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Dynamic defenses in cyber security:Techniques,methods and challenges Author links open overlay panel

Digital Communications and Networks 2022年第4期8卷 422-435页

作者： Yu zheng zheng Li Xiaolong Xu Qingzhan Zhao School of Computer and Software Nanjing University of Information Science and TechnologyNanjing210044JiangsuChina Key Laboratory for Novel Software Technology Nanjing UniversityNanjing210023JiangsuChina College of Information Science and Technology Shihezi University Geospatial Information Engineering Research CenterChina

Driven by the rapid development of the Internet of Things,cloud computing and other emerging technologies,the connotation of cyberspace is constantly expanding and becoming the fifth dimension of human activities.However,security problems in cyberspace are becoming serious,and traditional defense measures(e.g.,firewall,intrusion detection systems,and security audits)often fall into a passive situation of being prone to attacks and difficult to take effect when responding to new types of network attacks with a higher and higher degree of coordination and intelligence.By constructing and implementing the diverse strategy of dynamic transformation,the configuration characteristics of systems are constantly changing,and the probability of vulnerability exposure is increasing.Therefore,the difficulty and cost of attack are increasing,which provides new ideas for reversing the asymmetric situation of defense and attack in cyberspace.Nonetheless,few related works systematically introduce dynamic defense mechanisms for cyber security.The related concepts and development strategies of dynamic defense are rarely analyzed and summarized.To bridge this gap,we conduct a comprehensive and concrete survey of recent research efforts on dynamic defense in cyber security.Specifically,we firstly introduce basic concepts and define dynamic defense in cyber security.Next,we review the architectures,enabling techniques and methods for moving target defense and mimic defense.This is followed by taxonomically summarizing the implementation and evaluation of dynamic defense.Finally,we discuss some open challenges and opportunities for dynamic defense in cyber security.

关键词： Cyber security Dynamic defense Moving target defense Mimic defense

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Urban computing： enabling urban intelligence with big data

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Frontiers of Computer Science 2017年第1期11卷 1-3页

作者： Yu zheng Microsoft Research Beijing 100080 China School of Computer Science and Technology Xidian University Xi'an 710071 China Shenzhen Institutes of Adv.anced Technology Chinese Academy of Sciences Shenzhen 518055 China

Urban computing is a process of acquisition, integration and analysis of big and heterogeneous data generated by a diver- sity of sources in urban spaces, such as sensors, devices, ve- hicles, buildings and humans, to tackle the major issues that cities face, e.g., air pollution, energy consumption and traffic congestion. Urban computing connects unobtrusive and ubiq- uitous sensing technologies, advanced data management and analytics models, and novel visualization methods.

关键词： analysis big heterogeneous

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Analysis of genetic diversity and prediction of Larix species distribution in the Qinghai–Tibet Plateau,China

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Journal of Forestry Research 2023年第3期34卷 705-715页

作者： Qiqiang Guo Huie Li Weilie zheng Jinwen Pan Jie Lu Jiangrong Li Yu zheng Institute for Forest Resources&Environment of Guizhou Key Laboratory of Forest Cultivation in Plateau Mountain of Guizhou ProvinceGuizhou UniversityGuiyang 550025People’s Republic of China College of Forestry Guizhou UniversityGuiyang 550025People’s Republic of China College of Agriculture Guizhou UniversityGuiyang 550025People’s Republic of China Institute of Tibet Plateau Ecology Tibet Agriculture and Animal Husbandry UniversityNyingchi Tibet 860000People’s Republic of China Key Laboratory of Forest Ecology in Tibet Plateau(Tibet Agriculture and Animal Husbandry University) Ministry of EducationNyingchi Tibet 860000People’s Republic of China Plant Research Center Chengdu Botanical GardenChengdu 610083People’s Republic of China

