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Request pattern change-based cache pollution attack detection and defense in edge computing

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Digital Communications and Networks 2023年第5期9卷 1212-1220页

作者： Junwei wang Xianglin Wei Jianhua Fan Qiang Duan Jianwei Liu Yangang wang The 63rd Research Institute National University of Defense TechnologyNanjing210007China

Through caching popular contents at the network edge,wireless edge caching can greatly reduce both the content request latency at mobile devices and the traffic burden at the core ***,popularity-based caching strategies are vulnerable to Cache Pollution Attacks(CPAs)due to the weak security protection at both edge nodes and mobile *** CPAs,through initiating a large number of requests for unpopular contents,malicious users can pollute the edge caching space and degrade the caching *** paper firstly integrates the dynamic nature of content request and mobile devices into the edge caching framework,and introduces an eavesdroppingbased CPA ***,an edge caching mechanism,which contains a Request Pattern Change-based Cache Pollution Detection(RPC2PD)algorithm and an Attack-aware Cache Defense(ACD)algorithm,is proposed to defend against *** results show that the proposed mechanism could effectively suppress the effects of CPAs on the caching performance and improve the cache hit ratio.

关键词： Mobile edge computing Cache pollution attack Flash crowd

Polymer-chlorella cells conjugating with aggregation-induced functionality switch towards hydrogen evolution

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Science China(Technological Sciences) 2020年第8期63卷 1416-1425页

作者： wang ShengLiang XU ZhiJun LIN Song LIU XiaoMan wang Lei HUANG Xin MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage School of Chemistry and Chemical EngineeringHarbin Institute of TechnologyHarbin 150001China

The manipulation of physicochemical and biological properties of the encapsulated cells by cell surface engineering technique is now attracting more and more researchers’*** this study,we showed a mild and highly efficient way to build a type of polymer-living cell conjugates based on photoinduced electron transfer-reversible addition-fragmentation chain-transfer polymerization(PET-RAFT).The polymerization could proceed at room temperature under the blue light initiating and showed very less influence on the activity of the living ***,the constructed positively charged polymer-living cell conjugates could aggregate with the negatively charged native Chlorella pyrenoidosa(CP)cell to form a microscale aggregate which then allowed a functionality switching of the encapsulated CP cells from the normal photosynthetic O2 towards H2 production with an average rate of 0.26μmol H2h-^1(mg chlorophyll)-^1 for 42 *** is then anticipated that the method we show could contribute an effective way for generating different functionalized living cell-polymer hybrid structures on demand,and the demonstrated aggregation-induced functionality switching of the CP cells is also anticipated to inspire more applications of the cell-based materials towards biology green energy.

关键词： cell surface engineering reversible addition-fragmentation chain-transfer polymerization self-assembly biology green energy

A Superhydrophobic/Electrothermal/Photothermal Synergistically Anti-icing Strategy with Excellent Self-healable and Anti-abrasion Property

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Journal of Bionic Engineering 2021年第5期18卷 1147-1156页

作者： Peng wang Jian wang Wei Duan Chunyan Li Huilong Han Qing Xie School of Energy Power and Mechanical EngineeringNorth China Electric Power UniversityBaodingChina Hebei Key Laboratory of Electric Machinery Health Maintenance and Failure Prevention North China Electric Power UniversityBaoding 071003China School of Electrical and Electronic Engineering North China Electric Power UniversityBaodingHebeiChina

Unexpected ice accumulation tends to cause many problems or even disasters in our daily *** on the superior electrothermal and photothermal function of the carbon nanotubes,we introduced a superhydrophobic/electrothermal/photothermal synergistically anti-icing *** a voltage of 15 V was applied to the superhydrophobic sample,the surface could rapidly melt the ice layer(~3 mm thickness)within 530 s at the environmental temperature of-25℃.When the near-infrared light(808 nm)irradiates on the superhydrophobic sample,the ice could be rapidly removed after 460 *** was found that the superhydrophobicity helps the melted water to roll off immediately,and then solves the re-freeze problem the traditional surfaces ***,the ice can be completely melted with 120 s when the superhydrophobic/electrothermal/photothermal synergistically anti-icing strategy was *** improve the mechanical robustness for practical application,both nanoscale carbon nanotubes and microscale carbon powders were utilized to construct hierarchical *** these dual-scale fillers were sprinkled onto the semi-cured elastomer substrate to prepare partially embedded *** hierarchical structure and partially embedded structure were obtained after completely curing the substrate,which imparts excellent abrasion resistance(12.50 kPa,16.00 m)to the prepared ***,self-healable poly(urea–urethane)elastomer was introduced as the ***,the cutted superhydrophobic sample can be mended by simply contacting at room temperature.

