二维气相色谱法分析高纯硒化氢中的微量杂质

文中采用双通道二维气相色谱技术完成高纯硒化氢气体中微量杂质含量的测定。利用一根填充柱作为预柱,分离主组分和杂质组分,两根并联的填充柱作为分析柱完成杂质组分的分离,并通过阀事件时间程序的优化实现了一次进样完成硒化氢中微量氢、氧(氩)、氮、一氧化碳、二氧化碳、甲烷等杂质分析,结果表明该方法具有重复性好(<2%),检测限低(0.002～0.01?mol/mol),分析时间短,操作方便等特点。     

PDHID与中心切割技术在高纯气体分析中的应用

脉冲放电氦离子化检测器作为一种通用型检测器,对几乎所有气体组分均具有很高的灵敏度。中心切割技术通过对气体的切割,可有效分离低含量待测组分,防止底气干扰。二者的结合可较好的用于对高纯气体中痕量杂质测定。以He、N2、Ar三种高纯气体分析为例,阐述了中心切割技术及脉冲放电氦离子化气相色谱技术的应用,并对操作过程中可能遇到的问题进行了讨论。     

脉冲放电氦离子化气相色谱仪在特种气体分析中的应用

脉冲放电氦离子化检测器作为一种高灵敏度检测器,能够检测除氖以外所有气体组分。为了更高效地检测高纯气体中杂质,避免基底气对分析测试结果的影响,一般采用中心切割法将杂质组分从基底气中分离出来。以He、H2、Ar、N2、CH4等高纯特气为例,说明在中心切割技术基础上加装预切柱对5A分子筛色谱柱的寿命以及仪器性能稳定方面有很重要的作用。通过对高纯氨测试结果表明,预切柱中填料的选择对于高纯气中微量氧的准确测定起着至关重要的作用。     

P5100系列氦离子色谱仪测定高纯气体中微量永久性气体杂质的应用

介绍了P5100系列氦离子色谱仪测定高纯气体中微量永久性气体杂质的应用。P5100系列氦离子色谱仪采用三阀三柱设计,通过阀切换和选择性切割技术可一次进样同时分析H_2、O_2/Ar、N_2、CH4、CO、CO_2等永久性气体。同时可实现对上述种类气体的高纯气体中微量永久性杂质的有效分析。CO_2、H_2、O_2/Ar、N_2、CH_4、CO的最低检出限(×10~(-6))分别为0. 0291、0. 0183、0. 0192、0. 0187、0. 0195、0. 0273,满足高纯气体中微量杂质的分析要求。     

利用脉冲放电氦电离色谱检测高纯气体中微量无机杂质

利用脉冲放电氦电离色谱检测高纯气体中的微量无机杂质是近些年刚刚发展起来的一种新方法,它具有灵敏度高和检测限低等优点,可对高纯氮气、氧气、氢气以及稀有气体氦气、氖气、氩气、氪气、氙气中无机杂质进行定量分析.本文以实验室新近购买的脉冲放电氦电离色谱为例,简单介绍原理及其操作,并通过具体实例对高纯气体中无机杂质的定量分析时可能遇到的问题进行讨论.     

准确快速测定高纯氮气中的杂质含量

简介了基于中心切割和脱氧法的HE50型DID氦离子化放电色谱仪的工作原理和工作条件等参数。武钢氧气公司从实际生产出发,对色谱仪的气路流程进行了改进,经过分析试验,建立了一套完整的分析方法。对高纯氮气中杂质含量的测量结果显示,该分析方法可以满足生产需要,从而达到准确、快速测量高纯氮气中杂质含量的目的。     

GC-126PDD氦离子气相色谱仪在特气分析中的应用

特种气体在分析过程中出现了诸如取样困难,样品是否会失真,对气路有无腐蚀;多种特气化学性质决定了其重要杂质组分微量O2检测不准或者无法用微量氧仪分析等;采用GC-126PDD氦离子气相色谱仪可以很好地解决以上问题。国产色谱仪测量杂质O2在特气中的应用正在得到推广。     

火箭推进剂液氢中氦的分析方法

使用气相色谱法分析氢中氦时，在常用色谱柱上氦出峰在氢后面，并且位置很近，较大的氢峰会掩盖氦峰。针对上述问题，研制了一种新的色谱柱固定相，用于色谱法分析氢中氦组分。给出了这种固定相对氢、氦组分的分离原理、制作方法和实验过程。实验结果表明，采用气相色谱热导检测器，配用金属钯做色谱柱固定相，可成功地完成对氢、氦组分的分离和检测。     

用氦离子化(DID)气相色谱仪分析高纯四氟化碳

介绍了一种利用氦离子化检测器(DID)分析高纯四氟化碳中微量氧气、氮气、二氧化碳和六氟乙烷的方法.利用阀切割技术能够将大量的四氟化碳主成分切割,使其不进入检测器系统.该方法对杂质的检测限能够达到0.01×10-6,经过方法验证证明,该方法能够达到较高的准确度和精密度.     

