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DEFORMING METRICS WITH POSITIVE CURVATURE BY A FULLY NONLINEAR FLOW

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Acta Mathematica Scientia 2011年第1期31卷 159-171页

作者：岳赟盛为民 china mobile group Zhejiang Co. Ltd. Department of Mathematics Zhejiang University

By studying a fully nonlinear flow deforming conformal metrics on a compact and connected manifold, we prove the long time existence and the exponential convergence of the solutions of the flow for any initial metric ... 详细信息

关键词： Fully nonlinear flow conformal metrics Schouten tensor

Sludge composition and characteristics shaped microbial community and further determined process performance: A study on full-scale thermal hydrolysis-anaerobic digestion processes

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Journal of Environmental Sciences 2024年第3期137卷 96-107页

作者： Wei Liu Chenxiang Sun Wei Li Tianle Li Zhan Chen Jiawei Wang Zhengran Ren Xianghua Wen School of Environment Tsinghua UniversityBeijing 100084China Jinneng Holding group DatongShanxi 037000China Research and Development Center Beijing Drainage Group Co.Ltd.Beijing 100124China Beijing Dabeinong Science and Technology group Co. Ltd.Beijing 100080China

Anaerobic digestion (AD) with thermal hydrolysis (TH) pretreatment is a promising process for excess sludge treatment,while there lacks of the knowledge from full-scale process about the impact of sludge composition and characteristics on microbial community and performance.The sludge physiochemical indices,microbial community and performance data of four full-scale TH-AD plants were characterized,and their relationships was elucidated.The four plants were operated under almost similar total organic loading rate (OLR)but their methanogenesis performance differentiate into two groups,namely superior group(SupG) and the inferior group (Inf G).In both groups,TH effectively solubilized particulate organic compounds,meanwhile raised the ammonia nitrogen (NH_(4)^(+)-N) and volatile fatty acid (VFA) concentration.Compared with the Sup G,thermal hydrolyzed sludge of Inf G had higher level of VFAs,NH_(4)^(+)-N and total chemical oxygen demand (t COD),which showed higher inhibition effect on microbes,leading to a community with lower diversity,lower abundance of carbohydrate degrading functional guild,higher protein degrading one,and methanogens that adapted to limited substrates,and further declined the methane production rate.Thus,it was recommended that OLR alone was not sufficient for controlling the system in design and operation,the concentration of VFAs,NH_(4)^(+)-N and t COD should be equally considered.Their higher concentration,together with the higher abundance of Defluviitoga and Proteiniphilum were recommended as indicators for inferior running condition.Our results proposed that microbial communities played a role of bridge between environmental factors and performance,provided implications for engineering ecology and operational regulation for full-scale sludge TH-AD process.

关键词： Thermal hydrolysis Anaerobic digestion Microbial community Full-scale

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 set.Therefore,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 detection.This 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 features.The 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 groups.For datasets with outliers,Hotelling’s T^(2) can help identify the groups where the outliers are located and quantitatively measure the extent of the outliers.Finally,a multilayer convolutional neural network and a BiLSTM network are used to extract the spatial and temporal features of network traffic data.The empirical consequences exhibit that the suggested approach in this manuscript attains superior outcomes in precision,recall and F1-score juxtaposed with the prevailing techniques.The 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

Study on tungsten sintering temperature field based on electromagnetic simulation and computational fluid dynamics

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Tungsten 2024年第2期6卷 355-366页

作者： Lu-Yan Wang Yue-Guang Yu Jian-Xin Dong Kai-Ping Du Shan-Yu Liu Cao-Bing Li University of Science and Technology Beijing Beijing 100083China BGRIMM Technology group Beijing 100160China china Iron&Steel Research Institute group Beijing 100081China

In order to study the influence of various sintering variables more intuitively and clearly,electromagnetic field analysis and computational fl uid dynamics are used to analyze the infl uence of gas flow,heating power and other process parameters on the temperature range of medium-frequency sintering in this paper.The results indicate that the uniformity of temperature fi eld is determined by the gas flow rate and heating power.When the heating power is 50 kW,the stable temperature drops about 10 K for every 1 m^(3)·h^(−1)increase of hydrogen flow.The peak value of the maximum temperature diff erence on the tungsten rods gradually increases with the increase of the hydrogen flow rate,and it appears slightly later.The temperature distribution of tungsten rods in furnace is similar with diff erent hydrogen flow rate.At the same time,the closer to the furnace wall,the higher the temperature of the tungsten rod.The temperature diff erence between tungsten rods mainly occurred within 1 h after the beginning of heating.Increasing the heating power can improve the stable temperature,but has little eff ect on the heating time.Increasing heating power can increase the peak value of the maximum temperature diff erence on the tungsten rods,but has little eff ect on the occurrence time of the peak value of the maximum temperature diff erence on the tungsten rods.Increasing the heating power will increase the temperature diff erence of a single tungsten rod,but the temperature diff erence of a single tungsten rod never exceeds 65 K.This study can be used to guide the process optimization design.Combined with numerical simulation calculation,the sintering parameters with low energy consumption and high temperature uniformity can be quickly and eff ectively found,thus improving the microstructure and properties of sintered tungsten products.

