Spherical nanostructures with striped patterns on the surfaces resembling the essential structures of natural virus particles were constructed through a two-step self-assembly approach of polystyrene-boligo（acrylic a...Spherical nanostructures with striped patterns on the surfaces resembling the essential structures of natural virus particles were constructed through a two-step self-assembly approach of polystyrene-boligo（acrylic acid）（PS-b-oligo-AA） and poly（γ-benzyI L-glutamate）-b-poly（ethylene glycol）（PBLG-bPEG） copolymer mixtures in solution.On the basis of difference in hydrophilicity and self-assembly properties of the two copolymers,the two-step self-assembly process is realized.It was found that PS-boligo-AA copolymers formed spherical aggregates by adding a certain amount of water into polymer solutions in the first step.In the second step,two polymer solutions were mixed and water was further added,inducing the self-assembly of PBLG-b-PEG on the surfaces of PS-b-oligo-AA spheres to form striped patterns.In-depth study was conducted for the indispensable defects of striped patterns which are dislocations and ＋1/2 disclinations.The influencing factors such as the mixing ratio of two copolymers and the added water content in the first step on the morphology and defects of the striped patterns were investigated.This work not only presents an idea to interpret mechanism of the cooperative self-assembly behavior,but also provides an effective approach to construct virus-like particles and other complex structures with controllable morphology.展开更多
A hierarchical particle filter（HPF） framework based on multi-feature fusion is proposed.The proposed HPF effectively uses different feature information to avoid the tracking failure based on the single feature in a ...A hierarchical particle filter（HPF） framework based on multi-feature fusion is proposed.The proposed HPF effectively uses different feature information to avoid the tracking failure based on the single feature in a complicated environment.In this approach,the Harris algorithm is introduced to detect the corner points of the object,and the corner matching algorithm based on singular value decomposition is used to compute the firstorder weights and make particles centralize in the high likelihood area.Then the local binary pattern（LBP） operator is used to build the observation model of the target based on the color and texture features,by which the second-order weights of particles and the accurate location of the target can be obtained.Moreover,a backstepping controller is proposed to complete the whole tracking system.Simulations and experiments are carried out,and the results show that the HPF algorithm with the backstepping controller achieves stable and accurate tracking with good robustness in complex environments.展开更多
Microchannels are widely used in electronic device cooling due to their efficient heat dissipation per-formance,but particle deposition is still a major challenge limiting their performance.To design and optimize effi...Microchannels are widely used in electronic device cooling due to their efficient heat dissipation per-formance,but particle deposition is still a major challenge limiting their performance.To design and optimize efficient microfluidic devices,this paper proposes to introduce fan-shaped ribs within the microchannels to reduce particle deposition.The placement of fan ribs of different heights in the microchannel was first experimentally determined,and then the particle motion characteristics were further investigated by numerical simulations.The results show that the fan-shaped ribs can effectively reduce particle deposition and exhibit greater deposition inhibition with increasing rib height.The channel constriction induced by the rib structure promotes the radial diffusion of particles in the downstream,and at the same time significantly enhances the radial component of the particle flow,which is improved by 5.76%,7.98%,and 10.86%,respectively.In addition,recursive analysis revealed that the incorporation of fan-shaped ribs shifted the particle flow from a homogeneous,periodic mode to a more abrupt diffusion mode,which contributed to the improvement of particle dispersion.This study provides a new strategy without the use of surfactants,which provides a reference for the optimized design of microchannel cooling systems.展开更多
基金supported by the National Natural Science Foundation of China(Nos.21234002,51303055,21474029,and51573049)Support from projects of Shanghai municipality(Nos.15QA1401400 and 13JC1402000)
文摘Spherical nanostructures with striped patterns on the surfaces resembling the essential structures of natural virus particles were constructed through a two-step self-assembly approach of polystyrene-boligo（acrylic acid）（PS-b-oligo-AA） and poly（γ-benzyI L-glutamate）-b-poly（ethylene glycol）（PBLG-bPEG） copolymer mixtures in solution.On the basis of difference in hydrophilicity and self-assembly properties of the two copolymers,the two-step self-assembly process is realized.It was found that PS-boligo-AA copolymers formed spherical aggregates by adding a certain amount of water into polymer solutions in the first step.In the second step,two polymer solutions were mixed and water was further added,inducing the self-assembly of PBLG-b-PEG on the surfaces of PS-b-oligo-AA spheres to form striped patterns.In-depth study was conducted for the indispensable defects of striped patterns which are dislocations and ＋1/2 disclinations.The influencing factors such as the mixing ratio of two copolymers and the added water content in the first step on the morphology and defects of the striped patterns were investigated.This work not only presents an idea to interpret mechanism of the cooperative self-assembly behavior,but also provides an effective approach to construct virus-like particles and other complex structures with controllable morphology.
基金supported by the National Natural Science Foundation of China(61304097)the Projects of Major International(Regional)Joint Research Program NSFC(61120106010)the Foundation for Innovation Research Groups of the National National Natural Science Foundation of China(61321002)
文摘A hierarchical particle filter（HPF） framework based on multi-feature fusion is proposed.The proposed HPF effectively uses different feature information to avoid the tracking failure based on the single feature in a complicated environment.In this approach,the Harris algorithm is introduced to detect the corner points of the object,and the corner matching algorithm based on singular value decomposition is used to compute the firstorder weights and make particles centralize in the high likelihood area.Then the local binary pattern（LBP） operator is used to build the observation model of the target based on the color and texture features,by which the second-order weights of particles and the accurate location of the target can be obtained.Moreover,a backstepping controller is proposed to complete the whole tracking system.Simulations and experiments are carried out,and the results show that the HPF algorithm with the backstepping controller achieves stable and accurate tracking with good robustness in complex environments.
基金supports by National Natural Science Foundation of China(grant No.52376163)National Key Laboratory of Science and Technology on Aerodynamic Design and Research(grant No.614220121050327).
文摘Microchannels are widely used in electronic device cooling due to their efficient heat dissipation per-formance,but particle deposition is still a major challenge limiting their performance.To design and optimize efficient microfluidic devices,this paper proposes to introduce fan-shaped ribs within the microchannels to reduce particle deposition.The placement of fan ribs of different heights in the microchannel was first experimentally determined,and then the particle motion characteristics were further investigated by numerical simulations.The results show that the fan-shaped ribs can effectively reduce particle deposition and exhibit greater deposition inhibition with increasing rib height.The channel constriction induced by the rib structure promotes the radial diffusion of particles in the downstream,and at the same time significantly enhances the radial component of the particle flow,which is improved by 5.76%,7.98%,and 10.86%,respectively.In addition,recursive analysis revealed that the incorporation of fan-shaped ribs shifted the particle flow from a homogeneous,periodic mode to a more abrupt diffusion mode,which contributed to the improvement of particle dispersion.This study provides a new strategy without the use of surfactants,which provides a reference for the optimized design of microchannel cooling systems.