关键词： Superhydrophobic Electrothermal Photothermal Self-healing

Tuning microstructures of TC4 ELI to improve explosion resistance

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Defence Technology（防务技术） 2024年第3期33卷 78-99页

作者： Changle Zhang Yangwei wang Lin wang Zixuan Ning Guoju Li Dongping Chen Zhi-Wei Yan Yuchen Song Xucai wang School of Materials Science and Engineering Beijing Institute of TechnologyBeijing 100081China National Key Laboratory of Science and Technology on Materials under Shock and Impact Beijing 100081China State Key Laboratory of Explosive Science and Technology Beijing Institute of TechnologyBeijing 100081China Aerospace Information Research Institute Chinese Academy of SciencesBeijing 100094China School of Aeronautical Engineering Zhengzhou University of AeronauticsHenan ProvinceZhengzhou 450046China Shanxi Jiangyang Chemical Co. Ltd.Shanxi ProvinceTaiyuan 030041China Shandong Institute of Non-metallic Materials Shandong ProvinceJinan 250031China

A reasonable heat treatment process for TC4 ELI titanium alloy is crucial to tune microstructures to improve its explosion ***,there is limited investigation on tuning microstructures of TC4 ELI to improve explosion ***,the current challenge is quantifying microstructural changes'effects on explosion resistance and incorporating microstructural changes into finite element *** work aims to tune microstructures to improve explosion resistance and elucidate their anti-explosion mechanism,and find a suitable method to incorporate microstructural changes into finite element *** this work,we systematically study the deformation and failure characteristics of TC4 ELI plates with varying microstructures using an air explosion test and LS-DYNA finite element *** Johnson-Cook(JC)constitutive parameters are used to quantify the effects of microstructural changes on explosion resistance and incorporate microstructural changes into finite element *** of the heat treatment,one plate has equiaxed microstructure and the other has bimodal *** convex of the plate after the explosion has a quadratic relationship with the charge mass,and the simulation results demonstrate high reliability,with the error less than 17.5%.Therefore,it is feasible to obtain corresponding JC constitutive parameters based on the differences in microstructures and mechanical properties and characterize the effects of microstructural changes on explosion *** bimodal target exhibits excellent deformation *** response of bimodal microstructure to the shock wave may be more intense under explosive *** well-coordinated structure of the bimodal target enhances its resistance to deformation.

关键词： Microstructure Finite element modelling Parameter optimization Failure characteristics Explosion resistance

Zn-0.8Mn alloy for degradable structural applications:Hot compression behaviors,four dynamic recrystallization mechanisms,and better elevated-temperature strength

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Journal of Materials Science & Technology 2023年第6期137卷 159-175页

作者： Meng Li Zhang-Zhi Shi Qiang wang Yang Cheng Lu-Ning wang Beijing Advanced Innovation Center for Materials Genome Engineering School of Materials Science and EngineeringUniversity of Science and Technology BeijingBeijing 100083China

Environmentally degradable Zn-0.8Mn alloy is highly ductile,which lays the foundation for developing high-performance Zn-Mn-based ***,not only constitutive equation of this alloy is unknown,but also its dynamic recrystallization(DRX)behavior is unclear,which makes optimization of hot pro-cessing parameters of this alloy almost dependent on *** work aims to tackle these *** constitutive equation was deduced to be˙ε=1.38×10^(12)×[sinh(0.009σ)]^(8)exp(-135150/RT).A processing map of the alloy was obtained for the first time,which shows that it has excellent hot formability with narrow instability *** a final true strain of 0.8,the volume fraction of DRX grains increased from 37%to 79%with temperature increasing from 150℃to 350℃and strain rate decreas-ing from 10 s^(−1)to 10^(-3)s^(−1).Discontinuous DRX(DDRX),continuous DRX(CDRX),twinning-induced DRX(TDRX),and particle stimulated nucleation(PSN)were activated during hot *** was al-ways the main *** was completely suppressed at 300℃and *** arose from dis-persed MnZn 13 ***,Zn-0.8Mn alloy exhibited elevated-temperature strengths better than pure Zn and Zn-Al-based *** 300℃and 0.1 s^(−1),its peak stress was 1.8 times of pure Zn,owing to MnZn 13 particles of 277±79 nm impeding the motion of grain boundaries and dislocations.

