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Demand Prediction Based Slice Reconfiguration Using Dueling Deep Q-Network

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China Communications 2022年第5期19卷 267-285页

作者： Wanqing Guan haijun zhang School of Computer&Communication Engineering University of Science and Technology BeijingBeijing 100083China Beijing Engineering and Technology Research Center for Convergence Networks and Ubiquitous Services Institute of Artificial IntelligenceUniversity of Science and Technology BeijingBeijing 100083China

To satisfy diversified service demands of vertical industries,network slicing enables efficient resource allocation of a common infrastructure by creating isolated logical ***,uncertainty and dynamics of service demands will cause performance *** to operation costs and resource constraints,it is challenging to maintain high quality of user experience while obtaining high revenue for service providers(SPs).This paper develops an optimal and fast slice reconfiguration(OFSR)framework based on reinforcement learning,where a novel scheme is proposed to offer optimal decisions for reconfiguring diverse slices.A demand prediction model is proposed to capture changes in resource requirements,based on which the OFSR scheme is triggered to determine whether to perform slice *** the large state and action spaces generated from uncertain service time and resource requirements,deep dueling architecture is adopted to improve the convergence *** simulations validate the effectiveness of the proposed framework in achieving higher long-term revenue for SPs.

关键词： network slicing slice reconfiguration reinforcement learning resource allocation

Design and Thermal Analysis of the Large Fire Door for AP1000 Nuclear Reactor

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Journal of Thermal Science 2020年第1期29卷 122-130页

作者： zhang Shanwen LI Chong MIAO Hong zhang Jianfeng zhang haijun College of Mechanical Engineering Yangzhou UniversityJiangsu 225127China Institute of Automatic Door and Window Jinqiuzhu CompanyJiangsu 214500China

The large fire door is the key component to ensure the effectiveness of fire zone in AP1000 nuclear *** to the fire design requirements and design criteria,the global structure of the large fire door is *** on the designed structure,the thermal mathematical model of the large fire door is *** on the solid heat transfer theory,the multi-layer heat transfer theory and integrated heat transfer theory,the differential equations of heat conduction,initial conditions,and boundary conditions are *** analysis for the fire door leaf and the closure is carried out by using the method of numerical *** show that:considering the thermal load,the whole structure of the large fire door can meet the fire resistance limit of 3 hours and the design is reasonable and *** study provides theory basis for the design of the large fire door.

关键词： large fire door AP1000 nuclear reactor design thermal analysis

Carbon-containing electrospun nanofibers for lithium-sulfur battery:Current status and future directions

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Journal of Energy Chemistry 2021年第3期30卷 254-273页

作者： Zhaoming Tong Liang Huang Wen Lei haijun zhang Shaowei zhang The State Key Laboratory of Refractories and Metallurgy Wuhan University of Science and TechnologyWuhan 430081HubeiChina College of Engineering Mathematics and Physical SciencesUniversity of ExeterExeter EX44QFUnited Kingdom

Lithium-sulfur batteries(LSBs)have become promising next-generation energy storage technologies for electric vehicles and portable electronics,due to its excellent theoretical specific ***,the low conductivity of sulfur species,notorious lithium dendrites,the severe"shuttle effect"of polysulfides(LiPSs)and the inferior kinetic reaction for LiPSs/Li_(2)S conversion during discharge-charge have seriously hindered their practical application,and also pose potential safety *** to their superior porous architectures,high specific surface areas,excellent structural designability,functional modifiability,abundant active sites and flexibility of carbon-containing electrospun nanofibers(CENFs),they exhibited the superior characteristics that can simultaneously solve the above *** this review,we summarize the recent progress and application of CENFs in ***,we provide a brief introduction to the structure and composition controlled of carbon nanofibers by *** then review progress in recent developments of CENFs for LSBs including cathodes,anodes,separators,and *** focus on how to solve practical issues that arise when the CENFs are applied to various parts of LSBs,and the relevant working mechanisms are described,from high sulfur loading and Li dendrites suppression to LiPSs’confinement and ***,we summarize and propose the existing challenges and future prospects of CENFs,for the design and architecture of electrochemical components in Li-S energy storage systems.

