Quantum Heat Transfer in a Harmonic Chain with a Dephasing Reservoir

The quantum heat transfer in a harmonic chain with a dephasing reservoir is investigated based on the master equation method. The incoming phonons from the thermal reservoir will be scattered back partially into the reservoir at the contact site, leading to the contact resistance. Dephasing in the harmonic chain suppresses the transmitting of scattered phonons into the harmonic chain. Then the heat flux in the chain is reduced by dephasing. However, the heat t~ux is symmetric to interchanging the reservoirs temperatures even with the dephasing. Therefore, the thermal rectification csnnot be realized with pure depha~ing only.     

The Exact Harmonic Metric for a Moving Reissner-Nordstrom Black Hole

The exact harmonic metric for a moving Reissner-Nordstr6m black hole with an arbitrarily constant speed is presented. As an application, the post-Newtonian dynamics of a non-relativistic particle in this field is calculated.     

μ介子氢原子在双色激光场驱动下产生单个仄秒脉冲

本文利用强场近似理论研究了一束强度稍弱的X射线脉冲辅助另一束强X射线脉冲作用于μ介子氢原子产生高次谐波的过程.研究发现当弱X射线的频率为强X射线频率的一半时,可以生成超宽高次谐波频谱.通过合成高次谐波的连续谱,得到宽度为130 zs的单个仄秒脉冲.单个仄秒脉冲为超快变化过程的研究提供了工具.     

Application of wavelet-based active magnet power supply filter in accelerator

Since modern accelerators demand excellent stability to magnet power supply （PS）, it is necessary to decrease harmonic currents passing magnets. Aiming at depressing the rappel current from the PS in the Beijing electron-positron collider Ⅱ, a wavelet-based active power filter （APF） is proposed in this paper. An APF is an effective device to improve the quality of currents. As a countermeasure to these harmonic currents, the APF circuit generates a harmonic current, countervailing harmonic current from PS. An active power filter based on wavelet transformation is proposed. Discrete wavelet transformation is used to analyze the harmonic components in the supply current, and an active power filter circuit works according to the analysis results. Our simulation and experiment results are given to prove the effect of the APF.     

全正色散高阶谐波锁模掺Yb光纤激光器

在全正色散(ANDi)系统中,报道了最高为21阶的被动谐波锁模(HML)掺Yb光纤激光器。利用级联长周期光纤光栅(C-LPFG)作为全光纤结构的光谱滤波器,以非线性偏振演化(NPE)效应作为锁模机理,得到了重复频率可调谐的被动谐波锁模掺Yb激光输出,实现输出脉冲重复频率1.544~32.42MHz的可调谐。并进一步论证了谐波阶次的提高不仅与抽运功率有关,而且与光纤的长度有关。     

基于可调谐光纤激光器的C2H2气体光声光谱检测

研制了基于可调谐掺Er光纤激光器的共振式光声光谱乙炔气体检测系统,结合波长调制和锁相放大器的二次谐波信号检测技术,有效地消除了光声池窗片和池壁吸收入射光而引起的背景噪声,通过对该系统的光学、声学和电子检测系统的优化,实现了低浓度乙炔气体的流动式检测.实验结果证明,当气体浓度较低时,二次谐波振幅与气体浓度成正比,其线性响应相关度达到0.999 53.在常温常压和3.5 mW平均光功率以及100 ms锁相积分时间条件下,乙炔气体的极限检测灵敏度达到了0.3 ppm(1 ppm=1μg·mL-1)(SNR=1时),系统用可调谐掺Er光纤激光器代替半导体激光器作光源,降低了成本,为发展低成本、实用、便携式微量气体光谱榆测仪器奠定了基础.若采用多光程光声池,或者采用EDFA提高激光功率,可大幅度提高信噪比,将极限检测灵敏度提高至ppb(1 ppb=1 ng·mL-1)量级.     

A Weakly Nonlinear Model for Kelvin-Helmholtz Instability in Incompressible Fluids

A weakly nonlinear model is proposed for the Kelvin-Helmholtz instability in two-dimensional incompressible fluids by expanding the perturbation velocity potential to third order. The third-order harmonic generation effects of single-mode perturbation are analyzed, as well as the nonlinear correction to the exponential growth of the fundamental modulation. The weakly nonlinear results are supported by numerical simulations. Density and resonance effects exist in the development of mode coupling.     

A Unique Method to Describe the Bonding Strength in a Bonded Solid-S-olid Interface by Contact Acoustic Nonlinearity

We present a unique method to describe the bonding strength at a bonded solid-solid interface in a multilayered composite material by contact acoustic nonlinearity （CAN） parameter. A CAN model on the bonded solid-solid interface is depicted. It can be seen from the model that CAN parameter is very sensitive to the bonding strength at the interface. When an incident focusing acoustic longitudinal wave scans the interface in two dimensions, the transmitted wave can be used to extract CAN parameter. The contour of the bonding strength for a sample is obtained by CAN parameter. The results show that the region with weak bonding strength can be easily distinguished from the contour.     

Self-Stable Chaos Control of dc-dc Converter

A new concept related to self-stable chaos control is first put forward, and its theoretical basis and realization are presented from the frequency-domain perspective. With a new analogous-circuit realization of this control its applications in the voltage-mode Buck converter is discussed. The harmonic-balance method is applied to determine the control range of the control parameter. The experiment results given in the last part confirm the validity of the proposed control method.     

3 ω线法测量液体热参数影响因素分析

首先给出基于谐波探测技术测量液体导热系数和热扩散系数的3ω线法的基本原理.采用实验和理论分析相结合的方法,分析了加热丝结构参数和自身热参数对温度波动和测量结果的影响.给出了加热丝直径和长度的合理范围.液体导热系数比较小时可以利用三次谐波的实部和虚部的交点测量液体的比热容.