To wirelessly obtain the accurate location and orientation of an objective and exert an appropriate guidance for the objective, a feasible approach is to enclose a small rectangular permanent mag- net in the objective...To wirelessly obtain the accurate location and orientation of an objective and exert an appropriate guidance for the objective, a feasible approach is to enclose a small rectangular permanent mag- net in the objective. The magnetic field, produced by the rectangular magnet can be detected by magnetic sensors outside the objective. With these sensor data, the 3D localization and 3D orienta- tion parameters can be computed based on the mathematic model of the rectangular magnet magnetic field. In this 6D localization and orientation system, we first obtain 5D parameters of the objective by dipole model, then based on these parameters we can obtain 6D parameters by the model of rectangular magnet magnetic field using the particle swarm optimization （PSO） algorithm. Simulation experiments show that the proposed approach achieves ~ood performance.展开更多
We report on the ice-templated preparation and sodium storage of ultrasmall SnO2 nanoparticles （3--4 nm） embedded in three-dimensional （3D） graphene （SnO2@3DG）. SnO2@3DG was fabricated by hydrothermal assembly w...We report on the ice-templated preparation and sodium storage of ultrasmall SnO2 nanoparticles （3--4 nm） embedded in three-dimensional （3D） graphene （SnO2@3DG）. SnO2@3DG was fabricated by hydrothermal assembly with ice-templated 3DG and a tin source. The structure and morphology analyses showed that 3DG has an interconnected porous architecture with a large pore volume of 0.578 cm^3·g^-1 and a high surface area of 470.5 m^2·g^-1. In comparison, SnO2@3DG exhibited a pore volume of 0.321 cmg.g^-1 and a surface area of 237.7 m^2·g^-1 with a homogeneous distribution of ultrasmall SnO2 nanoparticles in a 3DG network. SnO2@3DG showed a discharge capacity of 1,155 mA-h·g^-1 in the initial cycle, a reversible capacity of 432 mA·h·g^-1 after 200 cycles at 100 mA·g^-1 （with capacity retention of 85.7% relative to that in the second cycle）, and a discharge capacity of 210 mAh·g^-1 at a high rate of 800 mA·g^-1 This is due to the high distribution of SnO2 nanoparticles in the 3DG network and the enhanced facilitation of electron/ion transport in the electrode.展开更多
The symmetries of surfaces which can be embedded into the symmetries of the 3-dimensional Euclidean space R3 are easier to feel by human＇s intuition. We give the maximum order of finite group actions on （R3 E） amon...The symmetries of surfaces which can be embedded into the symmetries of the 3-dimensional Euclidean space R3 are easier to feel by human＇s intuition. We give the maximum order of finite group actions on （R3 E） among all possible embedded closed/bordered surfaces with given geometric/algebraic genus greater than 1 in R3. We also identify the topological types of the bordered surfaces realizing the maximum order, and findsimple representative embeddings for such surfaces.展开更多
In the paper, the authors show that any abstract smooth surface can be locally isometricallyembedded into a class of 3-dimensional spaces Nρ0 (ρ0>0) with the non-positively sectionalcurvature being fixed sufficie...In the paper, the authors show that any abstract smooth surface can be locally isometricallyembedded into a class of 3-dimensional spaces Nρ0 (ρ0>0) with the non-positively sectionalcurvature being fixed sufficiently small.展开更多
文摘To wirelessly obtain the accurate location and orientation of an objective and exert an appropriate guidance for the objective, a feasible approach is to enclose a small rectangular permanent mag- net in the objective. The magnetic field, produced by the rectangular magnet can be detected by magnetic sensors outside the objective. With these sensor data, the 3D localization and 3D orienta- tion parameters can be computed based on the mathematic model of the rectangular magnet magnetic field. In this 6D localization and orientation system, we first obtain 5D parameters of the objective by dipole model, then based on these parameters we can obtain 6D parameters by the model of rectangular magnet magnetic field using the particle swarm optimization （PSO） algorithm. Simulation experiments show that the proposed approach achieves ~ood performance.
文摘We report on the ice-templated preparation and sodium storage of ultrasmall SnO2 nanoparticles （3--4 nm） embedded in three-dimensional （3D） graphene （SnO2@3DG）. SnO2@3DG was fabricated by hydrothermal assembly with ice-templated 3DG and a tin source. The structure and morphology analyses showed that 3DG has an interconnected porous architecture with a large pore volume of 0.578 cm^3·g^-1 and a high surface area of 470.5 m^2·g^-1. In comparison, SnO2@3DG exhibited a pore volume of 0.321 cmg.g^-1 and a surface area of 237.7 m^2·g^-1 with a homogeneous distribution of ultrasmall SnO2 nanoparticles in a 3DG network. SnO2@3DG showed a discharge capacity of 1,155 mA-h·g^-1 in the initial cycle, a reversible capacity of 432 mA·h·g^-1 after 200 cycles at 100 mA·g^-1 （with capacity retention of 85.7% relative to that in the second cycle）, and a discharge capacity of 210 mAh·g^-1 at a high rate of 800 mA·g^-1 This is due to the high distribution of SnO2 nanoparticles in the 3DG network and the enhanced facilitation of electron/ion transport in the electrode.
基金supported by National Natural Science Foundation of China(Grant Nos.11371034 and 11501239)
文摘The symmetries of surfaces which can be embedded into the symmetries of the 3-dimensional Euclidean space R3 are easier to feel by human＇s intuition. We give the maximum order of finite group actions on （R3 E） among all possible embedded closed/bordered surfaces with given geometric/algebraic genus greater than 1 in R3. We also identify the topological types of the bordered surfaces realizing the maximum order, and findsimple representative embeddings for such surfaces.
文摘In the paper, the authors show that any abstract smooth surface can be locally isometricallyembedded into a class of 3-dimensional spaces Nρ0 (ρ0>0) with the non-positively sectionalcurvature being fixed sufficiently small.
