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Alleviating limit cycling in training GANs with an optimization technique

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Science China mathematics 2024年第6期67卷 1287-1316页

作者： Keke Li Liping Tang Xinmin Yang national center for applied mathematics in chongqing Chongqing Normal UniversityChongqing401331China School of Mathematical Sciences University of Electronic Science and Technology of ChinaChengdu611731China

In this paper,we undertake further investigation to alleviate the issue of limit cycling behavior in training generative adversarial networks(GANs)through the proposed predictive centripetal acceleration algorithm(PCAA).Specifically,we first derive the upper and lower complexity bounds of PCAA for a general bilinear game,with the last-iterate convergence rate notably improving upon previous results.Then,we combine PCAA with the adaptive moment estimation algorithm(Adam)to propose PCAA-Adam,for practical training of GANs to enhance their generalization capability.Finally,we validate the effectiveness of the proposed algorithm through experiments conducted on bilinear games,multivariate Gaussian distributions,and the CelebA dataset,respectively.

关键词： GANs general bilinear game predictive centripetal acceleration algorithm lower and upper complexity bounds PCAA-Adam

Network Evolution Analysis of Vehicle Road-Driving Behavior Strategies and Design of Information Guidance Algorithm

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Journal of Social Computing 2024年第1期5卷 58-87页

作者： Tong Lyu Lefeng Shi Weijun He College of Economics and Management China Three Gorges UniversityYichang 443002China national center for applied mathematics in chongqing Chongqing Normal UniversityChongqing 401331China

By analyzing the influence of time and safety factors on the behavior strategies of vehicles on the road,a network game evolution model between drivers that considers the behavior strategies of the driving vehicle itself and its neighbors is constructed,and the competition relationship between different types of cars is studied.The influence of the proportion of driving vehicle types on the potential risk of the road is also discussed.This paper presents a guidance algorithm for vehicle dynamic behavior preference information.The correctness of the algorithm is verified by an example.Research shows:The choice of behavior strategies,such as speeding and lane changing,is related to the expected benefits of time,safety,and neighboring vehicle strategies,and the critical value of payable benefits is obtained.The higher the proportion of aggressive vehicles on the road,the greater the potential risk on the road.Whether there is a vehicle in the adjacent lane of the driving vehicle will affect the type of driving vehicle.Information guidance helps to stabilize the state of vehicles on the road,and the policy transition probability also helps stabilize the form of vehicles cars on the road.Still,information guidance has a more significant impact on the transition of vehicle types.Finally,the guidance strategy of managers is given when the road is smooth and congested.

关键词： user portrait information guidance network game risk appetite

Semi-Varying Coefficient Panel Data Model with Technical Indicators Predicts Stock Returns in Financial Market

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Journal of Systems Science & Complexity 2024年第4期37卷 1638-1652页

作者： HU Xuemei PAN Ying LI Xiang School of mathematics and Statistics Chongqing Technology and Business University chongqing Key Laboratory of Social Economy and applied Statistics Research center for Economy of Upper Reaches of the Yangtse River Chongqing Technology and Business University

Accurately predicting stock returns is a conundrum in financial market. Solving this conundrum can bring huge economic benefits for investors and also attract the attention of all circles of people. In this paper the authors combine semi-varying coefficient model with technical analysis and statistical learning, and propose semi-varying coefficient panel data model with individual effects to explore the dynamic relations between the stock returns from five companies: CVX, DFS, EMN, LYB,and MET and five technical indicators: CCI, EMV, MOM, ln ATR, ln RSI as well as closing price(ln CP), combine semi-parametric fixed effects estimator, semi-parametric random effects estimator with the testing procedure to distinguish fixed effects(FE) from random effects(RE), and finally apply the estimated dynamic relations and the testing set to predict stock returns in December 2020 for the five companies. The proposed method can accommodate the varying relationship and the interactive relationship between the different technical indicators, and further enhance the prediction accuracy to stock returns.

关键词： Fixed effects random effects semi-varying coefficient panel data model stock returns technical indicators

Current progress of research on heat -resistant Mg alloys: A review

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International Journal of Minerals,Metallurgy and Materials 2024年第6期31卷 1406-1425页

作者： Hong Yang Wenlong Xie Jiangfeng Song Zhihua Dong Yuyang Gao Bin Jiang Fusheng Pan national Engineering Research center for Magnesium Alloys Chongqing UniversityChongqing 400044China College of Materials Science and Engineering Chongqing UniversityChongqing 400044China

With the increasing attention received by lightweight metals,numerous essential fields have increased requirements for mag-nesium(Mg)alloys with good room-temperature and high-temperature mechanical properties.However,the high-temperature mechanic-al properties of commonly used commercial Mg alloys,such as AZ91D,deteriorate considerably with increasing temperatures.Over the past several decades,extensive efforts have been devoted to developing heat-resistant Mg alloys.These approaches either inhibit the gen-eration of thermally unstable phases or promote the formation of thermally stable precipitates/phases in matrices through solid solution or precipitation strengthening.In this review,numerous studies are systematically introduced and discussed.Different alloy systems,includ-ing those based on Mg–Al,Mg–Zn,and Mg–rare earth,are carefully classified and compared to reveal their mechanical properties and strengthening mechanisms.The emphasis,limitations,and future prospects of these heat-resistant Mg alloys are also pointed out and dis-cussed to develop heat-resistant Mg alloys and broaden their potential application areas in the future.

