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1.
快速、有效地识别饮用水中污染物类别对于降低突发饮用水污染事件影响十分重要。目前基于紫外-可见光光谱法的饮用水污染物判别模型大多使用主成分分析(PCA)进行特征提取,然而,对于光谱相似度较高的有机污染物,仅从数据驱动的角度提取其方差最大的方向作为特征进行识别效果往往不佳。针对有机污染物光谱数据多重共线性以及谱峰重叠干扰的问题,开展了基于连续投影算法(SPA)和多分类支持向量机(M-SVM)的紫外-可见光光谱饮用水有机污染物判别方法研究。首先,使用紫外光谱仪测量苯酚、对苯二酚、间苯二酚和间苯二胺的原始光谱数据并进行预处理,在对四种污染物进行了波长与浓度的相关关系对比分析后,发现苯酚和间苯二酚、对苯二酚和间苯二胺的谱峰重叠较为严重;特征提取时,引入SPA筛选有机污染物紫外-可见光光谱数据的特征波长组合,并对不同波长个数时的光谱吸光度进行多元线性回归分析,选取对应最小预测标准偏差的参数及波段组合作为最优参数组合;基于最优特征波长组合,构建基于多分类SVM的饮用水有机污染物分类识别模型;最后,对比分析了全光谱、 PCA及SPA特征提取后的光谱数据在不同分类方法及不同污染物浓度下的分类效果,进一步说明了SPA的适用性和稳定性。实验结果表明, SPA作为一种提取光谱数据原始特征波段的方法,可以有效的对有机污染物的紫外-可见光光谱进行特征提取,提升不同物质之间的差异,在一定程度上消除多重共线性和谱峰重叠干扰,从而提高分类模型的准确率。该方法对于解决饮用水中谱峰重叠的污染物类型判别问题具有参考价值。  相似文献   

2.
对不同岩性的岩石构建近红外光谱含水量反演模型过程中,其特征集是否会因岩性不同而变化,是建模时必须面对的关键问题。针对该问题,首先利用深部软岩水理作用智能测试系统进行了岩石吸水室内实验,分别采集了砾岩、粉砂岩、夯土不同时刻3种不同岩性的含水岩石的近红外光谱各为51条、 106条和149条;然后,采用一阶导数法对原始光谱进行预处理,消除环境干扰等对光谱的影响;接着,采用几何特征法提取光谱特征,进行归一化处理,消除量纲和变化幅度不同带来的影响;分析了初始特征变量之间以及初始特征变量与含水量之间的相关程度,并通过抑制阈值大小,剔除冗余特征,得到了两个强相关谱段处的特征变量;最后利用最大信息系数(MIC)值作为度量标准,对比分析了不同岩性的含水岩石近红外光谱的特征选择结果,以期评价岩性对含水岩石光谱特征的影响。结果表明:(1)砾岩、粉砂岩、夯土三种含水岩石的近红外光谱在1 400和1 900 nm附近都有着明显的吸收峰,且随着含水量的变化,吸收强度越来越强,与含水量大小有明显的相关性;(2)对比砾岩、粉砂岩、夯土近红外光谱特征变量与其含水量的最大相关系数MIC值,表明夯土的近红外光谱与含水量之间的相关性最强;(3)不同岩性的近红外光谱各个特征值与含水量的相关程度不同,具体表现为在1 400 nm附近峰高、右肩宽与含水量都具有较高相关系数,只是相关性大小会因岩性不同而不同, 1 900 nm附近的右肩宽和峰面积与含水量都具有较高相关系数,且右肩宽的相关程度高于峰面积;(4)不同岩性的含水岩石介质近红外光谱的特征变量与含水量相关性具有相似规律:峰高、右肩宽、峰面积是相关程度最高的三个特性。  相似文献   

