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On detecting primary user emulation attack using channel impulse response in the cognitive radio network

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Frontiers of information Technology & Electronic Engineering 2017年第10期18卷 1665-1676页

作者： Qiao-mu JIANG Hui-fang CHEN Lei XIE Kuang WANG College of information Science and Electronic Engineering Zhejiang University Hangzhou 310027 China zhejiang provincial key laboratory of information processing Communication and Networking Hangzhou 310027 China

Cognitive radio is an effective technology to alleviate the spectrum resource scarcity problem by opportunistically allocating the spare spectrum to unauthorized users. However, a serious denial-of-service(DoS) attack,named the ‘primary user emulation attack(PUEA)', exists in the network to deteriorate the system performance. In this paper, we propose a PUEA detection method that exploits the radio channel information to detect the PUEA in the cognitive radio network. In the proposed method, the uniqueness of the channel impulse response(CIR) between the secondary user(SU) and the signal source is used to determine whether the received signal is transmitted by the primary user(PU) or the primary user emulator(PUE). The closed-form expressions for the false-alarm probability and the detection probability of the proposed PUEA detection method are derived. In addition, a modified subspace-based blind channel estimation method is presented to estimate the CIR, in order for the proposed PUEA detection method to work in the scenario where the SU has no prior knowledge about the structure and content of the PU signal. Numerical results show that the proposed PUEA detection method performs well although the difference in channel characteristics between the PU and PUE is small.

关键词： Cognitive radio network Primary user emulation attack Subspace-based blind channel estimation Channel impulse response

M-ary information processing via an optimal nonlinear detector

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Chinese Physics B 2009年第12期18卷 5196-5202页

作者：李建龙 Department of information Science & Electronic Engineering Zhejiang University zhejiang provincial key laboratory of information Network Technology

This paper presents a novel approach of M-ary baseband pulse amplitude modulated signal processing via a parameter-optimized nonlinear dynamic system. This nonlinear system usually shows the phenomenon of stochastic resonance by adding noise. To thoroughly discuss the signal processing performance of the nonlinear system, we tune the system parameters to obtain a nonlinear detector with optimal performance. For characterizing the output of the nonlinear system, the derivation of the probability of detection error is given by the system response speed and the probability density function of the nonlinear system output. By varying the noise intensity with fixed system parameters, the phenomenon of stochastic resonance is shown and by tuning the system parameters with fixed noise, the probability of detection error is minimized and the nonlinear system is optimized. The detection performance of the two cases is compared with the theoretical probability of detection error, which is validated by numerical simulation.

关键词： nonlinear detector stochastic resonance tuning parameters probability of detection error

Parameters Optimization of a Novel 5-DOF Gasbag Polishing Machine Tool

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Chinese Journal of Mechanical Engineering 2013年第4期26卷 680-688页

作者： LI Yanbiao TAN Dapeng WEN Donghui JI Shiming CAI Donghai key laboratory of Special Purpose Equipment and Advanced processing Technology of Ministry of Education Zhejiang University of Technology zhejiang provincial key laboratory of Special Purpose Equipment and Advanced processing Technology Zhejiang University of Technology

The research on the parameters optimization for gasbag polishing machine tools, mainly aims at a better kinematics performance and a design scheme. Serial structural arm is mostly employed in gasbag polishing machine tools at present, but it is disadvantaged by its complexity, big inertia, and so on. In the multi-objective parameters optimization, it is very difficult to select good parameters to achieve excellent performance of the mechanism. In this paper, a statistics parameters optimization method based on index atlases is presented for a novel 5-DOF gasbag polishing machine tool. In the position analyses, the structure and workspace for a novel 5-DOF gasbag polishing machine tool is developed, where the gasbag polishing machine tool is advantaged by its simple structure, lower inertia and bigger workspace. In the kinematics analyses, several kinematics performance evaluation indices of the machine tool are proposed and discussed, and the global kinematics performance evaluation atlases are given. In the parameters optimization process, considering the assembly technique, a design scheme of the 5-DOF gasbag polishing machine tool is given to own better kinematics performance based on the proposed statistics parameters optimization method, and the global linear isotropic performance index is 0.5, the global rotational isotropic performance index is 0.5, the global linear velocity transmission performance index is 1.012 3 m/s in the case of unit input matrix, the global rotational velocity transmission performance index is 0.102 7 rad/s in the case of unit input matrix, and the workspace volume is 1. The proposed research provides the basis for applications of the novel 5-DOF gasbag polishing machine tool, which can be applied to the modern industrial fields requiring machines with lower inertia, better kinematics transmission performance and better technological efficiency.