关键词： magnesium alloys mechanical properties heat resistance microstructures high temperatures strengthening mechanisms

Revealing excited states of rotational Bose-Einstein condensates

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The Innovation 2024年第1期5卷 41-48页

作者： Jianyuan Yin Zhen Huang Yongyong Cai Qiang Du Lei Zhang School of Mathematical Sciences Laboratory of Mathematics and Applied MathematicsPeking UniversityBeijing 100871China Department of mathematics National University of SingaporeSingapore 119076Singapore Department of mathematics University of CaliforniaBerkeleyBerkeleyCA 94720USA School of Mathematical Sciences Beijing Normal UniversityBeijing 100875China Department of applied Physics and applied mathematics and Data Science Institute Columbia UniversityNew YorkNY 10027USA Beijing International center for Mathematical Research Center for Quantitative BiologyCenter for Machine Learning ResearchPeking UniversityBeijing 100871China

Rotational Bose-Einstein condensates can exhibit quantized vortices as topological excitations.In this study,the ground and excited states of the rotational Bose-Einstein condensates are systematically studied by calculating the stationary points of the Gross-Pitaevskii energy functional.Various excited states and their connections at different rotational frequencies are revealed in solution landscapes constructed with the constrained high-index saddle dynamics method.Four excitation mechanisms are identified:vortex addition,rearrangement,merging,and splitting.We demonstrate changes in the ground state with increasing rotational frequencies and decipher the evolution of the stability of ground states.

关键词： method rotational excited

Recent progress in the research on magnesium and magnesium alloy foils:A short review

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International Journal of Minerals,Metallurgy and Materials 2024年第5期31卷 842-854页

作者： Qiuyan Shen Yongxing Ba Peng Zhang Jiangfeng Song Bin Jiang Fusheng Pan national Engineering Research center for Magnesium Alloys Chongqing UniversityChongqing 400044China College of Materials Science and Engineering Chongqing UniversityChongqing 400044China national Key Laboratory of Advanced Casting Technologies Chongqing UniversityChongqing 400044China

Magnesium and magnesium alloy foils have great potential for application in battery anodes,electromagnetic shielding,optics and acoustics,and biology because of their excellent specific damping,internal dissipation coefficients,magnetic and electrical conductivities,as well as high theoretical specific capacity.However,magnesium alloys exhibit poor deformation ability due to their hexagonal close-packed crystal structure.Preparing magnesium and magnesium alloy foils with thicknesses of less than 0.1 mm is difficult because of surface oxidation and grain growth at high temperatures or severe anisotropy after cold rolling that leads to cracks.Numerous methods have been applied to prepare magnesium alloy foils.They include warm rolling,cold rolling,accumulative roll bonding,electric plastic rolling,and on-line heating rolling.Defects of magnesium and magnesium alloy foils during preparation,such as edge cracks and breakage,are important factors for consideration.Herein,the current status of the research on magnesium and magnesium alloy foils is summarized from the aspects of foil preparation,defect control,performance characterization,and application prospects.The advantages and disadvantages of different preparation methods and defect(edge cracks and breakage)mechanisms in the preparation of foils are identified.

关键词： magnesium alloy foil rolling defect performance application

Dual-Defect Engineering Strategy Enables High-Durability Rechargeable Magnesium-Metal Batteries

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Nano-Micro Letters 2024年第9期16卷 449-461页

作者： Fuyu Chen Bai‑Qing Zhao Kaifeng Huang Xiu‑Fen Ma Hong‑Yi Li Xie Zhang Jiang Diao Jili Yue Guangsheng Huang Jingfeng Wang Fusheng Pan national Innovation center for Lndustry‑Education Integration of Energy Storage Technology School of Materials Science and EngineeringChongqing UniversityChongqing 400044People’s Republic of China national Magnesium Alloy Material Engineering Technology Research center Chongqing UniversityChongqing 400044People’s Republic of China Materials and Energy Division Beijing Computational Science Research CenterBeijing 100193People’s Republic of China School of Materials Science and Engineering Northwestern Polytechnical UniversityXi’an 710072People’s Republic of China national Key Laboratory of Advanced Casting Technologies Chongqing UniversityChongqing 400044People’s Republic of China

