A systematic method for swimming control of the underwater snake-like robot is still lacking. We construct a simulation platform of the underwater snake-like robot swimming based on Kane's dynamic model and centra...A systematic method for swimming control of the underwater snake-like robot is still lacking. We construct a simulation platform of the underwater snake-like robot swimming based on Kane's dynamic model and central pattern generator(CPG). The partial velocity is deduced. The forces which contribute to dynamics are determined by Kane's approach. Hydrodynamic coefficients are determined by experiments. Then, we design a CPG-based control architecture implemented as the system of coupled nonlinear oscillators. The CPG, like its biological counterpart, can produce coordinated patterns of rhythmic activity while being modulated by simple control parameters. The relations between the CPG parameters and the speed of the underwater snake-like robot swimming are investigated. Swimming in a straight line, turning, and switching between swimming modes are implemented in our simulation platform to prove the feasibility of the proposed simulation platform. The results show that the simulation platform can imitate different swimming modes of the underwater snake-like robot.展开更多
A new theoretical method to study super-multiperiod superlattices has been developed.The method combines the precision of the 8-band kp-method with the flexibility of the shooting method and the Monte Carlo approach.T...A new theoretical method to study super-multiperiod superlattices has been developed.The method combines the precision of the 8-band kp-method with the flexibility of the shooting method and the Monte Carlo approach.This method was applied to examine the finest quality samples of super-multiperiod Al_(0.3)Ga_(0.7)As/GaAs superlattices grown by molecular beam epitaxy.The express photoreflectance spectroscopy method was utilized to validate the proposed theoretical method.For the first time,the accurate theoretical analysis of the energy band diagram of super-multiperiod superlattices with experimental verification has been conducted.The proposed approach highly accurately determines transition peak positions and enables the calculation of the energy band diagram,transition energies,relaxation rates,and gain estimation.It has achieved a remarkably low 5%error compared to the commonly used method,which typically results in a 25%error,and allowed to recover the superlattice parameters.The retrieved intrinsic parameters of the samples aligned with XRD data and growth parameters.The proposed method also accurately predicted the escape of the second energy level for quantum well thicknesses less than 5 nm,as was observed in photoreflectance experiments.The new designs of THz light-emitting devices operating at room temperature were suggested by the developed method.展开更多
Hydrodynamic force is an important factor that affects the performance of underwater vehicle.Adapting to the current underwater environment by changing its shape is an important feature of underwater snake-like robots...Hydrodynamic force is an important factor that affects the performance of underwater vehicle.Adapting to the current underwater environment by changing its shape is an important feature of underwater snake-like robots(USLR).An experiment was implemented to verify the swimming along the straight line of USLR.A simulation platform is also established for the analysis of the swimming of USLR.To figure out adaptive swimming of USLR to different underwater environments,the relationships between CPG parameters and maximum swimming speed have been discussed,and the switching between different swimming modes has been implemented.展开更多
A thermodynamic density of states, electron density in the subband and the entropy of the gas as function of the temperature and the total two-dimensional electron density are studied. Semiconductor conduction band di...A thermodynamic density of states, electron density in the subband and the entropy of the gas as function of the temperature and the total two-dimensional electron density are studied. Semiconductor conduction band dispersion is described by the simplified Kane model. Numerical simulation shows that with an increase in the total electron concentration, thermodynamic density of states at low temperatures changes abruptly and smoothes jumps at high temperatures. This change manifests itself in the peculiar thermodynamic characteristics. The results are used to interpret existing experimental data.展开更多
For nonparabolic dispersion law is determined by the density of the energy states (Ns) in a quantizing magnetic field. The effect of temperature on the expansion of the Lan-dau levels of electrons semiconductors with ...For nonparabolic dispersion law is determined by the density of the energy states (Ns) in a quantizing magnetic field. The effect of temperature on the expansion of the Lan-dau levels of electrons semiconductors with the nonquadratic dispersion is studied. The density of states at low temperatures is calculated from data on high-tem- perature Ns.展开更多
Higher-order topological phase in 2-dimensional(2D)systems is characterized by in-gap corner states,which are hard to detect and utilize.We numerically investigate transport properties of topological corner states in ...Higher-order topological phase in 2-dimensional(2D)systems is characterized by in-gap corner states,which are hard to detect and utilize.We numerically investigate transport properties of topological corner states in 2D honeycomb lattice,where the second-order topological phase is induced by an in-plane Zeeman field in the conventional Kane–Mele model.Through engineering multihollow structures with appropriate boundaries in honeycomb lattice,multiple corner states emerge,which greatly increases the probability to observe them.A typical two-probe setup is built to study the transport features of a diamond-shaped system with multihollow structures.Numerical results reveal the existence of global resonant states in bulk insulator,which corresponds to the resonant tunneling of multiple corner states and occupies the entire scattering region.Furthermore,based on the well separated energy levels of multiple corner states,a single-electron source is constructed.展开更多
基金the National Natural Science Foundation of China(No.51009091)the Special Research Fund for the Doctoral Program of Higher Education of China(No.20100073120016)
文摘A systematic method for swimming control of the underwater snake-like robot is still lacking. We construct a simulation platform of the underwater snake-like robot swimming based on Kane's dynamic model and central pattern generator(CPG). The partial velocity is deduced. The forces which contribute to dynamics are determined by Kane's approach. Hydrodynamic coefficients are determined by experiments. Then, we design a CPG-based control architecture implemented as the system of coupled nonlinear oscillators. The CPG, like its biological counterpart, can produce coordinated patterns of rhythmic activity while being modulated by simple control parameters. The relations between the CPG parameters and the speed of the underwater snake-like robot swimming are investigated. Swimming in a straight line, turning, and switching between swimming modes are implemented in our simulation platform to prove the feasibility of the proposed simulation platform. The results show that the simulation platform can imitate different swimming modes of the underwater snake-like robot.
