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Joint alignment and steering to manage interference

Digital Communications and Networks 2024年第2期10卷 429-438页

作者： Zhao Li Xiujuan Liang Yinghou liu Jia liu Zheng Yan School of Cyber Engineering Xidian UniversityXi'an710126China Technol.on Commun.Net.Lab. The 54th Research Inst.of China Elec.Technol.Group Corp.Shijiazhuang050081China School of Computer Science and Technology Xidian UniversityXi'an710126China The Department of Communications and Networking(Comnet) Aalto University02150EspooFinland

In wireless communication networks,mobile users in overlapping areas may experience severe interference,therefore,designing effective Interference Management(IM)methods is crucial to improving network ***,when managing multiple disturbances from the same source,it may not be feasible to use existing IM methods such as Interference Alignment(IA)and Interference Steering(IS)*** is because with IA,the aligned interference becomes indistinguishable at its desired Receiver(Rx)under the cost constraint of Degrees-of-Freedom(DoF),while with IS,more transmit power will be consumed in the direct and repeated application of IS to each *** remedy these deficiencies,Interference Alignment Steering(IAS)is proposed by incorporating IA and IS and exploiting their advantages in *** IAS,the interfering Transmitter(Tx)first aligns one interference incurred by the transmission of one data stream to a one-dimensional subspace orthogonal to the desired transmission at the interfered Rx,and then the remaining interferences are treated as a whole and steered to the same subspace as the aligned ***,two improved versions of IAS,i.e.,IAS with Full Adjustment at the Interfering Tx(IAS-FAIT)and Interference Steering and Alignment(ISA),are *** former considers the influence of IA on the interfering user-pair's *** orthogonality between the desired signals at the interfered Rx can be maintained by adjusting the spatial characteristics of all interferences and the aligned interference components,thus ensuring the Spectral Efficiency(SE)of the interfering communication *** ISA,the power cost for IS at the interfered Tx is minimized,hence improving SE performance of the interfered *** the proposed methods are realized at the interfering and interfered Txs cooperatively,the expenses of IM are shared by both *** in-depth simulation results show that joint use of IA and

关键词： Interference Interference management Interference alignment Interference steering Spectral efficiency

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Contact engineering for temperature stability improvement of Bi-contacted MoS2 field effect transistors

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Science China(Information Sciences) 2024年第6期67卷 172-179页

作者： Zizheng liu Qing ZHANG Xiaohe HUANG Chunsen liu Peng ZHOU State Key Laboratory of Integrated Chip and Systems School of MicroelectronicsZhangjiang Fudan International Innovation CenterFudan University Frontier Institute of Chip and System Shanghai Key Lab for Future Computing Hardware and SystemFudan University Shaoxin Laboratory

Semimetallic bismuth（Bi） is one of the most effective strategies for reducing the contact resistance of two-dimensional transition metal dichalcogenide field effect transistors（FETs）. However, the low melting point of Bi contact（271.5℃） limits its reliable applications. In this study, we demonstrated that the temperature stability of Bi-contacted electrodes could be improved by inserting a high-melting point semimetallic antimony（Sb） between the Bi contacting layer and the gold（Au） capping layer. The proposed Bi/Sb/Au contact electrodes tended to form a metal mixture with a continuous surface during the heating process（Voids appeared on the surface of the Bi/Au contact electrodes after heating at 120℃）. Because of the improved contacting layer formed by the semimetal Bi/Sb alloy, the fabricated Bi/Sb/Au-contacted molybdenum sulfide（MoS2） FETs with different gate lengths demonstrated higher on-state current stability after heating treatment than the Bi/Au contact. Because of the Bi/Sb/Au contact and poly（methyl methacrylate） package, the MoS2FETs demonstrated time stability of at least two months from the almost unchanged transfer characteristics. The electrical stability indicates that the insertion of semimetallic Sb is a promising technology for reliable Bi-based contact.

