热声驱动系统中的压力测量

介绍了自制的用于热声驱动脉管制冷装置的计算机压力波数据采集系统。该系统由硅压电压力传感器、数据采集卡、PC机和基于 Labview软件的图形化用户界面 GUI( Graphical User In-terface)组成。试验证明 ,它具有结构简单、高效精确、操作简便等特点 ,在捕捉被测系统内的动态压力变化方面具有优势 ,不但能很好地满足热声驱动器的压力测量要求 ,而且亦可移植到任何类似的测量气体压力的场合     

Residual stress profiling of an aluminum alloy by laser ultrasonics

A residual-stress profile along the thickness of an aluminum alloy sheet is determined by laser-ultrasonic technique. Surface acoustic waves are generated by a Nd:YAG pulse laser and detected by a Heterodyne interferometer on a lateral free surface of the sheet. The distribution of residual stress is determined by measuring the relative variation of the wavevelocities at different location of the sample along its thickness. This technique is validated by three different residual stress profiles obtained experimentally.     

第三类Painlevé方程(δ=0或γ=0)解的渐近性态

对带有一般实参数第三类Painlevé方程,已有γ<0,δ>0时,解的有界性以及振荡渐近解的表达形式的结论.在本文中,我们给出当δ=0或γ=0时其振荡渐近解的表达形式.     

具非线性中立项的二阶时滞微分方程的振动性质

By using the averaging technique, we obtain new oscillation criteria for second order delay differential equation with nonlinear neutral term. These results generalize and improve some known results about neutral delay differential equation of second order.     

超声波提取-等离子体原子发射光谱测定何首乌中的磷脂

采用超声波提取法提取中药何首乌中磷脂类化合物,探讨了提取溶剂用量、提取时间及超声功率等因素对磷脂提取率的影响,结合ICP-AES分析法对提取的磷脂类化合物进行了测定.结果表明,对于1.5 g何首乌,用20 mL Folch试剂,超声提取35 min,超声功率为24 kHz的条件下磷脂提取率较高.     

CH分子束的强度与CH4/He混合配比的关系及CH(A2△)振转温度的计算

为了获得CH分子束及其相关特性,以氦气为载气,利用直流脉冲放电技术产生了CH分子束.实验记录了放电时间相对于脉冲分子束不同延时CH光谱信号强度的变化,放电相对延时为460μs左右获得最大的信号强度.研究了在保持CH4/He总气压3 atm和放电电压-4 kV不变的条件下CH分子束强度与不同配比的关系,建立了理论模型,对实验数据进行了理论拟合,拟合曲线与实验结果符合较好,配比为1%(甲烷与氦的气压比为1:99)左右能够维持较稳定的放电现象和较强的放电强度而获得较强的CH自由基束流.在这一配比下对CH(A2△-X2П)(0,0)带发射光谱进行探测和分析,获得CH(A2△)转动温度和振动温度分别为2455 K和4575 K,并估计此时每个脉冲中大约包含1013～1014个CH自由基.     

驻波型热声制冷机熵产分析

声制冷机是一种新型制冷机,具有无机械运动部件,可靠性高寿命长,采用惰性气体为工质无污染等优点．驻波型热声制冷机的声功泵热效应是不可逆过程,内部不可逆损失导致热声制冷机效率偏低,制约了热声制冷机的发展和应用．本文研究了线性范围内驻波型制冷机换热器和回热器内的可压缩振荡流动与传热过程的熵产,分析了板间距,振荡频率和温度梯度对熵产的影响。     

有关力学谱和内耗工作的综合与回顾

本文广泛地收集了有关内耗，力学谱，超声衰减方面的专著及会议文集。反映了20世纪在此领域的英文，俄文出版的书籍。也列出了历次国际会议及前苏联，乌克兰，中国的国内会议。文中包括了点缺陷，电，声子，位错，晶界，电畴等诸方面在内的内耗与力学谱工作。     

Entangling Two Multi-atomic Clusters Through a Cavity Field

Two atomic clusters, which have NA and Ns two-level atoms, respectively, are placed in a cavity but separated spatially. There is no direct interaction between the atoms. All the atoms interact with a single-mode of the cavity field. Quantum entanglement between the two atomic clusters is investigated for various initial states of the two atomic clusters and the field. When the cavity field is initially in a Fock state, we find that the time evolution of entanglement quasi-periodically oscillates regardless of the initial states of atoms. The oscillation period increases as the initial photon number increases. When all the atoms in both of the atomic clusters are initially in the excited state, we show that there is no entanglement between the atomic clusters with NA = NB = 1 regardless the initial state of the cavity field. However, when either NA or NB is larger than one, we find that the entanglement always exists even for a strong thermal field. In cases with different initial states of the atomic clusters, we notice that the entanglement becomes stronger as number of the atoms increases. When all the atoms in both of the clusters in the ground state, we also find that the entanglement can be enhanced even by a thermal field. We also notice that a single qubit can be entangled with multi-atoms which are initially in the ground state by the cavity field initially being in vacuum, thermal, coherent, and squeezed states.     

一类非线性常微分方程振荡解的渐近表示

在本文中,我们讨论了非线性常微分方程y"=a0|x|αy3 a1|x|βy2 α2|x|γy α3|x|δ振荡解的渐近表示．在这个方程中将α0,α,α1,β,α2,γ,α3,δ分别换成0,0,6,0,0,0,sgn(x),1就是著名的第一类Painleve方程,而将α0,α,α1,β,α2,γ,α3,δ分别换成2,0,0,0,sgn(x),1,α0,就是著名的第二类Painleve方程．当α0,α,α1,β,α2,γ,α3,δ分别换成-β/3γ,0,0,0,1/γ,1,α,0时,可用于组合KdV方程孤立子解的化简．