Beyond the traditional focus on improvements in mechanical, electronic and absorption properties, controllability, actuation, and dynamic response of monoliths have received increasing attentions for practical applica...Beyond the traditional focus on improvements in mechanical, electronic and absorption properties, controllability, actuation, and dynamic response of monoliths have received increasing attentions for practical applications. However, most of them could only realize simple response to constant conditions(e.g. a stationary magnetic field) while carrying out humdrum motions. By controlling distribution of metal organic framework obtained carbon-enriched Fe304 nanoparticles in self-assembly reduced graphene oxide(RGO) monoliths, we could achieve two distinctive RGO-Fe_3 O_4 stirrers that could dynamically respond to the rapidly changing magnetic field while executing designed movements precisely: rotating with lying down posture or standing straight posture. These stirrers can not only be applied in environmental remediation(e.g.suction skimmer), but also be recycled as electrode active materials for supercapacitors after fulfilling their destiny, realizing transformation of trash to treasure, which will inspire other dynamically responsive monoliths for various applications.展开更多
Flow and temperature fields of slurry of A1-Si alloy in the process of cup-cast method is numerically simulated. The simulation results agree with the experiment by Shimasaki et al.under an estimated value of the over...Flow and temperature fields of slurry of A1-Si alloy in the process of cup-cast method is numerically simulated. The simulation results agree with the experiment by Shimasaki et al.under an estimated value of the overall heat transfer coefficient between the alloy and the cup.展开更多
In order to improve the quality of continuous casting hollow steel billet,especially the inner surface quality,the technology of installing magnetic stirrer in the inner-mold during the hollow billet continuous castin...In order to improve the quality of continuous casting hollow steel billet,especially the inner surface quality,the technology of installing magnetic stirrer in the inner-mold during the hollow billet continuous casting was put forward,and structure and electrical parameter of magnetic stirrer were studied by numerical simulation method,and static simulation experiment was done,the results show that:1)the greater the current strength,the solidification rate and temperature gradient of molten metal are lower,and therefore it helps to form fine equiaxial crystal structure,however when the current strength is too large,it is not obvious to change the equiaxial crystal size,and the excessive velocity of the melt will result in segregation defects.2)Three-phase magnetic stirrer has higher stirring effect than that of two-phase one.3)Tooth width of yoke should be small to improve the stirring effect.The numerical simulation results can provide the theory basis to optimize the electromagnetic continuous casting technology.展开更多
Die filling is a critical stage during powder compaction,which can significantly affect the product quality and efficiency.In this paper,a forced feeder is introduced attempting to improve the filling performance of a...Die filling is a critical stage during powder compaction,which can significantly affect the product quality and efficiency.In this paper,a forced feeder is introduced attempting to improve the filling performance of a lab-scale die filling system.The die filling process is analysed with a graphics processing units(GPU)enhanced discrete element method(DEM).Various stirrer designs are assessed for a wide range of process settings(i.e.,stirrer speed,filling speed)to explore their influence on the die filling performance of free-flowing powder.Numerical results show that die filing with the novel helical-ribbon(i.e.,type D)stirrer design exhibits the highest filling ratio,implying that it is the most robust stirrer design for the feeder configuration considered.Furthermore,die filling performance with the type D stirrer design is a function of the stirrer speed and the filling speed.A positive variation of filling ratio(ηf>0%)can be ensured over the whole range of filling speed by adjusting the stirrer speed(i.e.,increasing the stirrer speed).The approach used in this study can not only help understand how the stirrer design affects the die filling performance but also guide the optimization of feeder system and process settings.展开更多
Graphene nanoplatelets(GNPs)have attracted tremendous interest due to their unique properties and bonding capabilities.This study focuses on the effect of GNP dispersion on the mechanical,thermal,and morphological beh...Graphene nanoplatelets(GNPs)have attracted tremendous interest due to their unique properties and bonding capabilities.This study focuses on the effect of GNP dispersion on the mechanical,thermal,and morphological behavior of GNP/epoxy nanocomposites.This study aims to understand how the dispersion of GNPs affects the properties of epoxy nanocomposite and to identify the best dispersion approach for improving mechanical performance.A solvent mixing technique that includes mechanical stirring and ultrasonication was used for producing the nanocomposites.Fourier transform infrared spectroscopy was used to investigate the interaction between GNPs and the epoxy matrix.The measurements of density and moisture content were used to confirm that GNPs were successfully incorporated into the nanocomposite.The findings showed that GNPs are successfully dispersed in the epoxy matrix by combining mechanical stirring and ultrasonication in a single step,producing well-dispersed nanocomposites with improved mechanical properties.Particularly,the nanocomposites at a low GNP loading of 0.1 wt%,demonstrate superior mechanical strength,as shown by increased tensile properties,including improved Young's modulus(1.86 GPa),strength(57.31 MPa),and elongation at break(4.98).The nanocomposite with 0.25 wt%GNP loading performs better,according to the viscoelastic analysis and flexural properties(113.18 MPa).Except for the nanocomposite with a 0.5 wt%GNP loading,which has a higher thermal breakdown temperature,the thermal characteristics do not significantly alter.The effective dispersion of GNPs in the epoxy matrix and low agglomeration is confirmed by the morphological characterization.The findings help with filler selection and identifying the best dispersion approach,which improves mechanical performance.The effective integration of GNPs and their interaction with the epoxy matrix provides the doorway for additional investigation and the development of sophisticated nanocomposites.In fields like aerospace,automotive,and electronics where higher mechanical performance and functionality are required,GNPs'improved mechanical properties and successful dispersion present exciting potential.展开更多
基金supported by Natural Science Foundation of SZU (Grant No. 2017004)Early Career Scheme of the Research Grants Council of Hong Kong SAR, China, under the Project No. CityU 109213a Grant from the City University of Hong Kong (9610372)
文摘Beyond the traditional focus on improvements in mechanical, electronic and absorption properties, controllability, actuation, and dynamic response of monoliths have received increasing attentions for practical applications. However, most of them could only realize simple response to constant conditions(e.g. a stationary magnetic field) while carrying out humdrum motions. By controlling distribution of metal organic framework obtained carbon-enriched Fe304 nanoparticles in self-assembly reduced graphene oxide(RGO) monoliths, we could achieve two distinctive RGO-Fe_3 O_4 stirrers that could dynamically respond to the rapidly changing magnetic field while executing designed movements precisely: rotating with lying down posture or standing straight posture. These stirrers can not only be applied in environmental remediation(e.g.suction skimmer), but also be recycled as electrode active materials for supercapacitors after fulfilling their destiny, realizing transformation of trash to treasure, which will inspire other dynamically responsive monoliths for various applications.