关键词： temperature stability semimetallic bismuth contact semimetallic antimony contact MoS$_{2}$ FETs time stability

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Identification of the optimal doping position of hetero-atoms in chalcogen-doped Fe-N-C catalysts for oxygen reduction reaction

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Particuology 2024年第6期89卷 99-108页

作者： Weihao liu Huanhuan He Qingtao liu Xin Wan Jianglan Shui School of Materials Science and Engineering Beihang UniversityBeijing100191China School of Space and Environment Beihang UniversityBeijing102206China Tianmushan Laboratory Hangzhou310023China

The excellent oxygen reduction reaction(ORR)activity of Fe–N–C catalysts in acidic media makes them potential for low-cost proton exchange membrane fuel *** recent years,it has been shown that heteroatoms(B,O,S,P,Cl,F,etc.)can be used as electron-withdrawing groups to modulate the planar structure and electron distribution of the Fe–Nx active sites to achieve simultaneous improvement of catalytic activity and ***,the optimal location of the heteroatoms remains ***,taking chalcogen heteroatoms(S and Se)as an example,we control the doping positions and investigate their effect on the ORR performance of the Fe–N–C *** first coordination shell of the iron single atom is identified as the optimal doping *** optimized catalysts Fe–N_(3)Se_(1)/NC and Fe–N_(3)Se_(1)/NC demonstrate improved activity and stability in both half cells and fuel *** work provides insights into the enhancement mechanism of heteroatom doping in single-atom catalysts.

关键词： Oxygen reduction reaction Fe-N-C catalysts Hetero-atom doping Doping position Enhancement mechanism

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Stable hydrogen-bonded organic frameworks and their photo-and electro-responses

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Nano Research 2024年第8期17卷 7675-7699页

作者： Ying Hou Xin-Song Huang Sheng-Hao Gong Chen liu Yangyang liu Tian-Fu liu State Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhou 350002China University of Chinese Academy of Sciences Beijing 100049China Department of Chemistry and Biochemistry California State UniversityLos AngelesCalifornia 90032USA College of Chemistry and Materials Science Fujian Normal UniversityFuzhou 350007China

Hydrogen-bonded organic frameworks(HOFs)are a recent class of porous materials that have garnered considerable research interest owing to their distinctive *** can be constructed through judicious selection of H-bonding motifs,which are further enforced by other weak intermolecular interactions such asπ–πstacking,van der Waals forces,and framework *** advantage of these interactions,we can expand the functional field of HOFs by introducing active ***,researchers have made substantial advancements in using HOFs for chemical sensing,catalysis,proton conduction,biological applications,and *** low bonding energy of H-bonds allows for precise control over the concentration of ligands in solvents,forming diverse HOF *** varied structures offer significant advantages for producing HOFs with photo-responsive and electro-responsive ***,the presence of H-bonds in HOFs results in their inherent lower stability compared to metal-organic frameworks(MOFs)and covalent-organic frameworks(COFs)formed via coordination and covalent bonds,*** a result,the pursuit of stable and innovative HOF materials with novel functional sites remains an ongoing *** review provides an overview of recent research progress in the development of new strategies for stable HOF synthesis and applications of HOFs with stimuli-responsive *** first classified all synthetic methods reported to date and discussed the stable HOFs synthesized,as well as their unique properties and *** addition,we summarized the applications of HOFs utilizing their synergistic responses to external stimuli,including photo,electrical,pressure,and chemical *** systematically reviewed stable HOF synthesis and applications,which may lead to a deeper understanding of the structure–activity relationship for these materials and guide future HOF design.

关键词： stable hydrogen-bonded organic frameworks(HOFs) photo-response electro-response photoelectric synergistic response

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Effects of vibration conditions,spatial confinement and friction on mixing and segregation characteristics of mixed pebble beds for CFETR WCCB blanket

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Particuology 2024年第2期85卷 268-279页

作者： Yong liu Chongyang He Cong Wang Lei Chen Songlin liu Institute of Plasma Physics Hefei Institutes of Physical ScienceChinese Academy of SciencesHefei230031China University of Science and Technology of China Hefei230027China Chengdu University Chengdu610106China Zhejiang Lab Hangzhou310000China

This paper presents the study of the dynamic characteristics of confined mixed pebble beds with different friction under different vibration conditions using the discrete element ***λsegre-gation index is used to quantify the degree of particle mixing or *** percolation,convection and diffusion mechanisms are responsible for the segregation patterns of the mixed *** results show the degree of segregation can be suppressed by decreasing the vibration acceleration or free space height below a *** simulation reveals the threshold of vibration acceleration or free space height both are related to the bed height increment which determines the strength of the percolation *** addition,the strength of percolation and convection becomes weaker by decreasing the friction of particles and walls,which makes the pebbled bed remains in a mixed state under *** findings are significant to clarify the main factors behind the three segregation mechanisms and hence provide solutions to retaining the mixed state of the Li2TiO3&Be12Ti mixed pebble bed.

