补阴中药矿质元素主成分分析

以矿质元素含量为指标,对13种补阴中药进行主成分分析,研究其矿质元素(Fe、Zn、Ca、Mg、Mn、K、Al、Cu、Ni和Pb)的分布特征。主成分分析表明,前4个主因子含有补阴类中药矿质元素81.535%的信息。第一主成分是Ca、Zn、Mg;第二主成分是Fe、K;第三主成分是Ca;第四主成分是Zn、Pb。中药补阴作用的主要影响元素为Ca、Zn、Mg三种元素。结果表明中药的补阴作用与矿质元素分布有关。     

基于主成分回归模型的建筑人工单价预测研究

定额人工单价的主要影响因素与某一时期的劳动力市场供求关系、社会经济发展水平、物价增速、人口结构及就业偏好等因素有关。通过对定额人工单价影响因素的识别,确定影响建筑劳务单价的特征指标变量。结合特征指标变量标准化、适用性检验、提取主成分、主成分因子的计算等主成分分析法的实施,采用SPSS软件对选取的指标数据进行初步回归分析及多重共线性诊断,建立市场人工单价主成分回归预测模型并对2021年前三季度的市场人工单价进行预测。结果表明,预测值与实际值相对误差<3%,模型精度满足要求,该主成分回归预测模型可用于建筑行业市场劳务单价的预测工作。     

主成分分析法在东张水库水质污染特征分析与评价的应用

采用主成分分析法（PAc）对东张水库水质进行综合评价,分析了其水质的时间和空间变化特征及污染因子对水质的贡献,以揭示东张水库水质变化的时空分布规律和水质污染特征．分析评价结果表明：水质时间特征分析可由三个主成分反映。东张水库库心断面在2004-2009年时间跨度上表现为2005年水质污染综合评价排序最高。水质最好;20...     

基于改进核主成分分析的故障检测与诊断方法

针对传统基于核主成分分析的故障检测方法提取非线性特征时只考虑全局结构而忽略局部近邻结构保持的问题, 提出基于改进核主成分分析的故障检测与诊断方法。改进核主成分分析方法将流形学习保持局部结构的思想融入核主成分分析的目标函数中, 使得到的特征空间不仅具有原始样本空间的整体结构, 还保持样本空间相似的局部近邻结构, 可以包含更丰富的特征信息。在此基础上, 本文使用改进核主成分分析方法把原始变量空间映射到特征空间, 使用费舍尔判别分析在特征空间中构建距离统计量并通过核密度估计确定其控制限, 进一步利用相似度的性能诊断方法识别发生的故障类型。采用Tennessee Eastman过程故障检测数据集进行的仿真实验表明所提方法可以取得较好的效果。     

近红外透射光谱法测定黄芪提取液中总皂苷含量

应用傅立叶变换近红外光谱仪透射光谱技术对黄芪提取液中总皂苷含量进行检测分析,采用主成分分析(PCA)和偏最小二乘回归法(PLS)建立了黄芪提取液中皂苷类物质含量近红外数学校正集模型,其相关系数R为0.99943、校正集标准偏差(RMSEC)为 0.544、预测集标准偏差(RMSEP)为0.567.用建立的数学校正集模型检测未知样品的含量,预测标准偏差(RMSEP)为0.576.该方法快速、准确、无损,适于中药活性成分的快速检测分析.     

基于近红外光谱建立PE、PP和PET的识别分类模型

利用近红外高光谱成像仪在900~1 700 nm的范围采集PE、PP和PET样本的高光谱图像,并进行黑白校正,提取感兴趣区域的反射率光谱数据;利用主成分分析法对提取的数据去噪降维。结果表明,前3个主成分的累计贡献率达98.89%。把前3个主成分的载荷系数对波长作图,得到了6个特征波长;利用特征波长对应的反射率光谱数据进行判别分析,并建立了3种塑料的识别分类模型;用预测样本对模型进行检验,结果显示,预测样本的识别准确率为95.24%,表明该模型可准确有效地对PE、PP和PET进行识别分类。     

