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Optical detection method of discharge mode transition of inductively coupled plasma in an atmosphere-breathing electric propulsion system

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Chinese Journal of Aeronautics 2024年第10期37卷 172-183页

作者： yuxuan ZHONG yu zhang Jianjun WU Peng ZHENG College of Aerospace Science and Engineering National University of Defense TechnologyChangsha 410073China

Plasma discharge stability is an important problem in atmosphere-breathing electric propulsion system when maintaining long-term missions at ultra-low earth *** paper designed an inductively coupled plasma source to imitate the ionization *** effect of inflow rate and Radio Frequency(RF)power on the plasma discharge mode transition is experimentally studied.A discharge mode detection method is proposed,which determines the discharge mode by identifying the morphology of the plasma *** using the method,the discharge mode transition is quantified and a control model based on the parameter sensitivity is *** verify the method,the spectra are measured and the electron temperature spatial distribution is *** the method has been proven *** results show that the inductively coupled discharge contains capacitive components affected by the mass flow rate and the radio frequency *** plasma characteristics can be maintained stably by controlling the radio frequency power when the mass flow rate randomly changes in a certain *** is demonstrated that the application of detection method effectively identifies the discharge mode,which is a promising active control method for the plasma discharge mode.

关键词： Atmosphere-breathing electric propulsion Inductively coupled plasma Discharge mode transition Optical diagnosis Ultra-low earth orbit

Network Intrusion Traffic Detection Based on Feature Extraction

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Computers, Materials & Continua 2024年第1期78卷 473-492页

作者： Xuecheng yu Yan Huang yu zhang Mingyang Song Zhenhong Jia College of Information Science and Engineering Xinjiang UniversityUrumqi830046China Network Department China Mobile Communications Group Xinjiang CoLtd.UrumqiUrumqi830011China Xinjiang Signal Detection and Processing Key Laboratory Xinjiang UniversityUrumqi830000China

With the increasing dimensionality of network traffic,extracting effective traffic features and improving the identification accuracy of different intrusion traffic have become critical in intrusion detection systems(IDS).However,both unsupervised and semisupervised anomalous traffic detection methods suffer from the drawback of ignoring potential correlations between features,resulting in an analysis that is not an optimal ***,in order to extract more representative traffic features as well as to improve the accuracy of traffic identification,this paper proposes a feature dimensionality reduction method combining principal component analysis and Hotelling’s T^(2) and a multilayer convolutional bidirectional long short-term memory(MSC_BiLSTM)classifier model for network traffic intrusion *** method reduces the parameters and redundancy of the model by feature extraction and extracts the dependent features between the data by a bidirectional long short-term memory(BiLSTM)network,which fully considers the influence between the before and after *** network traffic is first characteristically downscaled by principal component analysis(PCA),and then the downscaled principal components are used as input to Hotelling’s T^(2) to compare the differences between *** datasets with outliers,Hotelling’s T^(2) can help identify the groups where the outliers are located and quantitatively measure the extent of the ***,a multilayer convolutional neural network and a BiLSTM network are used to extract the spatial and temporal features of network traffic *** empirical consequences exhibit that the suggested approach in this manuscript attains superior outcomes in precision,recall and F1-score juxtaposed with the prevailing *** results show that the intrusion detection accuracy,precision,and F1-score of the proposed MSC_BiLSTM model for the CIC-IDS 2017 dataset are 98.71%,95.97%,and 90.22%.

关键词： Network intrusion traffic detection PCA Hotelling’s T^(2) BiLSTM

Numerical investigations of the interactions between bubble induced shock waves and particle based on OpenFOAM

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Journal of Hydrodynamics 2024年第2期36卷 355-362页

作者： Jia-xin yu Jin-sen Hu yu-hang Liu Yi-fan Liu Dan Gao yu-ning zhang Key Laboratory of Power Station Energy Transfer Conversion and System Ministry of EducationSchool of Energy Power and Mechanical EngineeringNorth China Electric Power UniversityBeijing102206China

The presence of particles and the shock waves generated by the cavitation bubbles can significantly affect the safety and the performance of hydrodynamic *** the present paper,the shock waves generated by cavitation bubble collapsing near the particle are numerically investigated based on the OpenFOAM together with the numerical schlieren for the shock wave *** numerical results reveal that the stand-off distance is one of the paramount factors affecting the interactions between the particle and the shock *** different kinds of shock waves(e.g.,bubble-inception,jet formation,particle reflected and jet-split shock waves)are observed during the bubble collapsing near the *** stand-off distance smaller than 0.5 or larger than 1.1,the maximum pressure at particle surface generated by the bubble growth can surpass those of the collapse stage.

