用钕铁硼制作阻尼振动、受迫振动及共振演示仪

利用稀土永磁性材料钕铁硼(Nd-Fe-B)设计制作出了新型阻尼振动、受迫振动及共振演示仪.该演示仪器可演示阻尼振动的3种状态(欠阻尼状态、临界阻尼状态、过阻尼状态)、受迫振动及共振现象.     

能量共振及其频率条件

本文提出线性受迫谐振子能量共振的概念及其频率条件，此频率出现在振幅共振与速度、功率共振的频率之间．     

用功能原理讨论稳定受迫振动

应用功能原理讨论稳定受迫振动,得出受迫振动与强迫力之间的相位差关系式(9),定量讨论了在一周期中速度共振和振幅共振的能量,以及强迫力做功输入能量的阻力做功耗散能量的关系,从而得出了一些有意义的结论.     

自制受迫振动与共振演示探究仪

教材手摇式受迫振动与手动共振实验装置稳定性差,演示的实验现象不直观且不连续,均未达到定量探究.针对装置和实验现象的不足,制作了受迫振动与共振演示探究仪,该装置能直观演示阻尼振动、受迫振动和共振现象;借助Tracker、Origin和Pr视频软件的辅助能更高效率地实现可视化教学.     

用波尔共振仪研究混沌现象

用半导体激光器作为光源,用鼠标作为位移传感器,将波尔共振仪摆轮的振动转化为鼠标的运动轨迹,并通过Ghost Mouse-Setup软件记录鼠标轨迹,最后通过Labview软件对记录的轨迹进行信号处理,通过观察分析吸引子来研究波尔共振仪中的混沌现象。实验结果表明:波尔共振仪中摆轮做阻尼振动时,其振动振幅出现随时间逐渐减小,最终停止摆动的确定性规律,但每一次摆轮的运动过程都是随机的,各不相同。只要时间足够长,摆轮最终都会收缩成一点,形成稳定的焦点,即混沌吸引子。这就是波尔共振仪中摆轮做阻尼振动出现的混沌现象。     

从功能关系讨论受迫振动的振幅

本文通过由平衡位置到最大位移以及由最大移到平衡位置的两个四分之一周期中外力作的定量计算，根据功能原理，得到了各种情况下受迫振动的振幅均小于位移共振幅以及受迫振幅虽与强迫力频率有关但却稳定的结论，并给出了速度共振的振幅表达式。     

受迫阻尼振动系统动力学性质的研究

对受迫阻尼振动系统3种情况的动力学行为以及它们的能量状况作了较深入的定量研究,该研究对分析我们遇到的实际受迫振动系统有一定的指导意义。     

相位差法测受迫振动的阻尼系数

利用音叉在受迫阻尼振动中速度与驱动力之间的相位差测定了阻尼系数.该方法在系统的稳定状态下读数,克服了通常所用的振幅衰减方法中的不稳定性,可降低人为因素给测量带来的误差.     

音叉弦线受迫共振系统的计算机模拟研究

音叉弦线受迫共振系统的计算机模拟研究吴本科，蒋凉（合肥工业大学２３０００９）音叉带动弦线形成驻波并非能由简单理论而得到圆满解释［１］［２］，通常的注意力多集中在弦线的机械波上，而对弦线的初始振动以及它与音叉的关系研究很少，既使有个别研究［３］也只能给...     

非平衡功与自由能差的关系

以一个受迫谐振子为对象证明了Jarzynski等式,即两平衡态的自由能差可以用它们之间非平衡功的指数平均来表示,这里两个态的转换是在有限时间完成的.当外部驱动力是一个周期信号时,发现外界对系统所做的广义功存在一个共振现象.     

Chaos and reverse transitions in stochastic resonance

Stochastic resonance is a phenomenon that a weak signal can be amplified and optimized by the assistance of noise in bistable system. There is still not enough research on the mutual interplay among system, noise and signal. In this paper, we study the role of every parameter in nonlinear transfer and discover chaos phenomenon in stochastic resonance. To measure the influence of chaos, a trajectory decision function was proposed. Based on this function, we found two forms of stochastic resonance, clockwise resonance and counterclockwise resonance.     

Landau damping of electrons with bouncing motion in a radio-frequency plasma

One-dimensional particle simulations have been conducted to study the interaction between a radio-frequency electrostatic wave and electrons with bouncing motion. It is shown that bounce resonance heating can occur at the first few harmonics of the bounce frequency (nω_b,n=1,2,3,...). In the parameter regimes in which bounce resonance overlaps with Landau resonance, the higher harmonic bounce resonance may accelerate electrons at the velocity much lower than the wave phase velocity to Landau resonance region, enhancing Landau damping of the wave. Meanwhile, Landau resonance can increase the number of electrons in the lower harmonic bounce resonance region. Thus electrons can be efficiently heated. The result might be applicable for collisionless electron heating in low-temperature plasma discharges.     

