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981.
Hu  Yaogai  Zhou  Junjie  Tang  Ju  Xiao  Song 《Chromatographia》2013,76(11):687-696

The accuracy of spectrograms may be affected by baseline excursion or drift when infrared spectrometers are used in the analyses of gases. Background deduction or baseline correction is one of the effective pretreatment methods that can improve measurement accuracy. This paper presents a novel methodology based on complex wavelet transform algorithm to perform background deduction. The complex wavelet transform methodology establishes a complex wavelet filter to decompose the spectral signals first, and set the decomposition coefficients in the high-frequency section to zero, and then reconstruct the background signals; finally, the background deduction can be realized by deducting the background signals. In this study, the complex wavelet established by Daubechies was selected to demonstrate background deduction aiming at simulative spectral signals with different backgrounds and the real spectral signal of SF6 decomposition gases. Compared with the results done by the real wavelet transform in the same conditions, the results indicate that complex wavelet transform methodology can perform background deduction more efficiently than real wavelet transform methodology, thus improving the effectiveness and precision of spectrogram measurements greatly, which is useful for SF6 gas decomposition compositions analysis

  相似文献   
982.
介绍一种基于Labview的虚拟仪器开发平台,采用美国国家仪器公司的PCI-6221数据采集卡对单缝衍射光强分布的数据采集和测量的方法。测量结果理论值基本吻合,说明运用Labview的测量方案切实可行。  相似文献   
983.
<正>1引言美国气象学家E.N.Lorenz在1963年提出的用来刻画热对流不稳定性的模型,即Lorenz混沌模型,后来人们对这个系统进行了大量而深入的研究.到目前为止,Lorenz系统的动力学行为已经比较清楚.1998年,Mischaikow和Mrozek用Conley指标理论和严格的计算机辅助计算方法证明了Lorenz系统存在混沌行为.1999年,Tucker则用规范型理  相似文献   
984.
Electrospray deposition(ESD) as a patterning method of nanoparticles deposited on a substrate has attracted much attention due to several advantages over other methods.However,obtaining an optimum ESD processing condition for nanoparticle pattern relies much on trial experiments because of the lack of reliable numerical simulation.In this study,the deposition characteristics of nanoparticle generated by electrospray were investigated by using a three-dimensional Lagrangian model.Three important process parameters,including solution dielectric constant,applied voltage and surface charge density on mask were considered by fixing the geometrical parameters of the ESD device.Simulation result showed that under the condition of without a mask,the spray diameter increases with increasing solvent dielectric constant,and higher applied voltage makes the spray area wider.Controllability of focusing by changing surface charge density on the mask was confirmed:higher surface charge density on the mask results in more focused deposition.Validity of the numerical simulation developed in this study was verified by comparison with experimental data.  相似文献   
985.
986.
A fast and sensitive high performance liquid chromatography coupled with mass spectrometry (LC‐MS) method was developed and validated for the determination of cyclophosphamide in rat plasma with and without the combination of vitamin B6. After addition of digoxin used as the internal standard (IS), plasma samples were extracted by protein precipitation with acetonitrile (1:1, v/v), and the analytes were separated by a Kromasil C18 column (150 × 4.6 mm, 5 µm) with a mobile phase of acetonitrile–0.1% formic acid water (40:60, v/v). The detection of the analyte was monitored in positive electrospray ionization by selected ion monitoringmode. The linear range was 0.01–40 µg/mL for cyclophosphamide. The intra‐ and inter‐day precision and accuracy were all <15%. The extraction recoveries and matrix effects of the analyte and IS were all within acceptable range. The selectivity of the method was satisfactory with no endogenous interference. The results for stabilities of cyclophosphamide and IS under various conditions were all within the acceptance criteria. The validated method was successfully applied to evaluate the drug–drug interaction of cyclophosphamide and vitamin B6 in rat plasma. The results showed no differences of pharmacokinetic behaviors between cyclophosphamide administration with and without vitamin B6. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   
987.
Li  Haotian  Zeng  Fuping  Zhang  Mingxuan  Zhu  Kexin  Yao  Qiang  Wei  Gang  Ma  Guoming  Tang  Ju 《Plasma Chemistry and Plasma Processing》2022,42(3):505-518

In gas-insulated equipment, partial over-thermal faults may occur due to poor contact and other reasons. The main insulation medium SF6 may decompose under over-thermal conditions and produce harmful products such as SO2 and HF, which can damage the equipment and reduce the insulation strength of the equipment. The method of decomposition component analysis can monitor the operating status of equipment without interference from machinery, noise and optics, and provide early warning or reminder of faults, but the premise is that the decomposition mechanism of SF6 must have been fully and in-depth understood. In the decomposition process of SF6, O2 has a significant effect, but the mechanism of the effect is still unclear. Based on the isotope tracing method, this paper uses 18O2 instead of ordinary O2 for overheating experiments. Through the quantitative detection of the labeled products in the product and the abundance of 18O isotope in the products, the effect of O2 on the formation of the main decomposition products was analyzed. The work makes the reaction process and mechanism of SF6 with trace oxygen under over-thermal conditions basically clear, which provides an important theoretical basis for on-line monitoring and fault diagnosis of equipment based on chemical analysis methods.

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988.
989.
为解决当前发射场加注系统维修维护与状态监测所面临的问题,提出针对加注系统开展基于信息融合的健康监测;分析针对加注系统开展健康监测研究以及将信息融合技术引入系统健康监测的意义,总结加注系统健康监测现状,得出开展加注系统健康监测所面临的困难与启示;针对加注系统典型设备,设计融合式健康监测方案,包括健康监测信息特点分析、典型设备健康监测信息分析以及典型设备健康监测方案设计;为后续进一步深入开展加注系统融合式健康监测研究奠定了良好基础。  相似文献   
990.
A technology credit guarantee policy has been established to provide financial support to technology-based SMEs with a limited asset base. For an effective technology credit guarantee policy, risk management is essential. In this paper, we investigate a survival model that predicts start-up SMEs’ loan default probability at a given time based on technology attributes along with the economic environment and the firm’s characteristics at the time of the technology credit guarantee fund application. This, in turn, is used for the estimation of the technology fund risk along with a stress test. Our work is expected to contribute to reducing the risks associated with technology financing.  相似文献   
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