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前言在气体分析中,标准气是定性和定量的基本依据。称量法、压力法、针筒法都是常用的配气方法,但在配制1ppm左右氢标准气时,上述方法或因较繁琐,或因不够精确而很少采用。气敏色谱法是分析痕量氢的有效方法,但其线性响应范围很窄,要求有足够低浓度的标准气来定量。国标规定,被测样品的浓度应在标准气浓度的50%~200%范围内。 相似文献
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分析和识别了使用电子天平配制标准气体时称量过程不确定度分量的来源,根据数学模型对各分量进行了合成。通过实例分析,对称量过程不确定度的评定进行了量化。 相似文献
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电子天平是一种操作方便、快速、灵敏度高,用于称量物质重量的仪器,已经广泛用于高等院校、工业、农业、国防等部门。通过介绍电子天平的种类、使用及维护,使操作人员更好的使用天平。 相似文献
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对丁烯系列标准气体气相色谱分析方法进行了探讨,给出了丁烯系列同分异构体的实验条件,并就实验结果的误差进行了讨论。 相似文献
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标准气体配制计算系统、通信系统传统的操作方式需要人工进行繁琐的计算、推算,最终得出理想值,通过理想值再进行配制,整个过程对配气人员有着较高的要求,导致培训成本和后续管理成本较高。标准气体配制计算系统很好的解决了这一问题,该系统对操作人员的要求很低,操作人员只需要输入相应组分及含量,计算机自动计算配制所需的气体质量和压力,涉及爆炸性气体的自动计算爆炸极限,涉及液化性气体的自动计算最大配制压力,并实时自动采集控制系统实际配制数据进行再计算,不需要操作人员进行配制前及配制过程中的手工计算。 相似文献
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用气相色谱法测定清香型白酒中重要特征指标乙酸乙酯的两种定量方法:内标法和外标法,采用这两种方法对白酒样品进行测定。结果表明,内标法和外标法对清香型白酒中乙酸乙酯的测定无显著性差异,因此可以把外标法推广到平常的清香型白酒的检测工作中,简化了操作步骤,满足现代快速分析的需求。 相似文献
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穷举法是根据各个自变量所有可能取值相对应的函数值(输出值)寻找参数特征的一种分析方法。在动靶标标准装置的设计中,尽管其计算公式复杂,但用穷举法还是能比较方便地推算出各参数之间的关系,从而可以合理地设计出满足应用要求的动靶标标准装置。 相似文献
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静重式力标准机砝码交换力平衡控制技术 总被引:1,自引:0,他引:1
静重式力标准机利用少量的砝码,进行相等力值间隔逐级加、卸荷时,需要交换砝码。当砝码进行交换时出现逆负荷现象,会对被检测力仪的示值产生影响。阐述了静重式力标准机采用的交换砝码方法是建立在利用弹性力替代砝码重力,砝码交换过程中重力与弹性力达到平衡的基本原理。提出了实现静重式力标准机砝码交换时系统达到力平衡的一种预加荷装置,经砝码交换力平衡控制的力学分析与实验验证,静重式力标准机采用预加负荷实施倒码力平衡控制的方法在理论上和技术上是可行的、有效的。 相似文献
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Y. Kurano H. Kobayashi K. Yoshida H. Imai 《International Journal of Thermophysics》1992,13(4):643-657
Deming's method of least squares is introduced to make an accurate kinematic viscosity estimation for a series of 13 standard-viscosity liquids at any desired temperature. The empirical ASTM kinematic viscosity-temperature equation is represented in the form loglog(v+c)=a–b log T, where v (in mm2. s–1) is the kinematic viscosity at temperature T (in K), a and b are the constants for a given liquid, and c has a variable value. In the present application, however, c is assumed to have a constant value for each standard-viscosity liquid, as do a and b in the ASTM equation. This assumption has since been verified experimentally for all standard-viscosity liquids. The kinematic viscosities for the 13 standard-viscosity liquids have been measured with a high accuracy in the temperature range of 20–40°C using a series of the NRLM capillary master viscometers with an automatic flow time detection system. The deviations between measured and estimated kinematic viscosities were less than ±0.04% for the 10 standard-viscosity liquids JS2.5 to JS2000 and ±0.11% for the 3 standard-viscosity liquids JS15H to JS200H, respectively. From the above investigation, it was revealed that the uncertainty in the present estimation method is less than one-third that in the usual ASTM method. 相似文献
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Honghua Dai Zipu Yan Xuechuan Wang Xiaokui Yue Satya N. Atluri 《International journal for numerical methods in engineering》2023,124(2):458-481
Periodic dynamical systems ubiquitously exist in science and engineering. The harmonic balance (HB) method and its variants have been the most widely-used approaches for such systems, but are either confined to low-order approximations or impaired by aliasing and improper-sampling problems. Here we propose a collocation-based harmonic balance framework to successfully unify and reconstruct the HB-like methods. Under this framework a new conditional identity, which exactly bridges the gap between frequency-domain and time-domain harmonic analyses, is discovered by introducing a novel aliasing matrix. Upon enforcing the aliasing matrix to vanish, we propose a powerful reconstruction harmonic balance (RHB) method that obtains extremely high-order (>100) nonaliasing solutions, previously deemed out-of-reach, for a range of complex nonlinear systems including the cavitation bubble dynamics, the three-body problem and the two dimensional airfoil dynamics. We show that the present method is 2–3 orders of magnitude more accurate and simultaneously much faster than the state-of-the-art method. Hence, it has immediate applications in multidisciplinary problems where highly accurate periodic solutions are sought. 相似文献
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蒙特卡罗方法在无穷级数中的应用 总被引:1,自引:0,他引:1
柴中林 《中国计量学院学报》2007,18(3):257-260
将蒙特卡罗方法应用到无穷级数中去,证明了蒙特卡罗方法可以求收敛的无穷级数的和,也可以一定程度上判断无穷级数的敛散性.此外,通过模拟对随机变量及其参数的选择进行了讨论. 相似文献
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覆冰输电线的舞动是一种非线性振动。应用增量谐波平衡法推导了覆冰输电线的有限元分析模型及运动平衡方程,并对舞动方程进行了求解。该方程具有非线性平方及立方刚度项、平方及立方粘滞阻尼项。把振动过程分解成为瞬态的持续增量振动过程,迭代求出舞动频率及振幅,求得方程解的表达式。结合实例分析了输电线舞动的极限环现象和谐波项数的取值问题,与时程积分方法分析结果比较表明吻合较好。对风速增量进行了参数分析推导,算例表明不同风速下覆冰输电线舞动频率与振幅是不同的,在某个临界风速处会发生舞动分岔。 相似文献