基于数字化标尺的视觉读数系统研究

为了改进目视光学仪器的读数系统,设计了一种基于数字化标尺的视觉读数系统。该系统采用绝对码标尺做基准,使用由光学系统、CCD摄像机和计算机组成的读数系统来读取标尺数值。系统不仅消除了增量码标尺的累积误差的影响,而且还实现了刻线的自动瞄准定位和读取。实验证明,该读数系统的不确定度为0 12μm,其精度比目视读数系统提高了5倍以上。     

正交多铁性材料DyMnO3的磁性质研究

基于密度泛函理论结合投影缀加平面波方法, 通过VASP软件包执行计算, 在分别考虑电子自旋阻挫共线与非共线的磁性结构基础上, 研究了正交结构下多铁性DyMnO₃材料在不同磁性构型下的晶格参数、总能、磁性、电子态密度和能带结构. 计算过程中选取广义梯度近似赝势, 同时使用局域自旋密度近似+U方法处理强关联作用下3d电子的计算结果. 计算结果表明: Mn离子为A型反铁磁态磁性构型的情况下能量最低结构最为稳定, Dy稀土离子磁性甚微, 可忽略不计; 当考虑电子自旋为非共线排列时, 正交DyMnO₃的总能提高、磁矩增大; 从电子结构图分析可知, 材料为间接能隙绝缘体, 能隙宽度约为0.38 eV, 加U后为1.36 eV, 导致晶格畸变的主要原因为Mn-3d与O-2p电子之间强烈的杂化作用. 关键词： 多铁性 反铁磁 密度泛函理论 非共线     

Investigation of glucose concentration measurement based on tunable pulsed laser induced photoacoustic technique

A tunable pulsed laser induced photoacoustic （PA） measurement set-up is established in the forward mode to monitor in vitro glucose concentration. A series of experiments are investigated to verify the feasibility of this set-up and scheme. Peak-to-peak values （PPVs） of several glucose aqueous solutions are recorded and averaged 512 times at each wavelength. Experimental results demonstrate that the time-resolved PA profile of glucose solutions has a good agreement with the PA theories. The characteristic wavelengths of glucose solution are determined via differential method. The root-mean-square error （RMSE） of predicted concentration reaches 3.15 mg/dl at the optimum wavelength of 1 510 nm via least square （LS） fitting algorithm.     

飞秒激光辐照下单晶硅薄膜中超快能量输运的数值模拟

利用载流子输运模型对飞秒激光辐照下单晶硅亚微米薄膜中的能量输运过程进行数值模拟。研究了不同辐照能量密度和不同激光波长对载流子密度和温度超快变化过程的影响规律。结果表明,在800nm激光辐照下,不同入射能量密度仅影响载流子密度和温度响应的峰值,但达到峰值的时刻不变。平衡态的恢复过程受入射能量密度影响很小。在不同波长激光辐照下,光子能量越大,载流子密度和温度达到峰值所用时间越短,对应峰值越大,但衰减速度也越快。当入射光子能量大于单晶硅的直接带隙时,快速衰减时间常数可以与载流子能量弛豫时间相当。     

Successive phase transformation in ferromagnetic shape memory alloys Co37Ni34Al39 melt-spun ribbons

The martensitic transformation in Co37Ni34Al29 ribbon is characterized in detail by means of in-situ thermostatic x-ray diffraction and magnetic measurements.The results show a structural transition from the body-centred cubic to martensite with a tetragonal structure during cooling.Comparison between the results of the diffraction intensity with the magnetic susceptibility measurements indicates that the martensitic transformation takes place in several different steps during cooling from 273 to 163 K.During heating from 313 to 873 K,the peak width becomes very wide and the intensity turns very low.The γ-phase(face-centred cubic structure) emerges and increases gradually with temperature increasing from 873 to 1073 K.     

稠密气固两相流各向异性颗粒相矩方法

基于气体分子动力学和颗粒动理学方法,考虑颗粒速度脉动各向异性,建立颗粒相二阶矩模型.应用初等输运理论,对三阶关联项进行模化和封闭.考虑颗粒与壁面之间的能量传递和交换,建立颗粒相边界条件模型.采用Koch等计算方法模拟气固脉动速度关联矩.考虑气体-颗粒间相互作用,建立稠密气体-颗粒流动模型.数值模拟提升管内气固两相流动特性,模拟结果表明提升管内颗粒相湍流脉动具有明显的各向异性.预测颗粒速度、浓度和颗粒脉动速度二阶矩与Tartan等实测结果相吻合.模拟结果表明轴向颗粒速度脉动强度约为平均颗粒相脉动强度的1.5倍,轴向颗粒脉动能大约是径向颗粒脉动能3.0倍.     

高斯差分滤波多尺度损伤提取方法

提出了高斯差分滤波的多尺度损伤提取方法和流程,对大口径光学元件的损伤图像进行了处理,结果表明,该方法对微弱信号与强信号混杂有很好适应性,且能有效解决低信噪比光学元件损伤图像中的损伤提取难题,对于分辨率125 m、口径400 mm400 mm的光学元件损伤图像,该方法可以100％提取损伤图像中尺寸在50 m以上的所有损伤的种子,满足了大型激光装置安全运行的需要。     

Observation of giant magnetocaloric effect under low magnetic fields in EuTi_(1-x)Co_xO_3

The magnetic properties and magnetocaloric effect(MCE) in EuTi_(1-x)Co_xO_3(x = 0, 0.025, 0.05, 0.075, 0.1) compounds have been investigated. When the Ti~(4+) ions were substituted by Co2+ions, the delicate balance was changed between antiferromagnetic(AFM) and ferromagnetic(FM) phases in the EuTiO_3 compound. In EuTi_(1-x)Co_xO_3 system, a giant reversible MCE and large refrigerant capacity(RC) were observed without hysteresis. The values of -?S_M~(max) were evaluated to be around 10 J·kg~(-1)·K~(-1) for EuTi_(0.95)Co_(0.05)O_3 under a magnetic field change of 10 kOe. The giant reversible MCE and large RC suggests that EuTi_(1-x)Co_xO_3 series could be considered as good candidate materials for low-temperature and low-field magnetic refrigerant.     

大孔乙酰胺甲基聚苯乙烯吸附树脂的合成及胱氨酸和酪氨酸的分离

色谱;大孔乙酰胺甲基聚苯乙烯吸附树脂的合成及胱氨酸和酪氨酸的分离     

基于CCD积分时间自动调节的生化分析仪用分光光度计的研究

在利用生化分析仪用分光光度计对血液等样品进行分析时,由于样品中不同组分对不同波段的光吸收有所差异,尤其在能量衰减较大和非特征吸收波段表现得更加突出,并且电路中各种噪音和光路杂散光的存在,使得光度测量的准确率降低.本文使用线阵CCD积分时间的自动调节和分段分时采光等优化算法,将强吸收与弱吸收分开曝光,在保证强吸收正常的前提下,自动调整积分时间来增大弱吸收的信号.采用自行研制的基于Czerny-Turner型分光光路和线阵CCD探测的高分辨率生化分析仪作为分光光度计,经实验测试,该方法有效地提高了光度测量的准确度,同时提高了系统的性能和信噪比.此外,该分光光度计系统的光谱测量范围可达300～800 nm,波长分辨率优于2 nm.