基金The work was supported by the Ministry of Education and Science of the Russian Federation in the framework of experimental research(Nos.075-01438-22-06 and FSEE-2022-0018)the Russian Science Foundation in theoretical research(No.RSF 23-29-00216).
文摘A new theoretical method to study super-multiperiod superlattices has been developed.The method combines the precision of the 8-band kp-method with the flexibility of the shooting method and the Monte Carlo approach.This method was applied to examine the finest quality samples of super-multiperiod Al_(0.3)Ga_(0.7)As/GaAs superlattices grown by molecular beam epitaxy.The express photoreflectance spectroscopy method was utilized to validate the proposed theoretical method.For the first time,the accurate theoretical analysis of the energy band diagram of super-multiperiod superlattices with experimental verification has been conducted.The proposed approach highly accurately determines transition peak positions and enables the calculation of the energy band diagram,transition energies,relaxation rates,and gain estimation.It has achieved a remarkably low 5%error compared to the commonly used method,which typically results in a 25%error,and allowed to recover the superlattice parameters.The retrieved intrinsic parameters of the samples aligned with XRD data and growth parameters.The proposed method also accurately predicted the escape of the second energy level for quantum well thicknesses less than 5 nm,as was observed in photoreflectance experiments.The new designs of THz light-emitting devices operating at room temperature were suggested by the developed method.
文摘Hydrodynamic force is an important factor that affects the performance of underwater vehicle.Adapting to the current underwater environment by changing its shape is an important feature of underwater snake-like robots(USLR).An experiment was implemented to verify the swimming along the straight line of USLR.A simulation platform is also established for the analysis of the swimming of USLR.To figure out adaptive swimming of USLR to different underwater environments,the relationships between CPG parameters and maximum swimming speed have been discussed,and the switching between different swimming modes has been implemented.
文摘A thermodynamic density of states, electron density in the subband and the entropy of the gas as function of the temperature and the total two-dimensional electron density are studied. Semiconductor conduction band dispersion is described by the simplified Kane model. Numerical simulation shows that with an increase in the total electron concentration, thermodynamic density of states at low temperatures changes abruptly and smoothes jumps at high temperatures. This change manifests itself in the peculiar thermodynamic characteristics. The results are used to interpret existing experimental data.
文摘For nonparabolic dispersion law is determined by the density of the energy states (Ns) in a quantizing magnetic field. The effect of temperature on the expansion of the Lan-dau levels of electrons semiconductors with the nonquadratic dispersion is studied. The density of states at low temperatures is calculated from data on high-tem- perature Ns.
基金supported by the National Natural Science Foundation of China(Grant Nos.12174262 and 11774238)the Natural Science Foundation of Guangdong(Grant No.2020A1515011418)the Natural Science Foundation of Shenzhen(Grant Nos.20200812092737002,JCYJ20190808150409413,JCYJ20190808115415679,and JCYJ20190808152801642).
文摘Higher-order topological phase in 2-dimensional(2D)systems is characterized by in-gap corner states,which are hard to detect and utilize.We numerically investigate transport properties of topological corner states in 2D honeycomb lattice,where the second-order topological phase is induced by an in-plane Zeeman field in the conventional Kane–Mele model.Through engineering multihollow structures with appropriate boundaries in honeycomb lattice,multiple corner states emerge,which greatly increases the probability to observe them.A typical two-probe setup is built to study the transport features of a diamond-shaped system with multihollow structures.Numerical results reveal the existence of global resonant states in bulk insulator,which corresponds to the resonant tunneling of multiple corner states and occupies the entire scattering region.Furthermore,based on the well separated energy levels of multiple corner states,a single-electron source is constructed.
