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User Churn Prediction Hierarchical Model Based on Graph Attention Convolutional Neural Networks

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China Communications 2024年第7期21卷 169-185页

作者： Mei Miao tang Miao Zhou Long School of Economics and Management Beijing Jiaotong UniversityBeijing 100044China School of Automotive and Rail Transit Nanjing Institute of TechnologyNanjing 211167China Nanjing Intelligent Aviation Research Institute Co. LtdNanjing 210014China

The telecommunications industry is becoming increasingly aware of potential subscriber churn as a result of the growing popularity of smartphones in the mobile Internet era,the quick development of telecommunications services,the implementation of the number portability policy,and the intensifying competition among *** the same time,users'consumption preferences and choices are *** churn prediction models must be created in order to accurately predict the churn tendency,since keeping existing customers is far less expensive than acquiring new *** conventional or learning-based algorithms can only go so far into a single subscriber's data;they cannot take into consideration changes in a subscriber's subscription and ignore the coupling and correlation between various ***,the current churn prediction models have a high computational burden,a fuzzy weight distribution,and significant resource economic *** prediction algorithms involving network models currently in use primarily take into account the private information shared between users with text and pictures,ignoring the reference value supplied by other users with the same *** work suggests a user churn prediction model based on Graph Attention Convolutional Neural Network(GAT-CNN)to address the aforementioned *** main contributions of this paper are as follows:Firstly,we present a three-tiered hierarchical cloud-edge cooperative framework that increases the volume of user feature input by means of two aggregations at the device,edge,and cloud ***,we extend the use of users'own data by introducing self-attention and graph convolution models to track the relative changes of both users and packages ***,we build an integrated offline-online system for churn prediction based on the strengths of the two models,and we experimentally validate the efficacy of cloudside collaborative training and *** summary,the churn

关键词： cloud-edge cooperative framework GAT-CNN self-attention and graph convolution models subscriber churn prediction

Effect of bariatric surgery on metabolism in diabetes and obesity comorbidity:Insight from recent research

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World Journal of Diabetes 2024年第4期15卷 586-590页

作者： Hui-Hong tang Dong Wang Cheng-Chun tang Department of Cardiology Zhongda HospitalSoutheast UniversityNanjing 210009Jiangsu ProvinceChina School of Medicine Southeast UniversityNanjing 210009Jiangsu ProvinceChina

Obesity is a prevalent cause of diabetes mellitus(DM)and is a serious danger to human *** 2 DM(T2DM)mostly occurs along with *** obesity-induced DM is caused by an excessive long-term diet and surplus *** surgery can improve the symptoms of T2DM in some obese *** different types of bariatric surgery may have different *** are some models built by researchers to discuss the surgical procedures’effects on me-tabolism in diabetes animal models and diabetes *** is high time to conclude all this effects and recommend procedures that can better improve metabolism.

关键词： Bariatric surgery Obesity Diabetes Animal models Diabetes patients

The unique spontaneous polarization property and application of ferroelectric materials in photocatalysis

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Nano Research 2024年第5期17卷 3571-3585页

作者： Jinghua An Chang Xu Lu Li Bo tang College of Chemistry Chemical Engineering and Materials ScienceKey Laboratory of Molecular and Nano ProbesMinistry of EducationCollaborative Innovation Center of Functionalized Probes for Chemical Imaging in University of ShandongInstitute of Molecular and Nano ScienceShandong Normal UniversityJinan 250014China Laoshan Laboratory 168 Wenhai Middle RdAoshanwei JimoQingdao 266237China

The unique spontaneous polarization property of ferroelectric material makes it to be a special catalyst in *** spontaneous polarization property can induce the formation of built-in electric field,which can improve the separation of photoelectrons and holes to affect photocatalytic *** internal electric field induced by spontaneous polarization can be influenced by multiple factors such as the morphology,the concentration of defect,the type of doped heteroatoms,as well as the composition of ***,the preparation method,pretreating temperature,the strength of prepolarized external electric field of ferroelectric-based photocatalysts as well as the strength of external mechanical force or external magnetic field in photocatalytic reactions can influence the photocatalytic effectivity via influencing spontaneous polarization-induced internal electric ***,it is urgently to unveil the mystery of structure-activity relationships for ferroelectric materials-based photocatalysts,which is usually *** this in mind,this review was provided for the role of various complex influencing factors on ferroelectric materials-based photocatalysis based on the latest advancement in the fields of new energy development,environmental *** the beginning,the basic structure and properties of ferroelectric material are ***,popular synthesis methods of ferroelectric-based photocatalysts are *** that,two main mechanisms of ferroelectric photocatalysis are *** research progress of ferroelectric photocatalysis is then given emphatically according to the classification of photocatalytic ***,the problems existing nowadays and the challenges facing in the future on the application of ferroelectric materials-based photocatalysts are outlined in the summary and outlook section.