关键词： Tungsten products Sintering Hydrogen flow rate Heating power

Building mm Wave on the Evolving C-V2X:mm Wave NR-V2X

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china Communications 2024年第1期21卷 88-101页

作者： Shanzhi Chen Xinxin He Rui Zhao Jinling Hu Xin Zhang china Information and Communication Technology group Co. Ltd.(CICT)the State Key Laboratory of Wireless Mobile CommunicationsBeijing 100083China Beijing Laboratory of Advanced Information Networks Beijing Key Laboratory of Network System Architecture and ConvergenceBeijing University of Posts and TelecommunicationsBeijing 100876China CICT Connected and Intelligent Technologies Co. LtdChina Academy of Telecommunication TechnologyBeijing 100191China CICT mobile Communications Technology Co.Ltd.

Since the evolving standardization of cellular V2X(C-V2X)technologies is continuously developed by 3GPP,research on new radio(NR-V2X)has been on schedule by academic and industries.Though millimeter wave(mm Wave)frequency band is supposed to provide large transmission bandwidth,yet the development of mm Wave band in NR-V2X is still in preliminary stage.In this article,a comprehensive discussion of mm Wave NR-V2X is given covering trends,standardization landscape,and enabling technologies,aiming at tackling the challenge of channel modeling,directional channel access,beamforming and blockage management.The vision of mm Wave NR-V2X is to fully support the development of automated driving,holographic control display and improved in-car infotainment for the future.

关键词： C-V2X enabling technologies mmWave NR-V2X

Energy-Efficient Traffic Offloading for RSMA-Based Hybrid Satellite Terrestrial Networks with Deep Reinforcement Learning

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china Communications 2024年第2期21卷 49-58页

作者： Qingmiao Zhang Lidong Zhu Yanyan Chen Shan Jiang National Key Laboratory of Science and Technology on Communications University of Electronic Science and Technology of ChinaChengdu 611731China The Higher Educational Key Laboratory for Flexible Manufacturing Equipment Integration of Fujian Province Xiamen Institute of TechnologyXiamen 361021China china mobile(Jiangxi)Communications group Co. LtdYichun 336000China

As the demands of massive connections and vast coverage rapidly grow in the next wireless communication networks, rate splitting multiple access(RSMA) is considered to be the new promising access scheme since it can provide higher efficiency with limited spectrum resources. In this paper, combining spectrum splitting with rate splitting, we propose to allocate resources with traffic offloading in hybrid satellite terrestrial networks. A novel deep reinforcement learning method is adopted to solve this challenging non-convex problem. However, the neverending learning process could prohibit its practical implementation. Therefore, we introduce the switch mechanism to avoid unnecessary learning. Additionally, the QoS constraint in the scheme can rule out unsuccessful transmission. The simulation results validates the energy efficiency performance and the convergence speed of the proposed algorithm.

关键词： deep reinforcement learning energy efficiency hybrid satellite terrestrial networks rate splitting multiple access traffic offloading

Reliable Data Collection Model and Transmission Framework in Large-Scale Wireless Medical Sensor Networks

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Computer Modeling in Engineering & Sciences 2024年第7期140卷 1077-1102页

作者： Haosong Gou Gaoyi Zhang RenêRipardo Calixto Senthil Kumar Jagatheesaperumal Victor Hugo C.de Albuquerque china mobile group Sichuan Co. Ltd.Chengdu640041China Department of Teleinformatics Engineering Federal University of CearáFortaleza60455-970Brazil Department of Electronics&Communication Engineering Mepco Schlenk Engineering CollegeSivakasi626005India

