利用线性组合算符和幺正变换相结合的方法,研究了声子色散对抛物量子点中弱耦合磁极化子电子周围光学声子平均数的影响.计及纵光学(LO)声子色散,在抛物近似下导出了基态能量与量子点有效受限长度、声子色散系数、回旋共振频率以及电子-声子耦合常数之间的关系,电子周围光学声子平均数与声子色散系数以及电子-声子耦合常数的关系.数值计算结果表明在弱耦合情况下抛物量子点中磁极化子的基态能量随声子色散系数的增大而减小;电子周围光学声子平均数随声子色散系数增大而增大,随电子-声子耦合常数的增大而增大.

The influence of phonon dispersion on the average phonon number of weak-coupling magnetopolaron in a parabolic quantum dot is studied by using the linear-combination operator and unitary transformation meth-od.Taking account of the longitudinal optical ( LO) phonons dispersion in a parabolic approximation, the ground state energy as a function of the effective confinement length, the coefficient of the phonon dispersion, the cyclo-tron-resonance frequency and the electron-phonon coupling constant and the average number of virtual pho-nons around the electron as a function of the coefficient of the phonon dispersion and the electron-phonon cou-pling constant are obtained.Numerical calculations results show that the ground state energy decreases with in-creasing the coefficient of the phonon dispersion;the average number of virtual phonons around the electron in-creases with increasing the electron-phonon coupling constant and the coefficient of the phonon dispersion in the ele

声子晶体的负折射成像已成为当今国内外研究的热点问题.首先通过分析弹性波激励声子晶体元胞的局域共振响应特性,计算了局域共振型声子晶体的带隙特性,以此为基础构建了声子晶体相应的实验模型.然后基于Comsol仿真平台,把声子晶体元胞在XY平面内排列成声子晶体板后,模拟了近场点声源通过声子晶体板的负折射声成像过程.同时计算了模拟两个理想点声源经过声子晶体板后负折射成像的特性.仿真结果表明:声子晶体能较好地分辨两个点声源所成的像,点像的最小分辨率可达到0.2λ,很好地突破了声学成像中的衍射极限.

The negative refraction imaging of phononic crystal has become a research focus at home and abroad .Localized resonant resonance characteristics of elastic wave excitation phononic crystal cell were analyzed ,and the phonon crystal band gap was calculated ,on this basis ,corresponding ex-perimental model of phononic crystal was built .Based on comsol simulation platform ,the phononic crystal cell were arranged as phononic crystal plate in XY plane ,and negative refraction acoustic im-aging process was simulated when near field acoustic source past through phononic crystal plate .Nega-tive refraction imaging characteristics was obtained when two ideal point sound source past through the phononic crystal plate .Simulation results show that phononic crystals can distinguish better the image which is made by two sound source ,the minimum resolution can reach 0 .2λ,so it can make a breakthrough in the diffraction limit of the acoustic imaging .

用改进的Lee-Low-Pines变分方法研究纤锌矿In0.19Ga0.81N/GaN量子阱结构中束缚极化子能量和结合能等问题,给出基态结合能、不同支长波光学声子对能量和结合能的贡献随阱宽和杂质中心位置变化的数值结果.在数值计算中包括了该体系中声子频率的各向异性和内建电场对能量和结合能的影响、以及电子和杂质中心与长波光学声子的相互作用.研究结果表明,In0.19Ga0.81N/GaN量子阱材料中光学声子和内建电场对束缚极化子能量和结合能的贡献很大,它们都引起能量和结合能降低.结合能随着阱宽的增大而单调减小,窄阱中减小的速度快,而宽阱中减小的速度慢.不同支声子对能量和结合能的贡献随着阱宽的变化规律不同.没有内建电场时,窄阱中,定域声子贡献小于界面和半空间声子贡献,而宽阱中,定域声子贡献大于界面和半空间声子贡献.有内建电场时,定域声子贡献变小,而界面和半空间声子贡献变大,声子总贡献也有明显变化.在In0.19Ga0.81N/GaN量子阱中,光学声子对束缚极化子能量和结合能的贡献比GaAs/Al0.19Ga0.81As量子阱中的相应贡献(约3.2—1.8和1.6—0.3 meV)约大一个数量级.阱宽(d=8 nm)不变时,在In0.19Ga0.81N/GaN量子阱中结合能随着杂质中心位置Z0的变大而减小,并减小的速度变快.随着Z0的

