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        Barrier Optical Waveguide Fabrication in LiNbO3 Crystal by 4.5-MeV LithiumIon Implantation with Low Dose

        Xue-Lin Wang,Ding-Yu Shen,Gang Fu,Hong-Ji Ma,Ke-Ming Wang,Rui Nie,Shi-Ling Li 한국물리학회 2005 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.46 No.1

        A barrier planar waveguide was fabricated in z-cut LiNbdO3 crystals by 4.5-MeV lithium ion implantation at a dose of 3 £ 1014 ions/cm2 at room temperature. Dark modes were observed by the prism-coupling method with wavelengths of both 633 nm and 1539 nm. The refractive index pro¯les were reconstructed by using the re°ectivity calculation method. There were about 1.1 % and 0.7 % decreases at the optical barriers of the ordinary and extraordinary refractive index at the wavelength at 633 nm, and the positions of the optical barriers were close to those of the damage peaks calculated by the TRIM098 (Transport of Ions in Matter) code. It is found that the refractive index change may be partly due to the damage induced by nuclear collision.

      • KCI등재

        The Decoupled Active/Reactive Power Predictive Control of Quasi-Z-source Inverter for Distributed Generations

        Dazhong Ma,Ke Cheng,Rui Wang,Sen Lin,Xiangpeng Xie 제어·로봇·시스템학회 2021 International Journal of Control, Automation, and Vol.19 No.2

        For the quasi-Z-source inverter (qZSI), capacitor voltage stability control, high performance of the inductor current reference tracking and fast response of the active/reactive power are key issues. Thus, a decoupled active/reactive power model predictive control (MPC) of the qZSI for distributed generations (DGs) is proposed to fulfill these requirements without additional control loops. Firstly, the digital observer is constructed to remove the utilization of the front voltage sensor and reduce the number of hardware equipment. Moreover, based on the advance determination of the system operation mode and the simplified cost function, the calculation complexity of the proposed MPC algorithm is simplified. Further, the proposed improved MPC method with the digital observer is proved to achieve the high accuracy and the zero prediction error, of which stability is demonstrated through Lyapunov stability criteria. Eventually, the proposed controller is compared with conventional MPC and PI controller in detail and its effectiveness is verified by both simulation and experimental results from a grid-connected qZSI.

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        Physical property effects of the compression process with supercritical carbon dioxide as working fluid

        Jinlan Gou,Kelong Zhang,Yuansheng Lin,Yong Li,Can Ma,Hanbing Ke 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.8

        The compressor is one of the key components in the closed supercritical carbon dioxide (S-CO 2 ) Brayton cycle, but its design method is far from mature. It is naturally expected that the well-established design method of the air compressor can provide favorable guidelines, on the basis of further understanding the effects of the physical property on the compressor flow field. Considering that isentropic compression is one of the core physical processes in the compressor, the physical property effects on this process were mainly investigated in this work. Similarity criterion was considered, and the change rate discrepancy of the main variables in this process between S-CO 2 and the ideal air was fully analyzed. Results show that S-CO 2 is compressed faster than the ideal air in most cases, along with generating smaller Mach number and larger pressure rise ratio. It is noted the important parameter of the static pressure coefficient distribution with S-CO 2 in the compression process is almost the same as that with the ideal air at low Mach number, which is conductive to the extension of the air compressor research experience, but it is quite different at high Mach number. The simulation cases about compressor cascade are further applied and prove the suitability of the revealed physical property effects in the compressor passage. Understanding these effects on the compression process is helpful to improve the design method of the S-CO 2 compressor.

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        Optimization of preparation and properties of Gardenia yellow pigment-loaded alginate beads

        Yong Liu,Qing Zhou,Yan-Mei He,Xiu-Yun Ma,Lin-Na Liu,Yong-Jian Ke 한국화학공학회 2021 Korean Journal of Chemical Engineering Vol.38 No.8

        Gardenia yellow pigment (GYP) loaded alginate beads were prepared by the ionic gelation technique, and the preparation parameters were optimized by response surface methodology for high encapsulation efficiency. The optimized parameters were alginate concentration of 3.3%, CaCl2 concentration of 2.4%, and GYP concentration of 3.2mg/mL, under which the encapsulation efficiency was 73.61%. The surface morphology and bead size analysis showed that the GYP-loaded alginate beads had a roughly spherical morphology with a wrinkled surface, and their average diameter was 0.87 mm. In vitro release test revealed that the GYP release had a pH-dependent release profile and a two-step release process. The Rigter-Peppas model was the most proper model to assess the GYP release from alginate beads. The release mechanism of GYP at pH 1.2 and 7.4 was non-Fickian transport and case-II transport, respectively. The 2,2-diphenyl-1-picrylhydrazyl assay indicated that the encapsulated GYP had effectively maintained 82.56% of the antioxidant activity.

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