模糊PID在高精密球抛光机床压力控制中的应用

针对高精密球体抛光机床压力加载控制中,存在的加压精度低、抗干扰能力差等问题,提出了基于模糊PID控制策略的压力加载控制系统。分析了抛光机床的加压装置,并对机床整体控制系统进行设计;针对高精密抛光机床加压过程中存在的滞后性、非线性及时变性等特点,分析模糊PID控制器的设计过程及其软件实现;静态加载实验表明,运用模糊PID的控制系统可将静态加压误差控制在1%以内;同时,动态加工实验表明,动态误差可控制在4.2%以内。将模糊PID控制方法运用于高精密球体抛光压力控制中,提高了压力加载精度和稳定性,在实际加工中有较好的运用效果。     

基于ACR9000控制器的自动光学检测平台设计 

针对自动光学检测（AOI）平台运行过程中的定位精度控制问题,提出了一种基于速度和加速度前馈控制与PID反馈控制的复合控制算法,该算法对输入量进行跟踪补偿控制以消除系统稳态误差,用于提高AOI平台定位精度。基于开放式的数控系统设计方法设计了AOI平台。在Matlab/Simulink环境下,构建了基于该复合控制算法的定位精度控制仿真模型,仿真结果验证了复合控制算法的有效性。将该复合控制算法作为ACR9000控制器的控制算法,并基于ACR9000控制器进行AOI平台实验研究。应用该AOI平台进行了印刷电路板（PCB）检测实验,实验结果表明文中复合控制算法能够提高AOI平台定位精度,AOI平台的定位精度满足印刷电路板检测要求,可以将该AOI平台用于印刷电路板检测。     

Two step-down tests for equality of covariance matrices

The classical problem of testing the equality of the covariance matrices from k ? 2 p-dimensional normal populations is reexamined. The likelihood ratio (LR) statistic, also called Bartlett’s statistic, can be decomposed in two ways, corresponding to two distinct component-wise decompositions of the null hypothesis in terms of the covariance matrices or precision matrices, respectively. The factors of the LR statistic that appear in these two decompositions can be interpreted as conditional and unconditional LR statistics for the component-wise null hypotheses, and their mutual independence under the null hypothesis allows the determination of the overall significance level.     

Interactions Between Alkyl Triphenyl Phosphonium Bromides and Polyvinylpyrrolidones in Aqueous Media

The interactions of polyvinylpyrrolidones with alkyl triphenyl phosphonium bromide in aqueous media were investigated with conductometric, fluorimetric and tensiometric techniques. Formation of surfactant-polymer aggregates was detected in the case of C₁₆ and C₁₄ surfactant by these techniques. Tensiometric technique proved to be very sensitive to detect the early stage of association at very low concentrations. The Gibbs free energy of micellization and the dielectric constant values of the micellar interface values were obtained and discussed in terms of strength of interaction between the polymers and surfactants.     

用逸氢热导法测定超细陶瓷粉中游离硅和游离铝

利用游离硅和游离铝与碱溶液作用产生氢气，使它们与ＳｉＣ、Ｓｉ３Ｎ４、ＡｌＮ，ＳｉＯ２以及Ａｌ２Ｏ３等多种硅（铝）化合物分离。     

Precise isotope-ratio determination by CGC hyphenated to ICP– MCMS for speciation of trace amounts of gaseous sulfur,with SF<Subscript>6</Subscript> as example compound

Capillary gas chromatography coupled to an inductively coupled plasma mass spectrometer with multiple-collector detection (GC–ICP–MCMS) has been used to assess the precision and instrumental mass bias in sulfur isotope-ratio determination for the gaseous sulfur species SF₆. The isotopic composition of the compound was certified by the institute for reference materials and measurements (IRMM, Belgium) and is available as PIGS 2010. Integration of the peaks (peak half-width 1.4 s) was performed using a special peak-integration method based on definition of the integration area by assessment of a uniform isotope-ratio area within the chromatographic peak. Instrumental mass bias was determined to be approximately 12% per mass unit and proved to be stable in the concentration range measured. Replicate injections of 2, 10, 20, and 30 ng (as S) SF₆ diluted in argon gave precision for the ³²S/³⁴S ratio from 0.6% RSD for 2-ng injections to 0.03% RSD for 30-ng injections. The ³²S/³³S and ³³S/³⁴S isotope-ratio precision was better than 0.4% RSD for injections of 10 ng (as S) and higher. Detection limits were in the absolute pg range for all measured sulfur isotopes.     

Accuracy and precision of natural gas analysis

Summary Calculations of natural gas properties from chromatographic analysis is increasingly popular. An application of the significance of the various sources of error allows the overall uncertainty of the analytical procedure to be evaluated. Presented at the 15th International Symposium on Chromatography, Nürnberg, October 1984