关键词： Lithium-sulfur batteries Electrospinning Carbon-containing nanofibers Cathodes Anodes Separators and interlayers

Pressure-Driven Ne-Bearing Polynitrides with Ultrahigh Energy Density

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Chinese Physics Letters 2022年第5期39卷 49-57页

作者： Lulu Liu Shoutao zhang haijun zhang National Laboratory of Solid State Microstructures School of PhysicsNanjing UniversityNanjing 210093China Collaborative Innovation Center of Advanced Microstructures Nanjing UniversityNanjing 210093China Centre for Advanced Optoelectronic Functional Materials Research and Key Laboratory for UV Light-Emitting Materials and Technology of Ministry of Education Northeast Normal UniversityChangchun 130024China

Neon(Ne)can reveal the evolution of planets,and nitrogen(N)is the most abundant element in the Earth’s *** the inertness of neon,whether nitrogen and neon can react has aroused great interest in condensed matter physics and space ***,we identify three new Ne–N compounds(i.e.,NeN_(6),NeN_(10),and NeN_(22))under pressure by frst-principles *** fnd that inserting Ne into N_(2) substantially decreases the polymeric pressure of the nitrogen and promotes the formation of abundant polynitrogen ***,NeN_(22)acquires a duplex host-guest structure,in which guest atoms(Ne and N_(2)dimers)are trapped inside the crystalline host N_(20)***,both NeN_(10)and NeN_(22)not only are dynamically and mechanically stable but also have a high thermal stability up to 500K under ambient ***,ultra-high energy densities are obtained in NeN_(10)(11.1 kJ/g),NeN_(22)(11.5 kJ/g),tetragonal t-N_(22)(11.6 kJ/g),and t-N_(20)(12.0 kJ/g)produced from NeN_(22),which are more than twice the value of trinitrotoluene(TNT).Meanwhile,their explosive performance is superior to that of ***,NeN_(10),NeN_(22),t-N_(22),and t-N_(20)are promising green high-energy-density *** work promotes the study of neon-nitrogen compounds with superior properties and potential applications.

关键词： materials ambient crystalline

Decentralized model reference adaptive sliding mode control based on fuzzy model

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Journal of Systems Engineering and Electronics 2006年第1期17卷 182-186,192页

作者： Gu haijun zhang Tianping Shen Qikun Dept. of Computer Coll. of Information Engineering Yangzhou Univ. Yangzhou 225009 P. R. China

A new design scheme of decentralized model reference adaptive sliding mode controller for a class of MIMO nonlinear systems with the high-order interconnections is propcsed. The design is based on the universal approximation capability of the Takagi - Seguno （T-S） fuzzy systems. Motivated by the principle of certainty equivalenteontrol, a decentralized adaptive controller is designed to achieve the tracking objective without computafion of the T-S fuzz ymodel. The approach does not require the upper bound of the uncertainty term to be known through some adaptive estimation. By theoretical analysis, the closed-loop fuzzy control system is proven to be globally stable in the sense that all signalsinvolved are bounded, with tracking errors converging to zero. Simulation results demonstrate the effectiveness of the approach.

关键词： decentralized control model reference adaptive control sliding mode control fuzy model global stability.

Three-Dirac-fermion approach to unexpected universal gapless surface states in van der Waals magnetic topological insulators

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Science China(Physics,Mechanics & Astronomy) 2023年第9期66卷 79-85页

作者： Dinghui Wang Huaiqiang Wang Dingyu Xing haijun zhang National Laboratory of Solid State Microstructures School of PhysicsNanjing UniversityNanjing 210093China Collaborative Innovation Center of Advanced Microstructures Nanjing UniversityNanjing 210093China

Layered van der Waals(vdW) topological materials, especially the recently discovered MnBi_(2)Te_(4)-family magnetic topological insulators(TIs), have aroused great attention. However, there has been a serious debate about whether the surface states are gapped or gapless for antiferromagnetic(AFM) TI MnBi_(2)Te_(4), which is crucial to the prospect of various magnetic topological phenomena. Here, a minimal three-Dirac-fermion approach is developed to generally describe topological surface states of nonmagnetic/magnetic vdW TIs under the modulation of the interlayer vdW gap. In particular, this approach is applied to address the controversial issues concerning the surface states of vdW AFM TIs. Remarkably, topologically protected gapless Dirac-cone surface states are found to arise due to a small expansion of the interlayer vdW gap on the surface, when the Chern number equals zero for the surface ferromagnetic layer;while the surface states remain gapped in all other cases. These results are further confirmed by our first-principles calculations on AFM TI MnBi_(2)Te_(4). The theorectically discovered gapless Dirac-cone states provide a unique mechanism for understanding the puzzle of the experimentally observed gapless surface states in MnBi_(2)Te_(4).This work also provides a promising way for experiments to realize the intrinsic magnetic quantum anomalous Hall efect in MnBi_(2)Te_(4) films with a large energy gap.

