共查询到16条相似文献,搜索用时 62 毫秒
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选用8个不同材料涂层压电石英晶体组成传感器阵列,所获频移数据用逐步判别(SDA)法解析,对小分子脂肪醇类与非醇类溶剂蒸气用二类判别法分析,找到由少于8个传感器组成阵列可达最佳判别能力,训练集回测正确率平均为84.8%,预测集识别正确率平均为87.3%。此外,该阵列用于识别酒、饮料,结果较佳。 相似文献
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模式识别用于压电晶体传感器阵列识别可燃物质 总被引:4,自引:0,他引:4
用7个压电晶体组成传感器阵列,每个晶体上分别涂有不同种类的气相色谱固定液,通过测定各种可燃物质燃烧时放出的混合气体来识别所燃物质,在识别中分别应用了人工神经网络法(ANN)和逐步判别分析法(SDA)。讨论了解决神经网络开始训练时不收敛或产生麻痹现象的方法,提出了训练数据选取的新方法-训练集逐步扩展法,实验证明:人工神经网络对被测物质的识别准确率达100%,高于逐步判别分析法(83%)。 相似文献
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为模拟生物化学传感体系, 提出了可用于识别有机官能团的传感器阵列, 用作人工气味识别系统。该阵列由八个压电晶体传感器组成, 每个传感器涂以具有广谱响应性能的不同吸附活性材料, 阵列对常见小分子有机溶剂混合蒸气的响应频移数据采用逐步判别分析(SDA)处理, 选出五个供信能力最佳的判别变量, 以此构成的阵列用于小分子有机溶剂混合蒸气中醇羟基、羰基与其它官能团的识别, 并采用主成分分析(PCA)法降维投影, 在二维空间含相同官能团的物质聚为一类; 阵列可用于酒类、软饮料的识别。 相似文献
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将多个表面涂有不同选择性吸附材料的压电晶体传感器组成阵列,用于混合有机溶剂蒸气中乙醇的检测。对阵列输出的数据,采用逐步判别法进行二类判别,可以检测混合蒸气中少量的乙醇,采用主成分回归法,可由阵列输出数据预测未知样品中乙醇的浓度。 相似文献
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LiShunFENG JingTianHU QiKANG ChangYingGUO DaZhongSHEN 《中国化学快报》2005,16(4):509-512
An unexpected frequency response for a piezoelectric quartz crystal (PQC) sensor to liquid density and viscosity was reported. For a PQC oscillating in a liquid phase, the frequency shifts (△f) show a wave-shape response to liquid density (p) and viscosity 03) in fine structure, ifthe longitudinal wave effect was not eliminated. This result is different from the well-knownlinear relationship between of Af and (ρη)1/2. An oscillating frequency-temperature curve of thesensor was observed and explained. 相似文献
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Preparation and Application of Fullerene C60‐Polymers in Piezoelectric Quartz Crystal Sensors for Hemoglobin and Olefins 下载免费PDF全文
The C60—polycinnamaldehyde (C60—PCA) and C60—polyphenylacetylene (C60—PPA) polymers were synthesized by the Friedel—Craft reaction and applied as piezoelectric (PZ) quartz crystal coating materials. A C60—polycinnamaldehyde (PCA) coated piezoelectric quartz crystal liquid sensor with a homemade computer interface was prepared and applied as a PZ hemoglobin sensor. The adsorption of hemoglobin onto the C60—PCA coated crystal resulted in a decreased oscillating frequency. The variations in crystal frequency were converted to voltage with a frequency to voltage converter, followed by amplification with OPA and data acquisition with an analog to digital converter. The PZ hemoglobin sensor exhibited good sensitivity of 6530 Hz/(mg/mL) with a detection limit at the ppm level for hemoglobin. Further, a C60—polyphenylacetylene (C60—PPA) coated piezoelectric quartz crystal gas sensor with an Intell‐8255 data processing system for various olefin vapors was also made. The aromatic hydrocarbons such as toluene seem to have greater adsorption onto C60—PPA membrane than alkynes, alkenes, and alkanes. The adsorption of polycyclic aromatic hydrocarbons (PAHs) onto the C60—PPA membrane was also examined. The C60—PPA coated PZ crystal gas sensor showed much better sensitivity for PAHs than for other olefins such as toluene, 1‐hexyne and 1‐hexene, and a much larger frequency shift for naphthalene than other PAHs was also found. 相似文献
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《Analytical letters》2012,45(14):2715-2723
