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Applied Mathematics and Mechanics(English Edition) 2023年第1期44卷 1-20页

作者： Jianlin YI zheng WU Rongyu XIA zheng LI State Key Laboratory for Turbulence and Complex Systems College of EngineeringPeking UniversityBeijing 100871China

Elastic wave absorption at subwavelength scale is of significance in many engineering applications.Non-Hermitian metamaterials show the ability in high-efficiency wave absorption.However,the single functionality of metamaterials is an important limitation on their practical applications for lack of tunability and reconfigurability.Here,we propose a tunable and reconfigurable non-Hermitian piezoelectric metamaterial bar,in which piezoelectric bars connect with resonant circuits,to achieve asymmetric unidirectional perfect absorption(UPA)and symmetric bidirectional perfect absorption(PA)at low frequencies.The two functions can be arbitrarily switched by rearranging shunted circuits.Based on the reverberation-ray matrix(RRM)method,an approach is provided to achieve UPA by setting an exceptional point(EP)in the coupled resonant bandgap.By using the transfer matrix method(TMM)and the finite element method(FEM),it is observed that a non-Hermitian pseudo-band forms between two resonant bandgaps,and the EP appears at the bottom of the pseudo-band.In addition,the genetic algorithm is used to accurately and efficiently design the shunted circuits for desired low-frequency UPA and PA.The present work may provide new strategies for vibration suppression and guided waves manipulation in wide potential applications.

关键词： non-Hermitian metamaterial exceptional point(EP) unidirectional perfect absorption(UPA) piezoelectric metamaterial reverberation-ray matrix(RRM)method genetic algorithm

Asynchronous Output Regulation Control for Continuous-Time Markovian Jump Systems with Colored-Noise

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系统科学与复杂性学报:英文版 2023年第4期36卷 1463-1479页

作者： WANG Shitong wu zheng-Guang wu Zhaojing The Institute of Cyber-Systems and Control Zhejiang UniversityHangzhou 310027China The Institute of Intelligence Science and Engineering Shenzhen PolytechnicShenzhen 518055China The School of Mathematics and Informational Science Yantai UniversityYantai 264005China

The output regulation control problem for the Markovian jump systems with colored-noise is proposed in this paper.Since the modes mismatch problem often exists in the Markovian switching system,the authors design a modes asynchronous controller with an internal model form,which can not only deal with external disturbance,but also reduce the influence of stochastic noise on the system,such that the mean square of the regulation error can be made arbitrarily small by turning the designed parameters.Meanwhile,a criterion of the m-th moment noise-to-state exponential stability is presented for continuous-time Markovian jump systems under the asynchronous control.

关键词： Asynchronous control colored-noise Markovian jump systems output regulation control

Disagreement and Antagonism in Signed Networks: A Survey

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IEEE/CAA Journal of Automatica Sinica 2022年第7期9卷 1166-1187页

作者： Yuxin wu Deyuan Meng zheng-Guang wu Seventh Research Division Beihang University(BUAA)and also with the School of Automation Science and Electrical EngineeringBeihang University(BUAA)Beijing 100191China National Laboratory of Industrial Control Techno-logy Institute of Cyber-Systems and ControlZhejiang UniversityHangzhou 310027China IEEE

Signed networks refer to a class of network systems including not only cooperative but also antagonistic interactions among nodes.Due to the existence of antagonistic interactions in signed networks,the agreement of nodes may not be established,instead of which disagreement behaviors generally emerge.This paper reviews several different disagreement behaviors in signed networks under the single-integrator linear dynamics,where two classes of topologies,namely,the static topology and the dynamic topology,are considered.For the static signed networks with the adjacency weights as(time-varying)scalars,we investigate the convergence behaviors and the fluctuation behaviors with respect to fixed topologies and switching topologies,respectively,and give some brief introductions on the disagreement behaviors of general time-varying signed networks.Correspondingly,several classes of behavior analysis approaches are also provided.For the dynamic signed networks with the adjacency weights as transfer functions or linear time-invariant systems,we show the specific descriptions and characteristics of them such that the disagreement behaviors can be obtained by resorting to the derived static signed graphs.Furthermore,we give their applications to the behavior analysis of static signed networks in the presence of high-order dynamics or communication delays.

