共查询到20条相似文献,搜索用时 843 毫秒
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Miroslav Pardy 《International Journal of Theoretical Physics》2007,46(4):848-859
The Lagrange theory of particle motion in the noninertial systems is applied to the Foucault pendulum, isosceles triangle
pendulum and the general triangle pendulum swinging on the rotating Earth. As an analogue, planet orbiting in the rotating
galaxy is considered as the giant galactic gyroscope. The Lorentz equation and the Bargmann-Michel-Telegdi equations are generalized
for the rotation system. The knowledge of these equations is inevitable for the construction of LHC where each orbital proton
“feels” the Coriolis force caused by the rotation of the Earth. 相似文献
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Bo Liu 《Journal of sound and vibration》2008,312(3):509-525
This paper presents a systematic approach to stabilizing a kind of linear undamped systems of multiple degrees of freedom by using both position and delayed position feedbacks, namely, PDP feedbacks for short. For the fully actuated system, the approach enables one to complete the design of controller directly through the use of modal decoupling and a stability chart. For the under-actuated system, the approach includes two steps. The first step is to move all the eigenvalues of the system on the imaginary axis of the complex plane by using a position feedback, and the second step is to drag all the eigenvalues of the system to the left half open complex plane through the use of a delayed position feedback, which can be determined on the basis of sensitivity analysis of eigenvalues. Two examples, i.e., a fully actuated robotic manipulator and an under-actuated double inverted pendulum, are discussed in the paper to demonstrate the design of controllers for the two different types of systems and to support the efficacy of the proposed approach. 相似文献
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In this Letter, we propose a control method for establishing periodic rotation inherent in parametric pendulum based on a delayed feedback control. The experiments elucidate the existing range of periodic rotation in the domain of delay. The range of existence possibly represents the tolerance of proposed control with mistuned delay. It is confirmed that forced synchronization governs the existence and the width. The result assures that the frequency synchronization characteristics overcome the mistuned difference of delay in the control through entrainment. 相似文献
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H-type motion platform with linear motors is widely used in two-degrees-of-freedom motion systems, and one-direction dual motors need to be precisely controlled with strict synchronization for high precision performance. In this paper, a synchronous control method based on model decoupling is proposed. The dynamic model of an H-type air floating motion platform is established and one direction control using two motors with position dependency coupling is decoupled and converted into independent position and rotation controls, separately. For the low damping second-order oscillation system of the rotation control loop, a new fractional order biquad filtering method is proposed to generate an antiresonance peak to improve the phase and control gain of the open loop system, which can ensure system stability and quick attenuation for external disturbances. In the multiple-degree-of-freedom decoupled control loops, a systematic feedback controller design methodology is proposed to satisfy the given frequency domain design specifications; a feed-forward control strategy is also applied to compensate the disturbance torque caused by the platform motion. The simulation and experimental results demonstrate that the proposed synchronization control method is effective, and achieves better disturbance rejection performance than the existing optimal cancellation filtering method and biquad filtering method. 相似文献
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提出了外腔延时反馈半导体激光器法拉第效应控制下的新激光系统, 构造出两种类型结构光路, 建立了法拉第效应控制下的延时负反馈、延时正反馈激光动力学物理模型, 研究了激光混沌控制与反控制等. 利用法拉第效应原理及磁致旋光性和系统特点, 调节控制光路中的光旋转角度和光延时间可实现双参数控制激光器, 控制激光到双周期、三周期及多周期, 使激光产生拍动等现象, 反控制激光周期到混沌等. 发现了以磁致旋光角分布的激光混沌控制与反控制区域. 并研究了激光混沌控制与周期控制的动态情况, 演示讨论了激光态的转化演变过程等. 相似文献
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This paper presents a numerical study of an autoparametric system composed of two elements: a pendulum and an excited nonlinear oscillator. Owing to an inertial coupling between the two elements, different types of motion are possible, from periodic to chaotic. This study examines a linear induction of an energy harvester depending on the pendulum motion. The harvester consists of a cylindrical permanent magnet mounted on a rotor and of four windings fixed to the housing as a stator. When the pendulum is rotating or swinging, the converter is generating energy due to magnetic induction. In this paper, a method utilizing parametrical resonance for harvesting energy from low frequency vibrations is studied. The authors compare energy induced by different types of pendulum motion: swinging, rotation and chaotic dynamics. Additionally, voltage values for different parameters of excitation are estimated. 相似文献
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针对基础水平运动的弹簧摆的非线性动力学响应进行研究,利用拉格朗日方程建立了系统的动力学方程.将离散傅里叶变换、谐波平衡法以及同伦延拓方法相结合,对系统的周期响应进行求解,避免了传统方法计算中使用泰勒展开引起的小振幅的限制,与数值计算结果的对比表明该求解方法具有较高的精确度.利用Floquet理论分析了周期响应的稳定性,给出了基础运动振幅和频率对系统周期响应的影响.研究发现:对应某些基础频率和振幅,系统的周期响应可能发生Hopf分岔;利用数值计算研究了Hopf分岔后系统响应随基础频率和振幅的变化,发现系统出现了倍周期运动、拟周期运动和混沌等复杂的动力学行为.研究表明系统进入混沌的主要路径是拟周期环面破裂和阵发性. 相似文献
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A phenomenological study on the fitting method in real time has been done, and the method was applied to process and analyze the extensive data of a long period torsion pendulum used to determine Newtonian gravitational constant G. The result shows that the fitting method in real time is effective to determine the period of a torsion pendulum with a relative precision of 10-5 orders. 相似文献
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介绍一种傅科摆模拟演示装置.该装置具有体积小、操作方便、演示效果显著、演示时间短、摆振动平面的偏转周期可人为控制以及对摆锤的运动轨迹可作永久记录等优点. 相似文献
12.
