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Science China(Physics,Mechanics & Astronomy) 2021年第8期64卷 72-77页

作者： ya-ning ren Mo-Han Zhang Chao yan Yu Zhang Lin He Center for Advanced Quantum Studies Department of PhysicsBeijing Normal UniversityBeijing 100875China

Shubnikov-de Haas oscillations are the most well-known magneto-oscillations in transport measurements. They are caused by Landau quantization of two-dimensional(2D) electron systems in the presence of a magnetic field. Here we demonstrate that a scanning tunneling microscope(STM) can locally measure similar magneto-oscillations in 2D systems. In Landau level spectroscopy measurements with fine magnetic-field increments, we observed fixed-energy magnetic-field-dependent oscillations of the local density of states. From the measured tunneling magneto-conductance oscillations acquired by STM, energymomentum dispersions and Berry phases of a monolayer, Bernal-stacked bilayer, and ABC-stacked trilayer graphene were obtained. The reported method is applicable to a wide range of materials because it can obtain the magneto-oscillations of 2D systems larger than the magnetic length;importantly, it also requires no gate electrode.

关键词： graphene magneto-conductance oscillations scanning tunneling microscopy energy-momentum dispersion Berry phase

Twistronics in graphene-based van der Waals structures

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Chinese Physics B 2020年第11期29卷 1-16页

作者： ya-ning ren Yu Zhang Yi-Wen Liu Lin He Center for Advanced Quantum Studies Department of PhysicsBeijing Normal UniversityBeijing 100875China

The electronic properties of van der Waals(vd W) structures can be substantially modified by the moiré superlattice potential, which strongly depends on the twist angle among the compounds. In twisted bilayer graphene(TBG), two lowenergy Van Hove singularities(VHSs) move closer with decreasing twist angles and finally become highly non-dispersive flat bands at the magic angle(~1.1°). When the Fermi level lies within the flat bands of the TBG near the magic angle,Coulomb interaction is supposed to exceed the kinetic energy of the electrons, which can drive the system into various strongly correlated phases. Moreover, the strongly correlated states of flat bands are also realized in other graphene-based vd W structures with an interlayer twist. In this article, we mainly review the recent scanning tunneling microscopy(STM)advances on the strongly correlated physics of the magic-angle TBG(MATBG) and the small-angle twisted multilayer graphene. Lastly we will give out a perspective of this field.

关键词： twisted bilayer graphene correlated states superconductivity

Imaging field-tuned quantum Hall broken-symmetry orders and the quantum Hall conducting channel in a charge-neutral graphene/WSe_(2) heterostructure

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中国科学:物理学、力学、天文学英文版 2023年第7期66卷 88-93页

作者： Qi Zheng Mo-Han Zhang ya-ning ren Ruo-Han Zhang Lin He Center for Advanced Quantum Studies Department of PhysicsBeijing Normal UniversityBeijing 100875China

The zeroth Landau level(0LL)in graphene has emerged as a flat band platform in which distinct many-body phases can be explored with unprecedented control by simply tuning the strength and/or direction of the magnetic field.A rich set of quantum Hall ferromagnetic phases with different lattice-scale symmetry-breaking orders are predicted to be realized in high magnetic fields when the 0LL in graphene is *** we report on a field-tuned continuous phase transition of different valley orderings in a quantum Hall ferromagnetic phase of charge-neutral graphene on insulating tungsten diselenide(WSe_(2)).The phase transition is clearly revealed by an anomalous field-dependent energy gap in the half-filled *** atomic resolution imaging of electronic wavefunctions during the phase transition,we unexpectedly observe the microscopic signatures of fieldtuned continuous-varied valley polarization and valley inversion,which are beyond current theoretical ***,the quantum Hall conducting channel of the graphene is directly imaged when the substrate(WSe_(2))introduces band bending of the 0LL.

