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Preparation and Electromagnetic Properties of an Electromagnetic Wave Absorber
Sun Chang,Sun Kangning,Pang Laixue,Liu Jian 한국자기학회 2016 Journal of Magnetics Vol.21 No.1
In this study, we report the as-prepared MgO-doped BaFe12O19, which was prepared by calcination technique and high-energy ball milling process, as an electromagnetic wave absorber. The phase analysis of BaFe12O19 and the as-prepared MgO-doped BaFe12O19 was detected utilizing X-ray Diffractometer (XRD). The microstructure was characterized using Scanning Electron Microscope (SEM). By means of the transmission/reflection coaxial line method, the electromagnetic properties and microwave absorbing properties of the asprepared electromagnetic wave absorber were studied. It is found that the electromagnetic wave absorber has a minimum reflection loss value of –41 ㏈ at 4.27 ㎓ with a matching thickness of 2.6 ㎜. The experiment results revealed that the as-prepared electromagnetic wave absorber could find potential applications in many military as well as commercial industries.
Xiaofei Sun,Kangning Wang,Lu Lin 한국통계학회 2018 Journal of the Korean Statistical Society Vol.47 No.1
Partial linear varying coefficient models are often used in real data analysis for a good balance between flexibility and parsimony. In this paper, we propose a robust adaptive model selection method based on the rank regression, which can do simultaneous coefficient estimation and three types of selections, i.e., varying and constant effects selection, relevant variable selection. The new method has superiority in robustness and efficiency by inheriting the advantage of the rank regression approach. Furthermore, consistency in the three types of selections and oracle property in estimation are established as well. Simulation studies also confirm our method.
( Xing Hu ),( Linhua Ma ),( Shaocheng Huang ),( Jinke Huang ),( Kangning Sun ),( Tianyu Huang ) 한국인터넷정보학회 2017 KSII Transactions on Internet and Information Syst Vol.11 No.8
In high diversity node situation, single-channel MAC protocols suffer from many collisions. To solve this problem, the research of multichannel MAC protocol has become a hotspot. And the cyclic quorum-based multichannel (CQM) MAC protocol outperformed others owing to its high frequency utilization. In addition, it can avoid the bottleneck that others suffered from and can be easily realized with only one transceiver. To obtain the accurate performance of CQM MAC protocol, a Markov chain model, which combines the channel hopping strategy of CQM protocol and IEEE 802.11 distributed coordination function (DCF), is proposed. The metrics (throughput and average packet transmission delay) are calculated in performance analysis, with respect to node number, packet rate, channel slot length and channel number. The results of numerical analysis show that the optimal performance of CQM protocol can be obtained in saturation bound situation. And then we obtain the saturation bound of CQM system by bird swarm algorithm (BSA). Finally, the Markov chain model and saturation bound are verified by Qualnet platform. And the simulation results show that the analytic and simulation results match very well.