关键词： Vibration Segregation Binary pebble bed Discrete element method

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Dynamic analysis of axle box bearings on the high-speed train caused by wheel-rail excitation

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Applied Mathematics and Mechanics(English Edition) 2024年第3期45卷 441-460页

作者： Qiaoying MA Shaopu YANG Yongqiang liu Baosen WANG Zechao liu State Key Laboratory of Mechanical behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao UniversityShijiazhuang 050043China School of Transportation Shijiazhuang Tiedao UniversityShijiazhuang 050043China School of Mechanical Engineering Shijiazhuang Tiedao UniversityShijiazhuang 050043China

To explore the impact of wheel-rail excitation on the dynamic performance of axle box bearings,a dynamic model of the high-speed train including axle box bearings is ***,the dynamic response characteristics of the axle box bearing are *** investigation focuses on the acceleration characteristics of bearing vibration under excitation of track irregularities and wheel *** addition,experiments on both normal and faulty bearings are conducted separately,and the correctness of the model and some conclusions are *** to the research,track irregularity is unfavorable for bearing fault detection based on resonance *** the same speed conditions,the acceleration peak of bearing is inversely proportional to the length of the wheel flat and directly proportional to its *** paper will contribute to a deeper understanding of the dynamic performance of axle box bearings.

关键词： high-speed train track irregularity wheel flat dynamic simulation

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High-performance,stable CoNi LDH@Ni foam composite membrane with innovative peroxymonosulfate activation for 2,4-dichlorophenol destruction

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Journal of Environmental Sciences 2024年第7期141卷 235-248页

作者： Yu liu Weibao liu Xinrui Gan Jiangwei Shang Xiuwen Cheng College of Chemistry and Environmental Science Xinjiang Laboratory of Phase Transitions and Microstructures of Condensed Matter PhysicsYili Normal UniversityYining 835000China Key Laboratory for Environmental Pollution Prediction and Control Gansu ProvinceCollege of Earth and Environmental SciencesLanzhou UniversityLanzhou 730000China

In this study,the cobalt-nickel layered double hydroxides(CoNi LDH)were synthesized with a variety of Co/Ni mass ratio,as *** comparison,Co1Ni3LDH presented the best peroxymonosulfate(PMS)activation efficiency for 2,4-dichlorophenol ***,CoNi LDH@Nickel foam(CoNi LDH@NF)composite membrane was constructed for enhancing the stability of catalytic ***,CoNi LDH@NF-PMS system exerted high degradation efficiency of 99.22%within 90 min for 2,4-DCP when[PMS]_(0)=0.4 g/L,Co^(1)Ni^(3)LDH@NF=2 cm×2 cm(0.2 g/L),reaction temperature=298 *** the surface morphology and structure of the catalyst,it was demonstrated that the CoNi LDH@NF composite membrane possessed abundant cavity structure,good specific surface area and sufficient active ***,·OH,SO_(4)·^(-)and^(1)O_(2)played the primary role in the CoNi LDH@NF-PMS system for 2,4-DCP decomposition,which revealed the PMS activation mechanism in CoNi LDH@NF-PMS ***,this study eliminated the stability and adaptability of CoNi LDH@NF composite membrane,proposing a new theoretical basis of PMS heterogeneous catalysts selection.

