基于MNR算法和自适应局部均值滤波技术的电阻层析成像算法

在电阻层析成像的仿真计算中,当两相流的网格结构较简单时,重建图像与原始图像几乎相同,每个单元的电阻率仿真值几乎与设定值相同。当网格结构较复杂时,重建图像却不能达到上述效果,成像算法掉入局部最优点。提出一种局部自适应均值滤波算法,使原来的成像算法跳出局部最优点。并给出几个常见流型的图像重建结果。     

FTIR法测定EC乙氧基含量

对富立叶变换红外光谱（FTIR）法用于测定乙基纤维素（EC）乙氧基含量进行了研究，讨论了制样条件和水分对红外结果的影响，采用不同乙氧基含量范围的标准样品分别进行了化学法和红外光谱法测定，确立了两种方法之间的换算关系式，R检验效果良好，对比试验表明，在统计意义上红外法结果比化学法结果平均仅高0．25左右。     

玻璃光吸收系数测量

本文着重研究了样品表面反射对测量的影响。考虑到光在透明介质上的多次反射作用,推导出计算透明介质光吸收系数的普遍关系式,并分别给出玻璃光吸收为强和弱的两种情况下它们的近似计算公式。 最后,通过几种光学玻璃样品的实际测量,说明了这些公式的运用范围。     

两相流电阻层析成像测量电路与图像重建

提出一种用于两相流测量的高速电阻层析成像（electrical resistance tomography,ERT）系统。该系统采用双极性脉冲电流源为激励电极对提供激励信号,避免了直流激励造成的电极极化效应,同时简化了滤波电路的设计,相对于常规的交流激励ERT系统显著提高了数据采集速度。针对成像速度较快但成像质量差的线性反投影算法（linear back projection,LBP）,采用离线预迭代技术对其进行改进,提出一种改进型线性反投影算法（modified LBP, MLBP）,可高速重建较好质量的ERT图像。数值仿真和采用实际测量数据重建图像的结果表明,基于高速数据采集技术和改进的图像重建算法的高速ERT系统可实现两相流实时在线测量。     

邻苯二甲酸酯去除技术研究进展

在前人基础上综述了吸附法、生物法和高级氧化法对PAEs去除的研究,高级氧化法较其他两种方法显示出更高的效率,最后,对于目前的研究不足和未来的研究方向提出展望。     

无机纳米与聚合物基功能材料

无机纳米－聚合物基复合材料主要由溶胶－凝胶法，原位合成法，直接共混法，化学接枝法，插层原位聚合法，电化学合成法等制血而成，根据无机纳米粒子，基底物的不同性质，以及不同的材料制备方法，复合物可被赋予光，电，磁，催化，表面特性，阻燃特性等独特的功能性质，并就上述内容进行了较详细阐述。     

湿热空气脱酸法制备气相白炭黑

气相法白炭黑是一种特殊的化工产品，二氧化硅含量达99．8％以上（按干基计），对除氢酸外的各种酸，碱，溶剂等都非常稳定，粒子极细微，比表面积大，无毒，因含有特殊功能的表面羟基而形成初强，增稠，触变，防止固体物料结块等特殊性能。     

基于涡流搜索算法的支持向量机分类模型

提出一种将涡流搜索算法用于支持向量机参数选取的新算法,利用该算法不必遍历搜索空间内所有的参数点即可找到全局最优解。给出了具体的算法流程,并进行了仿真。仿真实验结果表明涡流搜索算法是选取SVM参数的有效方法。     

基于超声衍射反射回波渡越时间的缺陷识别技术

针对超声衍射回波渡越时间(TOFD)法对近表面缺陷不敏感、被测表面以下8 mm之内为盲区的现状,提出一种改进的基于衍射和反射回波的渡越时间(TOFDR)的缺陷识别技术.该法不再直接检测缺陷上下端部衍射的信号.通过检测经过底面反射一次的衍射信号,避免了侧向波和衍射波的叠加,将盲区缩减到被测表面以下2 mm,且可以实现在线检测.阐述了该法的原理,给出了缺陷参数的计算方法,分析了探头间距和频率的影响.实验表明,该法可以检测到表面下2～35 mm内94%的垂直裂缝,实际位置和尺寸同计算结果吻合,精度可达±0.3 mm.     

