According to the bio-characteristics of the lower and upper cavity surfaces of dental restoration, a stitching approach is proposed based on a virtual zipper working mechanism and a minimization of the surface total c...According to the bio-characteristics of the lower and upper cavity surfaces of dental restoration, a stitching approach is proposed based on a virtual zipper working mechanism and a minimization of the surface total curvature energy, which is used to resolve the stitching problems existing during computer-aided design for dental restorations. First, the two boundaries corresponding to the lower and upper surfaces are triangulated based on the zipper working mechanism to generate the initial stitching surface patch, of which the edges are distributed uniformly between the boundaries. Secondly, the initial stitching surface patch is subdivided and deformed to reconstruct an optimized surface patch according to the bio-characteristics of the teeth. The optimized surface patch is minimally distinguishable from the surrounding mesh in smoothness and density, and it can stitch the upper and lower cavity surfaces naturally. The experimental results show that the dental restorations obtained by the proposed method can satisfy both the shape aesthetic and the fitting accuracy, and meet the requirements of clinical oral medicine.展开更多
The effect of interface reaction on the fractal dimensions of fracture surface in aluminum borate whisker-reinforced aluminum alloy 6061 composite was investigated. The composite was fabricated by squeeze-casting tech...The effect of interface reaction on the fractal dimensions of fracture surface in aluminum borate whisker-reinforced aluminum alloy 6061 composite was investigated. The composite was fabricated by squeeze-casting technique. The fracture surfaces created in tensile test were measured by vertical sectioning method. Fractal phenomena were found in two plots, in which the measuring units were from 3 to 15 μm and 1 to 5 μm, respectively. The relation was established between the tensile properties and fractal dimension with measuring units of 3-15 μm. The results show that the ultimate tensile strength increases while the fracture surface roughness increases with fractal dimension increasing due to the change in fracture mode depending on the degree of interface reaction status induced by heat treatment. But when the measuring units are 1-5 μm, fractal dimension does not change with heat treatment.展开更多
The extended Riccati mapping approach^[1] is further improved by generalized Riccati equation, and combine it with variable separation method, abundant new exact complex solutions for the （2＋1）-dimensional modified...The extended Riccati mapping approach^[1] is further improved by generalized Riccati equation, and combine it with variable separation method, abundant new exact complex solutions for the （2＋1）-dimensional modified dispersive water-wave （MDWW） system are obtained. Based on a derived periodic solitary wave solution and a rational solution, we study a type of phenomenon of complex wave.展开更多
The radical-molecule reaction F＋propene （CH2CHCH3） was studied in detail by using the Becke＇s three parameter Lee-Yang-Parr-B3LYP/6-311G（d,p） and coupled cluster with single, double, and triple excitationsCCSD（...The radical-molecule reaction F＋propene （CH2CHCH3） was studied in detail by using the Becke＇s three parameter Lee-Yang-Parr-B3LYP/6-311G（d,p） and coupled cluster with single, double, and triple excitationsCCSD（T）/6-311＋G（2d,2p）. It is shown that F＋propene reaction mainly occurs through complex-formation mechanism： F attacks the double bond of propene leading to the formation of complex 1 and complex 2. As the two radical complexes are metastable, they can quickly dissociate to H＋C3HsF, CH3＋C2H3F and HF＋C3H5. Based on the ab initio calculations, the CH3＋C2H3F is the main channel, and the H elimination and HF forming channels also provide some contribution to products. The calculated values are in good agreement with the recently reported experimental results.展开更多
The lateral distributions of depth-averaged velocity in open compound channels with emerged and submerged vegetated floodplains were analyzed based on the analytical solution of the depth-integrated Reynolds-Averaged ...The lateral distributions of depth-averaged velocity in open compound channels with emerged and submerged vegetated floodplains were analyzed based on the analytical solution of the depth-integrated Reynolds-Averaged Navier-Stokes equation with a term to account for the effects of vegetation.The three cases considered for open channels were two-stage rectangular channel with emerged vegetated floodplain,rectangular channel with submerged vegetated corner,and two-stage rectangular channel with submerged vegetated floodplain,respectively.To predict the depth-averaged velocity with submerged vegetated floodplains,we proposed a new method based on a two-layer approach where flow above and through the vegetation layer was described separately.Moreover,further experiments in the two-stage rectangular channel with submerged vegetated floodplain were carried out to verify the results.The analytical solutions of the cases indicated that the corresponding analytical depth-averaged velocity distributions agree well with the simulated and experimental prediction.The analytical solutions of the cases with theoretical foundation and without programming calculation were reasonable and applicable,which were more convenient than numerical simulations.The analytical solutions provided a way for future researches to solve the problems of submerged vegetation and discontinuous phenomenon of depth-averaged velocity at the stage point for compound channels.Understanding the hydraulics of flow in compound channels with vegetated floodplains is very important for supporting the management of fluvial processes.展开更多