关键词： Antagonistic interaction disagreement behavior dynamic topology signed network static topology

Ferroelectric BaTiO_(3) /Pr_(2)O_(3) heterojunction harvesting roomtemperature cold–hot alternation energy for efficiently pyrocatalytic dye decomposition

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Journal of Advanced Ceramics 2024年第1期13卷 44-52页

作者： zheng WU Taosheng Xu Luohong Zhang Tingting Liu Zhansheng wu Gangqiang Zhu Yanmin Jia School of Environmental and Chemical Engineering Xi’an Key Laboratory of Textile Chemical Engineering AuxiliariesXi’an Polytechnic UniversityXi’an 710048China School of Physics and Information Technology Shaanxi Normal UniversityXi’an 710062China

The strong pyrocatalytic dye decomposition of the BaTiO_(3)/Pr_(2)O_(3) heterojunction catalyst under cold–hot alternation conditions has been demonstrated in this work.For pure BaTiO_(3) nanofibers,~54%rhodamine B(RhB)dye is decomposed under the cold–hot alternation of 29–57℃.With the loading content of Pr_(2)O_(3) increases from 0 to 4 wt%,the pyrocatalytic decomposition ratio of RhB solution increases first and then decreases,eventually achieving a maximum of 91%at 3 wt%.The enhanced pyrocatalytic performance after loading Pr_(2)O_(3) can be attributed to an internal electric field of the heterojunction,which effectively separates positive and negative charges.The strongly pyrocatalytic performance of BaTiO_(3)/Pr_(2)O_(3) makes it hopeful for applications in the dye wastewater treatment through harvesting the environmental cold–hot temperature alternation thermal energy in future.

关键词： pyroelectric materials BaTiO_(3) pyrocatalysis BaTiO_(3)/Pr_(2)O_(3)heterojunction dye decomposition

Application of deep learning to estimate stratospheric gravity wave potential energy

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Earth and Planetary Physics 2022年第1期6卷 70-82页

作者： Yue wu zheng Sheng XinJie Zuo College of Meteorology and Oceanology National University of Defense TechnologyChangsha 410073China Northwest Institute of Nuclear Technology Xi’an 710024China High-tech Institute Fan Gong-ting South Street on the 12thQingzhou 262500China

One of the most important dynamic processes in the middle and upper atmosphere,gravity waves(GWs)play a key role in determining global atmospheric circulation.Gravity wave potential energy(GW Ep)is an important parameter that characterizes GW intensity,so it is critical to understand its global distribution.In this paper,a deep learning algorithm(DeepLab V3+)is used to estimate the stratospheric GW Ep.The deep learning model inputs are ERA5 reanalysis datasets and GMTED2010 terrain data.GW Ep averaged over 20−30 km from 60°S−60°N,calculated by COSMIC radio occultation(RO)data,is used as the measured value corresponding to the model output.The results show that(1)this method can effectively estimate the zonal trend of GW Ep.However,the errors between the estimated and measured value of Ep are larger in low-latitude regions than in mid-latitude regions,possibly due to the large number of convolution operations used in the deep learning model.Additionally,the measured Ep has errors associated with interpolation to the grid;this tends to be amplified in low-latitude regions because the GW Ep is larger and the RO data are relatively sparse,affecting the training accuracy.(2)The estimated Ep shows seasonal variations,which are stronger in the winter hemisphere and weaker in the summer hemisphere.(3)The effect of quasi-biennial oscillation(QBO)can be clearly observed in the monthly variation of estimated GW Ep,and its QBO amplitude may be less than that of the measured Ep.