ABSTRACT A new method combining flow injection methodology with quartz crystal microbalance (QCM) detection is proposed for inorganic mercury analysis. A modified simplex method is used in order to maximise the observed analytical signals (crystal frequency decrease). Six parameters were optimised: the concentration of the acidic carrier solution, the lengths of the sample loop and mixing coil, and the flow rates of the sample carrier, the reductant stream (SnCl2), and the carrier of the mercury vapour (N2). An increase of 18% in the signal of the centroid of the calibration line was achieved, as well as an increase in the sensitivity from 290 Hz μg? to 313 Hz μg?. Following the proposed procedure, detection limits of 47 μg L? of inorganic mercury were found for sample volumes of 0.5 mL. 相似文献
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Ali Z. O'Hare W. T. Sarkodie-Gyan T. Theaker B. J. 《Journal of Thermal Analysis and Calorimetry》1999,55(2):371-381
Quartz crystal microbalances have high mass sensitivities. Their application in gas sensing has been limited because they
are required to have both high selectivity and reversibility. Yet by the inherent nature of their operation these properties
are mutually exclusive. One approach to this problem is to use an array of quartz crystal microbalances. We have used an array
of six coated quartz crystal microbalances for the classification of methanol, propan-1-ol, butan-1-ol, hexane, heptane and
toluene. A novel classification scheme using fuzzy membership functions was found to be highly efficient.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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《Analytical letters》2012,45(11-12):2601-2611
Abstract 2, 4-toluene diisocyanate (TDI) in air was detected and determined by a piezoelectric quartz crystal sensor coated with tetrakis(hydroxyethyl)ethylenediamine (THEED)/dithizone(diphenylthiocarbazone) solution (l:3v/v in acetone). The response curve is linear over the concentration range 3–24 ppb of TDI. The sensor can be used for more than 2 months without loss in sensitivity and presented good reversibility and reproducibility. Of the different possible interferents tested, only SO2 caused a frequency change. 相似文献
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A new piezoelectric quartz crystal (PQC) sensor using molecularly imprinted polymer (MIP) as sensing material has been developed for fast and onsite determination of pirimicarb in contaminated vegetables. Three MIPs particles have been prepared by conventional bulk polymerization (MIP-B) and precipitation polymerization in either acetonitrile (MIP-P1) or chloroform (MIP-P2). MIP-P2, with uniform spherical shape and mean diameter at about 50 nm, has shown the best performance as the sensing material for PQC sensor. The sensor fabricated with MIP-P2 can achieve a steady-state response within 5 min, a very short response time as compared to MIPs-coated PQC sensor reported in the literature. The sensor developed exhibits good selectivity (low response to those pesticides with similar structures to pirimicarb, such as atrazine, carbaryl, carbofuran and aldicarb) and high sensitivity to pirimicarb with a linear working range from 5.0 × 10−6 to 4.7 × 10−3 mol L−1 (following a regression equation (r = 0.9988) of −ΔF = 0.552 + 1.79 × 106 C), a repeatability (R.S.D., n = 5) of 4.3% and a detection limit (S/N = 3, n = 5) of 5 × 10−7 mol L−1. The MIP-coated PQC sensor developed is shown to provide a sensitive and fast method for onsite determination of pirimicarb in aqueous extract from contaminated vegetables with satisfactory recoveries from 96 to 103% and repeatability (R.S.D., n = 5) from 4.6 to 7.1% at pirimicarb concentrations ranging from 8.0 × 10−6 to 2.0 × 10−4 mol L−1. 相似文献