关键词： magnetic topological insulator van der Waals gap Dirac-fermion model gapless surface state

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Tunable dynamical magnetoelectric effect in antiferromagnetic topological insulator MnBi_(2)Te_(4) films

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npj Computational Materials 2021年第1期7卷 1101-1106页

作者： Tongshuai Zhu Huaiqiang Wang haijun zhang Dingyu Xing National Laboratory of Solid State Microstructures School of PhysicsNanjing UniversityNanjingChina Department of Physics University of ZurichZurichSwitzerland Collaborative Innovation Center of Advanced Microstructures Nanjing UniversityNanjingChina

Axion was postulated as an elementary particle to solve the strong charge conjugation and parity puzzle,and later axion was also considered to be a possible component of dark matter in the ***,the existence of axions in nature has not been ***,axions arise out of pseudoscalar fields derived from the Chern–Simons theory in condensed matter *** antiferromagnetic insulators,the axion field can become dynamical due to spin-wave excitations and exhibits rich exotic phenomena,such as axion ***,antiferromagnetic dynamical axion insulator has yet been experimentally identified in realistic *** recently,MnBi_(2)Te_(4)was discovered to be an antiferromagnetic topological insulator with a quantized static axion field protected by inversion symmetry P and magnetic-crystalline symmetry ***,we studied MnBi_(2)Te_(4)films in which both the P and S symmetries are spontaneously broken and found that substantially enhanced dynamical magnetoelectric effects could be realized through tuning the thickness of MnBi_(2)Te_(4)films,temperature,or element *** results show that thin films of MnBi_(2)Te_(4)and related compounds could provide a promising material platform to experimentally study axion electrodynamics.

关键词： materials dynamical insulator

One dimensional carbon-based composites as cathodes for lithium-sulfur battery

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Journal of Materials Science & Technology 2022年第27期122卷 101-120页

作者： Jin Luo Keke Guan Wen Lei Shaowei zhang Quanli Jia haijun zhang The State Key Laboratory of Refractories and Metallurgy Wuhan University of Science and TechnologyWuhan 430081China College of Engineering Mathematics and Physical SciencesUniversity of ExeterExeter EX44QFUnited Kingdom Henan Key Laboratory of High Temperature Functional Ceramics Zhengzhou UniversityZhengzhou 450052China

Lithium-sulfur batteries(LSBs),owing to their much higher energy density compared to the traditional lithium-ion battery,are deemed as one of the most promising candidates for the energy storage ***,several issues including shuttle effect,lithium dendrites,and volumetric expansion seriously impede the commercial applications of ***-dimensional carbon materials(1DCMs)have been widely used as the matrix material for LSBs due to their high surface area,superior conductivity,good flexibility,excellent mechanical stability,and functional *** this review,the recent progress in 1D carbon-based composites as cathode including metal compounds/1DCMs,MOFs/1DCMs,MXenes/1DCMs,and polymers/1DCMs were *** strategies for polysulfide confinement and analysis of the functions of various components in the composites were summarized *** the end,the current challenges of LSBs were systematically summarized,and the future outlooks were proposed,aiming at providing a comprehensive insight into the design of new host materials for nextgeneration LSBs.

关键词： One-dimensional carbon materials Composites Lithium-sulfur batteries Cathode Suttle effect

Synthesis and microwave characterization of Co-SiC core-shell powders by electroless plating

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Rare Metals 2006年第3期25卷 216-220页

作者： zhang haijun WU Xiangwei JIA Quanli JIA Xiaolin High Temperature Ceramics Zhengzhou University Zhengzhou 450052 China

Co-SiC core-shell powders were prepared by electroless plating. Scanning electron microscopy （SEM） revealed that Co-SiC core-shell powders were of nearly sphere-like shape and were about 0.3 pan. X-ray powder diffraction （XRD） patterns showed that the cobalt powder was hexagonal crystallite. The complex dielectric constant and the complex permeability of Co-SiC core-shell powders-paraffin wax composite were measured by the rectangle wavegnide method. It showed that the dielectric loss was less than 0.1 and the magnetic loss was about 0.2 in 8.2-12.4 GHz for prepared Co-SiC core-shell comoosite oowders.

关键词： Co-SiC core-shell powders electroless plating dielectric constant permeability