The energies and binding energies of the bound polarons in a wurtzite In0.19Ga0.81N/GaN quantum well are inves-tigated by means of a modified Lee-Low-Pines variational method. Contributions of ground state binding energies and different branches of a longwave optical phonon mode to the energies and binding energies of the bound polarons as a function of the well width and impurity center position are given. Effects of the anisotropy of phonon frequency and built-in electric field in the system on the energies and binding energies, and the electron and impurity center-optical phonon interaction, are included in the calculations. Results show that the contributions of optical phonons and built-in electric field to the ground state energy and binding energy of the bound polarons in a wurtzite In0.19Ga0.81N/GaN quantum well are very large, and result in the reduction of energy and binding energy. The binding energy decreases monotonically with increasing well width, and the speed of decrea

以单极子噪声源与单极子抗噪声源组成的声场为研究对象，得出用单极子抗噪声源控制单极子噪声源，使两声源所在的平面空间内的总声功率最小时两声源本身的声强的关系。并计算空间内任意一点的径向平均有功声强。得出最小径向平均有功声强与声源的频率和两声源的距离有关，在一定频率下，两声源距离越近，控制后的径向平均有功声强越小，距离一定的情况下，频率越小，径向平均有功声强越小。通过仿真实验进行验证，并最终得到某些低频噪声达到全空间消声时噪声源与抗噪声源的最短距离。

This article studies the sound fields of the monopole noise source and monopole anti-noise source. The relationship between the sound intensity of the noise source and the sound intensity of the anti-noise source under the condition of the least sound power in the plat sound field is obtained. In addition, the radial average active sound intensity at any point in the sound field is calculated, which is found to be related to the frequency of the sound source and the distance between the two sources. For a fixed frequency, the radial average active sound intensity decreases with the distance between the two sources increasing after the control. For the fixed distance between the two sources, the radial average active sound intensity decreases with the frequency decreasing after the control. Through the MATLAB simulation, the shortest distance between the noise source and anti-noise source when the sound intensities of some low-frequency noises in the whole space vanish is obtained.

本文将声波高吸收材料引入声子晶体，设计并制备一种由填充吸声棉的开缝钢管阵列形成的新型环形声子晶体结构，详细研究了吸声棉的声波高吸收性能对声子晶体禁带特性的影响。首先，实验测试了该声子晶体对声波的透射系数，作为对比，同时测试了在钢管内部不填充吸声棉时的透射系数；其次，建立了含有吸声棉的声子晶体有限元模型，采用有限元法仿真计算了该结构声子晶体的禁带特性；最后，通过改变散射体中吸声棉的比重，研究了吸声棉曝光度对禁带的影响规律。理论和实验结果表明，将吸声材料引入散射体内部时，材料的吸声特性并不会对禁带产生不利影响，而禁带外的声波则由于受到吸声材料的强烈吸收，表现出较低的透射系数，从而使声子晶体在整个频段表现出优良的降噪特性。

In this paper, by introducing the sonic high absorption material into the phononic crystal, a new circular phononic crystal composed of periodic slotted steel tubes with glass wool filled is designed and manufactured, and the effect of the high absorption property of the glass wool on the band gap of the phononic crystal is investigated detailedly. Firstly, the transmission coefficient of the phononic crystal is measured by experiment platform, and as a comparison, the transmission coefficient of the phononic crystal composed of tubes without glass wool filled inside is also measured;Secondly, the phononic crystal finite element method which contains the glass wool is built and the band characteristics are calculated;Finally, by varying the ratio of the glass wool in the inclusion, the influence of the surface exposure degree of the glass wool on the band gap of the phononic crystal is studied. Both the theoretical and experimental results show that, the introduction of the glass wool