关键词： Particle-bubble interaction shockwaves jetdynamics

Automated Identification of Ordered Phases for Simulation Studies of Block Copolymers

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Chinese Journal of Polymer Science 2024年第5期42卷 683-692,I0011页

作者： yu-Chen zhang Wei-Ling Huang Yi-Xin Liu State Key Laboratory of Molecule Engineering of Polymers Department of Macromolecular ScienceFudan UniversityShanghai200433China

In unit cell simulations,identification of ordered phases in block copolymers(BCPs)is a tedious and time-consuming task,impeding the advancement of more streamlined and potentially automated research *** this study,we propose a scattering-based automated identification strategy(SAIS)for characterization and identification of ordered phases of BCPs based on their computed scattering *** approach leverages the scattering theory of perfect crystals to efficiently compute the scattering patterns of periodic morphologies in a unit *** the first stage of the SAIS,phases are identified by comparing reflection conditions at a sequence of Miller *** confirm or refine the identification results of the first stage,the second stage of the SAIS introduces a tailored residual between the test phase and each of the known candidate ***,our strategy incorporates a variance-like criterion to distinguish background species,enabling its extension to multi-species BCP *** has been demonstrated that our strategy achieves exceptional accuracy and robustness while requiring minimal computational ***,the approach allows for real-time expansion and improvement to the candidate phase library,facilitating the development of automated research workflows for designing specific ordered structures and discovering new ordered phases in BCPs.

关键词： Block copolymer Phase identification Scattering function

Spherical Polyelectrolyte Brush Nanoreactor:Preparation of Hollow TiO_(2) Nanospheres and Characterization by Small Angle X-Ray Scattering

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Chinese Journal of Polymer Science 2024年第9期42卷 1393-1400,I0009页

作者： yu-Hua zhang Zi-yu zhang Xin Liu En-Guang Ma Jiang-Tao Guo Li Li Xu-Hong Guo State Key Laboratory of Chemical Engineering East China University of Science and TechnologyShanghai200237China Shandong Provincial Key Laboratory of Monocrystalline Silicon Semiconductor Materials and Technology College of Chemistry and Chemical EngineeringDezhou UniversityDezhou253023China Institute of Bast Fiber Crops&Center of Southern Economic Crops Chinese Academy of Agricultural SciencesChangsha410205China

Titanium dioxide(TiO_(2))hollow nanoparticles present significant potential for photocatalytic applications while their straightforward preparation with precise structure control is still *** work reports the approach to preparing tunable hollow TiO_(2) nanospheres by utilization of spherical polyelectrolyte brushes(SPB)as nanoreactors and *** the preparation,the evolution of the structure was characterized by small angle X-ray scattering(SAXS),and in combination with dynamic light scattering and transmission electron *** formation of TiO_(2) shell within the brush(SPB@TiO_(2))is confirmed by the significant increase of the electron density,and its internal structure has been analyzed by fitting SAXS data,which can be influenced by Titanium precursors and ammonia *** calcining SPB@TiO_(2) in a muffle furnace,hollow TiO_(2) nanospheres are produced,and their transition to the anatase crystal form is triggered,as confirmed by X-ray diffraction *** the advantages of their hollow structure,these TiO_(2) nanospheres exhibit exceptional catalytic degradation efficiency of methylene blue(MB),tetracycline(TC),and 2,4-dichlorophenoxyacetic acid(2,4-D),and also demonstrate excellent recyclability.

关键词： Spherical polyelectrolyte brush Nanoreactor Hollow titanium dioxide X-ray scattering

Study on Catalytic Behavior of Iron-based Catalyst with IITP as Electron Donor in the Polymerization of Butadiene

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Chinese Journal of Polymer Science 2024年第5期42卷 612-619,I0007页

作者： Shi-Liang Xu Ying-Nan Zhao Yao yu Qi Yang Li-Hua Na Heng Liu Chun-yu zhang Xue-Quan zhang Key Laboratory of Advanced Rubber Material Ministry of EducationSchool of Polymer Science and EngineeringQingdao University of Science&TechnologyQingdao266042China Shandong Provincial College Laboratory of Rubber Material and Engineering School of Polymer Science and EngineeringQingdao University of Science&TechnologyQingdao266042China Key Lab of Rubber-Plastics Ministry of Education/Shandong Provincial Key Lab of Rubber-plasticsSchool of Polymer Science and EngineeringQingdao University of Science&TechnologyQingdao266042China

In this study,a novel iron-based catalyst system,Fe(acac)3/(isocyanoimino)triptenylphosphorane(IITP)/AlR3,was employed for the synthesis of syndiotactic 1,2-polybutadiene in *** catalyst system exhibits remarkably high catalytic activity,achieving a polymerization activity of 762 kgpolymer·molcatalyst^(-1)·h^(-1)at 50℃with a[BD]/[Fe]molar ratio of ***,living polymerization characteristic were observed during the investigation of the polymerization kinetics of 1,3-butadiene *** characteristics were well demonstrated by a narrow molecular weight distribution(PDI≈2.0)of the resulting polybutadiene and a linear relationship between-ln(1-c)and polymerization time as well as number average molecular weight and polymer *** resultant polymer showed a 1,2-selectivity of approximately 76%and stereoregularity ranging from 62%to 73%(rrrr).Additionally,through kinetic studies on polymerization reaction,an apparent activation energy Ea value of this catalytic system was calculated to be 84.98 kJ·mol^(-1),which suggests that high polymerization temperature favors efficient polymerization.

