激光除锈过程的实时监测技术研究

对激光除锈过程中的实时监测技术进行了实验研究,结果表明:除锈过程中产生的声波强度会随着表面清洁度的变化而发生明显的变化,声波信号包含了除锈过程中的大量信息,可作为激光除锈实时监测的基本信号.     

增量式轴角编码器的电子细分及零位处理

使用单片机对增量式光电轴角编码器产生的叠栅条纹信号进行计数和电子细分,便可将轴的机械转动模拟量转换成数字量;加上固定参考零位后,可使编码器具有"记忆"功能,因此对如何解决零位技术问题做了详细分析说明,并给出了实际解决方案.     

洗牌型光电混合神经网络实验系统

在研究洗牌网局部互连光学实现问题的基础上 ,采用洗牌型图样间联想模型建立了具有完整的加权互连、求和、非线性处理及反馈功能的光电混合神经网络实验系统 ,进行了 8× 8数字样本的光学联想识别。实验结果证实了洗牌网理论的可行性和洗牌型图样间联想模型光学实现的优越性     

Soliton interaction under the influence of higher-order effects

In this paper, we present exact N-soliton solution by employing simple, straightforward Darboux transformation based on the Lax pair for Hirota equation, a higher-order nonlinear Schrödinger (HNLS) equation. As examples, one- and two-soliton solutions in explicit forms are given and their properties are also analyzed. A bound solution without interaction will be theoretically predicted if one can adjust frequency shift for each soliton appropriately. Further, we obtain the approximate eigenvalues by employing two-soliton solution and discuss analytically the interaction between neighboring solitons under the influence of the higher-order effects. It is shown that the combined effects of the higher-order effects can restrain the interaction between neighboring solitons to some extent. The results are proved by directly solving HNLS equation numerically.     

Atomic force microscopy studies on phase transitions and surface morphology transformation of CMTC crystals

Atomic force microscopy (AFM) has been used to investigate the phase transitions and surface morphology transformation of cadmium mercury thiocyanate (CMTC) crystals, which are highly efficient nonlinear optical (NLO) materials for generating blue-violet light by laser frequency doubling. Amorphous aggregates at the crystalline steps become greatly contracted and much more crystalloid after the crystal was kept for one day. Elimination of dangling bonds, which lower the surface free energy at the crystal surface, and structural adjustment inside the crystal are assumed to cause this phase transition. Surface morphology transformations were also observed in CMTC crystals during and after multiple scanning by AFM tips. We have visualized the continuous translation process from two-dimensional nuclei to trigonal microcrystals with almost equal sizes during multiple scanning. In other cases, however, the surface morphology did not change at all during scanning, but became greatly altered hours after scanning. These experimental results suggest that reconstruction is a characteristic growth phenomenon on CMTC crystal surfaces. Reconstruction probably results from the formation of intervening metastable phases that have the potential to arrive at more stable stages; however, multiple scanning of AFM tips greatly affects this translation process. Received: 28 August 2001 / Accepted: 7 November 2001 / Published online: 29 May 2002     

Quantum chemical construction of a reduced reaction Hamiltonian and T 1 -relaxation and pure T 2 -dephasing rates for the proton transfer in 3-chlorotropolone

Separating multidimensional problems into that of a relevant system which is coupled to a bath of harmonic oscillators is a common concept in condensed phase theory. Focusing on the specific problem of intramolecular proton transfer in an isolated tropolone derivative, we consider the reactive proton moving in the plane of the molecule as the system and the remaining substrate normal modes as the bath. An all-Cartesian system-plus-substrate Hamiltonian is constructed employing density functional theory. It is then used to determine the temperature-dependent effective reduced reaction Hamiltonian and the state-to-state dissipation rates induced via the system-substrate coupling up to the bi-quadratic order. The important substrate modes for the T₁-relaxation and the pure T₂-dephasing rates, which are either intra- or inter-well in nature, are identified numerically and analyzed physically with molecular details. Received 19 November 2001 and Received in final form 19 February 2002     

超导体磁场穿透深度测量中的数据分析问题

讨论了目前在超导体磁场穿透深度λ测量中常用的几种数据分析方法.着重指出对于那些只能测量λ随温度的变化值Δλ(T),而无法测量其绝对值的实验而言,一种合适的数据分析方法对于我们从实验中得出正确的结论尤其重要.而微分归一法将有效地克服目前此类实验中常用数据处理方法的不足,从而实现理论与实验间的无参量比较. 关键词： 超导体 磁场穿透深度     

镧与真空沉积银纳米粒子的金属间化合

根据HumeRothery规则,分析了银与镧两元素之间形成金属间化合物的倾向性,并根据真空蒸发沉积的条件,分析了在真空蒸发沉积情况下镧与银之间形成金属间化合物的可能性.用X射线光电子能谱化学位移方法对真空蒸发沉积的银、镧薄膜进行了分析,结果表明在真空沉积条件下镧与银之间的确形成了金属间化合物. 关键词： 金属间化合物 镧 银 纳米粒子     

源气体对沉积的a-C∶F∶H薄膜结构的影响

采用微波电子回旋共振等离子体化学气相沉积(MWPECRCVD)方法,使用不同的源气体(CHF3CH4,CHF3C2H2,CHF3C6H6)体系制备了aC∶F∶H薄膜.由于CH4,C2H2,C6H6气体在等离子体中的分解反应不同导致了薄膜的沉积速率和结构上的差异.红外吸收谱的结果表明,用C6H6CHF3作为源气体沉积的薄膜中几乎不含H,而用C2H2CHF3所沉积的薄膜中的含氟量最高,其相应的CF振动峰位向高频方向偏移.薄膜的真空退火结果表明,aC∶F∶H薄膜的热稳定性除了取决于薄膜的CC键浓度外,还与CC键 关键词： 氟化非晶碳膜 电子回旋共振化学气相沉积 红外吸收光谱     

Nd:Ca4ReO(BO3)3(Re=Gd,Y)晶体最佳激光、最佳倍频及最佳自倍频方向的确定

介绍了Nd:Ca4ReO(BO3)3(Re=Gd,Y)晶体最佳激光方向、最佳倍频方向的确定.综合考虑激光受激发射截面、抽运光吸收系数、有效非线性系数的各向异性,分析了自倍频性质的空间分布,并就此确定出最佳自倍频方向 关键词： Nd:Ca4ReO(BO3)3(Re=Gd Y)晶体 激光发射 倍频 自倍频