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Numerical investigation of the mechanical behavior of the backfill–rock composite structure under triaxial compression

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International Journal of Minerals,Metallurgy and Materials 2023年第5期30卷 802-812页

作者： Hongjian Lu Yiren Wang Deqing Gan Jie wu xiaojun wu School of Mining Engineering North China University of Science and TechnologyTangshan 063210China

To ensure safe and economical backfill mining,the mechanical response of the backfill–rock interaction system needs to be *** numerical investigation of the mechanical behavior of backfill–rock composite structure(BRCS)under triaxial compression,which includes deformation,failure patterns,strength characteristics,and acoustic emission(AE)evolution,was *** models used in the tests have one rough interface,two cement–iron tailings ratios(CTRs),four interface angles(IAs),and three confining pressures(CPs).Results showed that the deformation,strength characteristics,and failure patterns of BRCS under triaxial compression depend on IA,CP,and *** stress–strain curves of BRCS under triaxial compression could be divided into five stages,namely,compaction,elasticity,yield,strain softening,and residual *** relevant AE counts have corresponding relationships with different *** triaxial compressive strengths of composites increase linearly with the increase of the ***,the CP stress strengthening effect *** the IAs are45°and 60°,the failure areas of composites appear in the interface and *** the IAs are 75°and 90°,the failure areas of composites appear in the backfill,interface,and ***,the corresponding failure modes yield the combined shear *** research results provide the basis for further understanding of the stability of the BRCS.

关键词： backfill–rock composite structure triaxial compression mechanical behavior acoustic emission numerical simulation

维普期刊数据库

Insight into the large electro-strain in bismuth sodium titanate-based relaxor ferroelectrics:From fundamentals to regulation methods

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Journal of Materials Science & Technology 2023年第19期150卷 27-48页

作者： xiaojun wu Lanji Wen Chao wu Xiang Lv Jie Yin Jiagang wu College of Materials Science and Engineering Sichuan University610064PR China

Due to the demand for environmental protection,developing eco-friendly piezoelectric applica-tions/materials is an inevitable *** market share of lead-free materials is growing steadily every *** typical lead-free systems,Bi_(0.5)Na_(0.5)TiO_(3)(BNT)has attracted wide attention due to its supe-rior strain property(e.g.,dynamic piezoelectric coefficient d33*of most modified-BNT ceramics exceeds 600 pm/V,which is higher than commercial soft PZT ceramics PIC151).The excellent strain performance in BNT-based materials is thought to arise from the relaxor-ferroelectric transition,and currently,the mainstream strain regulation method is chemical *** far,amounts of effective dopants have been investigated,while the intrinsic strain regulation mechanism is still ambiguous(e.g.,how do dopants work?).Therefore,we review the intrinsic strain regulation mechanism,and strain origination and reg-ulation methods are also investigated to comprehend the regulation ***,the strain origination and regulation mechanism are investigated from different dimensions(e.g.,macro perspective and micro perspective),which is vacant in previous *** the macro view,the particular tai-lored relaxor-ferroelectric crossover is the critical key for the giant electro-strain,while from the micro view,the electro-strain is dominated by the cracked ferroelectric order and relaxor-ferroelectric transi-tion,resulting from the broken Bi-O bonds due to the local field *** the strain origination and regulation mechanism of BNT-based ceramics is of great importance to exclude the blind researching mode and rationally design the experimental scheme.

关键词： Strain origin Bi_(0.5)Na_(0.5)TiO_(3)(BNT) Strain regulation

FMR-GNet: Forward Mix-Hop Spatial-Temporal Residual Graph Network for 3D Pose Estimation

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Chinese Journal of Electronics 2024年第6期33卷 1346-1359页

作者： Honghong YANG Hongxi LIU Yumei ZHANG xiaojun wu Key Laboratory of Modern Teaching Technology Ministry of Education Shaanxi Normal University Key Laboratory of Intelligent Computing and Service Technology for Folk Song Ministry of Culture and Tourism School of Computer Science Shaanxi Normal University

Graph convolutional networks that leverage spatial-temporal information from skeletal data have emerged as a popular approach for 3D human pose estimation. However, comprehensively modeling consistent spatialtemporal dependencies among the body joints remains a challenging task. Current approaches are limited by performing graph convolutions solely on immediate neighbors, deploying separate spatial or temporal modules, and utilizing single-pass feedforward architectures. To solve these limitations, we propose a forward multi-scale residual graph convolutional network(FMR-GNet) for 3D pose estimation from monocular video. First, we introduce a mix-hop spatialtemporal attention graph convolution layer that effectively aggregates neighboring features with learnable weights over large receptive fields. The attention mechanism enables dynamically computing edge weights at each layer. Second,we devise a cross-domain spatial-temporal residual module to fuse multi-scale spatial-temporal convolutional features through residual connections, explicitly modeling interdependencies across spatial and temporal domains. Third, we integrate a forward dense connection block to propagate spatial-temporal representations across network layers, enabling high-level semantic skeleton information to enrich lower-level features. Comprehensive experiments conducted on two challenging 3D human pose estimation benchmarks, namely Human3.6M and MPI-INF-3DHP, demonstrate that the proposed FMR-GNet achieves superior performance, surpassing the most state-of-the-art methods.