关键词： Iron catalyst Syndiotactic 1,2-polybutadiene Elastomers Donor Selectivity

Simulating the GRF of Humanoid Robot Vertical Jumping Using a Simplified Model with a Foot Structure for Foot Design

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Journal of Bionic Engineering 2024年第1期21卷 112-125页

作者： Chuanku Yi Xuechao Chen yu zhang zhangguo yu Haoxiang Qi Yaliang Liu Qiang Huang School of Mechatronical Engineering Beijing Institute of TechnologyZizhuyaunHaidianBeijing 100081China Beijing Advanced Innovation Center for Intelligent Robots and Systems Beijing Institute of Tec

There are many theories and tools for human or robot motion simulation,but most of them require complex *** LNZN model(a simplified model named by the proposers)simplifies the human model and facilitates simulation of the Ground Reaction Force(GRF)of body landing by spring damping model and ignoring joint rotation movements,which can reduce the amount of computation *** this paper,the LNZN model of human running is selected as the basis and is modified to obtain the LNZN model of a robot,which expands the application of the LNZN *** to the structure of the human foot,a foot structure is then added to the simplified model to reduce the *** also applied driving forces to the new model to simulate the whole high jump motion of the robot to expand the functions of the LNZN *** obtained GRF data were anastomotic to the actual experimental *** addition,the effects of variables,such as the mass,hardness,and damping,of the foot on the GRF at the moment of landing were also ***,based on the guidelines obtained for the design of the robot’s foot structure,we fabricated new robot’s feet and installed them on the actual robot and achieved a better cushioning effect than the original foot in experiments.

关键词： LNZN model-GRF simulation Humanoid foot structure Foot parameters

Microstructure recognition of steels by machine learning based on visual attention mechanism

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Journal of Iron and Steel Research International 2024年第4期31卷 909-923页

作者： Xing-yu Chen Lin Cheng Cheng-yang Hu yu-peng zhang Kai-ming Wu The State Key Laboratory of Refractories and Metallurgy Hubei Province Key Laboratory of Systems Science on Metallurgical ProcessingInternational Research Institute for Steel TechnologyCollaborative Center on Advanced SteelsWuhan University of Science and TechnologyWuhan 430081HubeiChina Metals Valley and Band(Foshan)Metallic Composite Materials Co. Ltd.Foshan 528000GuangdongChina

U-Net has achieved good performance with the small-scale datasets through skip connections to merge the features of the low-level layers and high-level layers and has been widely utilized in biomedical image segmentation as well as recent microstructure image segregation of the *** representative visual attention mechanism modules,named as squeeze-and-excitation networks,convolutional block attention module,and extended calibration algorithm,were intro-duced into the traditional U-Net architecture to further improve the prediction *** is found that compared with the original U-Net architecture,the evaluation index of the improved U-Net architecture has been significantly improved for the microstructure segmentation of the steels with the ferrite/martensite composite microstructure and pearlite/ferrite composite microstructure and the complex martensite/austenite island/bainite microstructure,which demonstrates the advantages of the utilization of the visual attention mechanism in the microstructure *** reasons for the accuracy improvement were discussed based on the feature maps analysis.

关键词： Microstructure recognition-Steel Machine learning Visual attention mechanism Visualization

A nonlocal dispersal and time delayed HIV infection model with general incidences

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Applied Mathematics(A Journal of Chinese Universities) 2024年第3期39卷 448-457页

作者： WU Peng zhang yu-huai WANG Ling School of Sciences Hangzhou Dianzi UniversityHangzhou 310018China School of Humanities and Management Zhejiang Chinese Medical UniversityHangzhou 311402China Public Foundational Courses Department Nanjing Vocational University of Industry TechnologyNanjing 210023China

Biologically,because of the impact of reproduction period and nonlocal dispersal of HIV-infected cells,time delay and spatial heterogeneity should be *** this paper,we establish an HIV infection model with nonlocal dispersal and infection ***,applying the theory of Fourier transformation and von Foerster rule,we transform the model to an integrodifferential equation with nonlocal time delay and *** well-posedness,positivity,and boundedness of the solution for the model are studied.

关键词： HIV model nonlocal dispersal time delay general incidences