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Ling-Ling Xie,Xiao-Yu Cao,Li-Xu Zhang,Zhong-Xu Dai,Ling-Bo Qu 대한금속·재료학회 2013 ELECTRONIC MATERIALS LETTERS Vol.9 No.2
A LiV3O8/polyaniline (PAn) composite was prepared by the in-situ polymerization method assisted by sodium dodecyl sulfate and ammonium persulfate. The as-prepared powders were investigated by XRD, SEM, and galvanostatic discharge/charge analysis. It was found that the introduction of PAn to LiV3O8 can effectively buffer the mechanical stress and restrain the number of phase changes of composite material during the electrochemical cycling. Compared with pristine LiV3O8, LiV3O8/PAn composite maintains a reversible capacity of 212.1 mAh g−1 at the current density of 30 mA g−1 after 50 cycles, approximately 22.6%, much higher than the former.
Lingli Xie,Litao Kang,Yae Li,Mangwei Cui,Bo Chang,Haiwei Jiang,Lili Gao,Xiaomin Wang,Shan Yun 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2017 NANO Vol.12 No.4
Micro-porous activated carbons (ACs) with a narrow pore size distribution of 0.4–0.6 nm and high specific surface areas (1160–1315 m2 · g-1) are prepared from environment-friendly, lowgrade potassium humate (HA-K, carbon resource) and mild activating agent potassium acetate (CH3COOK). Microstructure characterizations indicate that the introduction of activating agent CH3COOK is a key step to achieve high specific surface area and carbonization degree. These ACs contain small amount of oxygen and nitrogen, and show obvious pseudo-capacitance besides double layer capacitance. As a result, the optimized ACs achieve high specific capacitances of 311 F · g-1 and 317 F · g-1 at 0.1 A · g-1 in 2 M KOH and 1 M H2SO4 aqueous electrolytes, respectively. This sample also shows a good charge-discharge cycling stability within 10 000 cycles.
Ling-Ling Xie,Ren-Xi Gong,Hao-Ze Zhuo,Jiong-Quan Wei 대한전기학회 2011 Journal of Electrical Engineering & Technology Vol.6 No.4
An investigation of the mechanism of period-doubling bifurcation in a voltage mode controlled buck-boost converter operating in discontinuous conduction mode is conducted from the viewpoint of nonlinear dynamical systems. The discrete iterative model describing the dynamics of the close-loop is derived. Period-doubling bifurcation occurs at certain values of the feedback factor. Results from numerical simulations and experiments are provided to verify the evolution of perioddoubling bifurcation, and the results are consistent with the theoretical analysis. These results show that the buck-boost converters exhibit a wide range of nonlinear behavior, and the system exhibits a typical period-doubling bifurcation route to chaos under particular operating conditions.
Co3(PO4)2-Coated LiV3O8 as Positive Materials for Rechargeable Lithium Batteries
Ling-Ling Xie,Li-Qin You,Xiao-Yu Cao,Chao-Feng Zhang,Da-Wei Song,Ling-Bo Qu 대한금속·재료학회 2012 ELECTRONIC MATERIALS LETTERS Vol.8 No.4
Co3(PO4)2-coated LiV3O8 has been successfully synthesized and used as positive material for rechargeable lithium batteries by a facile liquid phase method. The as-prepared powders were characterized by x-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), and the galvanostatic discharge/charge experiments. As-prepared Co3(PO4)2-coated LiV3O8 forms a good layered structure with a poor cyrstallinity. SEM reveals that Co3(PO4)2-coated LiV3O8 has uniform particle distribution and reduced particle size when compared with bare one. The Co3(PO4)2 coating layer is about 33 - 59 nm forming a continuous lumps attached to LiV3O8 particle surface. Co3(PO4)2-coated LiV3O8 electrode shows increased capacity and more stable cycling. The first and 35th discharge capacities of the Co3(PO4)2-coated LiV3O8electrode are 322.8 mAh g−1 and 235.7 mAh g−1 in the range of 4.0 - 1.8 V at a current rate of 30 mA g−1, respectively. The improved electrochemical performance is assigned to the greatly reduced LiV3O8 particle with uniform morphology. Co3(PO4)2-coating further benefits the phase transitions of LiV3O8 during discharge/charge while preventing parasite reactions between electrode surface and electrolyte.
