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Simulation of a helicon plasma source in a magnetoplasma rocket engine

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Plasma Science and Technology 2022年第7期24卷 53-62页

作者： Zhenyu YANG Wei FAN Jianguo WEI xianwei han Shaanxi Key Laboratory of Plasma Physics and Applied Technology Xi'an 710100People's Republic of China

The helicon plasma source,which generates high thrust and high impulse,is of vital importance for magnetoplasma rocket *** this work,a multi-component,two-dimensional,axisymmetric fluid model coupled with an electromagnetic field was developed to model the helicon *** simulation results demonstrate that:(i)the discharge mode changes twice—each conversion is accompanied by a plasma density jump and an electron temperature peak in the discharge;(ii)when the input current increases,the plasma density increases,and ionization occurs faster;(iii)the background magnetic field clearly enhances the discharge;(iv)the plasma density may be smaller if the discharge has not entered the wave mode.

关键词： space propulsion MPRE helicon plasma source discharge mode conversion

Electroformation and collection of giant liposomes on an integrated microchip

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Chinese Chemical Letters 2019年第2期30卷 353-358页

作者： Zhenyu Wang Chaoxiong Wu Ting Fan xianwei han Qiong Wang Jincan Lei Jun Yang State Key Laboratory of Ultrasound Engineering in Medicine Co-Founded by Chongqing ξ the Ministry of Science ξ Technology College of Biomedical Engineering Chongqing Medical University Key Laboratory of Biorheological Science and Technology (Chongqing University) Ministry of Education and Key Lab of Visual Damage and Regeneration ξ Restoration of ChongqingBioengineering College Chongqing University Chongqing Engineering and Technology Research Center of Intelligent Rehabilitation and Eldercare Chongqing City Management College

Giant liposome is an important lipid structure widely used in biological and medical fields. In its main preparation method, electroformation, many influencing factors must be optimized for good effect. How to collect the desired giant liposomes is another major issue. In this work, a microchip with a reactor chamber array was used to study the influences of multiple parameters, and a suitable condition could be achieved rapidly and efficiently. A tailor-made collection chamber was also integrated on the chip. Based on the multifactor and multilevel orthogonal experiment, optimal conditions of the lipid solution, buffer solution, and electric signal were achieved with high efficiency. More than one thousand giant liposomes could be formed in each microscale reactor chamber, and most of them were unilamellar. The on-chip collection ratio of giant liposome carriers could also approximate to 40%.

关键词： Giant liposome Microchip ITO Electroformation Collection

Study of double-chamber air arc plasma torch and the application in solid-waste disposal

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Plasma Science and Technology 2021年第6期23卷 48-58页

作者： Yawen CAO Bin LI xianwei han Chang TAN Zhihao ZhanG Xizhe ZhanG Jianguo WEI Shanxi Key Laboratory of Plasma Physics and Applied Technology Xi'an 710100People's Republic of China State Key Laboratory of Liquid Rocket Science and Technology Xi'an 710100People's Republic of China Academy of Aerospace Propulsion Technology Xi'an 710100People's Republic of China

Arc plasma can be applied in hazardous solid waste disposal for higher temperature than common heating methods,but some practical issues exist in practical engineering *** this study,an air arc plasma torch with double chambers and magnetic controlling is designed to realize wide variable power and long electrode *** detailed characteristics and laws of the air arc are *** condition parameters of arc current(I),air flow rate(G)and the structure parameters of inlet area ratios and electrode diameters influence both the arc voltage and arc root *** arc rotating driven by magnetic field effectively lengthens the electrode *** gasification process and product of organic wastes by air plasma are influenced largely by the waste compositions and the air flow rate.A furnace structure with more even atmosphere and longer residence time should be considered for better ***-deficient environment is important to suppress NOxformation during the application of air *** solid wastes can be melt by the air plasma and cooled down to form compact vitreous structures in which heavy metals can be locked and the leaching rates significantly decrease down.

关键词： air arc plasma electrical characteristic electrode life gasification melting

QARF: A Novel Malicious Traffic Detection Approach via Online Active Learning for Evolving Traffic Streams

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Chinese Journal of Electronics 2024年第3期33卷 645-656页

作者： Zequn NIU Jingfeng XUE Yong WANG Tianwei LEI Weijie han xianwei GAO School of Computer Science and Technology Beijing Institute of Technology School of Space Information Space Engineering University

In practical abnormal traffic detection scenarios,traffic often appears as drift,imbalanced and rare labeled streams,and how to effectively identify malicious traffic in such complex situations has become a challenge for malicious traffic *** have extensive studies on malicious traffic detection with single challenge,but the detection of complex traffic has not been widely *** adaptive random forests(QARF) is proposed to detect traffic streams with concept drift,imbalance and lack of labeled *** is an online active learning based approach which combines adaptive random forests method and adaptive margin sampling *** achieves querying a small number of instances from unlabeled traffic streams to obtain effective *** conduct experiments using the NSL-KDD dataset to evaluate the performance of *** is compared with other state-of-the-art *** experimental results show that QARF obtains 98.20% accuracy on the NSL-KDD *** performs better than other state-of-the-art methods in comparisons.