关键词： CoNi LDH@NF composite membrane Peroxymonosulfate 2,4-dichlorophenol Reactive radicals

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Unmanned Aerial Vehicles General Aerial Person-Vehicle Recognition Based on Improved YOLOv8s Algorithm

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Computers, Materials & Continua 2024年第3期78卷 3787-3803页

作者： Zhijian liu School of Electrical Engineering and Electronic Information Xihua UniversityChengdu610036China

Considering the variations in imaging sizes of the unmanned aerial vehicles(UAV)at different aerial photography heights,as well as the influence of factors such as light and weather,which can result in missed detection and false detection of the model,this paper presents a comprehensive detection model based on the improved lightweight You Only Look Once version 8s(YOLOv8s)algorithm used in natural light and infrared scenes(L_YOLO).The algorithm proposes a special feature pyramid network(SFPN)structure and substitutes most of the neck feature extraction module with the Special deformable convolution feature extraction module(SDCN).Moreover,the model undergoes pruning to eliminate redundant ***,the non-maximum suppression algorithm of intersection-union ratio based on minimum point distance(MPDIOU_NMS)algorithm has been integrated to eliminate redundant detection boxes,and a comprehensive validation has been conducted using the infrared aerial dataset and the Visdrone2019 *** comprehensive experimental results demonstrate that when the number of parameters and floating-point operations is reduced by 30%and 20%,respectively,there is a 1.2%increase in mean average precision at a threshold of 0.5(mAP(0.5))and a 4.8%increase in mAP(0.5:0.95)on the infrared ***,the mAP on the Visdrone2019 dataset has experienced an average increase of 12.4%.The accuracy and recall rates have seen respective increases of 9.2%and 3.6%.

关键词： YOLOv8s SPFN SDCN pruning MPDIOU_NMS

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Optimization performance of quantum endoreversible Otto machines with dual-squeezed reservoirs

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Chinese Physics B 2024年第10期33卷 198-204页

作者： Haoguang liu College of Science and Technology Nanchang Aeronautical UniversityNanchang 332020China

We consider a quantum endoreversible Otto engine cycle and its inverse operation-Otto refrigeration cycle,employing two-level systems as the working substance and operating in dual-squeezed *** demonstrate that the efficiency of heat engines at maximum work output and the coefficient of performance for refrigerators at the maximum c criterion will degenerate toη-=η_(C)/(2-η_(C))andε-=(√9+8ε_(C)-3)/2 when symmetric squeezing is satisfied,*** also investigated the influences of squeezing degree on the performance optimization of quantum Otto heat engines at the maximum work output and refrigerators at the maximum X *** analytical results show that the efficiency of heat engines at maximum work output and the coefficient of performance for refrigerators at the maximum X criterion can be improved,reduced or even inhibited in asymmetric ***,we also find that the efficiency of quantum Otto heat engines at maximum work output is lower than that obtained from the Otto heat engines based on a single harmonic oscillator ***,the coefficient of performance of the corresponding refrigerator is higher.

关键词： quantum Otto heat engine quantum Otto refrigerator optimization performance dual-squeezed reservoirs

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Active MoS_(2)-based electrode for green ammonia synthesis

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Chinese Journal of Chemical Engineering 2024年第1期65卷 268-275页

作者： Xin liu Lei Yang Tao Wei Shanping liu Beibei Xiao School of Energy and Power Engineering Jiangsu University of Science and TechnologyZhenjiang 212003China Institute Charles Gerhardt Montpellier UMR-5253Universite de MontpellierCNRSENSCMPlace E.Bataillon34095 Montpellier Cedex 05France

Nitrogen electro-reduction under mild conditions is one promising alternative approach of the energyconsuming Haber-Bosch process for the artificial ammonia *** critical aspect to unlocking this technology is to discover the catalysts with high selectivity and *** this work,the N_(2)-to-NH_(3)conversion on the functional MoS_(2)is fully investigated by density functional theory calculations since the layered MoS_(2)provides the ideal platform for the elaborating copies of the nitrogenase found in nature,wherein the functionalization is achieved via basal-adsorption,basal-substitution or edge-substitution of transition metal *** results reveal that the edge-functionalization is a feasible strategy for the activity promotion;however,the basal-adsorption and basal-substitution separately suffer from the electrochemical instability and the NRR ***,MoS_(2)functionalized via edge W-substitution exhibits an exceptional *** energetically favored reaction pathway is through the distal pathway and a limiting potential is less than 0.20 ***,this work escalates the rational design of the high-effective catalysts for nitrogen fixation and provides the explanation why the predicated catalyst have a good performance,paving the guidance for the experiments.

关键词： Nitrogen reduction reaction Density functional theory calculations Molybdenum disulfide Electrochemistry Catalyst Thermodynamics

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