激光珩磨专用机床的运动控制研究

 以发动机气缸/活塞环摩擦副为具体研究对象,研制了一种新型激光珩磨设备。由于发动机汽缸套载重大,且形状不规则,故设备采用激光头既旋转又直线运动的运动方案。该设备在移动轴和转轴中分别安装有高精度光栅尺和高精度增量旋转编码器以提高运动控制系统的精度。为了使微凹腔沿圆周均匀分布,采用了小数分频原理,能够实现任意小数分频。通过对运动控制卡与自制的调Q控制卡的软件编程,实现了运动控制系统与激光系统的协同控制,用以在气缸表面加工出特定的微观形貌。加工方法采用的是“单脉冲同点间隔多次”的激光微加工新方法。利用该方法能够方便地加工出微观或宏观的形貌且能显著地减少激光加工所带来的负面热效应。     

对-二甲氨基苯甲醛苯甲酰腙及其锌(Ⅱ)、镉(Ⅱ)配合物的合成与光学性质

合成了对-二甲氨基苯甲醛苯甲酰腙(配体)及其锌(Ⅱ)、镉(Ⅱ)配合物,通过元素分析、IR、MS对结构进行表征,研究了配体及锌(Ⅱ)、镉(Ⅱ)配合物的紫外光谱和荧光光谱。这些物质都有较强的荧光,适合掺入涂料中做成荧光涂料。     

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在外杜瓦系统上设置了爆破片装置,借助大型有限元分析程序ANSYS,对爆破片和托架进行了分析,所得结果与实验结果良好吻合,为同类装置的过压泄放提供了有益的参考。     

Generation of Broadband High Harmonics through Linear Mode Conversion in Inhomogeneous Plasmas

The generation of high order harmonics from an inhomogeneous ovderdense plasma target irradiated by an ultrashort intense laser pulse is studied by numerical simulation. During such interaction, ultrafast electron bunches are generated and excite electron plasma oscillations as they pass through the overdense target. These plasma oscillations will emit high-frequency electromagnetic emission by linear mode conversion. Instead of the integer harmonies generation, the emission appears with a broadband and even continuous spectrum corresponding to the electron plasma frequency range of the inhomogeneous plasma density.     

A new adaptive trust region algorithm for optimization problems

It is well known that trust region methods are very effective for optimization problems. In this article, a new adaptive trust region method is presented for solving unconstrained optimization problems. The proposed method combines a modified secant equation with the BFGS updated formula and an adaptive trust region radius, where the new trust region radius makes use of not only the function information but also the gradient information. Under suitable conditions, global convergence is proved, and we demonstrate the local superlinear convergence of the proposed method. The numerical results indicate that the proposed method is very efficient.     

贯彻启发教育思想改革《分析化学》教学

在大力提倡素质教育的21世纪,贯彻启发教育思想很有必要.按照启发的基础,论述以直接感性认识和理性知识以及以实物或教具挂图为基础的启发方法.根据思维活动的形式不同论述对概念、判断、推理和论证的启发方法.     

碳市场EUA与CER 期货价格变动关系的实证研究

基于VAR模型,对碳市场中的EUA期货价格和CER期货价格的变动关系进行了实证研究．选取欧洲气候交易所（ECX）的EUA期货价格和CER期货价格作为研究对象,运用Johansen协整检验、Granger因果关系检验、向量误差修正模型、广义脉冲响应函数和方差分解方法形成递进式的计量分析框架．研究结果表明：第一,EUA期货价格与CER期货价格之间存在着相互影响关系;第二,CER期货价格对市场信息的反映比EUA期货价格更为敏感,反映速度更快;第三,两种价格之间,CER期货价格变动的影响起主导作用,更好地发挥了期货的定价功能,两市场间存在杠杆效应．     

Research on intensity measurement in room impulse field

A new system of sound intensity measurement for impulse field in the room was proposed. This measurement system consists of a repeatable inspiriting sound source and a microphone fixed on a slowly rotating platform, which is equivalent to a circle microphone array composed of many perfectly matched microphones. The test principle was presented and typical application was described. Based upon this system the sound intensity measurement for impulse field in the room was realized. Therefore, not only time but also spatial information of room impulse response can be obtained.     

Magnetoresistance of Multiwalled Carbon Nanotube Yarns

We measure zero-field resistivity and magnetoresistance of multiwalled carbon nanotube yarns （CNTYs）. The CNTYs are drawn from superaligned multiwalled carbon nanotube arrays synthesized by the low-pressure chemical vapour deposition method. The zero-field resistivity shows a logarithmic decrease from 2 K to 300K. In the presence of a magnetic field applied perpendicular to the yarn axis, a pronounced negative magnetoresistance is observed. A magnetoresistance ratio of 22% is obtained. These behaviours can be explained by the weak localization effect.     

多尺度分析在激光微多普勒效应特征提取中的应用

由于小波变换具有准确度高、抗噪性好等优点,在微多普勒效应探测方面具有很好的应用前景。利用多尺度分析（MRA）将信号进行分解并提取出含有微多普勒效应的低频平滑信息,获取了目标微小振动引起的微多普勒效应。用频谱分析和基于瞬时频率(Instfreq)的时-频域联合分析方法对原始信号及通过MRA分解得到的结果进行了对比研究。结果表明：利用时-频分析对MRA处理后的低频信号进行分析,可更加有效地提取微多普勒效应中振动信号的特征,为目标特征的识别、分类和探测提供了便利。