关键词： 5-DOF gasbag polishing machine tool evaluation index kinematics analyses parameter optimization

Effects of error feedback on a nonlinear bistable system with stochastic resonance

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Chinese Physics B 2012年第11期21卷 108-113页

作者：李建龙周辉 Department of information Science&Electronic Engineering Zhejiang University zhejiang provincial key laboratory of information Network Technology

In this paper, we discuss the effects of error feedback on the output of a nonlinear bistable system with stochastic resonance. The bit error rate is employed to quantify the performance of the system. The theoretical analysis and the numerical simulation are presented. By investigating the performances of the nonlinear systems with different strengths of error feedback, we argue that the presented system may provide guidance for practical nonlinear signal processing.

关键词： stochastic resonance nonlinear bistable system error feedback bit error rate

Delay-Optimal Random Access in Large-Scale Energy Harvesting IoT Networks Based on Mean Field Game

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China Communications 2022年第4期19卷 121-136页

作者： Dezhi Wang Wei Wang Zhaoyang Zhang Aiping Huang College of information Science and Electronic Engineering Zhejiang UniversityHangzhou 310027China zhejiang provincial key laboratory of information processing Communication and Networking Zhejiang UniversityHangzhou 310027China

With energy harvesting capability, the Internet of things(IoT) devices transmit data depending on their available energy, which leads to a more complicated coupling and brings new technical challenges to delay optimization. In this paper,we study the delay-optimal random access(RA) in large-scale energy harvesting IoT networks. We model a two-dimensional Markov decision process(MDP)to address the coupling between the data and energy queues, and adopt the mean field game(MFG) theory to reveal the coupling among the devices by utilizing the large-scale property. Specifically, to obtain the optimal access strategy for each device, we derive the Hamilton-Jacobi-Bellman(HJB) equation which requires the statistical information of other ***, to model the evolution of the states distribution in the system, we derive the Fokker-PlanckKolmogorov(FPK) equation based on the access strategy of devices. By solving the two coupled equations,we obtain the delay-optimal random access solution in an iterative manner with Lax-Friedrichs method. Finally, the simulation results show that the proposed scheme achieves significant performance gain compared with the conventional schemes.

关键词： wireless communications energy harvesting random access mean field game

K-nearest neighborhood based integration of time-of-flight cameras and passive stereo for high-accuracy depth maps?

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Journal of zhejiang University-Science C(Computers and Electronics) 2014年第3期15卷 174-186页

作者： Li-wei LIU Yang LI Ming ZHANG Liang-hao WANG Dong-xiao LI Institute of information and Communication Engineering Zhejiang University zhejiang provincial key laboratory of information Network Technology

Both time-of-flight(ToF) cameras and passive stereo can provide the depth information for their corresponding captured real scenes, but they have innate limitations. ToF cameras and passive stereo are intrinsically complementary for certain tasks. It is desirable to appropriately leverage all the available information by ToF cameras and passive stereo. Although some fusion methods have been presented recently, they fail to consider ToF reliability detection and ToF based improvement of passive stereo. As a result, this study proposes an approach to integrating ToF cameras and passive stereo to obtain high-accuracy depth maps. The main contributions are:(1) An energy cost function is devised to use data from ToF cameras to boost the stereo matching of passive stereo;(2) A fusion method is used to combine the depth information from both ToF cameras and passive stereo to obtain high-accuracy depth maps. Experiments show that the proposed approach achieves improved results with high accuracy and robustness.

关键词： Depth map Passive stereo Time-of-flight camera Fusion

Deep Learning Aided SCL Decoding of Polar Codes with Shifted-Pruning

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China Communications 2023年第1期20卷 153-170页

作者： Yang Lu Mingmin Zhao Ming Lei Chan Wang Minjian Zhao College of information Science and Electronic Engineering Zhejiang UniversityHangzhou 310027China zhejiang provincial key laboratory of information processing Communication and Networking(IPCAN)Hangzhou 310027China

