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Xiao-Wen Zhang,Bing-Jie Mo,Li-Ming Liu,Hong-Hang Wang,Dan-Teng Chang,Ji-Wen Xu,Hua Wang,Bin Wei 한국물리학회 2014 Current Applied Physics Vol.14 No.11
2-methyl-9,10-bis(naphthalen-2-yl)anthracene (MADN) based fluorescent blue organic light-emitting diodes (OLEDs) are demonstrated. With MADN as emitting layer, experiments indicate that thick MADN (40e60 nm) is preferable for constructing efficient blue OLED. With MADN as hole-transport and emitting layer and tris(8-hydroxy-quinolinato)aluminium (Alq3) as electron-transport layer, the OLED electroluminescent characteristics show a mixture emission of MADN and Alq3 with Commission Internationale d'Eclairage (CIE) color coordinates of (0.25, 0.34), indicating feasible hole transporting in MADN. Using 4,7-diphenyl-1,10-phenanthroline (BPhen) replacing Alq3 as electron-transport layer, the OLED shows deep blue emission with a maximum luminous efficiency of 4.8 cd/A and CIE color coordinates of (0.16, 0.09). The hole transport characteristics of MADN are further clarified by constructing hole-only device and performing impedance spectroscopy analysis. The results indicate that MADN shows superior hole-transport ability which is almost comparable to typical hole-transport material of N,N0-bis(naphthalen-1-yl)-N,N0-bis(phenyl)-benzidine (NPB), suggesting a promising application for constructing efficient blue OLED with integrated hole-transport layer and emitting layer.
A Novel Dynamic Spectrum Access Algorithm for Cognitive Radio Networks
Zhao, Ming,Yin, Chang-Chuan,Wang, Xiao-Jun The Korea Institute of Information and Commucation 2013 Journal of communications and networks Vol.15 No.1
This paper proposes a new dynamic spectrum access (DSA) algorithm for cognitive radio networks. Once initialized, this algorithm works without the need of coordination overhead and hence can be used when no control channel is available. Secondary user (SU) lists and predetermined access control are used in this algorithm. We analyze the probability of no SU collision with primary user and the throughput of our proposed algorithm. Extensive simulations show that our algorithm outperforms the existing DSA algorithm in terms of both the aggregate throughput and the traffic distribution fairness. Furthermore, the validity of our analysis is confirmed by simulation results.
Lin Chang-Gang,Zou Ming-Song,Zhang Hai-Cheng,Qi Li-Bo,Liu Shu-Xiao 대한조선학회 2021 International Journal of Naval Architecture and Oc Vol.13 No.1
To investigate the mechanism of friction-induced vibration and noise of ship water lubricated stern bearings, a two-degree-of-freedom (2-DOF) nonlinear self-excited vibration model is established. The novelty of this work lies in the detailed analysis of influence of different parameters on the stability and nonlinear vibration characteristics of the system, which provides a theoretical basis for the various friction vibration and noise phenomenon and has a very important directive meaning for low noise design of water lubricated stern bearings. The results reveal that the change of any parameter, such as rotating speed of shaft, contact pressure, friction coefficient, system damping and stiffness, has an important influence on the stability and nonlinear response of the system. The vibration amplitudes of the system increase as (a) rotating speed of shaft, contact pressure, and the ratio of static friction coefficient to dynamic friction coefficient increase and (b) the transmission damping between motor and shaft decreases. The frequency spectrum of the system is modulated by the first mode natural frequency, which is continuous multi-harmonics of the first mode natural frequency. The response of the system presents a quasi-periodic motion.
Morphology control of mesoporous Cu<sub>2</sub>O by reductants and its photocatalytic activity
Chu, Xiao-Zhong,Cheng, Zhi-Peng,Zhao, Yi-Jiang,Xu, Ji-Ming,Li, Mei-Sheng,Hu, Lei,Zhou, Shou-Yong,Wu, Fei-Yue,Lee, Chang-Ha Elsevier 2017 CERAMICS INTERNATIONAL Vol.43 No.11
<P><B>Abstract</B></P> <P>Mesoporous Cu<SUB>2</SUB>O particles with different morphologies were synthesized via simple one-pot reactions. Effects of reducing agents, dispersant, template, and temperature on the <B>structure</B> of the prepared materials were investigated. Mesoporous flower-shaped Cu<SUB>2</SUB>O materials were obtained at 70℃ using glucose <B>as a reductant</B>. Different hollow microsphere shapes of Cu<SUB>2</SUB>O could be prepared at 40℃ using <B>another type of reductant, ascorbic acid</B>. The results indicated that the uniform morphology of synthesized Cu<SUB>2</SUB>O with mesopores presented a maximum specific surface area of 45.3m<SUP>2</SUP>/g. Furthermore, the as-prepared Cu<SUB>2</SUB>O particles showed good photodegradation efficiencies of methyl orange in the range of 86.0–93.7%, depending on their morphologies.</P>
Wen-ming Zhang,Jia-qi Chang,Xing-hang Shen,Xiao-fan Lu,Tian-cheng Liu 국제구조공학회 2023 Structural Engineering and Mechanics, An Int'l Jou Vol.88 No.1
With the gradual implementation of long-span suspension bridges into high-speed railway operations, the main beam’s bending stiffness contribution to the live load response permanently grows. Since another critical control parameter of railway suspension bridges is the beam-end rotation angle, it should not be ignored by treating the main beam deflection as the only deformation response. To this end, the current study refines the existing method of the main cable shape and simply supported beam bending moment analogy. The bending stiffness of the main beam is considered, and the main beam’s analytical expressions of deflection and rotation angle in the whole span are obtained using the cable-beam deformation coordination relationship. Taking a railway suspension bridge as an example, the effectiveness and accuracy of the proposed analytical method are verified by the finite element method (FEM). Comparison of the results by FEM and the analytical method ignoring the main beam stiffness revealed that the bending stiffness of the main beam strongly contributed to the live load response. Under the same live load, as the main beam stiffness increases, the overall deformation of the structure decreases, and the reduction is particularly noticeable at locations with original larger deformations. When the main beam stiffness is increased to a certain extent, the stiffening effect is no longer pronounced.