文摘Flow and temperature fields of slurry of A1-Si alloy in the process of cup-cast method is numerically simulated. The simulation results agree with the experiment by Shimasaki et al.under an estimated value of the overall heat transfer coefficient between the alloy and the cup.
基金Item Sponsored by Natural Science Foundation of Shandong Province(ZR2010EQ027)
文摘In order to improve the quality of continuous casting hollow steel billet,especially the inner surface quality,the technology of installing magnetic stirrer in the inner-mold during the hollow billet continuous casting was put forward,and structure and electrical parameter of magnetic stirrer were studied by numerical simulation method,and static simulation experiment was done,the results show that:1)the greater the current strength,the solidification rate and temperature gradient of molten metal are lower,and therefore it helps to form fine equiaxial crystal structure,however when the current strength is too large,it is not obvious to change the equiaxial crystal size,and the excessive velocity of the melt will result in segregation defects.2)Three-phase magnetic stirrer has higher stirring effect than that of two-phase one.3)Tooth width of yoke should be small to improve the stirring effect.The numerical simulation results can provide the theory basis to optimize the electromagnetic continuous casting technology.
基金the financial support from Genentech Ltd.,the Engineering and Physical Science Research Council(Grant No.EP/M02976X)the Marie Skłodowska-Curie Individual Fellowships under European Union's Horizon 2020 research and innovation programme(Grant No.840264)。
文摘Die filling is a critical stage during powder compaction,which can significantly affect the product quality and efficiency.In this paper,a forced feeder is introduced attempting to improve the filling performance of a lab-scale die filling system.The die filling process is analysed with a graphics processing units(GPU)enhanced discrete element method(DEM).Various stirrer designs are assessed for a wide range of process settings(i.e.,stirrer speed,filling speed)to explore their influence on the die filling performance of free-flowing powder.Numerical results show that die filing with the novel helical-ribbon(i.e.,type D)stirrer design exhibits the highest filling ratio,implying that it is the most robust stirrer design for the feeder configuration considered.Furthermore,die filling performance with the type D stirrer design is a function of the stirrer speed and the filling speed.A positive variation of filling ratio(ηf>0%)can be ensured over the whole range of filling speed by adjusting the stirrer speed(i.e.,increasing the stirrer speed).The approach used in this study can not only help understand how the stirrer design affects the die filling performance but also guide the optimization of feeder system and process settings.
基金the Puncak RM for the project under the grant 6733204-13069 to carry out the experiments。
文摘Graphene nanoplatelets(GNPs)have attracted tremendous interest due to their unique properties and bonding capabilities.This study focuses on the effect of GNP dispersion on the mechanical,thermal,and morphological behavior of GNP/epoxy nanocomposites.This study aims to understand how the dispersion of GNPs affects the properties of epoxy nanocomposite and to identify the best dispersion approach for improving mechanical performance.A solvent mixing technique that includes mechanical stirring and ultrasonication was used for producing the nanocomposites.Fourier transform infrared spectroscopy was used to investigate the interaction between GNPs and the epoxy matrix.The measurements of density and moisture content were used to confirm that GNPs were successfully incorporated into the nanocomposite.The findings showed that GNPs are successfully dispersed in the epoxy matrix by combining mechanical stirring and ultrasonication in a single step,producing well-dispersed nanocomposites with improved mechanical properties.Particularly,the nanocomposites at a low GNP loading of 0.1 wt%,demonstrate superior mechanical strength,as shown by increased tensile properties,including improved Young's modulus(1.86 GPa),strength(57.31 MPa),and elongation at break(4.98).The nanocomposite with 0.25 wt%GNP loading performs better,according to the viscoelastic analysis and flexural properties(113.18 MPa).Except for the nanocomposite with a 0.5 wt%GNP loading,which has a higher thermal breakdown temperature,the thermal characteristics do not significantly alter.The effective dispersion of GNPs in the epoxy matrix and low agglomeration is confirmed by the morphological characterization.The findings help with filler selection and identifying the best dispersion approach,which improves mechanical performance.The effective integration of GNPs and their interaction with the epoxy matrix provides the doorway for additional investigation and the development of sophisticated nanocomposites.In fields like aerospace,automotive,and electronics where higher mechanical performance and functionality are required,GNPs'improved mechanical properties and successful dispersion present exciting potential.
