A probabilistic description scheme for rotating machinery health evaluation

Qiang Miao,Dong Wang,Michael Pecht 대한기계학회 2010 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.24 No.12

Condition-based maintenance has become more popular in recent years because of its advantages in terms of minimizing downtime,extending lifetime, and reducing cost. This kind of maintenance strategy is based on condition monitoring of machinery in operation. Ccondition monitoring is a key step in maintenance decision analysis. Numerous non-stationary signal processing methods have been developed to reveal fault characteristics in rotating machinery. In this study, an adaptive signal analysis method called empirical mode decomposition is employed for gearbox vibration signal preprocessing. Considering a modulation phenomenon that appeared in a faulty gear, the Hilbert Transform is applied to obtain an envelope signature, which usually contains abundant fault-related signatures. Being different from other failure classification problems, this paper is concerned with determining the probability of normal condition based on current observations describing the condition of a gearbox. Moreover, according to Bayes rule, this problem can be translated to estimate the conditional probability of current observations given normal gearbox condition using a Hidden Markov Model. From this point, a novel probabilistic health description index called Average Probability Index is proposed for gearbox health evaluation. For automatic detection, a semi-dynamic threshold is presented to detect an early fault in a gear. At last, validation and comparative studies are performed using two sets of gearbox lifetime accelerated testing vibration data. The results show the advantages of the proposed method for gearbox condition monitoring.

Vehicular Communication Simulation Platform (VCSim) for Traffic-oriented Environment

Qiang Zheng,Xiaoting Wang,Minpeng Miao,Kan Zheng ICT플랫폼학회 2013 JOURNAL OF PLATFORM TECHNOLOGY Vol.1 No.1

Bioactive Compounds / Food Microbiology : Improvement of Natamycin Production by Cholesterol Oxidase Overexpression in Streptomyces gilvosporeus

( Miao Wang ),( Shao Hua Wang ),( Gong Li Zong ),( Zhong Wen Hou ),( Fei Liu ),( D Joshua Liao ),( Xi Qiang Zhu ) 한국미생물 · 생명공학회 2016 Journal of microbiology and biotechnology Vol.26 No.2

Natamycin is a widely used antifungal antibiotic. For natamycin biosynthesis, the gene pimE encodes cholesterol oxidase, which acts as a signalling protein. To confirm the positive effect of the gene pimE on natamycin biosynthesis, an additional copy of the gene pimE was inserted into the genome of Streptomyces gilvosporeus 712 under the control of the ermE* promoter (permE*) using intergeneric conjugation. Overexpression of the target protein engendered 72% and 81% increases in the natamycin production and cell productivity, respectively, compared with the control strain. Further improvement in the antibiotic production was achieved in a 1 L fermenter to 7.0 g/l, which was a 153% improvement after 120 h cultivation. Exconjugants highly expressing pimE and pimM were constructed to investigate the effects of both genes on the increase of natamycin production. However, the co-effect of pimE and pimM did not enhance the antibiotic production obviously, compared with the exconjugants highly expressing pimE only. These results suggest not only a new application of cholesterol oxidase but also a useful strategy to genetically engineer natamycin production.

Improved Resistance Switching Characteristics of BiFeO3 Thin Film by Increasing the Annealing Temperature

Zhilei Miao,Wei Wang,Rongchun Yuan,Jun Zhu,Shudong Wu,Haitao Chen,Xianghua Zeng,Qiang Wang 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2018 NANO Vol.13 No.09

We have fabricated BiFeO3 thin film deposited on Pt/Ti/SiO2/Si substrates by the chemical solution deposition method. The effects of annealing temperature on the thin film structure, resistance switching (RS) properties, conduction mechanisms are investigated. It exhibits improved RS window with high ON/OFF ratio ( ~10 4) for the sample annealed at 650 ℃. XPS characterization indicates that cation ratio of Fe2+/Fe3+ is increased with increasing annealing temperature. Crystal lattice distortion generated by Fe2+ cations, along with oxygen vacancies, commonly contribute to opening the RS window and the increment of conductive filaments. The film's conduction mechanisms under different annealing temperatures are fully discussed. The RS properties of this system can be effectively improved by increasing the annealing temperature, which is crucial prerequisite for future applications of BFO-based thin film device in resistance random access memory.

Corrosion Rate of API 5L Gr. X60 Multipurpose Steel Pipeline Under Combined Effect of Water and Crude Oil

Jian Miao,Qiang Wang 대한금속·재료학회 2016 METALS AND MATERIALS International Vol.22 No.5

Multipurpose pipeline is often seriously corroded during its service life, and the phenomenon is more prominent once the transportation medium is changed. Electrochemical polarization curves and impedance spectroscopy of the API 5L Gr. X60 steel pipeline’s corrosion process in sedimentary water with different ion types and their concentrations have been studied in this work. The results showed that the corrosion rates were found to be 0.00418 and 0.00232 mm/a for pure water and crude oil, respectively. However, for the mixtures of water and crude oil (with water content increased from 0.2 vol% to 10 vol%), the corrosion rate increased consistently and reached a maximum value of 0.15557 mm/a for 10 vol% water in crude oil. The effect of the concentration of various ions, namely, chloride, bicarbonate and sulfate in (oil/water) mixtures on the corrosion rate was characterized by weight-loss method. The results showed that with increasing the ions’ concentrations, the corresponding exchange current density increased significantly. The results were further supported by the observations of corrosion morphology using scanning electron microscopy and are helpful in devising guidelines which would help in reducing corrosion in multipurpose transport pipelines involving a change of transported medium during their service life.