高纯氟甲烷中杂质含量色谱分析

高纯氟甲烷作为新型的含氟电子气体,常温下是一种无毒、无色、无嗅、可燃的存储在钢瓶中的液化气体。一氟甲烷作为刻蚀气体对纯度要求甚为严格,往往需要大于99.99%,甚至99.999%。探讨了高纯氟甲烷的杂质含量分析方法,采用高灵敏度的氦离子化放电检测器(DID),高效的色谱柱系统,实现了对其中杂质含量的分析。     

Estimation of Parameters of Universal Distribution of Moments of Failure of Products

A method is proposed for estimating the parameters of a mixture of exponential and Weibull distributions for which the accuracy of preliminary estimates obtained by graphical analysis is refined in accordance with the criterion of maximum likelihood. The efficiency of the proposed method is supported by the results of statistical modeling.     

Evaluation of optical properties of highly scattering media by moments of distributions of times of flight of photons

A novel method for the determination of the optical properties of tissue from time-domain measurements is presented. The data analysis is based on the evaluation of the first moment and the second centralized moment, i.e., the mean time of flight and the variance of the measured distribution of times of flight (DTOF) of photons injected by short (picosecond) laser pulses. Analytical expressions are derived for calculation of absorption and of reduced scattering coefficients from these moments by application of diffusion theory for infinite and semi-infinite homogeneous media. The proposed method was tested on experimental data obtained with phantoms, and results for absorption and reduced scattering coefficients obtained by the proposed method are compared with those obtained by fitting of the same data with analytical solutions of the diffusion equation. Furthermore, the accuracy of the moment analysis was investigated for a range of integration limits of the DTOF. The moment analysis may serve as a comparatively fast method for evaluating optical properties with sufficient accuracy and can be used, e.g., for on-line monitoring of optical properties of biological tissue.     

Analysis of the rate of propagation of the wave of change of boiling modes

An approximate analytical expression is derived for the velocity of the front of the wave of change of boiling modes on a rod and on a plate. The impact of the Thomson effect and of the heater orientation in the gravity field is included. Adequate agreement is demonstrated between the derived relations and experimental data.     

Estimation of potentialities of methods of summation of direct measurement errors

Conventional methods for summation of direct measurement errors are considered. Conditions under which these methods provide consistent results are stated. It is proposed to utilize for characteristic of the total error, its interval estimator or the half-sum of the value obtained by adding up its arithmetic and geometric random errors.Translated from Izmeritel'naya Tekhnika, No. 4, pp. 10–12, April, 1995.     

空压机轴承箱蜗壳温度探头油封改造

由于空压机进气侧轴承箱蜗壳温度探头密封效果不好,使空压机及其后续管道受到油污染。后将温度探头的O形圈密封改为骨架油封,杜绝了轴承箱漏油问题。文章简介空压机的结构和技术参数,详细介绍了骨架油封的制作和优点。     

Characteristics of mechanical properties of materials in studies of conditions of attainment of marginal states

It is shown that conditions of attainment of marginal states in the material of structural components are formulated on the basis of analysis of force and deformation criteria of formation and development of destruction. The parameters of these criteria are data on types of structural materials, standard and special characteristics of their mechanical properties, structural forms of considered elements of the equipment, and their operating stress loading. In this case, the construction of a system of state equations for describing interrelation of current damage, external actions, and responses to them is based on the concept of calculating variations in properties of materials at all stages of the design life cycle.     

Determination of parameters of microstructural inhomogeneity of deformation of metals by the method of modeling

The article suggests a method of evaluating the microstructural inhomogeneity of deformation of metals by modeling. The method includes the measurement of deformations of metal according to meshes of a dividing grid with small base and the calculation of the distribution parameters of microdeformations in model representation. It is shown that the modeling method makes it possible objectively to evaluate the microinhomogeneity of deformation of metals independently of the chosen mesh size of the dividing grid. New structural characteristics are introduced: the base and wave of variation expressing the degree of crumbling or amalgamation of metal grains by inhomogeneity of deformation.Translated from Problemy Prochnosti, No. 7, pp. 40–44, July, 1991.     

水三相点复现的不确定度评定

水三相点是开尔文热力学温度的唯一基准点，也是ITS-90国际温标重要的定义固定点。因此，水三相点不确定度分析对整个温标的建立、温度量值传递起着至关重要的作用。近3年来，中国计量科学研究院研制出一系列高质量的水三相点容器，加强了水三相点的研究，为不确定度的分析提供了更为可靠的实验依据。同时，不确定度的分析也是客观评价新研制容器性能的一个重要指标。因此，根据实验结果对新研制容器所复现的水三相点进行了不确定度评定。评定结果表明，其扩展不确定度为0．16mK(k=2．69，P=0．99)。