关键词： graphene WSe_(2) quantum Hall ferromagnetic valley polarization valley inversion

Empirical model of concrete block fragment behavior under explosion loads

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Science China(Technological Sciences) 2024年第8期67卷 2515-2529页

作者： yaNG Shuai ning JianGuo ren HuiLan XU XiangZhao State Key Laboratory of Explosion Science and Safety Protection Beijing Institute of TechnologyBeijing 100081China

Concrete structures undergo integral fragmentation under explosion loads. The fragmentation degree and particle-size distribution of concrete blocks under explosion loads must be considered during mining to ensure safety. In this study, the impulse is calculated based on the relationship between overpressure and time, and the impact energy of the explosion wave is obtained based on blast theory. Subsequently, the Mohr-Coulomb shear strength fracture criterion is introduced to determine the ultimate shear stress of the concrete materials, and an empirical model that can effectively calculate the energy consumption of concrete blocks under explosion loads is established. Furthermore, concrete fragments with different particle sizes under explosion scenarios are quantitatively predicted with the principle of energy conservation. Finally, explosion tests with different top standoff distances are conducted, and the concrete fragments after the explosion tests are recovered, sieved, weighed, and counted to obtain experimental data. The effectiveness of the fragment empirical model is verified by comparing the model calculation results with the experimental data. The proposed model can be used as a reference for civil blasting, protective engineering design, and explosion-damage assessment.

关键词： concrete structures explosion loads fragment behavior empirical model

A Practical Approach for Missing Wireless Sensor Networks Data Recovery

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China Communications 2024年第5期21卷 202-217页

作者： Song Xiaoxiang Guo yan Li ning ren Bing The College of Communications Engineering Army Engineering University of PLANanjing 210007China The 63891 Unit of PLA Luoyang 471000China

In wireless sensor networks(WSNs),the performance of related applications is highly dependent on the quality of data ***,missing data is almost inevitable in the process of data acquisition and *** methods often rely on prior information such as low-rank characteristics or spatiotemporal correlation when recovering missing WSNs ***,in realistic application scenarios,it is very difficult to obtain these prior information from incomplete data ***,we aim to recover the missing WSNs data effectively while getting rid of the perplexity of prior *** designing the corresponding measurement matrix that can capture the position of missing data and sparse representation matrix,a compressive sensing(CS)based missing data recovery model is ***,we design a comparison standard to select the best sparse representation basis and introduce average cross-correlation to examine the rationality of the established ***,an improved fast matching pursuit algorithm is proposed to solve the *** results show that the proposed method can effectively recover the missing WSNs data.

关键词： average cross correlation matching pursuit missing data wireless sensor networks

Recent progress in CdS-based S-scheme photocatalysts

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Journal of Materials Science & Technology 2024年第4期171卷 162-184页

作者： yajing ren Yunfeng Li Guixu Pan ning Wang yan Xing Zhenyi Zhang College of Environmental and Chemical Engineering Xi’an Polytechnic UniversityXi’an 710048China Jilin Provincial Key Laboratory of Advanced Energy Materials Department of ChemistryNortheast Normal UniversityChangchun 130024China Key Laboratory of New Energy and Rare Earth Resource Utilization of State Ethnic Affairs Commission Key Laboratory of Photosensitive Materials and Devices of Liaoning ProvinceSchool of Physics and Materials EngineeringDalian Minzu UniversityDalian 116600China

Photocatalytic technology with sunlight as driving force can convert solar energy into other energy sources for storage and further *** sulfide(CdS),as a typical reducing semiconductor of metal sulfides,represents an interesting research hotspot in photocatalysis due to its suitable bandgap(2.4 eV)for utilizing visible light and strong reducing ability for inducing surface catalytic ***,the photocatalytic performance of CdS is still limited by its fast carrier recombination and serious *** far,CdS semiconductor has been widely developed as a typical reducing photocatalyst in constructing novel S-scheme heterojunction to overcome the above *** this review,the de-sign concepts,basic principles,and charge transfer characteristics of CdS-based S-scheme heterojunction photocatalysts have been comprehensively *** advanced and effective characterization methods for studying the mechanism of CdS-based S-scheme heterojunction are analyzed in ***-thermore,we also summarize the typical applications of CdS-based S-scheme heterojunctions for water splitting,CO_(2) reduction,pollutant degradation,***,according to the current investigation sta-tus,some drawbacks in the current synthetic strategy,mechanism exploration,and application prospect of CdS-based S-scheme heterojunction are proposed,which need to be addressed by further expansion and innovative research.

