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Joint Resource Allocation for Cellular and D2D Multicast Based on Cognitive Radio
( Xiaolu Wu ),( Yueyun Chen ) 한국인터넷정보학회 2014 KSII Transactions on Internet and Information Syst Vol.8 No.1
Device-to-device (D2D) communication is an excellent technology to improve the system capacity by sharing the spectrum resources of cellular networks. Multicast service is considered as an effective transmission mode for the future mobile social contact services. Therefore, multicast based on D2D technology can exactly improve the spectrum resource efficiency. How to apply D2D technology to support multicast service is a new issue. In this paper, a resource allocation scheme based on cognitive radio (CR) for D2D underlay multicast communication (CR-DUM) is proposed to improve system performance. In the cognitive cellular system, the D2D users as secondary users employing multicast service form a group and reuse the cellular resources to accomplish a multicast transmission. The proposed scheme includes two steps. First, a channel allocation rule aiming to reduce the interference from cellular networks to receivers in D2D multicast group is proposed. Next, to maximize the total system throughput under the condition of interference and noise impairment, we formulate an optimal transmission power allocation jointly for the cellular and D2D multicast communications. Based on the channel allocation, optimal power solution is in a closed form and achieved by searching from a finite set and the interference between cellular and D2D multicast communication is coordinated. The simulation results show that the proposed method can not only ensure the quality of services (QoS), but also improve the system throughput.
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Risk Assessment of Power System Security based on a Hybrid Optimization GP Method
Xiaobin Wu,Hui Li,Xiaolu Chen 보안공학연구지원센터 2015 International Journal of Security and Its Applicat Vol.9 No.12
In this paper, we propose a hybrid optimization algorithm based on Improved Differential Evolution (IDE) algorithm and Gaussian Process (GP). Firstly, the paper constructs the assessment index system using Fault Tree Analysis (FTA) based on the summary and classification of the factors that could affect the power system security. Secondly, establish the risk assessment model of power system security based on the hybrid optimization GP algorithm. Hyper-parameter of GP has a great influence on construction of evaluation model, while conjugate gradient method which is usually used has strong dependence on initial values and is easy to fall into local optimal solution. So the paper uses the IDE algorithm for the traditional Hyper-parameter optimization, then the optimal Hyper-parameter is used to construct evaluation model for power grid security risk assessment. In the process of improvement, this paper adds the local search (Bees accelerated evolution operation) and global search (Bees scout operation) thought of ABC algorithm into the DE algorithm to reduce the population size required by the algorithm. After that, do the risk assessment of power system by using the established assessment model. Finally, do the simulation experiments using the standard data IEEE-39 and IEEE-118 bus example, and besides compare the IDE-GP with other optimization model like ABC-GP, DE-GP, MA-GP, GA-GP, and the experimental results show that hybrid optimization algorithm has better performance in accuracy while the time-consuming difference is minor. The validity of the proposed method is also demonstrated.
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Tian Ai,Chunmei Xu,Lei Zhang,Ke Chen,Yonggui Wu,Shujuan Dai,Xiaolu Xiong,Shixin Jie,Xiaoni Jin,Zhongxu Yu 한국화학공학회 2022 Korean Journal of Chemical Engineering Vol.39 No.9
Novel efficient biochar of Goldenberry peels (GBPMW-H3PO4) was prepared through a microwave-assistedphosphoric acid activation method. It was characterized and used for removing two beta-lactamase inhibitors, sulbactam(SAM, first listed in Japan in 1986) and avibactam (AVI, first listed in the U.S. in 2015), from aqueous solution. Characterization confirmed that GBPMW-H3PO4 displayed a high surface area (720.046m2 g1), more abundant porestructure, smaller particle size, and higher thermal stability. The experimental results showed that the adsorption of thetwo antibiotics was a spontaneous, favorable, and endothermic process, highly dependent on solution pH. A contacttime of 60 min assured equilibrium, and GBPMW-H3PO4 followed pseudo-first-order kinetics (R2=0.9950-0.9977). Furthermore,the adsorption capacities of GBPMW-H3PO4 for SAM and AVI were 211.86 and 198.81mg g1, respectively,and the performance was better than that of unmodified biochar. Microscopically, the main mechanism could beexplained by - electron donor-acceptor interaction, hydrogen bonding interaction, -hydrogen bonding, hydrophobicinteraction, and electrostatic interaction. The study demonstrates that the microwave-assisted H3PO4 activationmethod could produce biochar, and GBPMW-H3PO4 was confirmed to be a low-cost and high-efficiency adsorbent forremoving beta-lactamase inhibitors from medical wastewater.
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