In this paper,the problem of axially symmetric deformation is examined for a composite cylindrical tube under equal axial loads acting on its two ends,where the tube is composed of two different incompressible neo-Hoo...In this paper,the problem of axially symmetric deformation is examined for a composite cylindrical tube under equal axial loads acting on its two ends,where the tube is composed of two different incompressible neo-Hookean materials.Significantly,the implicit analytical solutions describing the deformation of the tube are proposed.Numerical simulations are given to further illustrate the qualitative properties of the solutions and some meaningful conclusions are obtained.In the tension case,with the increasing axial loads or with the decreasing ratio of shear moduli of the outer and the inner materials,it is proved that the tube will shrink more along the radial direction and will extend more along the axial direction.Under either tension or compression,the deformation along the axial direction is obvious near the two ends of the tube,while in the rest,the change is relatively small.Similarly,for a large domain of the middle part,the axial elongation is almost constant;however,the variation is very fast near the two ends.In addition,the absolute value of the axial displacement increases gradually from the central cross-section of the tube and achieves the maximum at the two endpoints.展开更多
The effective thermal conductivity of composites with ellipsoidal fillers is analyzed by using a homogenization method that is able to represent the microstructure precisely.In this study,various parameters such as th...The effective thermal conductivity of composites with ellipsoidal fillers is analyzed by using a homogenization method that is able to represent the microstructure precisely.In this study,various parameters such as the volume fraction,shape,and distribution of the filler are quantitatively estimated to understand the mechanisms of heat transfer in the composite.First,thermal boundary resistance between resin and filler is important for obtaining composites with higher thermal conductivity.Second,the anisotropy of the effective thermal conductivity arises from contact between filler in the case of ellipsoidal filler and produces lower thermal resistance.Finally,the filler network and thermal resistance are essential for the heat transfer in composites because the path of thermal conduction is improved by contact between neighboring filler particles.展开更多
基金The National High Technology Research and Development Program of China(863 Program)(No.2005AA420240)the Key Science and Technology Program of Jiangsu Province (No.BE2005014)
文摘According to the bio-characteristics of the lower and upper cavity surfaces of dental restoration, a stitching approach is proposed based on a virtual zipper working mechanism and a minimization of the surface total curvature energy, which is used to resolve the stitching problems existing during computer-aided design for dental restorations. First, the two boundaries corresponding to the lower and upper surfaces are triangulated based on the zipper working mechanism to generate the initial stitching surface patch, of which the edges are distributed uniformly between the boundaries. Secondly, the initial stitching surface patch is subdivided and deformed to reconstruct an optimized surface patch according to the bio-characteristics of the teeth. The optimized surface patch is minimally distinguishable from the surrounding mesh in smoothness and density, and it can stitch the upper and lower cavity surfaces naturally. The experimental results show that the dental restorations obtained by the proposed method can satisfy both the shape aesthetic and the fitting accuracy, and meet the requirements of clinical oral medicine.
基金Project (20070213042) supported by Specialized Research Fund for the Doctoral Program of Higher Education, China
文摘The effect of interface reaction on the fractal dimensions of fracture surface in aluminum borate whisker-reinforced aluminum alloy 6061 composite was investigated. The composite was fabricated by squeeze-casting technique. The fracture surfaces created in tensile test were measured by vertical sectioning method. Fractal phenomena were found in two plots, in which the measuring units were from 3 to 15 μm and 1 to 5 μm, respectively. The relation was established between the tensile properties and fractal dimension with measuring units of 3-15 μm. The results show that the ultimate tensile strength increases while the fracture surface roughness increases with fractal dimension increasing due to the change in fracture mode depending on the degree of interface reaction status induced by heat treatment. But when the measuring units are 1-5 μm, fractal dimension does not change with heat treatment.
基金Supported by Science and Technology Foundation of Guizhou Province under Grant No.20072009
文摘The extended Riccati mapping approach^[1] is further improved by generalized Riccati equation, and combine it with variable separation method, abundant new exact complex solutions for the （2＋1）-dimensional modified dispersive water-wave （MDWW） system are obtained. Based on a derived periodic solitary wave solution and a rational solution, we study a type of phenomenon of complex wave.