Yang, Ming,Kim, Sang Woo,Zhang, Shuye,Park, Dae Young,Lee, Chang-Woo,Ko, Yong-Ho,Yang, Haifeng,Xiao, Yong,Chen, Gang,Li, Mingyu The Royal Society of Chemistry 2018 Journal of Materials Chemistry C Vol.6 No.27
<P>The fabrication of Ag nanowire (AgNW) patterns on a working substrate is a critical step to prepare flexible/stretchable electronics. The conventional method of making AgNW patterns is based on a 2-D mask, which suffers some serious drawbacks, such as low material usage, difficulty in preparing complex patterns, and susceptibility to damaged pattern edges. To overcome these drawbacks, this study proposes the use of a 3-D mask, which when combined with a vacuum filtration system, allowed efficient fabrication of complex AgNW patterns with clear edges. In addition, we controlled the microstructure of the patterned AgNW/polydimethylsiloxane (PDMS) electrodes transferred from the membrane filter, obtaining stretchable electrodes with anisotropic electrical properties. Moreover, we greatly improved the stability and reliability of the patterned electrodes in long-term stretch/release tests by developing a PDMS/AgNW/PDMS sandwich structure. Based on these improvements, robust stretchable electrodes with a stretchability of over 80% uniaxial strain and tunable gauge factors ranging from 0.07 to 520 (a much wider range than previously reported) were fabricated by optimizing the AgNW deposition density and PDMS peel-off direction. Finally, we demonstrated the applicability of the proposed method by fabricating stretchable circuits which were able to either maintain a stable resistance or sensitively monitor various human motions, revealing its tremendous potential for applications in flexible/stretchable electronics.</P>
Tube Voltage, DNA Double-Strand Breaks, and Image Quality in Coronary CT Angiography
Lin Zhu Xiao,Zhou Fan,Schoepf U. Joseph,Pillai Balakrishnan,Zhou Chang Sheng,Quan Wei,Bao Xue Qin,Lu Guang Ming,Zhang Long Jiang 대한영상의학회 2020 Korean Journal of Radiology Vol.21 No.8
Objective: To evaluate the effects of tube voltage on image quality in coronary CT angiography (CCTA), the estimated radiation dose, and DNA double-strand breaks (DSBs) in peripheral blood lymphocytes to optimize the use of CCTA in the era of low radiation doses. Materials and Methods: This study included 240 patients who were divided into 2 groups according to the DNA DSB analysis methods, i.e., immunofluorescence microscopy and flow cytometry. Each group was subdivided into 4 subgroups: those receiving CCTA only with different tube voltages of 120, 100, 80, or 70 kVp. Objective and subjective image quality was evaluated by analysis of variance. Radiation dosages were also recorded and compared. Results: There was no significant difference in demographic characteristics between the 2 groups and 4 subgroups in each group (all p > 0.05). As tube voltage decreased, both image quality and radiation dose decreased gradually and significantly. After CCTA, γ-H2AX foci and mean fluorescence intensity in the 120-, 100-, 80-, and 70-kVp groups increased by 0.14, 0.09, 0.07, and 0.06 foci per cell and 21.26, 9.13, 8.10, and 7.13 (all p < 0.05), respectively. The increase in the DNA DSB level in the 120-kVp group was higher than those in the other 3 groups (all p < 0.05), while there was no significant difference in the DSBs levels among these latter groups (all p > 0.05). Conclusion: The 100-kVp tube voltage may be optimal for CCTA when weighing DNA DSBs against the estimated radiation dose and image quality, with further reductions in tube voltage being unnecessary for CCTA.