Larix resources in the Qinghai-Tibet Plateau have important ecological and economic values.However,the lack of genetic diversity background and related research hinders the development of conservation strategies.In this study,genetic diversity and distribution of fi ve Larix species were investigated.Using 19 polymorphic microsatellite markers to study 272 representative individuals from 13 populations,the results show low genetic diversity at the population level,with variation explained mainly by diff erentiation among populations.The Larix populations were classifi ed into two clades,one formed by eight populations,including three of the species in this study,L.kongboensis,L.speciosa,and L.potaninii var.australis.The other clade consists of fi ve populations,including the other two species in this study,L.griffi thii and L.himalaica.Genetic distance of the species was aff ected by geographical isolation and genetic diversity was mainly aff ected by altitude.The area suitable for Larix spp.decreased during the Last Glacial Maximum compared to the current distribution according to the niche model,but should increase in future climate scenarios(2050s),expanding westward along the Himalayas.These results provide an important scientifi c basis for the development of conservation strategies and further the sustainable utilization of Larix resources in the Qinghai-Tibet Plateau.

关键词： Larix spp. Genetic diversity Phylogenetic relationship Genetic structure Ecological niche modeling Qinghai-Tibet Plateau

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Review on modification routes for SnO_(x)-based anodes for Li storage:morphological structure tuning and phase structure design

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Rare Metals 2023年第9期42卷 2840-2867页

作者： Yu zheng Xue-Xia Lan Xing-yu Xiong Bin yuan Ren-Zong Hu School of Materials Science and Engineering Guangdong Provincial Key Laboratory of Advanced Energy Storage MaterialsSouth China University of TechnologyGuangzhou510640China

Fascinating with high specific capacity and moderate lithiation potential,SnO_(x)-based materials have been intensively investigated as one of the most promising anodes for lithium-ion batteries.However,due to poor cycling stability,sluggish reaction kinetics,and limited electrochemical reaction reversibility,the development of SnO_(x)-based anodes has been hindered.And the current preparation and modification routes for SnO_(x)-based anodes lack direct and specific illustration.Herein,modification routes for SnO_(x)-based anodes have been emphasized.Firstly,to provide more direct instructions,the tuning routes of morphological structure for SnO_(x)-based electrodes(including slurry-based and self-supported)have been thoroughly discussed from the preparation perspective.Secondly,according to the properties of SnO_(x)-based anodes,the phase structure design ideas have also been properly classified and organized for addressing chemical reaction kinetics or thermodynamic issues.Finally,for future-oriented studies,new insights into the development and commercialization prospects of SnO_(x)-based anodes are also provided.This review,with comprehensive information on SnO_(x)-based anodes,aims to bring more specific guidance and valuable inspiration for peer researchers who are promoting the application of SnO_(x)-based materials for energy conversion and storage devices.

关键词： Lithium-ion battery(LIB) SnO_(x)-based anodes Reaction kinetics Morphological structure tuning Phase structure design

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Effect of SiO_(2) nano film deposited on copper and aluminium electrodes on the power frequency breakdown voltage of SF_(6) gas

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High Voltage 2023年第4期8卷 791-798页

作者： Yu zheng Shengle Gong Lei Liu Zhihui Xiang Yichen Lv Jianhui yu Wenjun Zhou School of Electrical Engineering and Automation Wuhan UniversityWuhanChina State Key Laboratory of HVDC Transmissions Technology China Southern Power GridGuangzhouChina

In order to reveal the effect of insulating nano film on the insulation strength of SF_(6) gas gap,SiO_(2) nano film was deposited on the electrode surface by the plasma-enhanced chemical vapour deposition technique.The power frequency breakdown characteristics of SF_(6) gas under Cu and Al electrodes were obtained before and after coating.The results showed that when the Cu electrode was coated,the breakdown voltage was up to at most 11.5% higher than that of an uncoated Cu electrode in the pressure range of 0.2-0.5 MPa.When the Al electrode was coated,the breakdown voltage of SF_(6) gas was lower than that of an uncoated one in the pressure range of 0.2-0.5 MPa.The breakdown voltage of SF_(6) gas under the Cu electrode was slightly lower than that under the Al electrode,but the breakdown voltages under the coated Cu electrode were significantly higher than that under the coated Al electrode.Through SEM tests,it was found that the surface roughness of the electrode decreases after coating,but particles were formed on the surface of the Al electrode.The content of metal fluoride formed on the coated Al electrode under multiple breakdowns was significantly higher than that on the coated Cu electrode.The research results could provide references for improving insulation performance of GIS equipment.