快速鉴别车用汽油清净剂主剂及清净性研究

用中红外光谱仪对市场上的胺类汽油清净剂进行检测,给出了18个汽油清净剂的红外光谱图,通过特征峰分析得出了其主剂成分。利用化学发光法和模拟进气阀沉积物分析法对其中5个汽油清净剂进行了总氮含量和沉积物下降率的测定。本文给出了不同主剂物质的识别原则。结果表明当主剂含有其中之一或者其复合物时,有优良的清净效果,当特征峰不明显且不含氮的汽油清净剂为劣质的胺类清净剂,无明显的清净作用。     

重庆地区种植的大马士革玫瑰精油成分分析

采取水蒸气蒸馏法提取重庆地区引种的大马士革玫瑰精油,用GC-MS、GC法对大马士革玫瑰精油成分进行了分析鉴定。GC-MS法共鉴定出39种成分,占总峰面积的99.9562%;气相色谱峰面积归一法对玫瑰精油主香特征成分进行了定量,并与玫瑰油国际标准(ISO 9842:2003)作了对比分析,结果发现,两者成分含量基本吻合。样品油具有甜润、浓郁玫瑰花香,大马士革玫瑰香特征突出,与高档大马士革香水玫瑰样品对比,其甜润气息稍稍欠缺,花蜡味重,水溶性香气部分不足。     

主成分-人工神经网络光度法在混合食用合成色素定量分析中的应用

对日落黄、胭脂红、苋菜红三种色素的吸收光谱数据进行了偏最小二乘法的主成分分解,用人工神经网络对原始吸光度数据及其主成分矩阵进行分析.结果表明,主成分-人工神经网络模型优于人工神经网络模型,其回收率在98%～102%范围内,结果令人满意.该方法具有简单、快捷、精度较高,可广泛应用于食品中多组分混合色素的检测.     

基于KPCA特征集成算法的SOFC系统多故障识别

针对固体氧化物燃料电池系统多模式、非线性及高维等特点,提出基于数据驱动的模式识别方法。首先用核主成分分析特征集成算法提取故障特征,然后在特征空间中使用多项式逻辑斯谛回归算法进行故障诊断。实验结果表明:核主成分分析特征集成算法可以全面提取出故障特征,能够大幅提高后续分类器故障的识别效果。     

The source identification and classification study of soot after combustion

Solid phase microextraction‐gas chromatography‐mass spectroscopy technology was used to extract and analyze three kinds of accelerant soot including diesel soot, gasoline soot, and diesel–gasoline mixture soot. A total of 60 spectrograms have been obtained, analyzed, and compared. It was found that these kinds of soot were quite different with each other in the difference of major target compounds and retention time span, and could be visually identified by the profile of the corresponding spectrogram. A data matrix of 60 * 41 was reached by the characteristic substances corresponding with the retention time in all these 60 spectrograms. With principal component analysis method, two major component variables were obtained to classify the attribution of soot, with perfect classification efficiency of 100%. Hierarchical cluster analysis was further applied for the dendrogram analysis. In spite of the absence of the training set, the classification of 100% accuracy of these kinds of soot could be achieved. Copyright © 2012 John Wiley & Sons, Ltd.     

DIESEL SOOT COMBUSTION WITH PEROVSKITE CATALYSTS

Diesel soot emissions from stationary or mobile sources can be reduced through physical trapping in particulate filters until periodical in situ combustion takes place. This study focuses on the development of several perovskites for the catalytic combustion of diesel particulates in multifunctional catalytic reactors. Several perovskites, with BET surface areas of 20–30 m²/g, were prepared by the solution combustion synthesis method and were characterized by XRD, SEM, TEM, and TPD techniques. Catalytic activity tests have shown that the most promising catalysts, namely, perovskite catalysts with Cr in the B site and Tb or Pr in the A site, can ignite soot combustion well below 400°C, i.e., at a temperature 200°–250°C lower than that of noncatalytic diesel soot combustion. The best catalytic formulation was deposited on a full-scale wall-flow filter and tested against the soot emissions of a diesel engine, resulting in reduced regeneration time and substantial fuel consumption saving compared to the corresponding bare filter performance.     

