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Web Data Extraction Based on Ensemble Learning
Yongquan Dong,Qiang Chu,Ping Ling 보안공학연구지원센터 2015 International Journal of Database Theory and Appli Vol.8 No.3
With the rapid development of Internet technology, Web has become a huge information source with massive amounts of data. But these data are usually embedded in the semi-structured pages. In order to use these data effectively, the primary problem is to extract the data and store them in structured form. Most of current approaches use a single classifier to extract web data, but relying on a single classifier is not sufficient and different classifier has different performance for the same problem. In this paper, we use the method of ensemble learning for web data extraction. Firstly, we parse the page as a Dom tree, identify the main data regions, and construct feature sets of text nodes in the region. Secondly, we choose multiple kinds of base classifiers (SVM, KNN and Random Forest) to build classification models and then use the linear method to integrate results of each classification model. Finally, we combine integration results with heuristic rules to get the final extraction results. The experiment results show that our approach outperforms the baseline approaches and has a good robustness.
Yongquan Zheng,Jun Xu,Fengshou Dong,Xingang Liu,Jing Li,Yuanbo Li,,Weili Shan 대한화학회 2011 Bulletin of the Korean Chemical Society Vol.32 No.12
A method based on ethyl acetate extraction and gas chromatography with tandem mass spectrometry was developed for determining tetraconazole residues in fruits and vegetables. A 10 g homogenized sample was mixed with 10 mL ethyl acetate, shaken vigorously for 3 min, stored at −20 oC for 15 min, and then vortexed vigorously for 1 min; 1 g NaCl and 4 g anhydrous MgSO4 were added. The clean-up was carried out by applying dispersive solid-phase with 150 mg MgSO4 and 50 mg primary secondary amine. Three precursor product ion transitions for tetraconazole were measured and evaluated to provide the maximum degree of confidence. Average recoveries in fruits and vegetables at three levels (0.005, 0.05 and 0.5 mg/kg) ranged from 85.53% to 110.66% with relative standard deviations (RSDr) from 1.3% to 17.5%. The LODs ranged from 0.002 to 0.004 μg/kg, and LOQs ranged from 0.006 to 0.012 μg/kg. This method was also applied to determine tetraconazole residue in cucumber dissipation experiment under field conditions. The half-lives of tetraconazole in cucumber were in the range of 2.1-3.1 days.
Xu, Jun,Dong, Fengshou,Liu, Xingang,Li, Jing,Li, Yuanbo,Shan, Weili,Zheng, Yongquan Korean Chemical Society 2011 Bulletin of the Korean Chemical Society Vol.32 No.12
A method based on ethyl acetate extraction and gas chromatography with tandem mass spectrometry was developed for determining tetraconazole residues in fruits and vegetables. A 10 g homogenized sample was mixed with 10 mL ethyl acetate, shaken vigorously for 3 min, stored at $-20^{\circ}C$ for 15 min, and then vortexed vigorously for 1 min; 1 g NaCl and 4 g anhydrous $MgSO_4$ were added. The clean-up was carried out by applying dispersive solid-phase with 150 mg $MgSO_4$and 50 mg primary secondary amine. Three precursor product ion transitions for tetraconazole were measured and evaluated to provide the maximum degree of confidence. Average recoveries in fruits and vegetables at three levels (0.005, 0.05 and 0.5 mg/kg) ranged from 85.53% to 110.66% with relative standard deviations ($RSD_r$) from 1.3% to 17.5%. The LODs ranged from 0.002 to 0.004 ${\mu}g$/kg, and LOQs ranged from 0.006 to 0.012 ${\mu}g$/kg. This method was also applied to determine tetraconazole residue in cucumber dissipation experiment under field conditions. The half-lives of tetraconazole in cucumber were in the range of 2.1-3.1 days.
Wu, Xiaohu,Xu, Jun,Liu, Xingang,Dong, Fengshou,Wu, Yanbing,Zhang, Ying,Zheng, Yongquan Korean Chemical Society 2013 Bulletin of the Korean Chemical Society Vol.34 No.3
A simple, quick and reliable analytical method for the confirmation and quantification of propisochlor was developed. The propisochlor was extracted from water, soil and rice (stalks, rice and hull) matrices using acetonitrile, and cleaned up with primary secondary amine and determined by UPLC-MS/MS. The LODs of propisochlor ranged from 0.03 ${\mu}g/kg$ to 0.12 ${\mu}g/kg$, while the LOQs ranged from 0.1 ${\mu}g/kg$ to 0.4 ${\mu}g/kg$ in different matrixes. The mean recoveries of propisochlor at three levels (0.005, 0.01 and 0.05 mg/kg) were in the range of 73.7-94.9% with intra-day relative standard deviations (RSD) of 1.1-13.9% and inter-day $RSD_R$ of 3.3-12.7%. This method is suitable for routine analysis of propisochlor under field conditions. The half-lives of propisochlor in rice stalks, water and soil were 1.7, 1.5 and 2.3 days in Hunan, 5.7, 1.0 and 1.9 days in Anhui and 4.8, 1.0 and 3.1 days in Guangxi.
A Study on Fracture Behavior and Impact Stability of Sintered Rare-earth Permanent Magnets
Li Wei,Li Anhua,Wang Huijie,Dong Shengzhi,Guo Yongquan 한국분말야금학회 2006 한국분말야금학회 학술대회논문집 Vol.2006 No.1
The fracture behavior and mechanical characteristics of sintered rare-earth magnets were investigated. It shows that the fracture behavior and bending strength of the magnets obviously exhibit anisotropy. Sm-Co magnets tend to cleavage fracture in the close-packed (0001) plane or in the (10 11 ) plane. The fracture mechanism of Nd2Fe14B magnet mainly appears to be intergranular fracture. The anisotropy of fracture behavior and mechanical strength of sintered rare-earth magnets is caused mainly by the strong crystal-structure anisotropy and the grain alignment texture. The effects of Nd content, and Pr, Dy substitution on the impact stability of Nd2Fe14B magnets were also reported.
Xiaohu Wu,Jun Xu,Xingang Liu,Feng Shou Dong,Yanbing Wu,Ying Zhang,Yongquan Zheng 대한화학회 2013 Bulletin of the Korean Chemical Society Vol.34 No.3
A simple, quick and reliable analytical method for the confirmation and quantification of propisochlor was developed. The propisochlor was extracted from water, soil and rice (stalks, rice and hull) matrices using acetonitrile, and cleaned up with primary secondary amine and determined by UPLC-MS/MS. The LODs of propisochlor ranged from 0.03 μg/kg to 0.12 μg/kg, while the LOQs ranged from 0.1 μg/kg to 0.4 μg/kg in different matrixes. The mean recoveries of propisochlor at three levels (0.005, 0.01 and 0.05 mg/kg) were in the range of 73.7-94.9% with intra-day relative standard deviations (RSD) of 1.1-13.9% and inter-day RSDR of 3.3-12.7%. This method is suitable for routine analysis of propisochlor under field conditions. The half-lives of propisochlor in rice stalks, water and soil were 1.7, 1.5 and 2.3 days in Hunan, 5.7, 1.0 and 1.9 days in Anhui and 4.8, 1.0 and 3.1 days in Guangxi.