同轴数字全息用于血吸虫尾蚴检测研究

由于水的表面易出现抖动或波动情况,而传统的显微镜成像需要精确的光学焦聚过程,因此不适于观察漂浮于水表面的血吸虫尾蚴.本文论述了用同轴数字全息检测血吸虫尾蚴的基本原理.通过对再现像进行小波分析发现,偏离焦点时的小波变换高频系数的幅值比聚焦时要小得多.针对这一特点,本文对小波变换清晰度评价函数进行了改进,将原来利用高频系数之和改为利用聚焦窗口中高频系数的最大幅值为清晰度评价依据.在模拟实验结果中清晰度评价函数极大值出现在再现距离与记录距离相等处,说明了该算法的准确性.建立了用于血吸虫尾蚴检测的实验装置,可方便获取普通显微图像及数字全息图.实验结果表明,本文提出的算法能实现实际情况下的数字全息自动聚焦,其再现像的分辨率与装有1倍显微镜头的数码显微镜分辨率相当,足以清晰地分辨出血吸虫尾蚴的尾部分叉特征.利用同轴数字全息技术可在水面与图像传感器之间的距离不确定的情况下实现对血吸虫尾蚴的检测.     

采用吸收修正Bronnikov算法的有机复合样品的X射线显微计算机层析研究

有机复合样品如大多数由低原子序数物质构成的多聚物组合材料、生物软组织等具有混合相位和振幅特性,采用传统吸收计算机层析(CT)或纯相位重构算法难以达到较高密度分辨的目的。采用基于吸收修正的Bronnikov相位恢复算法的X射线同轴相衬CT技术对高分子混合组份材料和药物医学样品进行了实验研究。结果表明该相位恢复算法可以实现多聚物组合材料的无损分辨和精确测量,能够清晰辨别各组份材料的电子密度分布;验证了药物样品多孔性结构三维测量的可行性,能够有效提供孔隙测量的阈值选择。该方法在材料科学尤其是聚合物组合材料、泡沫多孔材料都会发挥很好的作用;单距的低辐射优势,尤其适用于生物医学样品三维无损成像。     

X像转换为全息立体图像的像质评价方法

描述全息立体图像像质的评价方法,包括1)像的逼真度;2)像的相对结构容量;3)相关品质;4)面积元法。     

浅谈全息照相实验教学

为了提高全息照相实验的成功率和学生学习的积极性,本文从实验原理入手,分析了影响实验的诸因素,并提出了具体的解决方法。     

用光纤完成全息资料存储实验

本文提出了用光纤实现资料存储的方法 ,特点是操作简单 ,易于实现     

Terpolymerization monitoring with ATR-FTIR spectroscopy

Butyl acrylate, methyl methacrylate, and vinyl acetate solution and emulsion terpolymerizations were conducted. Attenuated total relflection-Fourier transform infrared spectroscopy equipped with conduit and diamond-composite sensor technology was used to monitor solution terpolymerizations off-line and emulsion terpolymerizations in-line. Monomer conversion and terpolymer composition changes as a function of time were calculated by monitoring the peak height of characteristic absorbances of each monomer. Results obtained from the ReactIR™ 1000 reaction-analysis system agreed well with those determined by traditional gravimetry and ¹H NMR spectroscopy. For the solution terpolymerizations, improved models developed previously to incorporate solvent effects on solution polymerizations of butyl acrylate and vinyl acetate monomers were applied to predict monomer conversion, copolymer composition, and molecular weight averages. Comparisons between experimental data and model predictions are presented. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1860–1876, 2001     

用CCD演示全息图再现

利用CCD演示全息图再现，取得了很好的教学效果。     

Dose distributions for containers electron sterilized at energies from 150–250 keV

An electron beam facility is described utilizing a 30 cm wide x 250 kV x 20 ma processor for the study of the in-line sterilization of containers for aseptic food and medical device packaging. The sterilizer permits the handling of containers of varying length to diameter ratios, ranging from 1.36 liter (46 oz) two piece cans, to 0.5 liter (16.9 oz) liquid food cartons to 3–90 ml pharmaceutical syringes and vials. The thin film dosimetric techniques used to survey these containers and the results obtained under in-line, continuous motion conditions are described.     

Viscous oscillatory flow around a circular cylinder at low Keulegan–Carpenter numbers and frequency parameters

The results of a numerical study of the viscous oscillating flow around a circular cylinder at low Keulegan–Carpenter numbers (KC) and frequency parameters (β) are presented in this paper. The finite element method was used for the solution of the Navier–Stokes equations in the formulation where the streamfunction and vorticity are the field variables. The computation was conducted at Keulegan–Carpenter numbers extending up to KC=15 and frequency parameters ranging between β=6 and 100. At low values of the Keulegan–Carpenter number the flow remains symmetrical. As the Keulegan–Carpenter number is increased over a certain value which depends also on the frequency parameter, asymmetries appear in the flow which are eventually amplified and lead finally to complex vortex-shedding patterns, some of which are markedly different from those observed at higher frequency parameters. The solution revealed that although for certain values of KC and β the shedding of vortices is periodic, there also exists a complicated flow regime in which the flow is not periodic but switches between different modes in consecutive cycles of flow oscillation. For the various flow cases examined, the traces of the hydrodynamic forces are presented and the hydrodynamic coefficients and RMS values of the in-line force are compared with experimental evidence. © 1998 John Wiley & Sons, Ltd.     

Investigations of wake flows of a flat plate in steady,oscillatory and combined flows

Numerical study on near wake flows of a flat plate in three kinds of oncoming flows is made by using the discrete vortex model and improved vorticity creation method. For steady oncoming flow, both gross and detailed features of the wake flow are calculated and discussed. Then, in harmonic oscillatory oncoming flow two different wake flow patterns withK _c=2,4 and 10 are obtained respectively. Our results present a new wake flow pattern for lowKc numbers (Kc<5) describing vortex shedding, pairing and moving in a period of the oscillatory flow starting from rest. The calculated drag and inertia force coefficients are closer to experimental data from the U-tube than the previous results of vortex simulation. For in-line combined oncoming flow the vortex lock-in and dynamic characteristics are simulated. The results are shown to be in good agreement with experiments. The project supported by National Natural Science Fundation of China and LNM of Institute of Mechanics. CAS