关键词： coating electrode film

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Range resolution and sampling frequency trade-off for GPS passive radar

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Journal of Systems Engineering and Electronics 2022年第1期33卷 28-37页

作者： ZHANG Zhuxian zheng yu zheng Linhua ZHU Peidong College of Electronic Science National University of Defense TechnologyChangsha 410073China College of Electronic Communication and Electrical Engineering Changsha UniversityChangsha 410022China

In a global positioning system(GPS)passive radar,a high resolution requires a high sampling frequency,which increases the computational load.Balancing the computational load and the range resolution is challenging.This paper presents a method to trade off the range resolution and the computational load by experimentally determining the optimal sampling frequency through an analysis of multiple sets of GPS satellite data at different sampling frequencies.The test data are used to construct a range resolution-sampling frequency trade-off model using least-squares estimation.The theoretical analysis shows that the experimental data are the best fit using smoothing and nthorder derivative splines.Using field GPS C/A code signal-based GPS radar,the trade-off between the optimal sampling frequency is determined to be in the 20461.25–24553.5 kHz range,which supports a resolution of 43–48 m.Compared with the conventional method,the CPU time is reduced by approximately 50%.

关键词： global positioning system(GPS)radar range resolution sampling frequency trade-off

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A multidisciplinary team for the diagnosis and management of psoriatic arthritis

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Chinese Medical Journal 2021年第12期134卷 1387-1389页

作者： yu-Xin zheng Min zheng Department of Dermatology Second Affiliated HospitalZhejiang University School of MedicineHangzhouZhejiang 310009China

Psoriatic arthritis(PsA)is a special subtype of psoriasis,which severely influences the quality of life of the affected people.Clinical manifestations of PsA are diverse.In addition to skin lesions,PsA patients often have musculoskeletal symptoms,nail changes,and ophthalmological features that simultaneously or successively occur with the skin lesions.[1]Therefore,the diagnosis and treatment of PsA are challenging because of its various symptoms.In recent years,multidisciplinary management of PsA is gradually being valued,because early screening,diagnosis,and treatment can effectively control signs and symptoms of PsA,improve patients’quality of life,and slow down the disease progression to a larger extent.[1]

关键词： diagnosis Clinical successively

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La-doped NiFe-LDH coupled with hierarchical vertically aligned MXene frameworks for efficient overall water splitting

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Journal of Energy Chemistry 2022年第7期31卷 472-479,I0012页

作者： Mengzhou yu Jiqi zheng Ming Guo School of Chemical Engineering Dalian University of TechnologyDalian 116024LiaoningChina College of Environment and Chemical Engineering Dalian UniversityDalian 116622LiaoningChina Shanghai Institute of Space Power-Sources Shanghai 200245China

The development of stable electrocatalysts with high hydrogen and oxygen evolution reactions (HER and OER) activity in alkaline electrolytes is critical to renewable energy conversion technologies,such as electrochemical water splitting.In this work,a novel strategy for engineering water splitting electrocatalysts in alkaline electrolyte was developed by synergistically coupling La-doped Ni Fe-layered double hydroxides (Ni Fe-LDH) nanosheets onto three-dimensional (3D) vertically aligned MXene nanosheets on macroporous nickel foam (NF) substrates (Ni Fe La-LDH/v-MXene/NF).The electrocatalytic performance of the prepared Ni Fe La-LDH/v-MXene/NF is enhanced by the synergy of strong electronic interaction among multiple metal centers and unique vertically aligned porous MXene with increased active surface area,accelerated reaction kinetics and improved water adsorption and dissociation ability.To reach the commercially required current density (500 m A cm^(-2)),the Ni Fe La-LDH/v-MXene/NF exhibits greatly reduced overpotentials of 233 and 255 m V for HER and OER,respectively,along with excellent durability.Moreover,an alkaline electrolyzer driven by Ni Fe La-LDH/v-MXene/NF delivers a lower cell voltage(1.71 V) compared with that of Pt/C-RuO_(2) couple to achieve the current density of 500 m A cm^(-2).

