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Nearly degenerate ground states of a checkerboard antiferromagnet and their bosonic interpretation

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Science China(Physics,Mechanics & Astronomy) 2024年第1期67卷 84-89页

作者： Haiyuan Zou fan Yang Wei Ku Key Laboratory of Polar Materials and Devices(MOE) School of Physics and Electronic ScienceEast China Normal UniversityShanghai 200241China Department of Physics Beijing Institute of TechnologyBeijing 100081China Tsung-Dao Lee Institute Shanghai 200240China Key Laboratory of Artificial Structures and Quantum Control(Ministry of Education) Shanghai 200240China Shanghai Branch Hefei National LaboratoryShanghai 201315China

The spin-1/2 model system with antiferromagnetic(AF) couplings on a J1-J2checkerboard lattice, known as the planar pyrochlore model, is strongly frustrated and associated with a two-to-one dimensional crossover. Using the Projected Entangled Simplex States tensor network ansatz, we identify a large number of nearly degenerate states in the frustrated region(J_(1)

关键词： tensor networks frustrated magnetism dimensional crossover degenerate states

Engineering tantalum nitride for efficient photoelectrochemical water splitting

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Science China Chemistry 2024年第7期67卷 2171-2180页

作者： Beibei Zhang Zeyu fan Yanbo Li Institute of Fundamental and Frontier Sciences University of Electronic Science and Technology of ChinaChengdu 610054China

Photoelectrochemical(PEC)water splitting is a promising energy conversion strategy for directly converting solar energy into green hydrogen *** an efficient PEC device,finding an efficient photoanode material with a suitable band gap and favorable band-edge positions is *** nitride(Ta_(3)N_(5))meets these fundamental requirements,and its theoretical maximum solar-to-hydrogen(STH)conversion efficiency can reach 15.9%.Consequently,it has been widely applied as a photoanode material for the PEC oxygen evolution reaction(OER).However,severe bulk and interface charge recombination,along with sluggish water oxygen kinetics,seriously limits its STH conversion efficiency for PEC water ***,this feature article briefly reviews recent advances by our research group in improving the STH conversion efficiency of the Ta_(3)N_(5)photoanode using various strategies,including defect engineering,construction of a gradient band structure,interface engineering,and surface modification of self-healing OER *** to now,the obtained half-cell STH efficiency has exceeded 4%,providing a solid foundation for the development of tandem PEC devices for unbiased solar-driven overall water splitting toward practical application.

关键词： Photoelectrochemical water splitting tantalum nitride defect engineering interface engineering oxygen evolution cocatalyst

Distributed Cell-Free Massive MIMO Versus Cellular Massive MIMO Under UE Hardware Impairments

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Chinese Journal of Electronics 2024年第5期33卷 1274-1285页

作者： Ning LI Pingzhi fan School of Information Science and Technology Southwest Jiaotong University

This paper first investigates and compares the uplink spectral efficiency(SE) of distributed cell-free massive multiple-input multiple-output(mMIMO) and cellular mMIMO networks, both with user equipment(UE)hardware impairments. We derive a lower bound on the uplink ergodic channel capacity of the cellular mMIMO with UE hardware impairments, based on which we determine the optimal receive combining that maximizes the instantaneous effective signal-to-interference-and-noise ratio. Then, a lower bound on the uplink capacity of a distributed cellfree mMIMO with UE hardware impairments is derived using the use-and-then-forget technique. On this basis, the optimum large-scale fading decoding vector is found using generalized Rayleigh entropy. By using three combining schemes of minimum mean-square error(MMSE), regularized zero-forcing(RZF), and maximum ratio, the uplink SEs of distributed cell-free mMIMO and cellular mMIMO networks are analyzed and compared. The results show that the two-layer decoding distributed cell-free mMIMO network with MMSE combining outperforms the cellular mMIMO network, and the advantage is more evident as the hardware impairment factor increases. Finally, the uplink energy efficiency(EE) of the distributed cell-free mMIMO networks is analyzed and evaluated through the established realistic power consumption model with hardware impairments. Simulation results show that two-layer decoding provides higher SE and EE than single-layer decoding. In addition, RZF achieves almost the same SE and EE as MMSE in a two-layer decoding architecture.