基于在位光还原银胶法的核酸碱基快速检测

核酸遗传物质是蛋白质合成过程中关键环节,对生物遗传和变异起着关键性作用。核酸碱基多样性特点决定了碱基反应性能,进而发生生物进化和衰老。组合核酸碱基能够得到足够多的信息,是形成高分子生物物质的基础。因此,提出了基于在位光还原银胶法的核酸碱基快速检测。制备表面增强拉曼光谱常规基底,准备核苷酸、核苷、碱基实验材料。制备核酸碱基、硝酸银溶液、银胶溶液和银膜,测量拉曼光谱。使用激光诱导获取银基质,利用NaClO_4分子的Cl-O键振动作为内标,分析在位光还原合成银胶法增强光谱效果。由分析结果可知,该方法可以获得高信噪比的表面增强拉曼光谱,且具有良好稳定性,在核酸碱基低浓度检测方面具有实用价值。     

Improving the Hawkyard method for generating reflectance functions

An iterative method was developed by Hawkyard in 1993 for generating reflectance functions, based on a given set of tristimulus values. In a recent article by Dupont (Col Res Appl 2002;27:88–99), many methods for generating reflectance functions were compared, and it was shown that the Hawkyard method is one of the best methods. However, one of the weak points of the Hawkyard method is its iterative nature. In addition, one important issue for the Hawkyard method is its convergence, which has not been addressed. In this article, this issue is examined. The necessary and sufficient condition to achieve convergence, using the Hawkyard method, is given. The method is then modified to make it an analytical method. © 2005 Wiley Periodicals, Inc. Col Res Appl, 30, 283–287, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.20126     

Recovery of reflectance spectra from CIE tristimulus values using a progressive database selection technique

A procedure for creating efficient reflectance spectra from CIE tristimulus colour values is described using a modified linear model. By fixing certain criteria based on colour difference values, the proposed technique preliminarily selects a series of suitable samples from a main data set containing the reflectance values of a large number of different coloured samples, based on the colour specifications of a given sample. In this way, a series of different databases containing the reflectance values of confirmed samples relating to the particular samples are formed. Then, a well-known principal components linear model is applied using three basis functions. This operation yields higher cumulative variances in comparison with the original database, having the same number of basis vectors. The performance of the proposed method is evaluated using a different collection of samples and the resulting spectra show considerable improvements in terms of root mean square error as well as colour difference values under different illuminants.     

A Continuous Spawning Method for Nonadiabatic Dynamics and Validation for the Zero-Temperature Spin-Boson Problem

A four-dimensional spin-boson model is used to study the convergence and accuracy of the full multiple spawning (FMS) method using two spawning algorithms. The original spawning algorithm, based on the idea of effective non-adiabatic coupling, is expected to be optimal when the coupling between electronic states is either spatially or temporally localized. The new “continuous spawning” algorithm ensures that at all times there is a (user defined) minimal overlap between a basis function traveling on one electronic state and one (or more) basis functions traveling on the other electronic state. The algorithm is expected to be numerically efficient when the electronic states are coupled by a constant, position-independent term, as is the case in spin-boson models. The fast convergence of the algorithm is demonstrated by direct comparison to numerically converged results obtained using the multi-configuration time-dependent Hartree method. The results of the FMS dynamics are also compared to the more classical surface-hopping and Ehrenfest methods. The surface-hopping and Ehrenfest methods are shown to be sensitive to the particular method used to choose the trajectory initial conditions (quasi-classical vs. Wigner), while the FMS method is not very sensitive to this choice.     

A new direct-synthesis tuning method for pi-controllers

A new efficient tuning method for proportional-integral (PI) controllers is proposed using overdamped closed-loop dynamics of the system. In line with other direct-synthesis and IMC methods, this new approach uses the desired closed-loop response to satisfy usual control and tuning objectives, but unlike the most other tuning methods hitherto-reported for PID controllers, it does not require that a process model be identified. Yet this new direct-synthesis (NDS) method is capable of making the controller perform the dual control functions of both good set-point tracking and disturbance rejection. Furthermore, it turns out that the new tuning method works equally well for difficult cases like large time delay and nonminimum phase processes. Finally, it can be said that this NDS method can be easily implemented and understood by the plant operating personnel because it has been developed emphasizing its on-site utility.     