3.
近红外光谱分析在工业过程故障检测方面具有独特的优势,是一种准确且高效的方法。结合互信息熵和传统的主成分分析,对近红外光谱特征信息进行提取,通过构建过程的模式来刻画工业过程的运行状态。利用近红外光谱数据,从有机分子含氢基团振动信息中获取工业系统的过程模式,从微观分子层面探索提高工业过程故障检测准确率的有效方法,结合贝叶斯统计学习技术,提出了基于近红外光谱数据的工业过程故障检测技术。针对近红外光谱信息量丰富,谱带较宽,特征性不强的特点,首先对工业过程不同运行状态下的近红外光谱吸光度数据进行一阶导数预处理,采用主成分分析法(principal component analysis,PCA)压缩光谱数据量,扩大不同运行状态下光谱特征信息的差异性,提取光谱的内部特征信息。然后采用互信息熵(mutual information entropy,MIE)作为光谱特征信息相关性度量函数,基于最小冗余最大相关算法进一步减少光谱特征信息间的冗余并最大化光谱特征信息与类别的相关性,弥补了PCA无监督特征波长选择的不足,提出一种基于PCA-MIE的过程模式构建方法,获得的过程模式子集更紧凑更具类别表现力。再利用贝叶斯统计学习算法,根据后验概率对构建的模式子集进行决策,判别生产过程的正常状态和故障状态。由于过程模式子集结合了PCA浓聚方差的优势和互信息熵相关性测度的特征信息选择方法,蕴含了更多的近红外光谱的本质信息与内在规律,从而更能刻画工业过程的运行状态。接着,设置测试准确率TA作为评估标准,用以评价故障检测方法的性能效果。最后利用某化工厂提供的原油脱盐脱水过程近红外光谱数据对所提方法进行验证,并与传统近红外光谱特征信息提取方法PCA和MIE方法性能进行对比分析,结果表明基于PCA-MIE的过程模式故障检测方法几乎在所有维数子集上性能都优于其他两种方法,在特征维数为18维时获得最高的准确率94. 6%,证明了方法的优越性。  相似文献   

4.
木材中的水分及其近红外光谱分析   总被引:19,自引:5,他引:14  
水分是木材的重要特征之一,用近红外光谱分析木材性质,必须考虑水分对预测结果的影响.文章分析了不同含水率状态下木材在近红外光谱区的吸收特性;用近红外光谱法预测木材中的水分含量,相关系数为0.99,校正标准偏差SEC和预测标准偏差SEP分别是0.041和0.043;通过在不同含水率(7%,12%,20%,30%,60%)状态下采集近红外光谱与固定含水率下的木材密度建立关联,结果表明,利用近红外光谱技术可以在不同含水率下采集近红外光谱来预测木材气干密度.  相似文献   

5.
多成分有机气体的近红外光谱定量检测方法   总被引:3,自引:0,他引:3  
在环境检测领域,运用近红外光谱分析技术对多成分挥发性有机物进行连续的在线监测具有重要意义。本文分析了三种挥发性有机物——丙烷、丙烯和甲苯的近红外光谱特征和丙烯浓度与吸光度的线性关系,采用线性回归建模方法——偏最小二乘法对丙烷、丙烯和甲苯混合气体存在特征吸收的近红外光谱(1620~1750 nm)进行了建模分析,基于该模型预测了验证集样品中三种气体的含量,并对模型进行了评价。实验结果表明,近红外光谱技术可以方便、准确的定量分析有机性挥发气体的多组分含量,可以应用于多成分挥发性有机物的连续在线监测。  相似文献   

6.
植物中的重金属离子以一定形式与具有近红外吸收的有机分子基团结合,因此可以借助近红外光谱技术间接检测其重金属离子含量。研究了基于近红外漫反射光谱技术快速检测丁香蓼叶片中重金属铜含量的方法。通过不同光谱数据预处理方法的对比,结合偏最小二乘法,建立了丁香蓼叶内重金属铜含量近红外光谱检测定量模型。实验结果为,经过平滑处理的光谱建模效果较理想,其建立的校正相关系数为0.950,校正均方根误差为5.99;外部验证相关系数为0.923,预测均方根误差为7.38。研究表明,近红外漫反射光谱技术用于丁香蓼叶片中重金属铜含量的快速检测具有可行性。  相似文献   

7.
探讨了环境光,对谷氨酸钠溶液的近红外激光拉曼光谱的影响.研究表明不同的环境光,自然光和室内荧光灯光,均会对近红外拉曼光谱产生不同的干扰效应,存在着特征谱峰,倒峰或尖锐正峰.虽干扰表现不同,但都有影响,不能忽略.建议在进行溶液近红外激光拉曼光谱检测时,须在暗室或暗罩中进行,以完全隔离环境光的影响.  相似文献   