关键词： Environmentally degradable Zn-0.8Mn alloy Hot deformation DRX Constitutive equations Microstructure

Strong room-temperature emission from defect states in CVD-grown WSe2 nanosheets

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Nano Research 2018年第7期11卷 3922-3930页

作者： Shudong Zhao Lei Tao Peng Miao Xianjie wang Zhiguo Liu Yi wang Bingsheng Li Yu Sui Yang wang Department of Physics Harbin Institute of Technology Harbin 150001 China School of Chemistry and Chemical Engineering Harbin Institute of Technology Harbin 150001 China Academy of Fundamental ond lnterdisciplinary Sciences Harbin Institute of Technology Harbin 150001 China

Monolayer transition metal dichalcogenides （TMDCs）, as direct bandgap semiconductors, show promise for applications in ultra-thin flexible optoelec- tronic devices. However, the optical properties and device performance are greatly affected by defects, such as vacancies, present in these materials. Vacancies exist unavoidably in mechanically exfoliated or grown by chemical vapor deposition （CVD） monolayer TMDCs; therefore, their influence on the electric and optical properties of host materials has been widely studied. Here, we report a new defect state located at 1.54 eV, which is 70 meV lower than the neutral exciton energy in as-prepared WSe2 monolayers grown by CVD. This defect state is clearly observed in photoluminescence （PL） and Raman spectra at ambient conditions. PL mapping, Rarnan mapping, and atomic force microscopy analysis indicate a solid-vapor reaction growth mechanism of the defect state formation. During a certain growth stage, nuclei with the composition of WOxSey do not fully react with the Se vapor, leading to the defect formation. This type of defects permits radiative recombination of bound neutral excitons, which can make the PL intensity as strong as the intrinsic excitation. Our findings reveal a new way to tailor the optical properties of two-dimensional TMDCs without any additional processes performed after growth.

关键词： monolayer WSe2 defects photoluminescence chemical vapordeposition (CVD) growth mechanism

Measuring orbital angular momentum of vortex beams in optomechanics

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Frontiers of physics 2021年第3期16卷 177-183页

作者： Zhucheng Zhang Jiancheng Pei Yi-Ping wang Xiaoguang wang Zhejiang Institute of Modern Physics Department of PhysicsZhejiang UniversityHangzhou310027China College of Science Northwest A&F UniversityYangling712100China Graduate School of China Academy of Engineering Physics Beijing100193China

Measuring the orbital angular momentum(OAM)of vortex beams,including the magnitude and the sign,has great application prospects due to its theoretically unbounded and orthogonal ***,the sign-distinguishable OAM measurement in optomechanics is proposed,which is achieved by monitoring the shift of the transmission spectrum of the probe field in a double Laguerre-Gaussian(LG)rotational-cavity *** with the traditional single LG rotational cavity,an asymmetric optomechanically induced transparency window can occur in our ***,the position of the resonance valley has a strong correlation with the magnitude and sign of *** originally comes from the fact that the effective detuning of the cavity mode from the driving field can vary with the magnitude and sign of OAM,which causes the spectral shift to be directional for different signs of *** scheme solves the shortcoming of the inability to distinguish the sign of OAM in optomechanics,and works well for high-order vortex beams with topological charge value±45,which is a significant improvement for measuring OAM based on the cavity optomechanical system.