关键词： Location awareness Three-dimensional displays Correlation Graph convolutional networks Fuses Aggregates Pose estimation Semantics Benchmark testing Skeleton

Kernel Estimation of Truncated Volterra Filter Model Based on DFP Technique and Its Application to Chaotic Time Series Prediction

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Chinese Journal of Electronics 2019年第1期28卷 127-135页

作者： ZHANG Yumei BAI Shulin LU Gang wu xiaojun Key Laboratory of Modern Teaching Technology Ministry of EducationShaanxi Normal University School of Computer Science Shaanxi Normal University School of Electronics and Information Northwestern Polytechnical University

In order to overcome some problems caused by improper parameters selection when applying Least mean square(LMS), Normalized LMS(NLMS) or Recursive least square(RLS) algorithms to estimate coefficients of second-order Volterra filter, a novel DavidonFletcher-Powell-based Second-order Volterra filter(DFPSOVF) is proposed. Analysis of computational complexity and stability are presented. Simulation results of system parameter identification show that the DFP algorithm has fast convergence and excellent robustness than LMS and RLS algorithm. Prediction results of applying DFPSOVF model to single step predictions for Lorenz chaotic time series illustrate stability and convergence and there have not divergence problems. For the measured multiframe speech signals, prediction accuracy using DFPSOVF model is better than that of Linear prediction(LP).The DFP-SOVF model can better predict chaotic time series and the real measured speech signal series.

关键词： Chaos Davidon-Fletcher-Powell algorithm Prediction model Second-order Volterra filter Speech signal

Sawtooth-Like Graphene Nanoribbon

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Nano Research 2008年第1期1卷 40-45页

作者： xiaojun wu Xiao Cheng Zeng Department of Chemistry and Nebraska Center for Materials and Nanoscience University of Nebraska-LincolnLincolnNE 68588USA

Motivated by recent successful synthesize of segmented graphene nanoribbons(GNRs)with junctions,we explore electronic properties of a novel form of GNR with sawtooth-like structure using the density-functional theory *** is found that the unique edge structures of the sawtooth-like GNR induce richer band-gap features than the straight GNR counterpart with either armchair or zigzag *** effect of external electric fi eld on the electronic properties of the sawtooth-like GNR is also *** theoretical results may be useful for designing GNR-based fi eld-effect transistors.

关键词： Graphene nanoribbons sawtooth-like GNR straight GNR edge effect

Inorganic Nanoribbons with Unpassivated Zigzag Edges： Half Metallicity and Edge Reconstruction

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Nano Research 2011年第2期4卷 233-239页

作者： Menghao wu xiaojun wu Yong Pei Xiao Cheng Zeng Department of Chemistry and Department of Physics and Astronomy University of Nebraska-Lincoln Lincoln Nebraska 68588 USA Department of Materials of Science and Engineering Hefei National Laboratory for Physical Materials at M icroscale University of Science and Technology of China Hefei Anhui 230026 China Key Laboratory of Environnlentally Friendly Chemistry and Application of Ministry of Education Xiangtan University Xiangtan 411105 China）

We have investigated the electronic and structural properties of inorganic nanoribbons （BN, AIN, GaN, SiC, and ZnO） with unpassivated zigzag edges using density functional theory calculations. We find that, in general, the unpassivated zigzag edges can lead to spin-splitting of energy bands. More interestingly, the inorganic nanoribbons A1N and SiC with either one or two edges unpassivated are predicted to be half metallic. Possible structural reconstruction at the unpassivated edges and its effect on the electronic properties are investigated. The unpassivated N edge in the BN nanoribbon and P edge in the AlP nanoribbon are energetically less stable than the corresponding reconstructed edge. Hence, edge reconstruction at the two edges may occur at high temperatures. Other unpassivated edges of the inorganic nanoribbons considered in this study are all robust against edge reconstruction.