8.
煤种信息为煤炭质量评价、进出境税收征管提供技术支撑。传统煤种鉴别方法需测定煤炭样品干燥无灰基挥发分、低煤阶煤透光率、粘结指数、恒湿无灰基高位发热量等指标,能耗大,检测周期长,不利于口岸快速通关。基于不消耗化学试剂、快速、低成本等优势,采用近红外光谱鉴别煤种受到广泛关注,但目前还未有针对全球不同产地来源煤炭的煤种鉴别应用,煤炭近红外光谱特征与煤种的相关关系仍有待挖掘。采集了来自澳大利亚、俄罗斯、印度尼西亚等9个国家410批进口煤炭代表性样品,涉及褐煤、烟煤和无烟煤3个煤种,对比分析了不同煤种煤炭样品的漫反射近红外光谱特征,发现不同煤种煤炭样品近红外光谱在吸光度、光谱斜率、特征峰上存在差异。结合样品成分信息、X射线衍射、近红外光谱进行数据挖掘,发现近红外光谱吸光度与煤炭中固定碳含量呈正相关,光谱斜率与煤炭芳构化呈负相关,煤炭芳构化增加导致长波长方向的吸收系数增大,光谱斜率变小,光谱特征吸收峰主要为水分和有机物质含氢基团的特征信息,特征峰强度取决于煤炭中水分和挥发分含量。采用主成分分析(PCA)进行数据降维,光谱变量从1 557个降到394个,对前10个主成分进行逐步判别,筛选出PC1,PC2,PC3,PC4,PC6,PC7,PC8,PC9和PC10代替原始数据作为模型输入变量,建立煤种鉴别的Fisher判别分析模型,建模样品验证准确率为98%,交叉验证准确率为97.8%,测试样品验证准确率为99.1%。PCA载荷图表明:PC1和PC2主要与煤炭挥发分含量相关,其次是水分含量。判别函数1(57.7%)与PC1的相关性最强,判别函数2(42.3%)与PC2的相关性最强,说明不同煤种中挥发分含量和水分含量的差异是近红外光谱进行煤种鉴别的内在依据。  相似文献   

9.
20种氨基酸近红外光谱及其分子结构的相关性   总被引:4,自引:0,他引:4  
旨在研究20种氨基酸的分子结构与其近红外光谱的相关性,为氨基酸近红外光谱在动物科学、食品和医药等方面的推广应用奠定一定的理论基础。应用岛津傅里叶变换红外光谱仪IRPrestige-21及其近红外附件FlexIRTM Near-Infrared Fiber Optics module,采集20种氨基酸标准物质在1 000~2 502nm波长范围内的近红外光谱,分辨率8cm-1,每个样品扫描3次,每次扫描50遍,取其平均值为氨基酸标准品的近红外光谱。根据氨基酸侧链基团的不同,分别比较脂肪族氨基酸、芳香族氨基酸和杂环氨基酸中各氨基酸分子结构与其近红外光谱的相关性。研究表明,20种氨基酸在1 000~2 502nm区域有非常明显的近红外光谱吸收且差异显著。分子量较大的脂肪族氨基酸其近红外光谱受侧链基团的影响较大,而甘氨酸近红外光谱受羧基和氨基的影响较大;两种芳香族氨基酸近红外光谱的差异主要来自于苯环,酪氨酸苯环上的—OH基团降低了苯分子的对称性,导致更多振动吸收峰的出现;杂环氨基酸因其侧链上杂环分子基团构成不同,其近红外光谱在1 600~1 800nm区域差异较大。综上,20种氨基酸主要存在4个特征光谱区:第1特征光谱区为1 050~1 200nm主要由C—H基团的二级倍频构成;第2特征光谱区为1 300~1 500nm主要由C—H基团的组合频构成;因侧链基团分子构成不同,在第3特征光谱区1 600~1 850nm和第4特征光谱区2 000~2 502nm表现出差异较大的特征吸收峰。因此,可以利用此4个近红外光谱特征区域对氨基酸进行定量和定性分析,提高氨基酸近红外光谱模型预测的准确性。  相似文献   

10.
水体有机污染物浓度检测中的紫外光谱分析方法   总被引:3,自引:0,他引:3  
水体中的大多数有机污染物在紫外区域有较强的吸收,因此可利用紫外吸光度检测水体中的有机污染物浓度。在检测过程中,通过平滑、导数、标准正态变量变换等光谱预处理后,采用主元回归、偏最小二乘、支持向量机等方法建立回归模型,并由该模型依据待测样本的紫外光谱数据计算出有机污染物浓度。为了探究不同的预处理方法、建模方法在有机污染物浓度检测中的特点及内在联系,本文对一组来自污水厂进出水的光谱数据采用不同的预处理和建模方法进行实验研究,研究结果表明:当获得的原始数据较好时,可以直接进行建模,进行光谱预处理反而会使模型效果下降;由于本实验中污水的样本数小于光谱数据点数,所以最小二乘支持向量机更适合于本组实验样本。  相似文献   

