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- 저자 : Yongpeng Shi (검색결과 4 건)
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( Yongpeng Shi ),( Yujie Xia ),( Ya Gao ),( Jianhua Cui ) 한국인터넷정보학회 2021 KSII Transactions on Internet and Information Syst Vol.15 No.8
The tone reservation (TR) scheme is an attractive method to reduce peak-to-average power ratio (PAPR) in the filter bank multicarrier with offset quadrature amplitude modulation (FBMC-OQAM) systems. However, the high PAPR of FBMC signal will severely degrades system performance. To address this issue, a cyclic shift based TR (CS-TR) scheme with embedding side information (SI) is proposed to reduce the PAPR of FBMC signals. At the transmitter, four candidate signals are first generated based on cyclic shift of the output of inverse discrete Fourier transform (IDFT), and the SI of the selected signal with minimum peak power among the four candidate signals is embedded in sparse symbols with quadrature phase-shift keying constellation. Then, the TR weighted by optimal scaling factor is employed to further reduce PAPR of the selected signal. At the receiver, a reliable SI detector is presented by determining the phase rotation of SI embedding symbols, and the transmitted data blocks can be correctly demodulated according to the detected SI. Simulation results show that the proposed scheme significantly outperforms the existing TR schemes in both PAPR reduction and bit error rate (BER) performances. In addition, the proposed scheme with detected SI can achieve the same BER performance compared to the one with perfect SI.
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Yongpeng Shi,Junjie Zhang,Ya Gao,Yujie Xia 한국통신학회 2022 Journal of communications and networks Vol.24 No.3
Combining mobile edge computing (MEC), themulti-drone aided space-air-ground integrated Internet of things(SAG-IoT) networks can provide ground IoT devices (GIDs) highqualitywireless access and computing services. However, the diversetasks, moving drones, and limited network resources revealgreat challenges for the task offloading and resource allocationscheme exploitation. Especially, given the restricted computationresources, how to make full use of available applications deployedon MEC servers (MECSs) to compute various types of tasks, iseven an important issue. To the best of our knowledge, it is anentirely new problem since most existing works in this line assumethat all types of applications can be deployed on one MECS so asto process various offloaded tasks. Toward this end, we presentthis paper to investigate inter-server computation offloading, resourceallocation, and drone deployment to minimize the overallcomputation overhead of all GIDs. An iteratively optimizationalgorithm is proposed which alternately utilizes heuristic greedyand successive convex approximation methods. Simulation resultsverify that, for different GID numbers, optimization schemes, andcomputing models, our devised schemes can not only significantlyreduce the overall computation overhead but also achieve optimaldecisions of computation offloading, spectrum allocation, anddrone deployment.
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Qi Shi,Yongpeng Lei,Yingde Wang,Huaping Wang,Lehua Jiang,Hongliang Yuan,Dong Fang,Bing Wang,Nan Wu,Yanzi Gou 한국물리학회 2015 Current Applied Physics Vol.15 No.12
B, N-codoped carbon nanofibers were massively prepared by heat treatment of electrospun carbon nanofibers with the mixture of boric acid/urea in N2 (BNCf-N) and subsequently activated in NH3 (BNCf- NA). The directly electrospun self-standing 3D non woven structure with void spaces between each fiber facilitates the mass transport of reactant and resulted molecules. Further NH3 activation gives BNCf-NA a high surface area of 306.3 m2 g-1 with micro/mesoporous structure, providing abundant passageway for proton transfer. Simultaneously, NH3 activation also realizes the optimization of surface functionalities, such as more BeNeC and pyridinic-N. These intriguing features render BNCf-NA excellent catalytic behavior with nearly four-electron oxygen reduction reaction (ORR) process in alkaline media, especially much better stability and methanol tolerance than the commercial Pt/C catalyst. Our work provides a large-scale preparation method for efficient metal-free catalysts toward ORR, thus further intensifying the commercial application of fuel cells.
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Zhenhang Kang,Yongpeng Lei,Zhonghua Shi,Quanwei Song,Jifeng Zhang 한국섬유공학회 2022 Fibers and polymers Vol.23 No.12
Co-cured metal/GFRP joints with groove structures can maintain the integrity of GFRP and the continuity of glassfibres. To improve the performance of the groove structure, it is necessary to design groove parameters (groove depth, width,etc.). Due to the repetitive structure of the groove morphology, the representative volume element (RVE) was used to buildthe model. Then, shearing and pulling-out simulations of the groove structures were carried out, and the simulated resultswere compared with the experimental results. In addition, the influence of groove depth and width on the bondingperformance of the structures was studied, and the optimal result was obtained (width: 1.00 mm, depth: 0.75 mm). Finally, the±45 ° groove structure (width: 1.414 mm, depth: 1.00 mm) was equivalent to a 0-thickness cohesive element layer throughthe stiffness equivalent method, and the results were compared with the previous test (DCB and shear test) results, and similarresults were obtained. The equivalent analysis not only verifies the applicability of the stiffness equivalent method but alsoverifies the practicability of the groove structure obtained by the RVE model.
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