关键词： spontaneous polarization photocatalysis ferroelectric separation of electrons and holes

Information-Theoretic Limits on Compression of Semantic Information

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China Communications 2024年第7期21卷 1-16页

作者： tang Jiancheng Yang Qianqian Zhang Zhaoyang College of Information Science and Electronic Engineering Zhejiang UniversityHangzhou 310007China

As conventional communication systems based on classic information theory have closely approached Shannon capacity,semantic communication is emerging as a key enabling technology for the further improvement of communication ***,it is still unsettled on how to represent semantic information and characterise the theoretical limits of semantic-oriented compression and *** this paper,we consider a semantic source which is characterised by a set of correlated random variables whose joint probabilistic distribution can be described by a Bayesian *** give the information-theoretic limit on the lossless compression of the semantic source and introduce a low complexity encoding method by exploiting the conditional *** further characterise the limits on lossy compression of the semantic source and the upper and lower bounds of the rate-distortion *** also investigate the lossy compression of the semantic source with two-sided information at the encoder and decoder,and obtain the corresponding rate distortion *** prove that the optimal code of the semantic source is the combination of the optimal codes of each conditional independent set given the side information.

关键词： rate distortion semantic communication semantic compression

Positive definiteness of real quadratic forms resulting from the variable-step L1-type approximations of convolution operators

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Science China Mathematics 2024年第2期67卷 237-252页

作者： Hong-Lin Liao Tao tang Tao Zhou School of Mathematics Nanjing University of Aeronautics and AstronauticsNanjing 211106China Division of Science and Technology BNU-HKBU United International CollegeZhuhai 519087China SUSTech International Center for Mathematics Shenzhen 518055China NCMIS&LSEC Institute of Computational Mathematics and Scientific/Engineering ComputingAcademy of Mathematics and Systems ScienceChinese Academy of SciencesBeijing 100190China

The positive definiteness of real quadratic forms with convolution structures plays an important rolein stability analysis for time-stepping schemes for nonlocal operators. In this work, we present a novel analysistool to handle discrete convolution kernels resulting from variable-step approximations for convolution *** precisely, for a class of discrete convolution kernels relevant to variable-step L1-type time discretizations, weshow that the associated quadratic form is positive definite under some easy-to-check algebraic conditions. Ourproof is based on an elementary constructing strategy by using the properties of discrete orthogonal convolutionkernels and discrete complementary convolution kernels. To our knowledge, this is the first general result onsimple algebraic conditions for the positive definiteness of variable-step discrete convolution kernels. Using theunified theory, we obtain the stability for some simple nonuniform time-stepping schemes straightforwardly.

关键词： discrete convolution kernels positive definiteness variable time-stepping orthogonal convolution kernels complementary convolution kernels

Performance of iron-air battery with iron nanoparticle-encapsulated C-N composite electrode

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Frontiers in Energy 2024年第1期18卷 42-53页

作者： Can FANG Xiangmei tang Jiaoyan WANG Qingfeng YI School of Chemistry and Chemical Engineering Hunan University of Science and TechnologyXiangtan 411201China Hunan Provincial Key Laboratory of Advanced Materials for New Energy Storage and Conversion Xiangtan 411201China

Highly efficient and stable iron electrodes are of great significant to the development of iron-air battery(IAB).In this paper,iron nanoparticle-encapsulated C–N composite(NanoFe@CN)was synthesized by pyrolysis using polyaniline as the C–N *** performance of the NanoFe@CN in different electrolytes(alkaline,neutral,and quasi-neutral)was investigated via cyclic voltammetry(CV).The IAB was assembled with NanoFe@CN as the anode and IrO_(2)+Pt/C as the *** effects of different discharging/charging current densities and electrolytes on the battery performance were also *** K_(2)SO_(4)electrolyte can effectively suppress the passivation of iron electrode,and the battery showed a good cycling stability during 180 charging/discharging *** to the pure nano-iron(NanoFe)battery,the NanoFe@CN battery has a more stable cycling stability either in KOH or NH_(4)Cl+KCl electrolyte.