11.
The use of activated carbon for removing organic contaminants in fixed beds is increasing. This is a dynamic process in which the kinetics plays an important role. The aim of this paper is to get more insight into adsorption of p-nitrophenol (PNP) in activated carbon under equilibrium and dynamic conditions. Five commercial activated carbons were studied. The analysis carried out were PNP adsorption isotherms in aqueous solution at 20 °C, N2 at 77 K isotherms, FT-IR and PNP adsorption under dynamic conditions. The results indicate that the external porous affinity toward the organic contaminants determines in large extent the adsorbents behaviour under dynamic conditions.  相似文献   

12.
The rising amount of persistent organic contaminants released into water reservoirs in the last years became a cause of concern for the industry, academy, and public administration, due to their bioaccumulation, mutagenicity, and photosynthesis reduction. Therefore, the search for processes that efficiently remove such contaminants became of primary importance. In this context, ultrasound (US) is one of the most promising and economically viable alternatives to degrade organic pollutants in varied environments. Whereas the use of other advanced oxidation processes (AOPs), such as Fenton and photocatalysis, has been widely reported for this purpose, only a few papers deal with ultrasound application as a possible AOP. In this review, a general overview of ultrasound is provided, covering the last twenty years. It includes fundamental aspects of ultrasound and applications, individually or combined with other AOPs, to deplete organic pollutants from various classes in an aqueous environment. Finally, the review concludes by indicating that additional research should be conducted worldwide to explore the full potential of ultrasound as a useful AOP.  相似文献   

13.
Atomic force microscopic (AFM) images of an H–Si(1 1 1) surface having the atomically flat structure were measured in a normal laboratory atmosphere. By monitoring time series changes in the AFM images, we found that islands grow on the surface. A comparison of the growth of islands with changes in Fourier-transfer IR (FTIR) spectra showed that the islands are formed by organic contaminants adsorbed from the air in the laboratory. Starting chiefly from the step sites, the islands extend to cover the whole surface in about 2 h. Following the adsorption of the organic contaminants, oxidation of the Si surface proceeds gradually. Although the growth rate was slightly slower, similar growth of islands was observed in a plastic bag filled with nitrogen gas with high purity.  相似文献   

14.
The interactions of common environmental contaminants with C60 have been studied to evaluate the environmental impact of carbon nanomaterials. The adsorption and desorption interaction of the hydrophobic contaminants naphthalene and 1,2-dichlorobenzene with C60 was characterized. Processes that cause the wetting and disaggregating of C60 particles also affect the extent of organic contaminant sorption to C60 aggregates by orders of magnitude. C60 dissolved in organic solvents such as toluene can form stable nanoscale aggregates upon vigorous mixing in water. These nanoscale C60 particles form stable suspensions in water and are referred to as ‘nano-C60’. Desorption of contaminants from stable suspensions of nano-C60 exhibits hysteresis. The experimentally observed adsorption/desorption hysteresis is described by a two-compartment desorption model: first, adsorption to the external surfaces that are in contact with water, and second, adsorption to the internal surfaces within the aggregates.  相似文献   

15.
The sonochemical degradation of a variety of chemical contaminants in aqueous solution has been investigated. Substrates such as chlorinated hydrocarbons, pesticides, phenols, explosives such as TNT, and esters are transformed into short-chain organic acids, CO2, and inorganic ions as the final products. Time scales of treatment in simple batch reactors over the frequency range of 20 to 500 kHz are reported to range from minutes to hours for complete degradation. Ultrasonic irradiation appears to be an effective method for the rapid destruction of organic contaminants in water because of localized high concentrations of oxidizing species such as hydroxyl radical and hydrogen peroxide in solution, high localized temperatures and pressures, and the formation of transient supercritical water.

The degradation of chemical compounds by acoustic cavitation is shown to involve three distinct pathways: 1) oxidation by hydroxyl radicals, 2) pyrolytic decomposition and 3) supercritical water oxidation. Detailed reaction mechanisms for the degradation of p-nitrophenol, carbon tetrachloride, parathion, p-nitrophenyl acetate and trinitrotoluene are presented.  相似文献   