侵入式光纤照相法测量气泡尺寸分布

基于光纤内窥镜技术构建了以光纤内窥镜、图像采集系统和照明系统组成的侵入式照相装置,测量了由微气泡发生器和两种不同孔径的膜管产生的气泡的尺寸分布,并与取样照相法进行了比较. 结果表明,3种气泡生成装置产生的气泡直径在50~2000 mm;对50~200 mm气泡两种方法的测量结果相差不大,200~2000 mm的微气泡取样照相法测量值比侵入式照相法高,可能是因为取样时大气泡易发生聚并和破碎. 侵入式照相法能较准确测量较宽的气泡尺寸,适用于在线测量气液体系中分布较宽的气泡尺寸动态分布,也可用于其他测量方法及数值模拟方法的验证.     

A new method for computing optimum weights for calculating CIE tristimulus values

Weighing tables are widely used for calculating CIE tristimulus values. In this article, a direct method for computing optimum weighing tables for any illuminant and observer combination is developed. A comprehensive set of 1‐nm reflectance functions based upon Munsell samples is used to test various methods. Four types of weighing tables are compared. They are ASTM E308 Tables 5 and 6, ASTM E2022, and new tables proposed by this study. The results clearly show that the newly developed optimum tables outperform the other three types of tables. The new method is simple and avoids the iterative process used by Venable and adopted by ASTM for some of its tables. It may be used for calculating weighing tables for any combination of illuminant and observer. A detailed procedure and a worked example are given in the article. © 2004 Wiley Periodicals, Inc. Col Res Appl, 29, 91–103, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.10229     

Numerical solution of multi-variable cell population balance models. III. Finite element methods

We have developed finite element approximations to the generalized multi-variable cell population balance problem under conditions of changing substrate concentration. We considered different sets of basis functions consisting of 1st-, 2nd-, 3rd-, 4th-, 5th- and 6th-order polynomials. For the time integration of the nonlinear system of ordinary differential equations that result from the finite element discretization in space, we implemented both time-implicit and time-explicit algorithms. The set of basis functions consisting of 4th-order polynomials was found to be the most appropriate for all test problems considered. It offered more than a 10-fold reduction in required CPU time, when compared to the linear basis functions. Time-explicit methods were found to be preferable to time-implicit methods in terms of computational efficiency. Despite the fact that the required CPU time of the best finite element algorithm for single-variable simulations is comparable to that of the best spectral and finite difference method, the comparison is highly unfavorable for the finite element method in the case of multi-variable simulations.     

Measurement and Analysis of Object Reflectance Spectra

Recent algorithms developed in the field of color vision make assumptions based on the spectral reflectance curves of Munsell chips and natural materials. Some of them rely on data collected many years ago. which is partially incomplete in the visible spectrum. or contains many occurrences of the same material in it. In this article. we present a set of new measurements of different materials. In particular. we measured the spectral reflectance of Munsell chips, paints. and various natural materials in the 390–730-nm range. In addition, we have analyzed. through principal-component analysis, the possibility of representing the data collected with a set of basis functions. We show the implications of varying the number of principal components used (from 7 down to 3) on the errors introduced using this method.     

关于聚乙烯改性沥青技术问题的探讨

储存稳定性、低温抗裂性等问题制约聚乙烯改性沥青技术在我国的推广应用。通过回顾和总结国内外相关研究报告,结合试验对这些问题进行探讨。大量研究工作并未解决储存稳定性问题,工程上仍停留在现制现用阶段。常规沥青试验难以客观评价聚乙烯改性沥青低温性能,需要开发特殊的试验方法进行研究。耐老化性能的相关研究不多,但旋转薄膜烘箱试验（RTFOT）表明耐老化性能优于基质沥青。聚乙烯改性沥青极易离析,必须对室内试验过程严格控制才能得到客观结果。     

3-正丙基-5-羧基-1-甲基吡唑的合成研究

以 2 -戊酮和草酸二乙酯为起始原料 ,经 Claisen缩合、环化、甲基化和皂化等反应制得目标化合物 3-正丙基 - 5 -羧基 - 1 -甲基吡唑 3。文献报道的合成方法为四步法 ,在此基础上加以改进 ,形成了两种新的合成路线 ,即三步法和两步法 ,其收率均高于四步法 ,高出 2 7.0 %