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Investigation of Atmospheric Pressure Dielectric Barrier Glow Discharge in Argon/Ammonia Mixture
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作者 ZHANG Zenghui ZHANG Guanjun +2 位作者 SHAO Xianjun CHANG Zhengshi GU Chtmhui 《高电压技术》 EI CAS CSCD 北大核心 2013年第9期2254-2259,共6页
In this paper,the influence of ammonia admixture on argon discharge properties is investigated.Electrical measurements,as well as ten-nanoseconds-exposure photographs taken by an intensified charge-coupled device(ICCD... In this paper,the influence of ammonia admixture on argon discharge properties is investigated.Electrical measurements,as well as ten-nanoseconds-exposure photographs taken by an intensified charge-coupled device(ICCD)camera,are employed to confirm the existence of atmospheric pressure glow discharge(APGD)in Ar/NH3mixture.The breakdown voltage and transition voltage between APGD and filamentary discharge are studied at various ammonia concentrations.The results show that a small amount of NH3can lead to APGD due to the Penning ionization of NH3molecules by metastable argon,and the breakdown voltage increases with the growth in NH3concentrations owing to the electronegative feature of NH3.The optical emission spectrum of Ar/NH3APGD is analyzed.Besides,gas temperature is estimated at 327 K by the diagnoses of the OH(A-X)(0,0)band of the spectrum. 展开更多
关键词 大气压辉光放电 混合物 氩气 介质阻挡 APGD 常压 电荷耦合器件
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Adaptive resource allocation for multi-user multi-server power-line communication OFDM systems
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作者 徐志强 翟明岳 +1 位作者 崔翔 赵宇明 《Journal of Central South University》 SCIE EI CAS 2011年第2期479-489,共11页
The bits and power allocation model of adaptive power-rate mixture for multi-user multi-server power-line communication systems was analyzed with the restrictions of maximal total power,fixed rate for each real time (... The bits and power allocation model of adaptive power-rate mixture for multi-user multi-server power-line communication systems was analyzed with the restrictions of maximal total power,fixed rate for each real time (RT) user,minimal rate for each non-real time (NRT) user,maximal bits and power for each subcarrier in each orthogonal frequency division multiplexing (OFDM) symbol. An algorithm of resource dynamic allocation in the first OFDM symbol of each frame and resource optimal adjustment in the latter OFDM symbol of each frame was proposed. In the first OFDM symbol of every frame,resource is firstly assigned for RT users so as to minimize their total used power until satisfying their fixed rates; secondly the remainder resource of power and subcarriers are assigned for NRT users so as to minimize their total used power until satisfying their minimal rates also; lastly the remainder resource is again assigned for NRT users according to the proportional fairness strategy so as to maximize their total assigning rate. In the latter OFDM symbol of each frame,bits are swapped and power is adjusted for every user based on the resource allocation results of anterior OFDM symbol. The algorithm is tested in the typical power-line channel scenarios and the simulation results indicate that the proposed algorithm has better performances than the classical multi-user resource allocation algorithms and it realizes the multiple aims of multi-user multi-server resource allocation for power-line communication systems. 展开更多
关键词 power-line communications adaptive orthogonal frequency division multiplexing resource allocation user priority swapadjustment
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Fatigue properties analysis of cracked rock based on fracture evolution process 被引量:7
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作者 张平 徐建光 李宁 《Journal of Central South University of Technology》 EI 2008年第1期95-99,共5页
Fracture evolution process (initiation, propagation and coalescence) of cracked rock was observed and the force- displacement curves of cracked rock were measured under uniaxial cyclic loading. The tested specimens ma... Fracture evolution process (initiation, propagation and coalescence) of cracked rock was observed and the force- displacement curves of cracked rock were measured under uniaxial cyclic loading. The tested specimens made of sandstone-like modeling material contained three pre-existing intermittent cracks with different geometrical distributions. The experimental results indicate that the fatigue deformation limit corresponding to the maximal cyclic load is equal to that of post-peak locus of static complete force?displacement curve; the fatigue deformation process can be divided into three stages: initial deformation, constant deformation rate and accelerative deformation; the time of fracture initiation, propagation and coalescence corresponds to the change of irreversible deformation. 展开更多
关键词 rock mechanics fatigue properties cyclic loading fracture evolution fatigue damage
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