关键词： Bifunctional electrocatalyst MXene Layered double hydroxide Lanthanum Overall water splitting

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In-process adaptive milling for large-scale assembly interfaces of a vertical tail driven by real-time vibration data

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Chinese Journal of Aeronautics 2022年第5期35卷 441-454页

作者： Xiong ZHAO LianYu zheng Lu yu School of Mechanical Engineering and Automation Beihang UniversityBeijing 100191China C919 Division Shanghai Aircraft Manufacturing Co.LtdShanghai 201324China

Assembly interfaces,the joint surfaces between the vertical tail and rear fuselage of a large aircraft,are thin-wall components.Their machining quality are seriously restricted by the machining vibration.To address this problem,an in-process adaptive milling method is proposed for the large-scale assembly interface driven by real-time machining vibration data.Within this context,the milling operation is first divided into several process steps,and the machining vibration data in each process step is separated into some data segments.Second,based on the real-time machining vibration data in each data segment,a finite-element-unit-force approach and an optimized space–time domain method are adopted to estimate the time-varying in-operation frequency response functions of the assembly interface.These FRFs are in turn employed to calculate stability lobe diagrams.Thus,the three-dimensional stability lobe diagram considering material removal is acquired via interpolation of all stability lobe diagrams.Third,to restrain milling chatter and resonance,the cutting parameters for next process step,e.g.,spindle speed and axial cutting depth,are optimized by genetic algorithm.Finally,the proposed method is validated by a milling test of the assembly interface on a vertical tail,and the experimental results demonstrate that the proposed method can improve the machining quality and efficiency of the assembly interface,i.e.,the surface roughness reduced from 3.2μm to 1.6μm and the machining efficiency improved by 33%.

关键词： Adaptive milling Assembly interfaces Data-driven Time-varying frequency response function Vertical tail

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De-noising of radiation pressure signal generated by bubble oscillation based on ensemble empirical mode decomposition

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Journal of Hydrodynamics 2022年第5期34卷 849-863页

作者： Xiang-hao zheng yu-ning Zhang Key Laboratory of Power Station Energy Transfer Conversion and System(Ministry of Education) School of EnergyPower and Mechanical EngineeringNorth China Electric Power UniversityBeijing102206China

The radiation pressure signals generated by the bubble oscillation are often utilized to recognize the characteristics of the target objects in many fields.However,these signals are easily contaminated by complex background noises.In order to accurately extract the effective components of the radiation pressure signal generated by the bubble oscillation,this paper proposes a de-noising procedure for the radiation pressure signal,based on the ensemble empirical mode decomposition(EEMD),the autocorrelation function and the modified wavelet soft-threshold de-noising method.In order to verify the effectiveness of the procedure,the typical radiation pressure signal generated based on the Keller-Miksis model under the acoustic excitation is employed for the subsequent de-noising analysis.The results of the qualitative analysis show that the amplitude and the period of the bubble oscillation can be clearly observed in the time-domain diagram of the de-noised signal based on the EEMD.In the quantitative analysis,the de-noised signal based on the EEMD has better performance with higher signal-to-noise ratio(SNR),smaller root-mean-square error,and larger correlation coefficient than that based on the wavelet transform(WT)and the empirical mode decomposition(EMD).Furthermore,with the increase of the complexity of the radiation pressure signal(e.g.,the increase of the dimensionless pressure amplitude of the acoustic wave and the decrease of the SNR of the input signal),the above three evaluation indexes of the de-noised signal based on the EEMD are all better than those based on the other two methods.When the signal is more complex,the de-noising capabilities of the WT,the EMD are greatly reduced,but the EEMD can still maintain the good de-noising capability,which shows the superiority of the signal de-noising procedure proposed in the present paper.

关键词： Radiation pressure cavitation bubble oscillation signal de-noising ensemble empirical mode decomposition(EEMD) autocorrelation function wavelet soft-threshold de-noising

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