Xie, Ling-Ling,Gong, Ren-Xi,Zhuo, Hao-Ze,Wei, Jiong-Quan The Korean Institute of Electrical Engineers 2011 Journal of Electrical Engineering & Technology Vol.6 No.4
An investigation of the mechanism of period-doubling bifurcation in a voltage mode controlled buck-boost converter operating in discontinuous conduction mode is conducted from the viewpoint of nonlinear dynamical systems. The discrete iterative model describing the dynamics of the close-loop is derived. Period-doubling bifurcation occurs at certain values of the feedback factor. Results from numerical simulations and experiments are provided to verify the evolution of perioddoubling bifurcation, and the results are consistent with the theoretical analysis. These results show that the buck-boost converters exhibit a wide range of nonlinear behavior, and the system exhibits a typical period-doubling bifurcation route to chaos under particular operating conditions.
Ling-Ling Xie,Yuan-Dong Xu,Jie-Jie Zhang,Cheng-Peng Zhang,Xiao-Yu Cao,Ling-Bo Qu 대한금속·재료학회 2013 ELECTRONIC MATERIALS LETTERS Vol.9 No.4
Er-doped LiV3O8 as cathode material for secondary lithium batteries was prepared through a rheological phase reaction method. The as-prepared materials were investigated by x-ray diffraction (XRD), scanning electron microscopy (SEM), and galvanostatic discharge/charge measurements. The results indicate that Er doped phase preserves the layered structure of the pristine LiV3O8 and has an enlarged interlayer spacing. Compared to LiV3O8 sample, Er-doped LiV3O8 sample displays more uniform particles and large surface area. The electrochemical test shows that Er doping does not change the process of Li+ insertion/deinsertion. Er-doped LiV3O8 electrode exhibits an initial discharge capacity of 294.2 mAh g−1 and maintains a stable capacity of 220.7 mAh g−1 after 50 cycles, indicating a greatly improved good cycleability comparing with the undoped one.
Ling Wan,Xiongyao Xie,Lujun Wang,Pan Li,Yong Lu 대한토목학회 2022 KSCE Journal of Civil Engineering Vol.26 No.1
The structural health of operational metro tunnels is closely related to public safety. Prior research has focused on the locations of structural damage, but few researchers have examined both the location of damage and identifying the degree of damage, especially in metro shield tunnels. This paper proposes a new method for identifying structural damage that entails locating and detecting the degradation of tunnel performance, with a special focus on characterizing the degree of damage. First, the dynamic behaviors (modal frequencies and shapes) of different damage levels are obtained from an analytical model of the original tunnel structure. Second, a modal strain energy damage indicator (MSEDI) is introduced to locate the damage, regardless of size. Once the location of the damage is identified using MSEDI, a fuzzy logic-based damage identification (FLBDI) method is used to determine the actual extent of the damage. Finally, a simplified model of the tunnel is created using the Euler-Bernoulli beam theory and Winkler’s foundation, to further test the procedure under an incomplete modal information condition and with differing noise levels. The results reveal that the fuzzy logic-based system can identify the degree of damage and structural degradation with very high accuracy, in which the location of damage and the prediction of performance degradation is satisfactorily confirmed.
Cavity Location Method for Operational Metro Tunnels Based on Perturbation Theory
Ling Wan,Xiongyao Xie,Lujun Wang,Pan Li,Hua Yin 대한토목학회 2021 KSCE Journal of Civil Engineering Vol.25 No.6
Disease in the liner back cavities of operational metro tunnels is alternately affected by groundwater environment, train cyclic load, and ambient environment conditions. Cavity disease is characterized by high levels of hiddenness and uncertainty; it also easily induces other tunnel diseases which can reduce the structure’s bearing capacity and degrade structural safety and stability throughout the tunnel. This paper proposes a novel cavity-locating method for operational shield tunnels, with special focus on single- and multiple-cavity diseases. Based on perturbation theory, dynamic behaviors (modal frequencies and shapes) of different cavity cases were obtained from an analytical model of the original tunnel structure. A modal strain energy cavity indicator (MSECI) was established to reveal the locations of both single cavity and multiple cavities. A typical shield tunnel was modeled as an Euler-Bernoulli beam on a Winkler foundation and evaluated to validate the proposed method. The perturbation theory appears to effectively characterize the dynamic characteristics of liner back cavities in metro tunnels. MSECI can be used to locate cavities accurately. This work may provide a valuable theoretical basis for the detection and analysis of tunnel cavity disease and other tunnel health-monitoring applications.