针对受外界海洋环境扰动的欠驱动船舶航向保持控制问题,设计一种基于鲁棒自适应扰动观测器的船舶航向保持控制算法。通过Lyapunov理论,证明设计的控制器半全局一致最终有界稳定(Semi-Global Uniform and Ultimately Bounded,SGUUB)。以...针对受外界海洋环境扰动的欠驱动船舶航向保持控制问题,设计一种基于鲁棒自适应扰动观测器的船舶航向保持控制算法。通过Lyapunov理论,证明设计的控制器半全局一致最终有界稳定(Semi-Global Uniform and Ultimately Bounded,SGUUB)。以“育鲲”轮为船舶模型,建立考虑外界干扰的非线性Nomoto数学模型,在4级海况下进行航向保持仿真试验,并且与已有的控制算法进行对比,仿真结果表明:在达到稳定之后,基于鲁棒自适应扰动观测器的船舶航向保持器能使舵机操舵频率明显下降,舵机损耗较低,进一步验证提出的控制器算法具有较好的控制效果和鲁棒性。展开更多
We investigate global entanglement in the ground state of single-molecular magnet Na9[Cu3Na3（H2O）9（α- AsW9O33）2]-26H2O with an external magnetic field. The concurrence, tangle, and measure function Q, which chara...We investigate global entanglement in the ground state of single-molecular magnet Na9[Cu3Na3（H2O）9（α- AsW9O33）2]-26H2O with an external magnetic field. The concurrence, tangle, and measure function Q, which characterize the pairwise entanglement, 3-party entanglement and total entanglement, respectively, are calculated numerically at zero temperature. The results show that the magnitude and direction of the applied magnetic field play a significant role in the properties of three kinds of entanglement measures. We give a physical interpretation of the variation of the global entanglement with the magnetic field. Finally, the phase diagram of the global entanglement characterized by the critical magnetic fields is presented.展开更多
According to Hertz theory, the difference of contact stress for non-circular gears and equivalent gears is compared in the paper, a calculating method of contact stress for non-circular gears by using equivalent gears...According to Hertz theory, the difference of contact stress for non-circular gears and equivalent gears is compared in the paper, a calculating method of contact stress for non-circular gears by using equivalent gears is researched, and computing formulas of power and rotation speed for equivalent gears are deduced. A numerical simulation of contact stress for non-circular gears has also been conducted based on the finite element method. By the comparison of fitting curves, the feasibility of using equivalent gears instead of non-circular gears to calculate the contact stress is testified.展开更多
文摘针对受外界海洋环境扰动的欠驱动船舶航向保持控制问题,设计一种基于鲁棒自适应扰动观测器的船舶航向保持控制算法。通过Lyapunov理论,证明设计的控制器半全局一致最终有界稳定(Semi-Global Uniform and Ultimately Bounded,SGUUB)。以“育鲲”轮为船舶模型,建立考虑外界干扰的非线性Nomoto数学模型,在4级海况下进行航向保持仿真试验,并且与已有的控制算法进行对比,仿真结果表明:在达到稳定之后,基于鲁棒自适应扰动观测器的船舶航向保持器能使舵机操舵频率明显下降,舵机损耗较低,进一步验证提出的控制器算法具有较好的控制效果和鲁棒性。
基金supported by the National Natural Science Foundation of China(Grant No.11274102)the Program for New Century Excellent Talents in Universities,China(Grant No.NCET-11-0960)the Specialized Research Fund for the Doctoral Program of Higher Education of China(Grant No.20134208110001)
文摘We investigate global entanglement in the ground state of single-molecular magnet Na9[Cu3Na3（H2O）9（α- AsW9O33）2]-26H2O with an external magnetic field. The concurrence, tangle, and measure function Q, which characterize the pairwise entanglement, 3-party entanglement and total entanglement, respectively, are calculated numerically at zero temperature. The results show that the magnitude and direction of the applied magnetic field play a significant role in the properties of three kinds of entanglement measures. We give a physical interpretation of the variation of the global entanglement with the magnetic field. Finally, the phase diagram of the global entanglement characterized by the critical magnetic fields is presented.
文摘According to Hertz theory, the difference of contact stress for non-circular gears and equivalent gears is compared in the paper, a calculating method of contact stress for non-circular gears by using equivalent gears is researched, and computing formulas of power and rotation speed for equivalent gears are deduced. A numerical simulation of contact stress for non-circular gears has also been conducted based on the finite element method. By the comparison of fitting curves, the feasibility of using equivalent gears instead of non-circular gears to calculate the contact stress is testified.