关键词： Training Streams Random forests

Recent Advances on Deep Learning for Sign Language Recognition

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Computer Modeling in Engineering & Sciences 2024年第6期139卷 2399-2450页

作者： Yanqiong Zhang xianwei Jiang School of Mathematics and Information Science Nanjing Normal University of Special EducationNanjing210038China

Sign language,a visual-gestural language used by the deaf and hard-of-hearing community,plays a crucial role in facilitating communication and promoting *** language recognition(SLR),the process of automatically recognizing and interpreting sign language gestures,has gained significant attention in recent years due to its potential to bridge the communication gap between the hearing impaired and the hearing *** emergence and continuous development of deep learning techniques have provided inspiration and momentum for advancing *** paper presents a comprehensive and up-to-date analysis of the advancements,challenges,and opportunities in deep learning-based sign language recognition,focusing on the past five years of *** explore various aspects of SLR,including sign data acquisition technologies,sign language datasets,evaluation methods,and different types of neural *** Neural Networks(CNN)and Recurrent Neural Networks(RNN)have shown promising results in fingerspelling and isolated sign ***,the continuous nature of sign language poses challenges,leading to the exploration of advanced neural network models such as the Transformer model for continuous sign language recognition(CSLR).Despite significant advancements,several challenges remain in the field of *** challenges include expanding sign language datasets,achieving user independence in recognition systems,exploring different input modalities,effectively fusing features,modeling co-articulation,and improving semantic and syntactic ***,developing lightweight network architectures for mobile applications is crucial for practical *** addressing these challenges,we can further advance the field of deep learning for sign language recognition and improve communication for the hearing-impaired community.

关键词： Sign language recognition deep learning artificial intelligence computer vision gesture recognition

Heterogeneous Task Allocation Model and Algorithm for Intelligent Connected Vehicles

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Computers, Materials & Continua 2024年第9期80卷 4281-4302页

作者： Neng Wan Guangping Zeng xianwei Zhou School of Computer and Communication Engineering University of Science and Technology BeijingBeijing100083China School of Mechanical and Transportation Southwest Forestry UniversityKunming650224China

With the development of vehicles towards intelligence and connectivity,vehicular data is diversifying and growing dramatically.A task allocation model and algorithm for heterogeneous Intelligent Connected Vehicle(ICV)applications are proposed for the dispersed computing network composed of heterogeneous task vehicles and Network Computing Points(NCPs).Considering the amount of task data and the idle resources of NCPs,a computing resource scheduling model for NCPs is *** the heterogeneous task execution delay threshold as a constraint,the optimization problem is described as the problem of maximizing the utilization of computing resources by *** proposed problem is proven to be NP-hard by using the method of reduction to a 0-1 knapsack problem.A many-to-many matching algorithm based on resource preferences is *** algorithm first establishes the mutual preference lists based on the adaptability of the task requirements and the resources provided by *** enables the filtering out of un-schedulable NCPs in the initial stage of matching,reducing the solution space *** solve the matching problem between ICVs and NCPs,a new manyto-many matching algorithm is proposed to obtain a unique and stable optimal matching *** simulation results demonstrate that the proposed scheme can improve the resource utilization of NCPs by an average of 9.6%compared to the reference scheme,and the total performance can be improved by up to 15.9%.

关键词： Task allocation intelligent connected vehicles dispersed computing matching algorithm

ASYMPTOTIC THEORY FOR THE CIRCUIT ENVELOPE ANALYSIS

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Journal of Computational Mathematics 2024年第4期42卷 955-978页

作者： Chunxiong Zheng xianwei Wen Jinyu Zhang Zhenya Zhou College of Mathematics and Systems Science Xinjiang UniversityUrumqi 830046China Department of Mathematical Sciences Tsinghua UniversityBeijing 100084China Empyrean Software Empyrean Technology Co.Ltd.Beijing 100102China

Asymptotic theory for the circuit envelope analysis is developed in this paper.A typical feature of circuit envelope analysis is the existence of two significantly distinct timescales:one is the fast timescale of carrier wave,and the other is the slow timescale of modulation *** first perform pro forma asymptotic analysis for both the driven and autonomous *** resorting to the Floquet theory of periodic operators,we make a rigorous justification for first-order asymptotic *** turns out that these asymptotic results are valid at least on the slow *** speed up the computation of asymptotic approximations,we propose a periodization technique,which renders the possibility of utilizing the NUFFT *** experiments are presented,and the results validate the theoretical findings.

