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RISS 인기검색어
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- 저자 : Weicai Liu (검색결과 4 건)
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A Modified Adaptive Sparse Channel Estimator for OFDM Systems Based On Singular Value Decomposition
Liu Zhiyong,Wang Yiron,Liu Weicai 보안공학연구지원센터 2016 International Journal of Future Generation Communi Vol.9 No.11
In this paper, a modified adaptive sparse channel estimator based on singular value decomposition (SVD) for OFDM systems is proposed. The conventional adaptive sparsity matching pursuit (ASMP) based compressive channel estimation has bad anti-noise performance, although not needing the information of sparsity. Because using the SVD to modify the measurement matrix of CS can improve the robustness to noise. So we use the SVD to modify the measurement matrix of ASMP based compressive channel estimation. The proposed channel estimation has better robustness to noise and low error. The simulation results show that comparing with ASMP based compressive channel estimation, the proposed algorithm has 1 dB gain at MSE and 1.3 dB gain at BER.
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Weicai Wu,Leijing Liu,Yinhua Zhou,Shanpeng Wen,Wenjing Tian 한국물리학회 2009 Current Applied Physics Vol.9 No.5
The influence of two components blend ratio, solution concentration and thermal annealing on the morphology of poly(2-methoxy-5-(2'-ethyl-hexyloxy)-p-phenylenevinylene) (MEH-PPV): N,N'-bis(1-ethylpropyl)-3,4:9,10-perylene bis(tetracarboxyl diimide) (EP-PTC) blend films spin-cast from chloroform solutions has been studied using atomic force microscopy (AFM). The AFM images show that the dimension of the phase separation increases with the EP-PTC content and total solution concentration. When the annealing temperature increases from 90 to 150 ℃, the EP-PTC crystal-like clusters grow rapidly. Solar cells based on MEH-PPV:EP-PTC blend films with different weight ratios were fabricated. The device with 1:3 weight ratio has a higher power conversion efficiency (PCE) of 0.072% compared with the devices with 1:1, 1:2 and 1:4 ratio, which increases by about 14 times over that of the device with 1:1 ratio that has a PCE of 0.005%. It is indicated that the optimum performance of the photovoltaic device is strongly related to the finer phase separation between MEH-PPV and EP-PTC on a submicron scale which enables an efficient dissociation of photogenerated excitons, and the pure EP-PTC phase can build up a percolating network with pathways large enough to enhance electron transport.
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Muwang Wei,Jianhe Xie,Weicai Liu 국제구조공학회 2021 Steel and Composite Structures, An International J Vol.41 No.2
To meet the demands of the sustainable development of construction, the combination of precast structures and recycled aggregate concrete made from construction and demolition waste is being promoted as a promising green construction technology. In this study, a new prefabricated member, a buckling-restrained steel plate shear wall with a cover plate made of recycled aggregate concrete (PBRW), was developed and experimentally studied. Eight specimens were tested to study the effect of the cover plate with different recycled aggregate substitution ratios and various bolt arrangements on the seismic behavior of this shear wall system. Based on the high-order buckling in the inner steel plate, a theoretical method was proposed to predict the shear resistance of PBRWs. The test results indicated that the PBRWs exhibited high shear strength, an adequate initial stiffness, a favorable energy absorption capacity, and a stable hysteresis curve. A full replacement of recycled aggregate with natural aggregate had almost no adverse impact on the seismic behavior of the PBRWs. The wall with an insufficient number of bolts (bolt arrangement of 3×2) imposed weaker lateral constraints on the inner plate, resulting in a reduction in the seismic behavior.
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Task-oriented energy benchmark of machining systems for energy-efficient production
Wei Cai,Li Li,Shun Jia,Conghu Liu,Jun Xie,Luoke Hu 한국정밀공학회 2020 International Journal of Precision Engineering and Vol.7 No.1
The energy benchmark has been recognised as an effective analytical methodology and management tool that help to improve the efficiency and performance of energy utilisation. With a wide distribution and large amount of energy consumption at a low efficiency, machining systems have considerable energy-saving potential. This paper proposes a task-oriented energy benchmark in machining systems, and illustrates the concept of the task-oriented energy benchmark and indicators. A method for developing the task-oriented energy benchmark considering the certainty production task and the uncertainty production task is proposed, which lays a solid foundation for studying the energy benchmark, benchmark rating system and energy certification. Furthermore, a case study of the task-oriented energy benchmark not only verifies the reliability but the effectiveness for energy-efficient production.
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