关键词： energy storage and conversion metallic composites nanocomposites iron-air battery iron anode

Solvent effects on Diels-Alder reaction in ionic liquids:A reaction density functional study

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Chinese Journal of Chemical Engineering 2024年第2期66卷 180-188页

作者： Zijiang Dou Weiqiang tang Peng Xie Shuangliang Zhao Guangxi Key Laboratory of Petrochemical Resource Processing and Process Intensification Technology and School of Chemistry and Chemical Engineering Guangxi UniversityNanning 530004China State Key Laboratory of Chemical Engineering and School of Chemical Engineering East China University of Science and TechnologyShanghai 200237China

Extensive experimental studies have been performed on the Diels-Alder(DA)reactions in ionic liquids(ILs),which demonstrate that the IL environment can significantly influence the reaction rates and ***,the underlying microscopic mechanism remains *** this work,the multiscale reaction density functional theory is applied to explore the effect of 1-butyl-3-methylimidazolium hexafluorophosphate([BMIM][PF_(6)])solvent on the reaction of cyclopentadiene(CP)with acrolein,methyl acrylate,or *** analyzing the free energy landscape during the reaction,it is found that the polarization effect has a relatively small influence,while the solvation effect makes both the activation free energy and reaction free energy *** addition,the rearrangement of local solvent structure shows that the cation spatial distribution responds more evidently to the reaction than the anion,and this indicates that the cation plays a dominant role in the solvation effect and so as to affect the reaction rates and selectivity of the DA reactions.

关键词： Solvent effect Ionic liquids Diels-Alder reaction Reaction density functional theory

Effect of Air Distribution on the Transport Characteristics of Solid Particles in the Thermal Storage and Release System of Circulating Fluidized Bed

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Journal of Thermal Science 2024年第4期33卷 1554-1563页

作者： JI Zengcai SONG Guoliang tang Zihua SUN Liwei State Key Laboratory of Coal Conversion Institute of Engineering ThermophysicsChinese Academy of SciencesBeijing100190China University of Chinese Academy of Sciences Beijing100049China Dalian National Laboratory for Clean Energy Dalian116023China

Solid particle heat storage technology offers a potential solution to the challenges posed by the significant growth of renewable energy sources,particularly in terms of grid security and ***,it has the capability to optimize the energy utilization efficiency of the power *** order to investigate the transport regulation characteristics of solid particles in the thermal storage and release system of a circulating fluidized bed(CFB),a test rig with a capacity of 0.1 MW(th)was *** rig was utilized to systematically study the transport regulation characteristics of solid particles under the double U-type valve feed structure and U-type valve discharge *** experimental findings indicate that the system's design enables efficient and rapid storage and release of solid particles in the *** air distribution mode,specifically the double U-type valve feed structure and the U-type valve discharge structure,significantly influence the feed and discharge characteristics of the ash storage *** was observed that the impact of loose air on these characteristics is more substantial than that of the return air,irrespective of the feed structure or the return *** adjusting the feed and discharge rate,it is recommended to adopt a scheme that involves coarse adjustment through loose air and fine adjustment through return air.

关键词： solid particle thermal storage air distribution mode transport regulation

A Novel Multi-Stream Fusion Network for Underwater Image Enhancement

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China Communications 2024年第2期21卷 166-182页

作者： Guijin tang Lian Duan Haitao Zhao Feng Liu Jiangsu Key Laboratory of Image Processing and Image Communication Nanjing University of Posts and TelecommunicationsNanjing 210003China Jiangsu Key Laboratory of Wireless Communications Nanjing University of Posts and TelecommunicationsNanjing 210003China

Due to the selective absorption of light and the existence of a large number of floating media in sea water, underwater images often suffer from color casts and detail blurs. It is therefore necessary to perform color correction and detail restoration. However,the existing enhancement algorithms cannot achieve the desired results. In order to solve the above problems, this paper proposes a multi-stream feature fusion network. First, an underwater image is preprocessed to obtain potential information from the illumination stream, color stream and structure stream by histogram equalization with contrast limitation, gamma correction and white balance, respectively. Next, these three streams and the original raw stream are sent to the residual blocks to extract the features. The features will be subsequently fused. It can enhance feature representation in underwater images. In the meantime, a composite loss function including three terms is used to ensure the quality of the enhanced image from the three aspects of color balance, structure preservation and image smoothness. Therefore, the enhanced image is more in line with human visual ***, the effectiveness of the proposed method is verified by comparison experiments with many stateof-the-art underwater image enhancement algorithms. Experimental results show that the proposed method provides superior results over them in terms of MSE,PSNR, SSIM, UIQM and UCIQE, and the enhanced images are more similar to their ground truth images.

关键词： image enhancement multi-stream fusion underwater image