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- 저자 : ( Qi Yanyan ) (검색결과 4 건)
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Performance Optimization of Two-Way AF Relaying in Asymmetric Fading Channels
( Qi Yanyan ),( Wang Xiaoxiang ) 한국인터넷정보학회 2014 KSII Transactions on Internet and Information Syst Vol.8 No.12
It is widely observed that in practical wireless cooperative communication systems, different links may experience different fading characteristics. In this paper, we investigate into the outage probability and channel capacity of two-way amplify-and-forward (TWAF) relaying systems operating over a mixed asymmetric Rician and Rayleigh fading scenario, with different amplification policies (AP) adopted at the relay, respectively. As TWAF relay network carries concurrent traffics towards two opposite directions, both end-to-end and overall performance metrics were considered. In detail, both uniform exact expressions and simplified asymptotic expressions for the end-to-end outage probability (OP) were presented, based on which the system overall OP was studied under the condition of the two source nodes having non-identical traffic requirements. Furthermore, exact expressions for tight lower bounds as well as high SNR approximations of channel capacity of the considered scenario were presented. For both OP and channel capacity, with different APs, effective power allocation (PA) schemes under different constraints were given to optimize the system performance. Extensive simulations were carried out to verify the analytical results and to demonstrate the impact of channel asymmetry on the system performance.
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Yanyan Yang,Yue Qi,Wenli Zhai,Jianing Tan,Suyang Feng,Jie Zhang,Mengxiao Shen,Liuding Wang,Xiaoyang Yu,Xiaoshu Qu 대한금속·재료학회 2020 ELECTRONIC MATERIALS LETTERS Vol.16 No.5
Tungsten oxide (WO3) has received attention as an electrochromic material because of its excellent properties. However,the long switch time and low coloration efficiency of WO3film limit its use. Herein, a nanocomposite film containingPreyssler-type polyoxometalate (POM) K12.5Na1.5[NaP5W30O110]·15H2O (P5W30) and WO3nanoparticles has been fabricatedby layer-by-layer (LbL) self-assembly methods and characterized by UV-Vis spectra, scanning electron microscopy, X-rayphotoelectron spectroscopy and electrochemical workstation. Compared to the pure WO3film, the [P5W30/WO3]20 filmhas better electrochromic properties. Then, the electrochromic properties of [P5W30/WO3]20 film were studied in differentelectrolyte. The results indicated that the composite film show high coloration efficiency (191.62 cm2C−1), fast switch time(2.58 s, 1.48 s), good CV stability (500 th) in 0.5 M LiClO4/PC electrolyte, and successfully assembled of an electrochromicdevice. These advantages can make the nanocomposite film become a promising candidate for potential application inelectrochromic devices.
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Preparation and Properties of Cellulose Nanocrystals Based Self-healing Polyurethane
Yang Qiao,Qi Xu,Shouxiang Liu,Zhiqiang Li,Yanyan Wei 한국고분자학회 2023 폴리머 Vol.47 No.3
First, cellulose nanocrystals were extracted from microcrystalline cellulose using the sulfuric acid hydrothermal method. Second, imine aromatic diol (Imine) was synthesized from p-hydroxybenzaldehyde and 4,4'-diaminodiphenylmethane as raw materials. Then the imine was introduced into the polyurethane, and the reversible covalent bond between the imine and the C = N group was used to endow the polyurethane with self-healing properties. Finally, cellulose nanocrystalline (CNC) was added into the self-healing polyurethane as the dispersed phase to prepare the composite. The experimental results show that with the increase of the amount of CNC, the properties of the composites increase first and then decrease, which is due to the physical cross-linking effect of proper CNC distribution in the self-healing polyurethane, it is beneficial to the mechanical properties, but the self-healing property is reduced by further increasing the content, which restricts the movement of the molecular chain. The mechanical properties of the composite with 0.049 g CNC are the best, with fracture strength reaching 20.59 MPa, approximately 1.56 times higher than that of pure self-healing polyurethane, and its elongation at break is 979%, and the self-healing efficiency reaches 84.7%, keeping an excellent level.
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Ping Kou,Yu-Fei Kang,Li-Tao Wang,Li-Jun Niu,Ying Xiao,Na Guo,Qi Cui,Yanyan Liu,Yu-Jie Fu 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.80 No.-
This study explored an integrated strategy for extraction and preparative separation of four anthocyaninsfrom Ribes nigrum L. using DES-based microwave assisted extraction andflash chromatography. Theextraction yield of anthocyanins reached 2.03 mg/g after optimization. An efficient preparativeseparation process of four main anthocyanins by macroporous resin andflash chromatography wasestablished afterwards. The yields of D3G, D3R, C3G and C3R reached 0.32 mg/g, 0.47 mg/g, 0.18 mg/g and0.43 mg/g with the purities of more than 95%, respectively. The developed procedure represents anefficient and convenient alternative for the systematic utilization of natural products from plantmaterials.
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