关键词： Asymptotic analysis Circuit envelope analysis Floquet theory Singularly perturbed problem

A Survey on Chinese Sign Language Recognition:From Traditional Methods to Artificial Intelligence

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Computer Modeling in Engineering & Sciences 2024年第7期140卷 1-40页

作者： xianwei Jiang Yanqiong Zhang Juan Lei Yudong Zhang School of Mathematics and Information Science Nanjing Normal University of Special EducationNanjing210038China School of Computing and Mathematical Sciences University of LeicesterLeicesterLE17RHUK Department of Information Technology Faculty of Computing and Information TechnologyKing Abdulaziz UniversityJeddah21589Saudi Arabia

Research on Chinese Sign Language(CSL)provides convenience and support for individuals with hearing impairments to communicate and integrate into *** article reviews the relevant literature on Chinese Sign Language Recognition(CSLR)in the past 20 *** Markov Models(HMM),Support Vector Machines(SVM),and Dynamic Time Warping(DTW)were found to be the most commonly employed technologies among traditional *** from the rapid development of computer vision and artificial intelligence technology,Convolutional Neural Networks(CNN),3D-CNN,YOLO,Capsule Network(CapsNet)and various deep neural networks have sprung *** Neural Networks(DNNs)and their derived models are integral tomodern artificial intelligence *** addition,technologies thatwerewidely used in the early days have also been integrated and applied to specific hybrid models and customized identification *** language data collection includes acquiring data from data gloves,data sensors(such as Kinect,LeapMotion,etc.),and high-definition ***,facial expression recognition,complex background processing,and 3D sign language recognition have also attracted research interests among *** to the uniqueness and complexity of Chinese sign language,accuracy,robustness,real-time performance,and user independence are significant challenges for future sign language recognition ***,suitable datasets and evaluation criteria are also worth pursuing.

关键词： Chinese Sign Language Recognition deep neural networks artificial intelligence transfer learning hybrid network models

Numerical simulation research on multiphase flow of aviation centrifugal pump based on OpenFOAM

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Chinese Journal of Aeronautics 2024年第4期37卷 256-275页

作者： xianwei LIU Jiangfeng FU Junjie YANG Dewen YIN Zhenhua ZHOU Huacong LI College of Power and Energy Northwestern Polytechnical UniversityXi’an 710072China Norinco Group Testing and Research Institute Huayin 714200China AECC Xi’an Engine Control Technology Co.Ltd. Xi’an 710077China AECC Guizhou Honglin Aero Engine Control Technology Co.Ltd. Guiyang 550009China

This paper aims to tackle the calculation efficiency problem raised in the cavitation-flow simulation of the aviation centrifugal pump due to the fading-away interface resulting from the dissipation of numerics used in the phase-change control equation for unstructured-grid multiphase flow,and due to the limitation of flow time-step in whole flow regimes,the control equation of vapor–liquid two-phase flow considering cavitation mass transport is established firstly,modifying the momentum equation by introducing the surface tension,and adding the artificial convective flow to the phase equation to solve the numerical dissipation ***,in consideration of the local time step principle and based on the multi-dimensional general limiter algorithm with explicit solutions under the OpenFOAM platform,a solution method of steady-state VOF (Volume of Fluid) model considering cavitation two-phase change is constructed,and the feasibility of this method is verified by NACA hydrofoil and NASA flat plate ***,based on the platform developed,the cavitation performance of an aviation centrifugal pump inducer is *** research results show that the error of the calculated cavitation pressure distribution for NACA hydrofoil between the simulation test and the experimental-test is less than 5%,and the maximum error of calculated cavitation number at pump head dropping for NASA high-speed flat plate inducer between the simulation test and the experimental-test is 2.1%.The cavitation area observed in the simulation test is the same as that obtained in the high-speed photography *** on the OpenFOAM simulation method,the position of pump head dropping of the fuel centrifugal pump can be accurately *** error of the calculated cavitation number at pump head dropping between the simulation test and the experimental test is about 3.7%,showing high calculation accuracy.

关键词： Aero engine Fuel centrifugal pump Multiphase flow OpenFOAM Volume of fluid