion, electron conduction, and structural stability, resulting in high rate capability and excellent cyclability. For lithium storage, the corresponding electrode stores a steady reversible capacity of 970 mAh·g^-1 at a rate of 0.1 A·g^-1 after 10 cycles, and stabilizes at 229 mAh·g^-1 after 10,000 cycles at a high rate of 25 A·g^-1（33 s for full-charging） while delivering a large specific power of 37 kW·kgelectrode^-1 and specific energy of 339 Wh·kgelectrode^-1. For sodium storage, the hCNC reaches a high discharge capacity of -50 mAh·g^-1 even at a high rate of 10 A·g^-1.
基金supported by the National Natural Science Foundation of China(U0934003,20903120,20821001&20731005)the Research Fund for the Doctoral Program of Higher Education of Chinathe Fundamental Research Funds for the Central Universities
文摘Reaction of Zn(NO3)2.6H2O with 5-(isonicotinamido) isophthalic acid(H2INAIP) in N,N-dimethylformamide(DMF) affords a new three-dimensional(3D) coordination polymer {[Zn(INAIP)(DMF)].0.5DMF.4H2O}n(1).The X-ray crystallographic structural analysis reveals that complex 1 is a 3D porous framework containing a potential open metal site inside the pores.Topology analysis confirms that complex 1 is a two-fold interpenetrated(10,3)-b net with both metal ion and ligand acting as 3-connecting nodes.The thermal stability,variable temperature X-ray diffraction pattern and N2 adsorption property of the complex are investigated.
基金supported by the National Natural Science Foundation of China(Grants Nos.51374213,51674251&51727807)the State Key Research Development Program of China(Grant No.2016YFC0600705)+2 种基金the National Natural Science Fund for Distinguished Young Scholars(Grant No.51125017)the Fund for Creative Research and Development Group Program of Jiangsu Province(2014-27)the Priority Academic Program Development of Jiangsu Higher Education Institutions(Grant No.PAPD-2014)
文摘The understanding and prediction of preferential fluid flow in porous media have attracted considerable attention in various engineering fields because of the implications of such flows in leading to a non-equilibrium fluid flow in the subsurface. In this study, a novel algorithm is proposed to predict preferential flow paths based on the topologically equivalent network of a porous structure and the flow resistance of flow paths. The equivalent flow network was constructed using Poiseuille's law and the maximal inscribed sphere algorithm. The flow resistance of each path was then determined based on Darcy's law. It was determined that fluid tends to follow paths with lower flow resistance. A computer program was developed and applied to an actual porous structure. To validate the algorithm and program, we tested and recorded two-dimensional(2 D) water flow using an ablated Perspex sheet featuring the same porous structure investigated using the analytical calculations. The results show that the measured preferential flow paths are consistent with the predictions.
基金This work was supported by the National Natural Science Fund for the Distinguished Young Scholars,China(51525204)the National Natural Science Foundation of China(51702229 and 51872195)the CAS Key Laboratory of Carbon Materials(KLCM KFJJ1704).
文摘Conventional carbon materials cannot combine high density and high porosity,which are required in many applications,typically for energy storage under a limited space.A novel highly dense yet porous carbon has previously been produced from a three-dimensional(3D)reduced graphene oxide(r-GO)hydrogel by evaporation-induced drying.Here the mechanism of such a network shrinkage in r-GO hydrogel is specifically illustrated by the use of water and 1,4-dioxane,which have a sole difference in surface tension.As a result,the surface tension of the evaporating solvent determines the capillary forces in the nanochannels,which causes shrinkage of the r-GO network.More promisingly,the selection of a solvent with a known surface tension can precisely tune the microstructure associated with the density and porosity of the resulting porous carbon,rendering the porous carbon materials great potential in practical devices with high volumetric performance.
基金supported by the National High Technology Research and Development Program of China(2015AA033502)the National Natural Science Foundation of China(51372087,51232002 and 51541201)+3 种基金the Science and Technology Planning Project of Guangdong Province,China(2014A010105048)the Natural Science Foundation of Guangdong Province(2015A030313493 and 2016A030308014)the State Key Laboratory for Mechanical Behavior of Materials,China(20141607)the Technological Projects of Guangzhou,China(201604020110)
文摘Construction of functional porous titanium scaffold is drawing ever growing attention, due to its effectiveness in solving the mechanical mismatch between titanium implant and bone tissue. However, the poor water permeability as well as the problem in achieving uniform surface modification inside scaffold hinders the further biomedical application of porous titanium scaffold. In this study, largescale functional Ti O2 nanostructures（nanonetwork, nanoplate and nanowire） were constructed on three-dimensional porous titanium scaffolds surface via an effective hydrothermal treatment method. These nanostructures increase the hydrophilicity of the titanium scaffold surface, facilitating the cell culture medium to penetrate into the inner pore of the scaffold. Zeta potential analyses indicate that the surface electrical properties depend on the nanostructure, with nanowire exhibiting the lowest potential at p H 7.4. The influence of the nano-functionalized scaffold on protein adsorption and cell adhesion was examined. The results indicate that the nano-functionalized surface could modulate protein adsorption and bone marrow derived mesenchymal stem cells（BMSCs） adhesion, with the nanowire functionalized porous scaffold homogeneously promoting protein adsorption and BMSCs adhesion. Our research will facilitate future research on the development of novel functional porous scaffold.
