基于目前新近提出的离散机械最优控制(Discrete Mechanics and Optimal Control)算法针对水下机器人的路径规划进行了仿真研究,设计的轨迹的轨迹经仿真实验能够按照能量或者最优的路径对设定的障碍进行有效避让。证明此算法能够有较强...基于目前新近提出的离散机械最优控制(Discrete Mechanics and Optimal Control)算法针对水下机器人的路径规划进行了仿真研究,设计的轨迹的轨迹经仿真实验能够按照能量或者最优的路径对设定的障碍进行有效避让。证明此算法能够有较强的实用性。同时文章涉及的理论算法为进一应用到其它类似机械装置,比如无人飞行器,机器人的路径规划与控制提供了一种新的方法思路。展开更多
The discrete element method (DEM) was used to simulate the flow characteristic and strength characteristic of the conditioned sands in the earth pressure balance (EPB) tunneling. In the laboratory the conditioned sand...The discrete element method (DEM) was used to simulate the flow characteristic and strength characteristic of the conditioned sands in the earth pressure balance (EPB) tunneling. In the laboratory the conditioned sands were reproduced and the slump test and the direct shear test of the conditioned sands were implemented. A DEM equivalent model that can simulate the macro mechanical characteristic of the conditioned sands was proposed,and the corresponding numerical models of the slump test and the shear test were established. By selecting proper DEM model parameters,the errors of the slump values between the simulation results and the test results are in the range of 10.3%-14.3%,and the error of the curves between the shear displacement and the shear stress calculated with the DEM simulation is 4.68%-16.5% compared with that of the laboratory direct shear test. This illustrates that the proposed DEM equivalent model can approximately simulate the mechanical characteristics of the conditioned sands,which provides the basis for further simulation of the interaction between the conditioned soil and the chamber pressure system of the EPB machine.展开更多
In this paper, we propose a scheme to generate an entangled state between two spatially separated movable mirrors by injecting the two-mode squeezed optical reservoir to the dissipative optomechanics, in which the mov...In this paper, we propose a scheme to generate an entangled state between two spatially separated movable mirrors by injecting the two-mode squeezed optical reservoir to the dissipative optomechanics, in which the movable mirrors can modulate the linewidth of the cavity modes. When the coupling between the mirrors and the corresponding cavity modes is weak, the two driven cavity fields can respectively behave as the squeezed-vacuum reservoir for the two movable mirrors by utilizing the effect of completely destructive interference of quantum noise. Thus the mechanical modes are prepared in a two-mode squeezed vacuum state. Moreover,when the coupling between the two mirrors and the cavities modes is strong, the entanglement between the two movable mirrors decreases because photonic excitation can preclude the completely destructive interference of quantum noise, but the movable mirrors are still entangled.展开更多
文摘基于目前新近提出的离散机械最优控制(Discrete Mechanics and Optimal Control)算法针对水下机器人的路径规划进行了仿真研究,设计的轨迹的轨迹经仿真实验能够按照能量或者最优的路径对设定的障碍进行有效避让。证明此算法能够有较强的实用性。同时文章涉及的理论算法为进一应用到其它类似机械装置,比如无人飞行器,机器人的路径规划与控制提供了一种新的方法思路。
基金Project (2007CB714006) supported by the National Basic Research Program of China
文摘The discrete element method (DEM) was used to simulate the flow characteristic and strength characteristic of the conditioned sands in the earth pressure balance (EPB) tunneling. In the laboratory the conditioned sands were reproduced and the slump test and the direct shear test of the conditioned sands were implemented. A DEM equivalent model that can simulate the macro mechanical characteristic of the conditioned sands was proposed,and the corresponding numerical models of the slump test and the shear test were established. By selecting proper DEM model parameters,the errors of the slump values between the simulation results and the test results are in the range of 10.3%-14.3%,and the error of the curves between the shear displacement and the shear stress calculated with the DEM simulation is 4.68%-16.5% compared with that of the laboratory direct shear test. This illustrates that the proposed DEM equivalent model can approximately simulate the mechanical characteristics of the conditioned sands,which provides the basis for further simulation of the interaction between the conditioned soil and the chamber pressure system of the EPB machine.
基金supported by the National Natural Science Foundation of China(Grant Nos.61275123,11474119 and 11304024)the National Basic Research Program of China(Grant No.2012CB921602)
文摘In this paper, we propose a scheme to generate an entangled state between two spatially separated movable mirrors by injecting the two-mode squeezed optical reservoir to the dissipative optomechanics, in which the movable mirrors can modulate the linewidth of the cavity modes. When the coupling between the mirrors and the corresponding cavity modes is weak, the two driven cavity fields can respectively behave as the squeezed-vacuum reservoir for the two movable mirrors by utilizing the effect of completely destructive interference of quantum noise. Thus the mechanical modes are prepared in a two-mode squeezed vacuum state. Moreover,when the coupling between the two mirrors and the cavities modes is strong, the entanglement between the two movable mirrors decreases because photonic excitation can preclude the completely destructive interference of quantum noise, but the movable mirrors are still entangled.