16.
In this study, a novel alginate complex was developed for removal of mixed contaminants containing both organic and inorganic compounds. The alginate complex was generated by impregnating synthetic zeolite and powdered activated carbon (PAC) into alginate gel bead. The adsorption of zinc and toluene as target contaminants onto the alginate complex was investigated by performing both equilibrium and kinetic batch tests. Equilibrium tests showed that adsorption of two contaminants followed Langmuir isotherm and that the alginate complex was capable of removing zinc (maximum binding energy β = 4.3 g/kg) and toluene (β = 13.0 g/kg) best compared to other adsorbents such as granular activated carbon (GAC), zeolite, and alginate impregnated with PAC (AG–AC bead). These values were higher than those of any other adsorbents for each contaminant. It was further revealed from kinetic tests that removal efficiency of zinc and toluene was 54% and 86% for the initial solution concentrations of 250 mg/L, respectively. This indicates that the alginate complex developed in this study can be used as promising adsorbents for simultaneous removal of organic and inorganic compounds from industrial wastewater or groundwater containing mixed contaminants.  相似文献   

17.
Recently electron cyclotron resonance (ECR) plasma have been explored for wafer cleaning applications, since it is known to do less damage to silicon surface than conventional plasma. Organic contaminants removal efficiency and plasma radiation damage of the ECR plasma cleaning have been investigated. In oxygen ECR plasma cleaning, the plasma exposure time needed to remove the organic contaminants on the silicon surface down to the detection limit is 40 s, but the one to reach the lowest surface roughness is 10 s. The leakage current level of the MOS capacitor made using the Si substrate exposed to oxygen ECR plasma for 40 s is 8 × 10−9 A. The optimum exposure time determined by considering the contaminants removal efficiency and the plasma radiation damage (or the leakage current level) is 40 s. Organic contaminants seem to be removed through both sputter-off mechanism by oxygen ion bombardment and evaporation mechanism by chemical reactions with excited oxygen atoms.  相似文献   

18.
Sediments play a fundamental role in the aquatic environment, so that the presence of contaminants poses severe concern for the possible negative effects on both environmental and human health. Sediment remediation is thus necessary to reduce pollutant concentrations and several techniques have been studied so far. A novel approach for sediment remediation is the use of Advanced Oxidation Processes, which include ultrasound (US). This paper focuses on the study of the ultrasonic effects for the simultaneous reduction of both organic and inorganic contaminants from sediments. To this end, the US technology was investigated as a stand-alone treatment as well as in combination with an electro-kinetic (EK) process, known to be effective in the removal of heavy metals from soil and sediments. The US remediation resulted in higher organic compound degradation, with an average 88% removal, but promising desorption yields (47–84%) were achieved for heavy metals as well. The combined EK/US process was found to be particularly effective for lead. Experimental outcomes highlighted the potential of the ultrasonic technology for the remediation of contaminated sediments and addressed some considerations for the possible scale-up.  相似文献   

19.
Substances such as pharmaceuticals, pesticides, dyes, synthetic and natural hormones, plasticizers, and industrial chemicals enter the environment daily. Many of them are a matter of growing concern worldwide. The use of ultrasound to eliminate these compounds arises as an interesting alternative for treating mineral water, seawater, and urine. Thereby, this work presents a systematic and critical review of the literature on the elimination of organic contaminants in these particular matrices, using ultrasound-based processes. The degradation efficiency of the sonochemical systems, the influence of the nature of the pollutant (volatile, hydrophobic, or hydrophilic character), matrix effects (enhancement or detrimental ability compared to pure water), and the role of the contaminant concentration were considered. The combinations of ultrasound with other degradation processes, to overcome the intrinsic limitations of the sonochemical process, were considered. Also, energy consumptions and energy costs associated with pollutants degradation in the target matrices were estimated. Moreover, the gaps that should be developed in future works, on the sonodegradation of organic contaminants in mineral water, seawater, and urine, were discussed.  相似文献   

20.
董祥  吕海兵  严鸿维  黎波  向霞  蒋晓东 《强激光与粒子束》2021,33(7):071002-1-071002-6
本文采用溶胶-凝胶法制备了SiO2增透膜,然后对其进行等离子体结合六甲基二硅胺烷(HMDS)表面改性处理。研究了后处理改性对增透膜表面形貌、微观结构、光学性能及激光损伤性能的影响规律,获得了抗真空有机污染的二氧化硅增透膜。结果表明,增透膜在采用等离子体结合HMDS表面改性处理后,膜层收缩、粗糙度下降、极性羟基等有机基团含量减少;两步后处理改善了增透膜膜层结构和光学性能,显著提高了膜层疏水能力和真空条件下的抗污染性能,并且对溶胶-凝胶二氧化硅增透膜的高损伤阈值属性不产生影响。  相似文献   

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