关键词： deep learning stratospheric gravity wave potential energy

Resilient observer-based event-triggered control for cyber-physical systems under asynchronous denial-of-service attacks

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Science China(Information Sciences) 2022年第4期65卷 182-196页

作者： Yifang ZHANG zheng-Guang wu Zongze wu Deyuan MENG State Key Laboratory of Industrial Control Technology Institute of Cyber-Systems and ControlZhejiang University School of Automation Guangdong University of Technology Seventh Research Division Beihang University (BUAA) School of Automation Science and Electrical Engineering Beihang University (BUAA)

We develop the resilient observer-based event-triggered control update strategy in this paper.It is utilized to achieve the input-to-state stability(ISS) of cyber-physical systems(CPSs) when there is an asynchronous denial-of-service(DoS) attack, which is launched by malicious adversaries both on measurement channel and control channel in a random attack strategy. To estimate the unmeasurable states while saving the limited networked bandwidth, an H∞observer-based event-triggered control scheme is first designed to guarantee the ISS of CPSs with economic communication. Moreover, the occurrence of Zeno behavior can be eliminated by providing the existence of a lower positive bound of any two inter-event times. Then, a recursive model of asynchronous DoS attacks is introduced. A resilient control update strategy is proposed and further analyzed to derive the stability criterion of CPSs. At last, a numerical simulation example is given to demonstrate the effectiveness of the introduced control update policy.

关键词： cyber-physical systems input-to-state stability asynchronous DoS attacks $H_\infty~$ observer event-triggered control

A buffer overflow detection and defense method based on RiSC-V instruction set extension

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Cybersecurity 2024年第2期7卷 28-43页

作者： Chang Liu Yan-Jun wu Jing-zheng WU Chen Zhao Intelligent Software Research Center Institute of SoftwareChinese Academy of SciencesBejingChina University of Chinese Academy of Sciences BeijingChina State Key Laboratory of Computer Science Institute of SoftwareChinese Academy of SciencesBeijingChina

Buffer overflow poses a serious threat to the memory security of modern operating systems.It overwrites the con-tents of other memory areas by breaking through the buffer capacity limit,destroys the system execution environ-ment,and provides implementation space for various system attacks such as program control flow hijacking.That makes it a wide range of harms.A variety of security technologies have been proposed to deal with system security problems including buffer overflow.For example,No eXecute(NX for short)is a memory management technology commonly used in Harvard architecture.It can refuse the execution of code which residing in a specific memory,and can effectively suppress the abnormal impact of buffer overflow on control flow.Therefore,in recent years,it has also been used in the field of system security,deriving a series of solutions based on NX technology,such as ExecShield,DEP,StackGuard,etc.However,these security solutions often rely too much on the processor archi-tecture so that the protection coverage is insufficient and the accuracy is limited.Especially in the emerging system architecture field represented by RiSC-V,there is still a lack of effective solutions for buffer overflow vulnerabilities.With the continuous rapid development of the system architecture,it is urgent to develop defense methods that are applicable to different system application environments and oriented to all executable memory spaces to meet the needs of system security development.Therefore,we propose BOP,A new system memory security design method based on RISC-V extended instructions,to build a RISC-V buffer overflow detection and defense system and deal with the buffer overflow threat in RIsC-V.According to this method,NX technology can be combined with program control flow analysis,and Nx bit mechanism can be used to manage the executability of memory space,so as to achieve a more granular detection and defense of buffer overflow attacks that may occur in RISC-V system environment.In addition,The memory management an

关键词： RISc-V Operating system security Buffer overflow Control flow hijacking Nx bit Xibop

Asynchronous Learning-Based Output Feedback Sliding Mode Control for Semi-Markov Jump Systems: A Descriptor Approach

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IEEE/CAA Journal of Automatica Sinica 2024年第6期11卷 1358-1369页