Rechargeable magnesium-metal batteries(RMMBs)are promising next-generation secondary batteries;however,their development is inhibited by the low capacity and short cycle lifespan of cathodes.Although various strategies have been devised to enhance the Mg^(2+)migration kinetics and structural stability of cathodes,they fail to improve electronic conductivity,rendering the cathodes incompatible with magnesium-metal anodes.Herein,we propose a dual-defect engineering strategy,namely,the incorporation of Mg^(2+)pre-intercalation defect(P-Mgd)and oxygen defect(Od),to simultaneously improve the Mg^(2+)migration kinetics,structural stability,and electronic conductivity of the cathodes of RMMBs.Using lamellar V_(2)O_(5)·nH_(2)O as a demo cathode material,we prepare a cathode comprising Mg0.07V_(2)O_(5)·1.4H_(2)O nanobelts composited with reduced graphene oxide(MVOH/rGO)with P-Mgd and Od.The Od enlarges interlayer spacing,accelerates Mg^(2+)migration kinetics,and prevents structural collapse,while the P-Mgd stabilizes the lamellar structure and increases electronic conductivity.Consequently,the MVOH/rGO cathode exhibits a high capacity of 197 mAh g^(−1),and the developed Mg foil//MVOH/rGO full cell demonstrates an incredible lifespan of 850 cycles at 0.1 A g^(−1),capable of powering a light-emitting diode.The proposed dual-defect engineering strategy provides new insights into developing high-durability,high-capacity cathodes,advancing the practical application of RMMBs,and other new secondary batteries.

关键词： Rechargeable magnesium-metal batteries Dual-defect engineering Vanadium-based cathode High durability Lamellar structure

A perspective on the key factors of safety for rechargeable magnesium batteries

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Journal of Energy Chemistry 2024年第7期94卷 656-676页

作者： Shuangshuang Tan Jie Xu Rongrui Deng Qiannan Zhao Chaohe Xu Guangsheng Huang Jingfeng Wang Fusheng Pan national Engineering Research center for Magnesium Alloys Chongqing UniversityChongqing 400044China national Innovation center for Industry-Education Integration of Energy Storage Technology College of Materials Science and EngineeringChongqing UniversityChongqing 400044China chongqing Institute of New Energy Storage Materials and Equipment Chongqing 401135China

Rechargeable Mg batteries(RMBs)have become one of the best subsitutes for lithium-ion batteries due to the high volumetric capacity,abundant resources,and uniform plating behavior of Mg metal anode.However,the safety hazard induced by the formation of high-modulue Mg dendrites under a high current density(10 mA cm^(-1))was still revealed in recent years.It has forced researchers to re-examine the safety of RMBs.In this review,the intrinsic safety factors of key components in RMBs,such as uneven plating,pitting and flammability of Mg anode,heat release and crystalline water decomposition of cathode,strong corrosion,low oxidition stability and flammability of electrolytes,and soforth,are systematacially summarized.Their origins,formation mechanisms,and possible safety hazards are deeply discussed.To develop high-performance Mg anode,current strategies including designing artificial SEI,three-dimensional substrates,and Mg alloys are summarized.For practical electrolytes,the configurations of boron-centered anions and simple Mg salts and the functionalized solvent with high boiling point and low flammability are suggested to comprehensively design.In addition,the future study should more focus on the investigation on the thermal runaway and decomposition of cathode materials and separa-tors.This review aims to provide fundamental insights into the relationship between electrochemistry and safety,further promoting the sustainable development of RMBs.

关键词： Rechargeable Mg batteries Battery safety Mg dendrites Electrolyte decomposition Intrinsic safety issues

Emerging perovskite materials for supercapacitors:Structure,synthesis,modification,advanced characterization,theoretical calculation and electrochemical performance

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Journal of Energy Chemistry 2024年第2期89卷 41-70,I0003页

作者： Yuehua Qian Qingqing Ruan Mengda Xue Lingyun Chen Department of applied Chemistry School of Chemistry and Chemical EngineeringChongqing UniversityChongqing 401331China

As a new generation electrode materials for energy storage,perovskites have attracted wide attention because of their unique crystal structure,reversible active sites,rich oxygen vacancies,and good stability.In this review,the design and engineering progress of perovskite materials for supercapacitors(SCs)in recent years is summarized.Specifically,the review will focus on four types of perovskites,perovskite oxides,halide perovskites,fluoride perovskites,and multi-perovskites,within the context of their intrinsic structure and corresponding electrochemical performance.A series of experimental variables,such as synthesis,crystal structure,and electrochemical reaction mechanism,will be carefully analyzed by combining various advanced characterization techniques and theoretical calculations.The applications of these materials as electrodes are then featured for various SCs.Finally,we look forward to the prospects and challenges of perovskite-type SCs electrodes,as well as the future research direction.

关键词： Perovskite Modification engineering Oxygen vacancy Theoretical calculation methodology Supercapacitor