关键词： Massive multiple-input multiple-output (mMIMO) Cell-free mMIMO Cellular mMIMO Hardware impairments Uplink Energy efficiency Optimal receive combining Massive multiple-input multiple-output (mMIMO) Cell-free mMIMO Spectral efficiency Spectral efficiency Hardware impairments Uplink Energy efficiency Optimal receive combining ENERGY EFFICIENCY SYSTEMS NETWORKS DESIGN UPLINK PERFORMANCE

Structural superlubricity at homogenous interface of pentagraphene

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Friction 2024年第9期12卷 2004-2017页

作者： Xinqi ZHANG Jiayi fan Zichun CUI Tengfei CAO Junqin SHI Feng ZHOU Weimin LIU Xiaoli fan State Key Laboratory of Solidification Processing Center for Advanced Lubrication and Seal MaterialsSchool of Material Science and EngineeringNorthwestern Polytechnical UniversityXi’an 710072China School of Material Science and Engineering Northwestern Polytechnical UniversityXi’an 710072China State Key Laboratory of Solid Lubrication Lanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhou 730000China

Two-dimensional(2D)van der Waals layered materials have been widely used as ***-graphene(PG),a 2D carbon allotrope exclusively composed of irregular carbon pentagons has recently been predicted to have superlubricating *** the present study,by combining the molecular dynamics simulation and first-principles calculations,we investigated the frictional property of PG in both commensurate and incommensurate *** calculations show the ultra-low friction at the interface of relatively rotated bilayer PG with twist angles of more than 10°away from the commensurate ***,our calculations demonstrate the isotropy of the ultra-low friction at the interface of incommensurate contact,in contrast to the anisotropic of the commensurate contacting ***,the evolution of friction force and the fluctuation of potential energy along sliding path correlate closely with the interface’s *** energetics and charge density explain the difference between the friction at the interfaces of the commensurate and incommensurate *** only that,we found the correlation between the intrinsic structural feature and interlayer binding ***,our findings on the retainment of the ultra-low friction under work conditions indicates that the superlubricating state of PG has good practical adaptability.

关键词： structural superlubricity penta-graphene molecular dynamics incommensurate contact

Magneto-optical Kerr Effect of Mono-layer NiX_(2)(X=Cl,Br,I):A Density Functional Theory Study

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Journal of Wuhan University of Technology(Materials Science) 2024年第5期39卷 1121-1128页

作者： fan Qingqian DU Chaochao School of Economics and Management Shanghai Institute of TechnologyShanghai 200235China College of Information Science&Electronic Engineering Zhejiang UniversityHangzhou 310027China

The full-potential linearized augmented plane wave plus local orbital method is utilized for exploring the electronic,magnetic,and magneto-optical properties of the NiX_(2)(X=Cl,Br,and I)single *** first-principles calculation demonstrates that these compounds are ferromagnetic indirect semiconductors,and the energy band gaps of NiX_(2)for X=Cl,Br,and I are 3.888,3.134,and 2.157 eV,*** magnetic moments of Ni atoms in NiX_(2)monolayer are 1.656,1.588,1.449μB,and their magneto-crystalline anisotropy energies are 0.167,0.029,0.090 meV,*** on the macro-linear response theory,we systematically studied the influences of the external magnetic field and out-of-plane strain on the magneto-optical Kerr effect(MOKE)spectrum of the NiX_(2)single *** is found that,when the external magnetic field is perpendicular to the sample plane,the value of the Kerr rotation angle reaches the maximum,and the single-layer NiI_(2)material has a Kerr rotation angle of 1.89°at the photon energy of 1.986 ***,the Kerr rotation spectrum of NiCl_(2)and NiBr_(2)monolayers redshift as the out-of-plane strain increases,while NiI_(2)monolayer *** computation of the MOKE spectrum of NiX_(2)materials provides an opportunity for applications of 2D magnetic material ranging from sensing to data storing.