Holger R. Dullin 《Zeitschrift für Physik B Condensed Matter》1994,93(4):521-528
Melnikov's method is applied to the planar double pendulum proving it to be a chaotic system. The parameter space of the double pendulum is discussed, and the integrable cases are identified. In the neighborhood of the integrable case of two uncoupled pendulums Melnikov's integral is evaluated using residue calculus. In the two limiting cases of one pendulum becoming a rotator or an oscillator, the parameter dependence of chaos, i.e. the width of the separatrix layer is analytically discussed. The results are compared with numerically computed Poincaré surfaces of section, and good agreement is found. 相似文献
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本文在实验教学中引入一种非线性混沌摆系统,通过调节混沌摆的驱动力周期演示了该非线性动力学系统出现混沌现象的过程,从而让学生了解混沌现象的参数敏感性、相图特点、频谱特性等基本特性.为了进一步了解该混沌摆的特性,本文建立了该非线性摆系统的简化动力学方程,在数值上对其进行了研究.基于动力学方程的数值模拟,克服了实验上相关参数定量改变困难、摆动稳定性不易控制、实验时间周期长等问题.在数值模拟中,通过改变不同参数得到了相图、频谱图以及分岔图,比较深入详细地对这种混沌摆的相关特性进行了描述,也有利于学生加深对混沌摆的理解. 相似文献
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本研究旨在提高扭摆精度。扭摆采用大理石——这取自地球的天然材料作摆盘;通过试验,挑选了Q值高、内耗小、剪切模量温度系数接近于零的恒弹性合金丝作为吊丝。特别是,我们把Saxl类型的每周期吸合一次的间断振荡摆回复到小阻尼情况下的自由振荡摆,减少对摆振动的人为干预;增加真空条件,以减少周围环境干扰,延长了阻尼时间;同时在摆盘中央安放多面反射镜环,增加测量点,变一周期仅测一次时间为同一周期测四次以上。这就提供了用计算机求阻尼振荡方程θi=Ae-ti/τsin(ωti+φ)数值解的条件,不但可直接测得周期T的变化,而且可望计算得振幅A、阻尼时间τ、初相角φ的变化。另外,在光电接收方面也作了一些改进。通过这些措施,我室的精密扭摆对周期的探测精度已比美国Saxl 1964年发表第一篇文章时的扭摆精度提高100倍;比其运转17年,经一再改进的扭摆精度提高10倍。测量有效数字6位至7位,周期相对误差一般达2×10-6,最佳状况可达8×10-7,基本达到预期设计要求,为将来探测引力异常,“区分长期间与短期间内频率起伏”提供了可能性。
关键词: 相似文献
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由于不同的非惯性系具有不同的加速度,导致单摆在不同的非惯性系中具有不同的振动周期,所以有必要掌握非惯性系下单摆振动周期的计算.基本的计算方法是利用非惯性系动力学方程,结合受力分析求解,但这种方法既要考虑惯性力,又需要进行力的分解,比较麻烦.本文通过引入惯性力势能,给出非惯性系机械能守恒定律,并利用机械能守恒定律对处于特定非惯性系中的单摆周期进行分析计算,得出非惯性系中单摆的振动周期不仅与单摆自身属性有关,而且与非惯性系的运动加速度或角速度有关的结论. 相似文献
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对不确定混沌系统控制问题, 研究了一种基于径向基函数神经网络(radial basis function neural network, RBFNN)的反馈补偿控制方法. 该方法首先用RBFNN对混沌系统的动力学特性进行学习, 然后用训练好的RBFNN模型对混沌系统进行反馈补偿控制. 该方法的特点是不需要被控混沌系统的数学模型,可以快速跟踪任意给定的参考信号. 数值仿真试验表明了该控制方法不仅具有响应速度快、控制精度高, 而且具有较强的抑制混沌系统参数摄动能力和抗干扰能力. 相似文献