关键词： A1N and SiC nanoribbons half metallicit unpassivated zigzag edge edge reconstruction density functional theory

Enhanced Fenton-like process over Cu/L(+)-ascorbic acid co-doping mesoporous silica for toxicity reduction of emerging contaminants

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Frontiers of Environmental Science & Engineering 2024年第4期18卷 49-60页

作者： Yuhang Liu Wenxuan Deng xiaojun wu Chun Hu Lai Lyu Key Laboratory for Water Quality and Conservation of the Pearl River Delta(Ministry of Education) Institute of Environmental Research at Greater BayGuangzhou UniversityGuangzhou 510006China

Effective removal of emerging contaminants(ECs)to minimize their impacts on human health and the natural environment is a global *** the removal of ECs in water,we fabricated a seaweed spherical microsphere catalyst with Cu cation-πstructures by in situ doping of Cu species and ascorbic acid in mesoporous silica(Cu-C-MSNs)via a hydrothermal *** results indicate that bisphenol A(BPA)is substantially degraded within 5 min under natural conditions,with its biological toxicity considerably ***,industrial wastewater could also be effectively purified by Cu-C-MSNs/H_(2)O_(2) *** presence of metal sites and the complexation of ECs via cation-πinteraction andπ-πstacking on the catalyst surface were directly responsible for the polarization distribution of electrons,thus activating H_(2)O_(2) and dissolved oxygen(DO).The removal of contaminants could be attributed primarily to 1)the activation of H_(2)O_(2) into ^(·)OH to attack the contaminants and 2)self-cleavage because of the transfer of electrons from the contaminants to the *** study provides an innovative solution for the effective treatment of ECs and has positive implications for easing global environmental crises.

关键词： Cation-πstructures Polarization electric field Fenton-like process Contaminants cleavage

Multi-Traffic Targets Tracking Based on an Improved Structural Sparse Representation with Spatial-Temporal Constraint

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Chinese Journal of Electronics 2022年第2期31卷 266-276页

作者： YANG Honghong SHANG Junchao LI Jingjing ZHANG Yumei wu xiaojun Key Laboratory of Modern Teaching Technology Ministry of EducationShaanxi Normal University School of Computer Science Shaanxi Normal University School of Journalism and Communication Shaanxi Normal University

Vehicles or pedestrians tracking is an important task in intelligent transportation system. In this paper, we propose an online multi-object tracking for intelligent traffic platform that employs improved sparse representation and structural constraint. We first build the spatial-temporal constraint via the geometric relations and appearance of tracked objects, then we construct a robust appearance model by incorporating the discriminative sparse representation with weight constraint and local sparse appearance with occlusion analysis. Finally, we complete data association by using maximum a posteriori in a Bayesian framework in the pursuit for the optimal detection estimation. Experimental results in two challenging vehicle tracking benchmark datasets show that the proposed method has a good tracking performance.

关键词： road vehicles multiobject tracking target tracking improved structural sparse representation object tracking Bayes methods image representation robust appearance model object detection data association pedestrians intelligent traffic platform optimisation road traffic geometric relations local sparse appearance optimal detection estimation spatial-temporal constraint intelligent transportation system multitraffic targets tracking weight constraint pedestrians tracking Bayesian framework occlusion analysis intelligent transportation systems

Fluorine-induced dual defects in NiP_(2) anode with robust sodium storage performance

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Nano Research 2022年第3期15卷 2147-2156页

作者： Liang wu Lifeng Wang Xiaolong Cheng Mingze Ma Ying wu xiaojun wu Hengpan Yang Yan Yu Chuanxin He College of Chemistry and Environmental Engineering Shenzhen UniversityShenzhen 518060China College of Physics and Optoelectronic Engineering Shenzhen UniversityShenzhen 518060China Hefei National Laboratory for Physical Sciences at the Microscale Department of Materials Science and EngineeringCAS Key Laboratory of Materials for Energy ConversionUniversity of Science and Technology of ChinaHefei 230026China

Metal phosphides have shown great application potential as anode for sodium-ion batteries(NIBs)owing to high theoretical capacity,suitable operation voltage and abundant ***,the application of NiP_(2) anode is severely impeded by low practical capacity and fast capacity decay due to the huge volume variation and low reactivity of internal phosphorus(P)component towards Na^(+).Herein,electronic structure modulation of NiP_(2) via heteroatoms doping and introducing vacancies defects to enhance Na+adsorption sites and diffusion kinetics is successfully *** as-synthesized three-dimensional(3D)bicontinuous carbon matrix decorated with well-dispersed fluorine(F)-doped NiP_(2) nanoparticles(F-NiP_(2)@carbon nanosheets)delivers a high reversible capacity(585 mAh·g^(−1) at 0.1 A·g^(−1))and excellent long cycling stability(244 mAh·g^(−1) over 1,000 cycles at 2 A·g^(−1))when tested as anode in *** functional theory(DFT)calculations reveal that F doping in NiP_(2) induces the formation of P vacancies with increased Na+adsorption energy and accelerates the alloying of internal P *** F-NiP_(2)@carbon nanosheets//Na_(3)V_(2)(PO_(4))_(3) full cell is evaluated showing stable long cycling *** heteroatoms doping-induced dual defects strategy opens up a new way of metal phosphides for sodium storage.

关键词： NiP_(2) electronic structure modulation F doping P vacancies dual defects sodium-ion batteries