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Motor Current Signal Analysis using a Modified Bispectrum for Machine Fault Diagnosis
Fengshou Gu,Yimin Shao,Niaoqin Hu,Bruno Fazenda,Andrew Ball 제어로봇시스템학회 2009 제어로봇시스템학회 국제학술대회 논문집 Vol.2009 No.8
This paper presents the use of the induction motor current to identify and quantify common faults within a two-stage reciprocating compressor. The theoretical basis is studied to understand current signal characteristics when themotor undertakes a varying load under faulty conditions. Although conventional bispectrum representation of currentsignal allows the inclusion of phase information and the elimination of Gaussian noise, it produces unstable results dueto random phase variation of the sideband components in the current signal. A modified bispectrum based on theamplitude modulation feature of the current signal is thus proposed to combine both lower sidebands and highersidebands simultaneously and hence describe the current signal more accurately. Based on this new bispectrum a more effective diagnostic feature namely normalised bispectral peak is developed for fault classification. In association with the kurtosis of the raw current signal, the bispectrum feature gives rise to reliable fault classification results. Inparticular, the low feature values can differentiate the belt looseness from other fault cases and discharge valve leakage and intercooler leakage can be separated easily using two linear classifiers. This work provides a novel approach to theanalysis of stator current for the diagnosis of motor drive faults from downstream driving equipment.
Tian, Fengshou,Chen, Han,Du, Yuchang,Chen, Junhui,Wang, Xiaohong,Lu, Hongbo,Cho, Kilwon,Zhang, Guobing,Qiu, Longzhen The Royal Society of Chemistry 2019 Journal of Materials Chemistry C Vol.7 No.37
<P>Achieving good electrical properties and ductility of polymer semiconductors has always been challenging. In this work, a series of isoindigo derivative-based conjugated polymers was studied in an effort to gain a better understanding of the influence of polymer main and side chain structures on their electrical and mechanical properties. The results suggested that the introduction of alkyl side chains onto the donors can significantly enhance the mechanical properties of isoindigo-based polymers; however, the electrical properties of the films greatly deteriorated due to the large steric hindrance by the chain. The insertion of strong electron-withdrawing units, such as benzodifurandione, into the isoindigo chain during the synthesis of a bis(2-oxoindolin-3-ylidene)-benzodifuran-dione (BIBDF)-based polymer (PBIBDF-BT) significantly boosted the electrical properties of the films without decreasing their mechanical properties. The crack onset in PBIBDF-BT thin films was observed at 50% tensile strain. In addition, PBIBDF-BT thin films exhibited bipolar transport properties with both electron and hole mobilities greater than 0.1 cm<SUP>2</SUP> V<SUP>−1</SUP> s<SUP>−1</SUP> at 100% strain. It is found that the improvement of PBIBDF-BT performance is attributed to its proper molecular structure. The long alkyl side chains significantly increase the ductility of PBIBDF-BT thin films, and the strong electron-withdrawing BIBDF unit in the main chains enhances the local aggregation, resulting in a significant increase in mobility. These results indicate that the mechanical and electrical properties of conjugated polymers could simultaneously be improved through reasonable molecular design.</P>
Measurement and Diagnostic of Engine Belt Physical Condition from Acoustic Signals
Bruno Fazenda,Fengshou Gu,Mark Avis,Andrew Ball 제어로봇시스템학회 2009 제어로봇시스템학회 국제학술대회 논문집 Vol.2009 No.8
This paper presents an investigation into the diagnosis of transmission belt condition through acousticmonitoring. A relevant belt model and laser interferometry measurements are used to guide the design and analysis of the acoustic monitoring system. The fault under scrutiny is the development of a loss of tension in the belt which mayoccur due to degradation of belt material. Results show that it is possible to diagnose this kind of fault using acoustic diagnostic techniques. Analysis of acoustic signals reveals changes in the natural frequencies of the belt which arematched by results for laser interferometry.
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.
Acoustic Based Safety Emergency Vehicle Detection for Intelligent Transport Systems
Bruno Fazenda,Hidajat Atmoko,Fengshou Gu,Luyang Guan,Andrew Ball 제어로봇시스템학회 2009 제어로봇시스템학회 국제학술대회 논문집 Vol.2009 No.8
A system has been investigated for the detection of incoming direction of an emergency vehicle. Acoustic detection methods based on a cross microphone array have been implemented. It is shown that source detection based on time delay estimation outperforms sound intensity techniques, although both techniques perform well for the application. The relaying of information to the driver as a warning signal has been investigated through the use of ambisonic technology and a 4 speaker array which is ubiquitous in most modern vehicles. Simulations show that accurate warning information may be relayed to the driver and afford correct action.
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.
Luyang Guan,Yimin Shao,Fengshou Gu,Bruno Fazenda,Andrew Ball 제어로봇시스템학회 2009 제어로봇시스템학회 국제학술대회 논문집 Vol.2009 No.8
In this paper, a new method is proposed by combining ensemble empirical mode decomposition (EEMD) with order tracking techniques to analyse the vibration signals from a two stage helical gearbox. The method improves EEMD results in that it overcomes the potential deficiencies and achieves better order spectrum representation for fault diagnosis. Based on the analysis, a diagnostic feature is designed based on the order spectra of extracted IFMs for detection and separation of gearbox faults. Experimental results show this feature is sensitive to different fault severities and robust to the influences from operating conditions and remote sensor locations.
A Simulation Study of Defects in a Rolling Element Bearing using FEA
Yimin SHAO,Wenbing Tu,Fengshou GU 제어로봇시스템학회 2010 제어로봇시스템학회 국제학술대회 논문집 Vol.2010 No.10
An internal impact usually happens when there is a small defect in one part of rolling bearings. The Fault signal from this impact is always masked by different noises such as strong vibrations from other parts and the random noise of instrumentation, which makes it difficult to extract an accurate feature signal for early fault diagnosis. In this paper, a simulation study is conducted using the method of finite element analysis (FEA) to understand the vibration characteristics from the small impact. The vibration responses have been modelled based on a typical bearing assembly. Common faults including outer ring defect, inner ring defect and rolling ball defect are simulated and their vibration responses are compared between different faults and at different locations in the bearing housing. The results obtained have shown that under the same defect size, the vibration from the outer ring is the highest whereas that from the rolling ball is the smallest. In addition the vibration close to the mounting hole attenuates considerably compared to that close to outer ring. These findings provide fundamental information to place vibration sensors and to analyse vibration signals.
Novelty detection methods for online health monitoring and post data analysis of turbopumps
Hu Lei,Hu Niaoqing,Zhang Xinpeng,Gu Fengshou,Gao Ming 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.7
As novelty detection works when only normal data are available, it is of considerable promise for health monitoring in cases lacking fault samples and prior knowledge. We present two novelty detection methods for health monitoring of turbopumps in large-scale liquidpropellant rocket engines. The first method is the adaptive Gaussian threshold model. This method is designed to monitor the vibration of the turbopumps online because it has minimal computational complexity and is easy for implementation in real time. The second method is the one-class support vector machine (OCSVM) which is developed for post analysis of historical vibration signals. Via post analysis the method not only confirms the online monitoring results but also provides diagnostic results so that faults from sensors are separated from those actually from the turbopumps. Both of these two methods are validated to be efficient for health monitoring of the turbopumps.
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.