Large-scale wireless sensor networks(WSNs)play a critical role in monitoring dangerous scenarios and responding to medical emergencies.However,the inherent instability and error-prone nature of wireless links present significant challenges,necessitating efficient data collection and reliable transmission services.This paper addresses the limitations of existing data transmission and recovery protocols by proposing a systematic end-to-end design tailored for medical event-driven cluster-based large-scale WSNs.The primary goal is to enhance the reliability of data collection and transmission services,ensuring a comprehensive and practical approach.Our approach focuses on refining the hop-count-based routing scheme to achieve fairness in forwarding reliability.Additionally,it emphasizes reliable data collection within clusters and establishes robust data transmission over multiple hops.These systematic improvements are designed to optimize the overall performance of the WSN in real-world scenarios.Simulation results of the proposed protocol validate its exceptional performance compared to other prominent data transmission schemes.The evaluation spans varying sensor densities,wireless channel conditions,and packet transmission rates,showcasing the protocol’s superiority in ensuring reliable and efficient data transfer.Our systematic end-to-end design successfully addresses the challenges posed by the instability of wireless links in large-scaleWSNs.By prioritizing fairness,reliability,and efficiency,the proposed protocol demonstrates its efficacy in enhancing data collection and transmission services,thereby offering a valuable contribution to the field of medical event-drivenWSNs.

关键词： Wireless sensor networks reliable data transmission medical emergencies cluster data collection routing scheme

Design and verification of an FPGA programmable logic element based on Sense-Switch pFLASH

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Frontiers of Information Technology & Electronic Engineering 2024年第4期25卷 485-499页

作者： Zhengzhou CAO Guozhu LIU Yanfei ZHANG Yueer SHAN Yuting XU No.58 Research Institute China Electronics Technology Group CorporationWuxi 214035China

This paper proposes a kind of programmable logic element(PLE)based on Sense-Switch pFLASH technology.By programming Sense-Switch pFLASH,all three-bit look-up table(LUT3)functions,partial four-bit look-up table(LUT4)functions,latch functions,and d flip flop(DFF)with enable and reset functions can be realized.Because PLE uses a choice of operational logic(COOL)approach for the operation of logic functions,it allows any logic circuit to be implemented at any ratio of combinatorial logic to register.This intrinsic property makes it close to the basic application specific integrated circuit(ASIC)cell in terms of fine granularity,thus allowing ASIC-like cell-based mappers to apply all their optimization potential.By measuring Sense-Switch pFLASH and PLE circuits,the results show that the“on”state driving current of the Sense-Switch pFLASH is about 245.52μA,and that the“off”state leakage current is about 0.1 pA.The programmable function of PLE works normally.The delay of the typical combinatorial logic operation AND3 is 0.69 ns,and the delay of the sequential logic operation DFF is 0.65 ns,both of which meet the requirements of the design technical index.

关键词： Field programmable gate array(FPGA) Programmable logic element(PLE) Boolean logic operation Look-up table Sense-Switch pFLASH Threshold voltage

A novel complex-high-order graph convolutional network paradigm:ChyGCN

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Chinese Physics B 2024年第5期33卷 665-672页

作者：郑和翔苗书宇顾长贵 Business School University of Shanghai for Science and TechnologyShanghai 200093China Ant group Shanghai 200000China

In recent years,there has been a growing interest in graph convolutional networks(GCN).However,existing GCN and variants are predominantly based on simple graph or hypergraph structures,which restricts their ability to handle complex data correlations in practical applications.These limitations stem from the difficulty in establishing multiple hierarchies and acquiring adaptive weights for each of them.To address this issue,this paper introduces the latest concept of complex hypergraphs and constructs a versatile high-order multi-level data correlation model.This model is realized by establishing a three-tier structure of complexes-hypergraphs-vertices.Specifically,we start by establishing hyperedge clusters on a foundational network,utilizing a second-order hypergraph structure to depict potential correlations.For this second-order structure,truncation methods are used to assess and generate a three-layer composite structure.During the construction of the composite structure,an adaptive learning strategy is implemented to merge correlations across different levels.We evaluate this model on several popular datasets and compare it with recent state-of-the-art methods.The comprehensive assessment results demonstrate that the proposed model surpasses the existing methods,particularly in modeling implicit data correlations(the classification accuracy of nodes on five public datasets Cora,Citeseer,Pubmed,Github Web ML,and Facebook are 86.1±0.33,79.2±0.35,83.1±0.46,83.8±0.23,and 80.1±0.37,respectively).This indicates that our approach possesses advantages in handling datasets with implicit multi-level structures.

关键词： raph convolutional network complex modeling complex hypergraph