关键词： magneto-optical Kerr effect(MOKE) first-principles calculations external magnetic field out-of-plane strain

OnFractional(g,f,n′,m)-Critical Covered Graphs

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Journal of the Operations Research Society of China 2024年第2期12卷 446-460页

作者： Wei Gao Wei-fan Wang School of Information Science and Technology Yunnan Normal UniversityKunming 650500YunnanChina Department of Mathematics Zhejiang Normal UniversityJinhua 321004ZhejiangChina

The main contribution in this article is threefold:(1)we show the necessary and sufficient condition for graphs to be fractional(g,f)-covered which can be expressed in different forms,and extended to fractional(g,f,m)-covered graphs;(2)the concept of fractional-critical covered graph is put forward and its necessary and sufficient condition is given;(3)we present the degree condition for a graph to be fractional(g,f,n′,m)-critical covered,and show that degree bound is sharp when m is ***,the related result in fractional(a,b,n′,m)-critical covered setting is also verified.

关键词： Network Fractional factor Data transmission Fractional covered graph Fractional critical covered graph

Proposition of atomic and close-to-atomic scale manufacturing

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Advances in Manufacturing 2024年第1期12卷 1-5页

作者： Ju‑fan Zhang Jens Ducree School of Mechanical and Materials Engineering University College DublinDublin 4Ireland School of Physical Sciences Dublin City UniversityDublinIreland

Atomic and close-to-atomic scale manufacturing(ACSM)is the core competence of Manufacturing *** other conceptions or terminologies that only focus on the atomic level precision,ACSM defnes a new realm of manufacturing where quantum mechanics plays the dominant role in the atom/molecule addition,migration and removal,considering the uncertainty principle and the discrete nature of *** ACSM is still in its infant stage,only little has been systematically elaborated at the core proposition of ACSM by now,hence there is a need to understand its concept and *** article elucidates the development of ACSM and clarifes its proposition,which aims to achieve a clearer understanding on ACSM and direct more efective eforts toward this promising area.

关键词： Atomic and close-to-atomic scale manufacturing(ACSM) Atomic Precision Manufacturing Paradigm Manufacturing III

Testing Linearity in Functional Partially Linear Models

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Acta Mathematicae Applicatae Sinica 2024年第3期40卷 875-886页

作者： fan-rong ZHAO Bao-xue ZHANG School of Mathematical Sciences Shanxi UniversityTaiyuan 030006China School of Statistics Capital University of Economics and BusinessBeijing 100070China

For the functional partially linear models including flexible nonparametric part and functional linear part,the estimators of the nonlinear function and the slope function have been studied in existing *** to test the correlation between response and explanatory variables,however,still seems to be ***,a test procedure for testing the linearity in the functional partially linear models will be proposed in this paper.A test statistic is constructed based on the existing estimators of the nonlinear and the slope ***,we prove that the approximately asymptotic distribution of the proposed statistic is a chi-squared distribution under some regularity ***,some simulation studies and a real data application are presented to demonstrate the performance of the proposed test statistic.

关键词： asymptotic theory functional partially linear model Nadaraya-Watson estimate test statistic

Prediction of subsurface settlement induced by shield tunnelling in sandy cobble stratum

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第1期16卷 192-212页

作者： fan Wang Xiuli Du Pengfei Li Key Laboratory of Urban Security and Disaster Engineering Ministry of EducationBeijing University of TechnologyBeijing100124China

This study focuses on the analytical prediction of subsurface settlement induced by shield tunnelling in sandy cobble stratum considering the volumetric deformation modes of the soil above the tunnel crown.A series of numerical analyses is performed to examine the effects of cover depth ratio(C/D),tunnel volume loss rate(h t)and volumetric block proportion(VBP)on the characteristics of subsurface settle-ment trough and soil volume *** the ground loss variation with depth,three modes are deduced from the volumetric deformation responses of the soil above the tunnel ***,analytical solutions to predict subsurface settlement for each mode are presented using stochastic medium *** influences of C/D,h t and VBP on the key parameters(i.e.B and N)in the analytical expressions are discussed to determine the fitting formulae of B and ***,the proposed analytical solutions are validated by the comparisons with the results of model test and numerical *** show that the fitting formulae provide a convenient and reliable way to evaluate the key ***,the analytical solutions are reasonable and available in predicting the subsurface settlement induced by shield tunnelling in sandy cobble stratum.

关键词： Shield tunnelling Sandy cobble stratum Subsurface settlement Volumetric deformation mode Stochastic medium theory