作者： zheng WU Yiyun Zhao Fanbiao Li Tao Yang Yang Shi Weihua Gui School of Automation Central South UniversityChangsha 410083China Power Electronics Machines and Control GroupThe University of NottinghamNottingham NG72RDUK Department of Mechanical Engineering University of VictoriaVictoria BC V8W 3P6Canada IEEE

This paper presents an asynchronous output-feed-back control strategy of semi-Markovian systems via sliding mode-based learning technique.Compared with most literature results that require exact prior knowledge of system state and mode information,an asynchronous output-feedback sliding sur-face is adopted in the case of incompletely available state and non-synchronization phenomenon.The holonomic dynamics of the sliding mode are characterized by a descriptor system in which the switching surface is regarded as the fast subsystem and the system dynamics are viewed as the slow subsystem.Based upon the co-occurrence of two subsystems,the sufficient stochastic admissibility criterion of the holonomic dynamics is derived by utilizing the characteristics of cumulative distribution functions.Furthermore,a recursive learning controller is formulated to guarantee the reachability of the sliding manifold and realize the chattering reduction of the asynchronous switching and sliding motion.Finally,the proposed theoretical method is substantia-ted through two numerical simulations with the practical contin-uous stirred tank reactor and F-404 aircraft engine model,respectively.

关键词： Asynchronous switching learning-based control output feedback semi-Markovian jump systems sliding mode con-trol(SMC).

Simulation of RFI Cancellation Using Subspace Projection Algorithm for PAF Receiver

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Research in Astronomy and Astrophysics 2024年第1期24卷 237-244页

作者： Peng wu Jian Li Mao-zheng Chen Xinjiang Astronomical Observatory Chinese Academy of SciencesUrumqi 830011China University of Chinese Academy of Sciences Beijing 100049China Xinjiang Key Laboratory of Microwave Technology Urumqi 830011China

The simulation of radio frequency interference(RFI) cancellation by applying a spatial filtering technique for phased array feed(PAF) is presented. In order to better reflect the characteristics of PAF, a new signal model is to add the coupling coefficient among elements of PAF to the conventional array signal model. Then the subspace projection(SP) algorithm is used to cancel RFI from the correlation matrix of the signal, and finally, the 2D power image is drawn. The power variation of signal-of-interest direction and RFI direction before and after using the SP algorithm is analyzed. The new signal model and simulation strategy can be used to test and verify the beamformer.

关键词： methods:analytical techniques:radar astronomy telescopes

Study on risk assessment and factors ranking of the LTE-M communication system

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Transportation Safety and Environment 2023年第4期5卷 45-57页

作者： Xiaochun wu Yu Gao Weichao zheng School of Automation Electrical Engineering Lanzhou Jiaotong UniversityAnning West RoadLanzhou 730070GansuChina Communication Center Tianjin Rail Transit Operation Group Co.LtdNo.36Xuefu Industrial ParkTianjin 300000China

To assess the operational safety risk of long-term evolution for the metro(LTE-M)communication system more accurately,the guide maintenance strategy,the improved evidence theory and the multi-attribute ideal reality comparative analysis(MAIRCA)approaches are proposed.According to the features of LTE-M system,the risk evaluation system is established.The enhanced structural entropy weight method is used to obtain the weight.Furthermore,it is combined with nine-element fuzzy mathematics to transform the degree of membership,modifying the conflict and fusion rules to solve the confidence degree clashed problem of evidence theory.Then,the system risk grade assessment result is obtained.For the purpose of forming the ranking of indicator importance,the MAIRCA is introduced and the ranking is three-dimensional.The operational state of the metro line is used as the data source in various ways the obtained risk grade increased by 7.12%.It is verified that MAIRCA can be applied to the field of urban rail transit because it has based on the test and calculation.The results show that the method is effective;compared with others,the confidence degree of excellent stability and the ranking result of risk factors is reasonable.The influencing indicator with the highest importance is the'equipment failure rate".

关键词： long-term evolution for the metro(LTE-M)system operational safety risk assessment improved evidence theory multi-attribute ideal reality comparative analysis(MAIRCA)method