关键词： Photocatalysis CdS semiconductor Heterojunction S-scheme Metal sulfide

Microstructures and micromechanical behaviors of high -entropy alloys investigated by synchrotron X-ray and neutron diffraction techniques: A review

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International Journal of Minerals,Metallurgy and Materials 2024年第6期31卷 1333-1349页

作者： Yubo Huang ning Xu Huaile Lu yang ren Shilei Li yandong Wang Beijing Advanced Innovation Center of Materials Genome Engineering State Key Laboratory for Advanced Metals and MaterialsUniversity of Science and Technology BeijingBeijing 100083China AnSteel Beijing Research Institute Co.Ltd. Beijing 102200China Spallation Neutron Source Science Center Dongguan 523803China Department of Physics City University of Hong KongHong Kong 999077China Institute for Materials Intelligent Technology Liaoning Academy of MaterialsShenyang 110004China

High-entropy alloys(HEAs)possess outstanding features such as corrosion resistance,irradiation resistance,and good mechan-ical properties.A few HEAs have found applications in the fields of aerospace and *** studies on the deformation mech-anisms of HEAs can guide microstructure control and toughness design,which is vital for understanding and studying state-of-the-art structural *** X-ray and neutron diffraction are necessary techniques for materials science research,especially for in situ coupling of physical/chemical fields and for resolving macro/microcrystallographic information on ***,several re-searchers have applied synchrotron X-ray and neutron diffraction methods to study the deformation mechanisms,phase transformations,stress behaviors,and in situ processes of HEAs,such as variable-temperature,high-pressure,and hydrogenation *** this review,the principles and development of synchrotron X-ray and neutron diffraction are presented,and their applications in the deformation mechanisms of HEAs are *** factors that influence the deformation mechanisms of HEAs are also *** review fo-cuses on the microstructures and micromechanical behaviors during tension/compression or creep/fatigue deformation and the application of synchrotron X-ray and neutron diffraction methods to the characterization of dislocations,stacking faults,twins,phases,and intergrain/interphase stress *** on future developments of synchrotron X-ray and neutron diffraction and on research directions on the deformation mechanisms of novel metals are discussed.

关键词： high-entropy alloys microstructures micromechanical behaviors synchrotron X-ray diffraction neutron diffraction

In-situ interfacial passivation and self-adaptability synergistically stabilizing all-solid-state lithium metal batteries

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Journal of Energy Chemistry 2024年第1期88卷 282-292,I0007页

作者： Huanhui Chen Xing Cao Moujie Huang Xiangzhong ren Yubin Zhao Liang Yu ya Liu Liubiao Zhong Yejun Qiu Shenzhen Engineering Lab of Flexible Transparent Conductive Films School of Materials Science and EngineeringHarbin Institute of TechnologyShenzhen 518055GuangdongChina Guangdong Provincial Key Laboratory of Semiconductor Optoelectronic Materials and Intelligent Photonic Systems School of Materials Science and EngineeringHarbin Institute of TechnologyShenzhen 518055GuangdongChina College of Chemistry and Environmental Engineering Shenzhen UniversityShenzhen 518060GuangdongChina School of Resource and Environmental Sciences Wuhan UniversityWuhan 430072HubeiChina

The function of solid electrolytes and the composition of solid electrolyte interphase(SEI)are highly significant for inhibiting the growth of Li ***,we report an in-situ interfacial passivation combined with self-adaptability strategy to reinforce Li_(0.33)La_(0.557)TiO_(3)(LLTO)-based solid-state ***,a functional SEI enriched with LiF/Li_(3)PO_(4) is formed by in-situ electrochemical conversion,which is greatly beneficial to improving interface compatibility and enhancing ion *** the polarized dielectric BaTiO_(3)-polyamic acid(BTO-PAA,BP)film greatly improves the Li-ion transport kinetics and homogenizes the Li *** expected,the resulting electrolyte offers considerable ionic conductivity at room temperature(4.3 x 10~(-4)S cm^(-1))and appreciable electrochemical decomposition voltage(5.23 V)after electrochemical *** Li-LiFePO_(4) batteries,it shows a high specific capacity of 153 mA h g^(-1)at 0.2C after 100 cycles and a long-term durability of 115 mA h g^(-1)at 1.0 C after 800 ***,a stable Li plating/stripping can be achieved for more than 900 h at 0.5 mA cm^(-2).The stabilization mechanisms are elucidated by ex-situ XRD,ex-situ XPS,and ex-situ FTIR techniques,and the corresponding results reveal that the interfacial passivation combined with polarization effect is an effective strategy for improving the electrochemical *** present study provides a deeper insight into the dynamic adjustment of electrode-electrolyte interfacial for solid-state lithium batteries.

