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Qing Xiong,Yanhai Xu,Yiqiang Peng,Weihua Zhang,Yongjian Li,Lan Tang 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.4
When low-speed rolling bearings fail, it is hard to diagnose the extent of their damage. We developed a test rig to simulate the lowspeed rolling bearing operating condition, where bearings with various fault states are installed on the test wheelset and subjected to the same external loading condition. The collected bearing box acceleration time histories are processed with the Empirical mode decomposition (EMD) method combined with kurtosis criterion to filter the trend and noise components. Five characteristic parameters of Alpha stable distribution (ASD) are identified by fitting the ASD distribution to the vibration acceleration signals and computing the Probability density function (PDF). To highlight the advantage of ASD method in feature extraction, kurtosis also has be calculated. Through sensitivity and stability analysis of the six parameters and utilization of Least squares support vectors machine (LSSVM) with Particle swarm optimization (PSO), three most sensitive and stable feature parameters including the characteristic exponent a, the scale factor g and the peak value of the PDF h are located and applied to evaluate the low-speed rolling bearings’ damage position and damage extent. The proposed method was validated by test data, and the results demonstrated that the ASD characteristics combined with PSO-LSSVM can not only achieve fault diagnosis of low-speed rolling bearings' damage position and damage extent, but also have better diagnosis accuracy and operational efficiency than other methods.
Huixia Zhu,Shiru Jia,Hongjiang Yang,Weihua Tang,Zhilei Tan,Yuanyuan Jia 한국식품과학회 2010 Food Science and Biotechnology Vol.19 No.6
The feasibility of a novel bacteriostatic sausage casing made of bacterial cellulose (BC) embedded with ε-polylysine (ε-PL) was evaluated. The ε-PL/BC composite was prepared by immersing BC tubes in ε-PL solution and its characteristics were analyzed with Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD),and atomic force microscopy (AFM) techniques, respectively. The results suggested that ε-PL molecules were incorporated into the cellulose fiber networks and the ε-PL/BC composite might have a novel unique structure. No significant loss of antimicrobial activity was observed even after autoclaving at 121℃ for 30 min and the oxygen permeability was far below than that of polyethylene (PE) and polyvinyl alcohol (PVA) membrane. Its tensile strength was 51.8 MPa. The ε-PL/BC composite exhibits bacteriostatic and/or bacteriocidal activities against a broad spectrum of Gram-positive and Gram-negative bacteria; as a result, an extended shelf life than controls was observed for sausage packaged with the ε-PL/BC composite.
Conduction Mechanism in (La0.7Sr0.3MnO3)n(BiFeO3)n Multilayered Thin Films
Huiwen Zhu,Shunli Wang,Ping Jiang,Jingqin Shen,Weihua Tang 한국물리학회 2010 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.57 No.2
(La0.7Sr0.3MnO3)n(BiFeO3)n multilayered thin films were deposited on (0 0 1) SrTiO3 substrates by using the RF magnetron sputtering method, and their conduction mechanisms in the temperature range between 150 K and 300 K were investigated using several common dielectric conduction models. The results indicate the current-voltage characterization of the as-fabricated thin films obey Ohm’s law at 300 K, but the space-charge-limited conduction mechanism becomes dominant in the as-fabricated thin films as the temperature is decreased.
Daoyou Guo,Xinyuan Qin,Ming Lv,Haoze Shi,Yuanli Su,Guosheng Yao,Shunli Wang,Chaorong Li,Peigang Li,Weihua Tang 대한금속·재료학회 2017 ELECTRONIC MATERIALS LETTERS Vol.13 No.6
Highly (201) oriented Zn-doped β-Ga2O3 thin films with differentdopant concentrations were grown on (0001) sapphire substrates byradio frequency magnetron sputtering. With the increase of Zn dopantconcentration, the crystal lattice expands, the energy band gap shrinks,and the oxygen vacancy concentration decreases. Both the metalsemiconductor metal (MSM) structure photodetectors based on thepure and Zn-doped β-Ga2O3 thin films exhibit solar blind UVphotoelectric property. Compared to the pure β-Ga2O3 photodetector,the Zn-doped one exhibits a lower dark current, a higher photo/darkcurrent ratio, a faster photoresponse speed, which can be attributed tothe decreases of oxygen vacancy concentration.
A self-powered β-Ga2O3/CsCu2I3 heterojunction photodiode responding to deep ultraviolet irradiation
Gao Ang,Jiang Weiyu,Ma Guoliang,Liu Zeng,Li Shan,Yan Zuyong,Sun Weiming,Zhang Shaohui,Tang Weihua 한국물리학회 2022 Current Applied Physics Vol.33 No.-
In this paper, a lead-free halide perovskite CsCu2I3 film with high stability was prepared by the anti-solvent assisted crystallization method. Then, we coupled it with Ga2O3 to prepare a corresponding heterojunction deep ultraviolet (UV) photodetector. After testing, we concluded that the photodetector is sensitive to 254 nm UV light. The photodetector has good reproducibility, and has an ultra-high photo-to-dark current ratio (PDCR) of more than 105. In addition, under a bias of 10 V and an illuminated intensity of 200 μW/cm2, the responsivity (R) and specific detectivity (D*) reached 20 mA/W and 107 cm Hz1/2 W 1 (Jones), and the external quantum efficiency (EQE) is 10%. Meanwhile, the prepared photodetector could operate at zero bias, i.e., self-powered operation, along with a photocurrent of about 1 nA under illumination with UV light intensity of 200 μW/cm2.