基金Ⅴ. ACKN0WLEDGMENTS This work was supported by the National Natural Science Foundation of China （No.20328304, No.10574068, No.20533060 and No.20525313）.
文摘The radical-molecule reaction F＋propene （CH2CHCH3） was studied in detail by using the Becke＇s three parameter Lee-Yang-Parr-B3LYP/6-311G（d,p） and coupled cluster with single, double, and triple excitationsCCSD（T）/6-311＋G（2d,2p）. It is shown that F＋propene reaction mainly occurs through complex-formation mechanism： F attacks the double bond of propene leading to the formation of complex 1 and complex 2. As the two radical complexes are metastable, they can quickly dissociate to H＋C3HsF, CH3＋C2H3F and HF＋C3H5. Based on the ab initio calculations, the CH3＋C2H3F is the main channel, and the H elimination and HF forming channels also provide some contribution to products. The calculated values are in good agreement with the recently reported experimental results.
基金Under the auspices of National Basic Research Program of China(No.2011CB403303)National Key Research and Development Program of China(No.2016YFC0402408-5)National Natural Science Foundation of China(No.51179181,40788001)
文摘The lateral distributions of depth-averaged velocity in open compound channels with emerged and submerged vegetated floodplains were analyzed based on the analytical solution of the depth-integrated Reynolds-Averaged Navier-Stokes equation with a term to account for the effects of vegetation.The three cases considered for open channels were two-stage rectangular channel with emerged vegetated floodplain,rectangular channel with submerged vegetated corner,and two-stage rectangular channel with submerged vegetated floodplain,respectively.To predict the depth-averaged velocity with submerged vegetated floodplains,we proposed a new method based on a two-layer approach where flow above and through the vegetation layer was described separately.Moreover,further experiments in the two-stage rectangular channel with submerged vegetated floodplain were carried out to verify the results.The analytical solutions of the cases indicated that the corresponding analytical depth-averaged velocity distributions agree well with the simulated and experimental prediction.The analytical solutions of the cases with theoretical foundation and without programming calculation were reasonable and applicable,which were more convenient than numerical simulations.The analytical solutions provided a way for future researches to solve the problems of submerged vegetation and discontinuous phenomenon of depth-averaged velocity at the stage point for compound channels.Understanding the hydraulics of flow in compound channels with vegetated floodplains is very important for supporting the management of fluvial processes.
基金supported by the National Natural Science Foundation of China(Grant Nos.10872045 and 11232003)the Program for New Century Excellent Talents in University(Grant No.NCET-09-0096)+1 种基金the Fundamental Research Funds for the Central Universities(Grant No.DC120101121)the Program for Liaoning Excellent Talents in University(Grant No.LR2012044)
文摘In this paper,the problem of axially symmetric deformation is examined for a composite cylindrical tube under equal axial loads acting on its two ends,where the tube is composed of two different incompressible neo-Hookean materials.Significantly,the implicit analytical solutions describing the deformation of the tube are proposed.Numerical simulations are given to further illustrate the qualitative properties of the solutions and some meaningful conclusions are obtained.In the tension case,with the increasing axial loads or with the decreasing ratio of shear moduli of the outer and the inner materials,it is proved that the tube will shrink more along the radial direction and will extend more along the axial direction.Under either tension or compression,the deformation along the axial direction is obvious near the two ends of the tube,while in the rest,the change is relatively small.Similarly,for a large domain of the middle part,the axial elongation is almost constant;however,the variation is very fast near the two ends.In addition,the absolute value of the axial displacement increases gradually from the central cross-section of the tube and achieves the maximum at the two endpoints.
文摘The effective thermal conductivity of composites with ellipsoidal fillers is analyzed by using a homogenization method that is able to represent the microstructure precisely.In this study,various parameters such as the volume fraction,shape,and distribution of the filler are quantitatively estimated to understand the mechanisms of heat transfer in the composite.First,thermal boundary resistance between resin and filler is important for obtaining composites with higher thermal conductivity.Second,the anisotropy of the effective thermal conductivity arises from contact between filler in the case of ellipsoidal filler and produces lower thermal resistance.Finally,the filler network and thermal resistance are essential for the heat transfer in composites because the path of thermal conduction is improved by contact between neighboring filler particles.
