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关于拓跋氏继统制的几个问题
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作者 王滨生 《晋阳学刊》 CSSCI 北大核心 1991年第3期49-51,共3页
一、兄终弟及史学界通常认为,北魏之前的拓跋鲜卑王位继承实行兄终弟及制。如王仲犖先生说:“在拓跋氏自拓跋诘訜以下酋长的氏族传统中,例如兄弟轮替继承王位的兄终弟及方面,到了道武帝之后,兄终弟及制才为严格的嫡长子继承制所代替。... 一、兄终弟及史学界通常认为,北魏之前的拓跋鲜卑王位继承实行兄终弟及制。如王仲犖先生说:“在拓跋氏自拓跋诘訜以下酋长的氏族传统中,例如兄弟轮替继承王位的兄终弟及方面,到了道武帝之后,兄终弟及制才为严格的嫡长子继承制所代替。”①这种看法多少有些不确。拓跋鲜卑建立长子继统制始自圣武帝诘訜。《魏书·序纪》:“初。 展开更多
关键词 北魏 拓跋氏 继统制 兄终弟及 嫡庶制 太子建制
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Quantum Key Distribution Network: Optimal Secret- Key- Aware Routing Method for Trust Relaying 被引量:2
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作者 Chao Yang Hongqi Zhang Jinhai Su 《China Communications》 SCIE CSCD 2018年第2期33-45,共13页
Since the QKD network can overcome the distance limitation and expand the point-to-point QKD system to a multi-user key distribution system, some testing QKD networks have been built. However, all of this previous res... Since the QKD network can overcome the distance limitation and expand the point-to-point QKD system to a multi-user key distribution system, some testing QKD networks have been built. However, all of this previous research seldom focused on the routing mechanism of QKD network in detail. Therefore, this paper focuses on the routing issue in trust relaying QKD network, builds a model of the trust relaying QKD network and proposes a secret-key-aware routing method. In our method, a dynamic model for the residual local key is proposed to forecast the residual local key quantity of each QKD link more accurately, and the cost of QKD link and relaying path are defined by multiple affecting factors, e.g. the generation, consumption rate and the local key depletion index. The proposed method is implemented and evaluated in a simulation environment. The simulation results show that our routing method can increase the success rate of key exchange, make all the QKD links participate key exchange with almost equal opportunity to achieve load balance, and trade off the local key generation and consumption of each QKD link. Therefore, our proposed method can contribute to effectively improve the holistic performance of the trust relaying QKD network. 展开更多
关键词 quantum key distribution QKDnetwork routing algorithm
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Iterative Noncoherent Block Detection of Coded MPSK for Cooperative Relay Systems
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作者 Yucheng He Jingjing Zhang +1 位作者 Rui Zhao Lin Zhou 《China Communications》 SCIE CSCD 2016年第7期1-6,共6页
Maximum likelihood(ML) noncoherent block detection techniques are investigated for block-coded MPSK modulation in cooperative decode-and-forward relay systems over slow fading channels.A decision-directed iterative Vi... Maximum likelihood(ML) noncoherent block detection techniques are investigated for block-coded MPSK modulation in cooperative decode-and-forward relay systems over slow fading channels.A decision-directed iterative Viterbi algorithm(IVA) is derived for a suboptimal ML noncoherent detection.Simulation results show that the IVA can approach the error performances of the exhaustive detection method but at a lower complexity. 展开更多
关键词 Coded modulation cooperative communication M-ray phase shift keying noncoherent detection
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Impact of Maximum Transmit Power Limit on the First-Order and Second-Order Performance of Cognitive Opportunistic Relaying
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作者 JIA Xiangdong DENG Pengfei +2 位作者 ZHOU Ming YANG Longxiang ZHU Hongbo 《China Communications》 SCIE CSCD 2015年第5期75-85,共11页
Abstract: This paper focuses on the first-or- der and second-order performance of dual-hop underlay cognitive radio systems with oppor- tunistic relaying (UCR-OR) over indepen- dent and non-identically distributed ... Abstract: This paper focuses on the first-or- der and second-order performance of dual-hop underlay cognitive radio systems with oppor- tunistic relaying (UCR-OR) over indepen- dent and non-identically distributed (i.ni.d) Rayleigh fading channels. For the UCR-OR systems, the tolerable maximum interference power (TMIP) Q at primary users (PUs) and the allowable maximum transmission power limit (AMTP) P at secondary users (SUs) are considered, simultaneously. We first obtain the closed-form solutions to the first-order performance such as outage probability, ave- rage symbol error ratio (SER), and ergodic capacity (EC). Secondly, we investigate the second-order statistical performance, i.e., ave- rage outage rate (AOR) and average outage duration (AOD). With the consideration that in practice implementation the receiver perfor- mance is primarily influenced by the signal- to-noise ratio (SNR) (not the signal envelope), the second-order statistical performance is investigated based on the equivalent instan- taneous end-to-end SNR. Finally, we present the detailed performance comparison analysis of UCR-OR systems by defining a random variable ,μ=Pmax/Q. The results show that the effect of μ on the first-order and second-or- der performances is different greatly. For the first-order performance, the perlbrmance gap is negligible when the value of// is relatively large. However, for the second-order one, the gap is distinct. 展开更多
关键词 cognitive radio opportunistic relaying outage probability average outage rate average outage duration
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