Separation of Nattokinase from Bacillus subtilis Fermentation Broth by Expanded Bed Adsorption with Mixed-mode Adsorbent

Lu Miao-Hua,Lin Dong-Qiang,Wu Yuan-Chun,Yun Jun-Xian,Mei Le-He,Yao Shan-Jing The Korean Society for Biotechnology and Bioengine 2005 Biotechnology and Bioprocess Engineering Vol.10 No.2

Mixed-mode hydrophobic/ionic matrices exhibit a salt-tolerant property for adsorbing target protein from high-ionic strength feedstock, which allows the application of undiluted feedstock via an expanded bed process. In the present work, a new type of mixed-mode adsorbent designed for expanded bed adsorption, Fastline $PRO^{\circledR}$, was challenged for the capture of nattokinase from the high ionic fermentation broth of Bacillus subtilis. Two important factors, pH and ion concentration, were investigated with regard to the performance of nattokinase ad-sorption. Under initial fermentation broth conditions (pH 6.6 and conductivity of 10 mS/cm) the adsorption capacity of nattokinase with Fastline PRO was high, with a maximum capacity of 5,350 U/mL adsorbent. The elution behaviors were investigated using packed bed adsorption experiments, which demonstrated that the effective desorption of nattokinase could be achieved by effecting a pH of 9.5. The biomass pulse response experiments were carried out in order to evaluate the biomass/adsorbent interactions between Bacillus subtilis cells and Fastline PRO, and to demonstrate a stable expanded bed in the feedstock containing Bacillus subtilis cells. Finally, an EBA process, utilizing mixed-mode Fastline PRO adsorbent, was optimized to capture nattokinase directly from the fermentation broth. The purification factor reached 12.3, thereby demonstrating the advantages of the mixed-mode EBA in enzyme separation.

Parameter optimization of electromagnetic pulse compaction driven by aluminum tube for tungsten copper powder

Fen-Qiang Li,Juehao Ding,Miao Zheng,Jianlin Xu,Xiaohong Ge,Hui Li,Jun Zhao 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.7

A combination of multi-physics numerical simulation and experiment was conducted to study the magnetic pulse compaction technology driven by two aluminum tubes of tungsten copper powder. Then, the effects of different process parameters on the density and uniformity of the compact were studied by tuning the thickness of the pack and driver tubes and the gap between them. Results show that the density of compact is the highest when the thickness of the driver tube is 1.0 mm. More energy is consumed for force conduction as the thickness of the pack tube increases. Thus, the density of the compact is the highest when the thickness of the packer tube is 0.8 mm. The speed of the driver tube impacting the pack tube also increases with the rise in the gap. Accordingly, the compaction density with the gap of 1.5 mm is the highest under the same other parameters.

Study on the effect of gait cycle improvement with robot assisted rehabilitation

Sun Qiang,Miao Qi 한양대학교 세라믹연구소 2022 Journal of Ceramic Processing Research Vol.23 No.2

The classification based on flat training is proposed with training of exoskeleton lower limb rehabilitation robot and the flatwalking training robot. The method from the system composition, training characteristics, indications, from the subacutephase and chronic phase of rehabilitation training, in the subacute stage, 60 cases were selected, including 33 patients withhemiplegia and 27 normal patients who underwent rehabilitation training, after 6 weeks of robot training for chronichemiplegia, training outcome scores higher than 9 on the Berg balance Scale and shorter course of illness were highlycorrelated with improved walking ability.

Rolling element bearing fault detection using an improved combination of Hilbert and Wavelet transforms

Dong Wang,Qiang Miao,Xianfeng Fan,Hong-Zhong Huang 대한기계학회 2009 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.23 No.12

As a kind of complicated mechanical component, rolling element bearing plays a significant role in rotating machines, and bearing fault detection benefits decision-making of maintenance and avoids undesired downtime cost. However, extraction of fault signatures from a collected signal in a practical working environment is always a great challenge. This paper proposes an improved combination of the Hilbert and wavelet transforms to identify early bearing fault signatures. Real rail vehicle bearing and motor bearing data were used to validate the proposed method. A traditional combination of Hilbert and wavelet transforms was employed for comparison purpose. An indicator to evaluate fault detection capability of methods was developed in this research. Analysis results showed that the extraction capability of bearing fault signatures is greatly enhanced by the proposed method.

High Temperature Oxidation Resistance of NiCoCrAl High Entropy Alloy Coating on the TiAl Alloy

Yuanyuan Sun,Qiang Miao,Wenping Liang,Kai Zang,Yuting Wu,Haiyang Yu,Mengjuan Yin,Xiguang Gao,Yindong Song 대한금속·재료학회 2024 METALS AND MATERIALS International Vol.30 No.1

The high entropy alloy coating is considered as one of the most promising methods to improve the high-temperature oxidationresistance of titanium aluminum alloys due to its fine mechanical property and thermal stability. However, the high entropyalloy coating prepared so far has poor coating quality, and low coating forming efficiency and there are certain requirementsfor the substrate alloys. To this end, a NiCoCrAl high entropy alloy coating was developed using the double glow plasmaalloying technique on the TiAl alloy. The morphology, phase structure, and high temperature oxidation resistance of thecoating were comprehensively studied. The results indicate that a uniform and dense coating with a single solid solution offace-centered cube phase formed on the alloy surface. Furthermore, isothermal oxidation test was performed, and the oxidationfailure process of the TiAl substrate and the NiCoCrAl-coated sample with different oxidation times was analyzed. It isfound that the coating efficiently prevented the TiAl alloy from degeneration for up to 100 h at 900 °C.