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81.
The benefits of applying automated fault detection and diagnosis (AFDD) to chillers include less expensive repairs, timely maintenance, and shorter downtimes. This study employs feature selection (FS) techniques, such as mutual-information-based filter and genetic-algorithm-based wrapper, to help search for the important sensors in data driven chiller FDD applications, so as to improve FDD performance while saving initial sensor cost. The ‘one-against-one’ multi-class support vector machine (SVM) is adopted as a FDD tool. The results show that the eight features/sensors, centered around the core refrigeration cycle and selected by the GA-SVM wrapper from the original 64 features, outperform the other three feature subsets by the GA-LDA (linear discriminant analysis) wrapper, with an overall classification correct rate (CR) as high as 99.53% for the 4000 test samples randomly covering the normal and seven typical faulty modes. The CRs for the four cases with FS are all higher than that without FS (97.45%) and the test time is much less, about 28-36%. The FDD performance for normal or each of the faulty modes is also evaluated in details in terms of hit rate (HR) and false alarm rate (FAR). 相似文献
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83.
the salt residue is one of the quality indexes of silk fibroin products.The products with low salt residue are not only healthier for human body, hut also more stable in exterior qualities, such as color and smell.Instrumental analysis and chemical analysis are currently methods to accurately determine salt residues in silk fibroin products, but they still need to be supplemented by real-time and quick detection methods in practical production.This paper discusses the determination method with a water quality testing pen and investigates the response of the water quality pen to the changes in the concentration of a variety of solutions, and associates with application examples.The results show that the TDS measured by the water quality pen is highly linearly correlated with the changes in the concentrations of CaCU , NaCl, and fibroin-CaCU solutions.The principle and method of the TDS water quality testing pen have an application prospect in the field of real-time and rapid approximate evaluation of salt residue in silk fibroin solution. © 2021 China Silk Association. All rights reserved. 相似文献
84.
强力输送带纵向防撕裂系统的设计与实现 总被引:1,自引:0,他引:1
强力输送带(输送机)广泛应用于钢铁、煤炭、冶金、矿山、港口等领域的物料输送。普通强力输送带存使用中,常因尖锐物料扎入或输送机马力大、速度快,造成纵向大范围撕裂。据不完全统计,全国每年因撕裂报废的输送带价值数亿元,因输送带撕裂造成停产带来的损失就更惊人。研制开发强力输送带纵向防撕裂系统,可以实时检测输送带的状况,一旦发现撕裂立即停机并报警,防止撕裂范围的扩大,避免了因输送带撕裂造成的巨大损失,具有重大的经济效益。强力输送带纵向防撕裂系统是国务院重大攻关项目“大型高强度输送带”的重要课题,已经通过部级鉴定,达到国际同类装置的先进水平,并申请获得两项专利。系统原理先进,性价比高。抗干扰能力强,现场安装方便,并在应用中得到不断的改进与完善. 相似文献
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86.
Eu(btc)metal organic frameworks(MOFs)were prepared by co-precipitation method via 1,2,4-benzenetricarboxylic acids(H3btc)connecting with Eu3+ions,and the morphology was controlled from compact spherical to irregular honeycomb by adjusting the pH of reaction solutions.The luminescence properties of Eu(btc)MOFs are found to be related to the surface morphology of products,and the compact spherical one performs stronger emission intensity.The sensing ability of Eu(btc)MOFs to 11 kinds of metal ions was investigated and a prominent quenching effect occurrs in Fe3+,or Ni2+solutions.Based on UV—vis absorption analysis,an“ion-fence”model presents the competition to absorb exciting light between Eu(btc)MOFs and adsorbed metal ions.Based on Stern-Volmer equation,the Eu(btc)detection is found with higher Ksv value and a lower detection limit.Meanwhile,a higher sensing efficiency is confirmed in the Eu(btc)MOFs with loose honeycomb due to aggravating porous surface offering much more sites for metal ions. 相似文献
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88.
端点检测是语音信号处理的一个关键环节。为提高语音在低性噪比以及非平稳噪声环境下的端点检测性能,在长时信号变化特征(LTSV)的基础上提出一种新的D-LTSV语音端点检测方法。采用Bartlett-Welch方法估计语音谱,分析语音谱在长时域上的熵,利用倒谱的动态特性分析方法提取连续帧熵值的动态变化特征。实验结果表明,D-LTSV综合考虑了语音的非平稳性和帧间非平稳性的动态变化情况,具有比LTSV更好的分辨能力,特别是在低性噪比和非平稳噪声的环境下,D-LTSV的分辨能力提升了50.77%,能够准确地进行端点检测,具有更强的鲁棒性。 相似文献
89.
针对现有三维形状配准方法中存在左右翻转的错误匹配问题,提出了基于内蕴对称特征检测的高效形状配准算法。首先,通过热核与几何约束构建模型的内蕴自对称点对;其次,基于谱嵌入特征空间分析提取模型的内蕴对称平面,并依据模型表面法向量有效识别模型的左右结构属性;然后,根据内蕴对称点对获得模型的一致性谱对称结构描述;最后,引入一致性点漂移算法(CPD),实现基于谱对称的非刚性模型的形状配准,有效避免了模型配准中的左右结构翻转问题。实验进一步论证了这种方法不仅有效提高了模型匹配的效率,而且能有效识别同类模型的结构特征,对于非刚性模型的配准具有较强的鲁棒性。 相似文献
90.
Nasirullah K. N. Ankaiah M. N. Krishnamurthy K. V. Nagaraja 《Journal of the American Oil Chemists' Society》1991,68(6):446-447
Two edible oil blends, namely groundnut oil:rice-bran oil and mustard oil:rice-bran oil, were prepared in different proportions
and stored for a period of three years. Their physicochemical characteristics were determined. The results agreed with expected
values except for free fatty acid percents and butyrorefrac-tometer readings, presumably due to rancidity. Fatty acid compositions
of the blends were determined and ratios of characteristic fatty acids, like lignoceric to palmitic for groundnut oil:rice-bran
oil blends, and erucic to palmitic for mustard oil:rice-bran oil blends, were calculated to identify individual oils in the
blend. 相似文献