Thermal Separation of Soot Carbon

We present here a simple and versatile variant of the thermal analysis of soot carbon, and a discussion on the encountered analytical artifacts. The method is based on a two-step combustion procedure; the removal of the organic material that does not absorb visible light is optimized during a precombustion step at 340°C during 2 hours under a pure oxygen flow, and the remaining carbon is then determined by coulometric titration of the CO₂ evolved from the combustion of the samples. These analytical conditions minimize the crossover between the different components of the aerosol, but better to a clear-cut division between organics and soot carbon, the quantitative evaluation of their thermal evolution is obtained. Artifacts have been tested thoroughly with various standards and replicates of ambient air samples collected. The method gives reliable soot carbon determination at the microgram level in samples from a wide variety of environments. Combined H / C atomic ratio measurements and investigations of the problems associated with the thermal determination of soot carbon permit gaining some insight on the nature of carbonaceous aerosols. They reinforce the indication that soot carbon is not composed primarily of elemental carbon. Also, it is suggested that highly polymerized natural organic aerosols though different in nature could behave thermally and optically like soot.     

Reduction of diesel particulate emissions by catalytic filtration

Several kinds of diesel soot filters and filter materials of high melting points with eleven different catalytic coatings were prepared. They were calcined at a maximum temperature of 1000°C. The reaction rate and the kinetic parameters of the combustion of diesel soot were determined in a closed loop laboratory reactor. A packed bed of alumina particulates was the most active filter in soot combustion. Catalytic coatings with oxides of vanadium, copper or cerium accelerated the reaction. In each case the effect of the coating was dependent on specific interactions between the catalyst and the filter material. The manner of filtration and the nature of the soot filter are found to be more important for the overall result than the nature of the catalytic coating.     

柴油车尾气四效组合催化剂的研究

提出设计双层组合催化剂净化新技术,即碳黑氧化燃烧催化剂床层和NOx还原催化剂床层的组合,该组合催化剂对柴油机尾气四种污染物的消除具有较高的催化活性。采用浸渍法制备了Al₂O₃负载不同量的La_0.8K_0.2MnO₃和相同负载量、不同K含量的La_1-xK_xMnO₃/Al₂O₃催化剂作为氧化催化剂处理碳烟、CO和HC;采用等体积浸渍法制备Cr/HZSM-5、Mo/HZSM-5、W/HZSM-5三系列催化剂作为还原催化剂处理NOx,并将其进行组合,得到优良的氧化还原组合催化剂,同时处理柴油车尾气中的四种污染物。在模拟柴油车尾气组成条件下,用乙炔代表烃类物质并采用固定床微型反应装置,考察了所制备的双层四效组合催化剂净化柴油车尾气的催化性能。研究发现,负载质量分数为50%的La_0.5K_0.5MnO₃/Al₂O₃和负载量为1.42×10^-4mol·g^-1的W/HZSM-5组合催化剂对于同时消除柴油车尾气NO、碳颗粒、CO和HC有较好的效果。NO还原为N₂的转化率在反应温度范围最高可达79%,同时碳颗粒的燃烧峰值温度为448 ℃,碳颗粒燃烧生成CO₂ 的最大选择性可达98%,乙炔完全转化的温度为364 ℃,从而实现了四种有害物质的同时催化净化。     

One-pot synthesis of mesoporous CuOx/CeO2 co-loaded ZrO2–TiO2 nanocomposites via surfactant-free solvothermal method for catalytic removal of soot under NO/O2

A novel porous CuO_x/CeO₂ co-loaded ZrO₂–TiO₂ (ZT) nanocomposite with tunable pore structure and high surface area was prepared by a simple surfactant-free solvothermal method. The pore structure could be well controlled by adjusting the ratio of ethanol to H₂O during the solvothermal process. Both copper oxides and ceria species could be homogeneously loaded into porous ZT nanocomposite by either incorporation into ZT framework or dispersion into the pore channels. Two kinds of novel catalysts with different pore structures have been synthesized and exhibit excellent soot catalytic combustion performance, owing to the porous structure and the active components of CuO_x/CeO₂.     