弯曲共振法测量材料的杨氏模量实验改进

针对共振法测量杨氏模量实验中存在精确度和获取共振频率上的不足,在原装置中增加高度调节装置和水平仪,通过实验操作对共振阶数进行判断.实验结果证明选用共振二阶型态测量杨氏模量较有优势.     

具有涨落质量的线性谐振子的共振行为

Brown运动中,环境分子的吸附能力使Brown粒子的质量存在涨落. 本文将这一质量涨落建模为对称双态噪声, 以考察其对系统共振行为的影响. 首先,利用Shapiro-Loginov公式和Laplace变换推导系统稳态响应振幅的解析表达式, 并根据相应数值结果, 研究系统的共振行为; 然后, 通过仿真实验对理论与实际的符合情况进行对比分析, 验证理论结果的可靠性及其对实际应用的指导意义. 理论结果和仿真实验均表明: 1) 系统稳态响应为频率与外部驱动相同的简谐振动; 2) 稳态响应振幅随外部驱动频率、振子质量、噪声强度及相关率的变化分别相应出现真实共振、参数诱导共振、随机共振现象; 3) 质量涨落噪声导致系统共振形式出现多样化现象, 包括单峰共振、单峰单谷共振、双峰共振等. 关键词： 质量涨落噪声 随机共振 双峰共振     

Extraction of resonance parameters from meson production reaction

We have developed an analytic continuation method for extracting parameters of nucleon resonances within a Hamiltonian formulation of meson-nucleon reactions. The method was tested for simple solvable models and then applied for our recent coupled channels model （πN, ηN, π△, ρN, and σN ） of the π＊N and γ＊N reactions. The resonance pole positions and their properties are studied for P11and P11 channels.     

固体材料拉伸波速的共振法测量

文章系统论述了利用弯曲共振和纵向共振两种方式测量拉伸波速的方法，作者改进了传统的纵向共振测试装置，指出了两种方式各自的适用性．在理论上纵向共振方法更为严谨，且误差来源较少，从而具有较高测量精度，实验上测量操作更为方便．     

表面等离子体波传感器角度敏感特性的研究

研究了表面等离子体波共振(SPR)光谱对入射光角度变化的敏感特性,提出了对共振波长和共振强度进行双参数检测的方法。理论分析和实验表明,共振波长和共振强度同时对入射角度的微小改变非常敏感,且相互之间具有良好的对应关系。通过选择合适的棱镜、金属薄膜、调制层等结构参数,能有效地调整角度敏感的范围和灵敏度。     

Resonance condition for asymmetrical triple-barrier structures

The resonance condition for triple-barrier structures with arbitrary potential is studied systematically. The quasisymmetrical triple-barrier (QST) resonance mode and the quasi-asymmetrical double-barrier (QAD) resonance mode may both exist in asymmetric triple-barrier structures. The QST consists of two submodes: a normal mode (doublet) and a degenerate mode (singlet). The critical condition for distinguishing the two modes is examined. It is confirmed that there are both unity resonant transmission and below-unit resonant transmission in the asymmetrical triple-barrier structure. Furthermore, the wavefunctions of an electron at resonance level are calculated and the confining phenomenon is studied.     

High-frequency modes in magnetic spectra of carbonyl iron

Magnetic spectra of composites filled with carbonyl iron powder were measured at frequencies of up to 30 GHz. Two previously unknown intensive high-frequency peaks of magnetic absorption have been found at frequencies surpassing the ferromagnetic resonance frequency. The peaks may be attributed to Aharoni exchange resonance modes. The resonances are excited inside magnetically isolated nanocrystallites that constitute carbonyl iron grains. Features of homogeneous ferromagnetic resonance in carbonyl iron powder grains are also discussed.     

表面磁极化子的回旋共振性质

在磁场中有不少的极性晶体,电子和体纵光学声子的耦合弱,而与表面光学声子的耦合强。本文讨论电子和体纵光学声子耦合弱,与表面光学声子耦合强时对表面磁极化子的性质的影响。采用改进了的线性组合算符法导出了磁场中表面极化子的回旋共振频率和回旋共振质量,对AgCl晶体进行了数值计算。结果表明,磁场中表面极化子的回旋共振频率和回旋共振质量随磁场的增加而增加。