关键词： Solid-state lithium batteries Composite solid electrolyte In-situ polymerization Interfacial passivation layer Self-adaptability

An Interpretable Light Attention-Convolution-Gate Recurrent Unit Architecture for the Highly Accurate Modeling of Actual Chemical Dynamic Processes

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Engineering 2024年第8期39卷 104-116页

作者： Yue Li ning Li Jingzheng ren Weifeng Shen School of Chemistry and Chemical Engineering Chongqing UniversityChongqing 400044China Chongqing Key Laboratory of Catalysis and New Environmental Materials School of Environment and ResourcesChongqing Technology and Business UniversityChongqing 400067China Department of Industrial and Systems Engineering The Hong Kong Polytechnic UniversityHong Kong 999077China

To equip data-driven dynamic chemical process models with strong interpretability,we develop a light attention–convolution–gate recurrent unit(LACG)architecture with three sub-modules—a basic module,a brand-new light attention module,and a residue module—that are specially designed to learn the general dynamic behavior,transient disturbances,and other input factors of chemical processes,*** with a hyperparameter optimization framework,Optuna,the effectiveness of the proposed LACG is tested by distributed control system data-driven modeling experiments on the discharge flowrate of an actual deethanization *** LACG model provides significant advantages in prediction accuracy and model generalization compared with other models,including the feedforward neural network,convolution neural network,long short-term memory(LSTM),and ***,compared with the simulation results of a deethanization model built using Aspen Plus Dynamics V12.1,the LACG parameters are demonstrated to be interpretable,and more details on the variable interactions can be observed from the model parameters in comparison with the traditional interpretable model *** contribution enriches interpretable machine learning knowledge and provides a reliable method with high accuracy for actual chemical process modeling,paving a route to intelligent manufacturing.

关键词： Interpretable machine learning Light attention-convolution-gate recurrent unit architecture Process knowledge discovery Data-driven process model Intelligent manufacturing

Mechanism of high-energy pulsed current-assisted rolling of 08AL carbon steel ultra-thin strip

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Journal of Iron and Steel Research International 2024年第2期31卷 416-427页

作者： Zhong-kai ren ya-nan Xu Jia-zhao Chen He Li Rui-lin Yuan Zhen-hua Wang Tao Wang Xiao Liu College of Mechanical and Vehicle Engineering Taiyuan University of TechnologyTaiyuan030024ShanxiChina Engineering Research Center of Advanced Metal Composites Forming Technology and Equipment(Ministry of Education) Taiyuan University of TechnologyTaiyuan030024ShanxiChina National Key Laboratory of Metal Forming Technology and Heavy Equipment China National Heavy Machinery Research Institute Co.Ltd.Xi’an710016ShaanxiChina

To improve the plastic deformation performance of a 08AL carbon steel ultra-thin strip,a pulsed electric field was integrated into the plastic processing of the ultra-thin strip,and the effects of high-energy current on its deformation ability were ***-assisted tensile tests were employed,and the results clarified that the pulsed current could reduce the activation energy of faults and promoted dislocation slip within grains and at grain boundaries,leading to a decrease in the deformation resistance of the metal and an increase in its plastic *** the current density of 2.0 A/mm2,the yield strength,tensile strength,and elongation of the rolled sample reached 425 MPa,467 MPa,and 12.5%,*** the rolling process,it was found that the pulsed current promoted the dynamic recrystallization of the ultra-thin strip,reduced its dislocation density and deformation resistance,and promoted the coordinated deformation of the metal.

关键词： 08AL ultra-thin strip High-energy pulsed current Mechanical property Dislocation density Dynamic recrystallization