关键词： orbital angular momentum optomechanically induced transparency Laguerre-Gaussian rotational-cavity system optomechanics

Volatile organic compound emissions from straw-amended agricultural soils and their relations to bacterial communities:A laboratory study

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Journal of Environmental Sciences 2016年第7期28卷 257-269页

作者： Juan Zhao Zhe wang Ting Wu Xinming wang Wanhong Dai Yujie Zhang Ran wang Yonggan Zhang Chengfei Shi College of Environmental Science and Engineering Anhui Normal UniversityWuhu 242000China State Key Laboratory of Organic Geochemistry Guangzhou Institute of GeochemistryChinese Academy of SciencesGuangzhou 510640China

A laboratory study was conducted to investigate volatile organic compound（VOC） emissions from agricultural soil amended with wheat straw and their associations with bacterial communities for a period of 66 days under non-flooded and flooded conditions. The results indicated that ethene, propene, ethanol, i-propanol, 2-butanol, acetaldehyde, acetone,2-butanone, 2-pentanone and acetophenone were the 10 most abundant VOCs, making up over 90% of the total VOCs released under the two water conditions. The mean emission of total VOCs from the amended soils under the non-flooded condition（5924 ng C/（kg·hr）） was significantly higher than that under the flooded condition（2211 ng C/（kg·hr））. One ＂peak emission window＂ appeared at days 0–44 or 4–44, and over 95% of the VOC emissions occurred during the first month under the two water conditions. Bacterial community analysis using denaturing gradient gel electrophoresis（DGGE） showed that a relative increase of Actinobacteria, Bacteroidetes, Firmicutes and γ-Proteobacteria but a relative decrease of Acidobacteria with time were observed after straw amendments under the two water conditions. Cluster analysis revealed that the soil bacterial communities changed greatly with incubation time, which was in line with the variation of the VOC emissions over the experimental period. Most of the above top 10 VOCs correlated positively with the predominant bacterial species of Bacteroidetes, Firmicutes and Verrucomicrobia but correlated negatively with the dominant bacterial species of Actinobacteria under the two water conditions. These results suggested that bacterial communities might play an important role in VOC emissions from straw-amended agricultural soils.

关键词： Volatile organic compounds(VOCs) Emission fluxes Microbial communities Correlations Straw amendment Agricultural soils

Atomistic mechanism of high ionic conductivity in lithium ytterbium-based halide solid electrolytes:A first-principles study

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Journal of Rare Earths 2024年第1期42卷 155-162,I0006页

作者： Limin wang Wei Xiao Lu Sun Rong Yang Jinqiu Yu Ligen wang State Key Laboratory of Nonferrous Metals and Processes China GRINM Group Co.Ltd.Beijing100088China GRIMAT Engineering Institute Co. Ltd.Beijing101407China General Research Institute for Nonferrous Metals Beijing100088China China Automotive Battery Research Institute Co. Ltd.Beijing101407China Rare Earth Functional Materials(Xiong'an)Innovation Center Co. Ltd.Xiong'an071700China

As the next generation of commercial automotive power batteries begins replacing liquid lithium batteries,many look towards all-solid-state batteries to pioneer the ***-so lid-state batteries have attracted the attention of countless researchers around the world because of their high safety and high energy *** recent times,halide solid-state electrolytes have become a research hotspot within solid-state electrolytes because of their potentially superior *** this paper,in the framework of DFT,we investigated the atomic mechanisms of improving the ionic conductivity and stability of Li_(3)YbCl_(6).Our calculations show that both trigonal and orthorhombic Li_(3)YbCl_(6) exhibit wide electrochemical windows and metastable properties(100 meV/atom>Ehull>0 meV/atom).However,the orthorhombic Li_(3)YbCl_(6) can be stabilized at high temperatures by taking the vibrational entropy into account,which is supported by the experimental ***,it is expected that because of the Yb/Li synergistic interactions that,due to their strong mutual coulomb repulsion,influence the Li^(+)transport behavior,the orthorhombic Li_(3)YbCl_(6) might have superior ionic conductivities with appropriate Li+migration paths determined by the Yb^(3+) ***,higher ionic conductivities can be obtained by regulating the random distribution of Li^(+) *** Li^(+)-deficiency can also largely increase the ionic conductivity by invoking *** study helps gain a deeper understanding of the laws that govern ionic conductivities and stabilities and provides a certain theoretical reference for the experimental development and design of halide solid-state electrolytes.

关键词： Halide solid-state electrolytes Phase stability Ionic conductivity First-principles calculations Rare earths