Activation energy for soot formation by C2-hydrocarbon/air flames

Engineering design and computer models in combustion often require data on the temperature dependence of the non-equilibrium, rate-controlled process of soot formation. Global apparent activation energies usually satisfy these needs in operational reaction kinetics, but they are not understood. A review of the combustion literature revealed that methods for determining the apparent global activation energy for combustion and soot formation are often rather involved and typically yield results with large uncertainties. The objective of the paper is to introduce and demonstrate a straightforward and more precise procedure for determining the pseudo-activation energy for soot formation. The method is based on the measurement of flame temperature and generates a result with a factor of 10 better precision. The new procedure has been demonstrated for soot formation by C₂-hydrocarbon/air flames.     

Nanometric La1−x K x MnO3 Perovskite-type oxides – highly active catalysts for the combustion of diesel soot particle under loose contact conditions

The La_1−xK_xMnO₃ perovskite-type oxides whose sizes were in nanometric range were prepared by the citric acid-ligated method. The structures of these perovskite-type oxides were examined by XRD and FT-IR. The catalytic activity for the combustion of soot particulate was evaluated by a technique of the temperature-programmed reaction. In the LaMnO₃ catalyst, the partial substitution of K for La at A-site enhanced the catalytic activity for the combustion of soot particle. In the La_1−xK_xMnO₃ catalysts, the combustion temperature of soot particle decreases with increasing x values. The La_1−xK_xMnO₃ oxides with the substitution quantity between x=0.20 and x=0.25 are good candidate catalysts for the soot particle removal reaction, and the combustion temperature of soot particle is between 285 and 430 °C when the contact of catalysts and soot is loose, and their catalytic activities for the combustion of soot particle are as good as supported Pt catalysts, which is the best catalyst system so far reported for soot combustion under loose contact conditions.     

锰铈相互作用对催化碳烟燃烧性能的影响

采用等体积浸渍法制备HZSM-5分子筛负载Mn（9Mn/Z）,Ce（9Ce/Z）和同时负载Mn、Ce（4.5Mn4.5Ce/Z）催化剂,并考察了它们的催化碳烟颗粒燃烧的性能。结果表明,同时负载Mn、Ce的催化剂（4.5Mn4.5Ce/Z）具有更好的催化碳烟燃烧的活性,碳烟转化率为50%时所对应的温度（T₅₀）为400℃,低于9Mn/Z（T₅₀=414℃）和9Ce/Z（T₅₀=447℃）催化剂。相比于纯碳烟的燃烧,T₅₀降低了128℃。通过氢气程序升温还原（H₂-TPR）测试,相比较催化剂9Mn/Z和9Ce/Z,催化剂4.5Mn4.5Ce/Z中混合氧化物的氢气的还原温度向低温方向产生了偏移,具有更好的氧化还原性,说明MnO_x和CeO₂产生了一定的相互作用;X射线光电子能谱（XPS）测试表明,样品4.5Mn4.5Ce/Z具有更多的表面化学吸附氧物种,这些氧物种有助于碳烟氧化燃烧,因而表现出较高的催化碳烟燃烧活性。     

Catalytic ceramic papers for diesel soot oxidation: A spray method for enhanced performance

A spray method is proposed to improve the catalytic properties of ceramic papers to be used as catalytic filters for removing diesel soot particles. Small particles of Ce and Co oxides, acting as active centers for the combustion of the soot retained by the filter, are efficiently and homogeneously deposited. On the contrary, the application of the conventional drip method results in bigger particles mainly agglomerated at the crossings between the fibers of the ceramic paper. As a result, catalytic papers prepared by the spray method exhibit much higher performance with soot combustion temperatures decreased by ~ 30 °C.