Recently,a generalized successive cancellation list(SCL)decoder implemented with shiftedpruning(SP)scheme,namely the SCL-SP-ωdecoder,is presented for polar codes,which is able to shift the pruning window at mostωtimes during each SCL re-decoding attempt to prevent the correct path from being *** candidate positions for applying the SP scheme are selected by a shifting metric based on the probability that the elimination ***,the number of exponential/logarithm operations involved in the SCL-SP-ωdecoder grows linearly with the number of information bits and list size,which leads to high computational *** this paper,we present a detailed analysis of the SCL-SP-ωdecoder in terms of the decoding performance and complexity,which unveils that the choice of the shifting metric is essential for improving the decoding performance and reducing the re-decoding attempts ***,we introduce a simplified metric derived from the path metric(PM)domain,and a custom-tailored deep learning(DL)network is further designed to enhance the efficiency of the proposed simplified *** proposed metrics are both free of transcendental functions and hence,are more hardware-friendly than the existing *** results show that the proposed DL-aided metric provides the best error correction performance as comparison with the state of the art.

关键词： polar codes successive cancellation list decoding deep learning shifted-pruning path metric

An Unprecedented Efficiency with Approaching 21%Enabled by Additive‑Assisted Layer‑by‑Layer processing in Organic Solar Cells

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Nano-Micro Letters 2025年第2期17卷 372-375页

作者： Shuai Xu Youdi Zhang Yanna Sun Pei Cheng Zhaoyang Yao Ning Li Long Ye Lijian Zuo Ke Gao key laboratory of Advanced Green Functional Materials College of ChemistryChangchun Normal UniversityChangchun 130032People’s Republic of China Shandong provincial key laboratory for Science of Material Creation and Energy Conversion School of Chemistry and Chemical EngineeringShandong UniversityQingdao 266237People’s Republic of China College of Polymer Science and Engineering Sichuan UniversityChengdu 610065People’s Republic of China State key laboratory and Institute of Elemento‑Organic Chemistry Centre of Nanoscale Science and Technology and Key Laboratory of Functional Polymer MaterialsRenewable Energy Conversion and Storage Center(RECAST)College of ChemistryNankai UniversityTianjin 300071People’s Republic of China Institute of Polymer Optoelectronic Materials and Devices State key laboratory of Luminescent Materials and Devices South China University of TechnologyGuangzhou 510640People’s Republic of China Tianjin key laboratory of Molecular Optoelectronic Sciences School of Materials Science and EngineeringTianjin UniversityTianjin 300350People’s Republic of China State key laboratory of Silicon Materials MOE Key Laboratory of Macromolecular Synthesis and FunctionalizationDepartment of Polymer Science and EngineeringZhejiang UniversityHangzhou 310027People’s Republic of China

Recently published in Joule,Feng Liu and colleagues from Shanghai Jiaotong University reported a record-breaking 20.8%power conversion efficiency in organic solar cells(OSCs)with an interpenetrating fibril network active layer morphology,featuring a bulk p-in structure and proper vertical segregation achieved through additive-assisted layer-by-layer *** optimized hierarchical gradient fibrillar morphology and optical management synergistically facilitates exciton diffusion,reduces recombination losses,and enhances light capture *** approach not only offers a solution to achieving high-efficiency devices but also demonstrates the potential for commercial applications of OSCs.

关键词： Organic solar cells Additive-assisted layer-by-layer processing Three-dimensional fibril morphology Bulk p-i-n structure Optical management

LESO-based Position Synchronization Control for Networked Multi-Axis Servo Systems With Time-Varying Delay

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IEEE/CAA Journal of Automatica Sinica 2020年第4期7卷 1116-1123页

作者： Qi Wu Li Yu Yao-Wei Wang Wen-An Zhang the College of information Engineering Zhejiang University of TechnologyZhejiang Provincial United Key Laboratory of EmbeddedHangzhou 310023China

The position synchronization control(PSC) problem is studied for networked multi-axis servo systems(NMASSs) with time-varying delay that is smaller than one sampling period. To improve the control performance of the system, time-varying delays, modeling uncertainties, and external disturbances are first modeled as a lumped disturbance. Then, a linear extended state observer(LESO) is devised to estimate the system state and the lumped disturbance, and a linear feedback controller with disturbance compensation is designed to perform individual-axis tracking control. After that, a cross-coupled control approach is used to further improve synchronization performance. The bounded-input-bounded-output(BIBO) stability of the closedloop control system is analyzed. Finally, both simulation and experiment are carried out to demonstrate the effectiveness of the proposed method.

关键词： Active-disturbance rejection controller extended state observer networked motion control system(NMCS) timevarying delays