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Stress-corrosion coupled damage localization induced by secondary phases in bio-degradable Mg alloys:phase-field modeling

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Journal of Magnesium and Alloys 2024年第1期12卷 361-383页

作者： Chao Xie Shijie Bai xiao Liu Minghua zhang Jianke Du The Faculty of Mechanical Engineering and Mechanics Ningbo UniversityNingbo 315211P.R.China Key Laboratory of High Temperature Wear Resistant Materials Preparation Technology of Hunan Province Hunan University of Science and TechnologyXiangtan 411201P.R.China

In this study,a phase-field scheme that rigorously obeys conservation laws and irreversible thermodynamics is developed for modeling stress-corrosion coupled damage(SCCD).The coupling constitutive relationships of the deformation,phase-field damage,mass transfer,and electrostatic field are derived from the entropy *** SCCD localization induced by secondary phases in Mg is numerically simulated using the implicit iterative algorithm of the self-defined finite *** quantitative evaluation of the SCCD of a C-ring is in good agreement with the experimental *** capture the damage localization,a micro-galvanic corrosion domain is defined,and the buffering effect on charge migration is *** cases are investigated to reveal the effect of localization on corrosion acceleration and provide guidance for the design for resistance to SCCD at the crystal scale.

关键词： Phase field Mg alloys Stress-corrosion coupled damage Damage localization Finite element method

Data augmentation method for insulators based on Cycle-GAN

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Journal of Electronic Science and Technology 2024年第2期22卷 36-47页

作者： Run Ye Azzedine Boukerche xiao-Song Yu Cheng zhang Bin Yan xiao-Jia Zhou School of Automation Engineering University of Electronic Science and Technology of ChinaChengdu611731China School of Electrical Engineering and Computer Science University of OttawaOttawaK1N6N5Canada Yangtze River Delta Research Institute(Huzhou) University of Electronic Science and Technology of ChinaHuzhou313001China

Data augmentation is an important task of using existing data to expand data *** generative countermeasure network technology to realize data augmentation has the advantages of high-quality generated samples,simple training,and fewer restrictions on the number of generated ***,in the field of transmission line insulator images,the freely synthesized samples are prone to produce fuzzy backgrounds and disordered samples of the main insulator *** solve the above problems,this paper uses the cycle generative adversarial network(Cycle-GAN)used for domain conversion in the generation countermeasure network as the initial framework and uses the self-attention mechanism and channel attention mechanism to assist the conversion to realize the mutual conversion of different insulator *** attention module with prior knowledge is used to build the generation countermeasure network,and the generative adversarial network(GAN)model with local controllable generation is built to realize the directional generation of insulator belt defect *** experimental results show that the samples obtained by this method are improved in a number of quality indicators,and the quality effect of the samples obtained is excellent,which has a reference value for the data expansion of insulator images.

关键词： Data expansion Deep learning Generate confrontation network Insulator

Multiscale spatiotemporal meteorological drought prediction:A deep learning approach

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Advances in Climate Change Research 2024年第2期15卷 211-221页

作者： Jia-Li zhang xiao-Meng HUANG Yu-Ze SUN Department of Earth System Science Ministry of Education Key Laboratory for Earth System ModellingInstitute for Global Change StudiesTsinghua UniversityBeijing 100084China

Reliable monitoring and thorough spatiotemporal prediction of meteorological drought are crucial for early warning and decision-making regarding drought-related *** utilisation of multiscale methods is effective for a comprehensive evaluation of drought occurrence and progression,given the complex nature of meteorological ***,the nonlinear spatiotemporal features of meteorological droughts,influenced by various climatological,physical and environmental factors,pose significant challenges to integrated prediction that considers multiple indicators and time *** address these constraints,we introduce an innovative deep learning framework based on the shifted window transformer,designed for executing spatiotemporal prediction of meteorological drought across multiple *** formulate four prediction indicators using the standardized precipitation index and the standard precipitation evaporation index as core methods for drought definition using the ERA5 reanalysis *** indicators span time scales of approximately 30 d and one ***-term indicators capture more anomalous variations,whereas long-term indicators attain comparatively higher accuracy in predicting future *** focus on the East Asian region,notable for its diverse climate conditions and intricate terrains,to validate the model's efficacy in addressing the complexities of nonlinear spatiotemporal *** model's performance is evaluated from diverse spatiotemporal viewpoints,and practical application values are analysed by representative drought *** results substantiate the effectiveness of our proposed model in providing accurate multiscale predictions and capturing the spatiotemporal evolution characteristics of *** of the four drought indicators accurately delineates specific facets of the meteorological drought ***,three representative drought events,namely flash drought,sustained drought and severe drought,

关键词： Meteorological drought Spatiotemporal prediction Multiscale Swim transformer Deep learning

Adsorption and sensing characteristics of insulating gas C4F7N on 3d late transition metal-phthalocyanine:Theoretical and experimental study

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High Voltage 2024年第4期9卷 870-878页

作者： Dachang Chen Ziang Zheng Cong zhang Yi Luo Song xiao Qing Miao Ke Liu Beibei xiao School of Electrical and Electronic Engineering Wuhan Polytechnic UniversityWuhanChina Beijing International S&T Cooperation Base for Plasma Science and Energy Conversion Institute of Electrical EngineeringChinese Academy of SciencesBeijingChina School of Electrical Engineering and Automation Wuhan UniversityWuhanChina School of Energy and Power Engineering Jiangsu University of Science and TechnologyZhenjiangChina

Heptafluoroisobutyronitrile(C_(4)F_(7)N)is being considered as a promising alternative to the greenhouse gas SF6 in the electrical ***,its biotoxicity necessitates the development of gas sensing technology to detect leaked C_(4)F_(7)N.A combination of density functional theory and experiments was employed to evaluate the adsorption and sensing performance of different metal-phthalocyanines as potential sensing materials for C_(4)F_(7)N *** study included exploring adsorption configurations with adsorption energies,electron transfer,and adsorption distance,as well as comparisons of electronic properties,electron distribution,and density of states(DOS)among the ***,gas sensing experiments were conducted using different MPcs to detect 25-100 ppm C_(4)F_(7)*** results revealed that Mn-Pc,Fe-Pc,Co-Pc,and Zn-Pc exhibited considerable chemical interactions,while Ni-Pc and Cu-Pc showed weaker adsorption *** findings were further elucidated based on the electron density and DOS of atomic ***,gas sensing experiments indicated that Co-Pc demonstrated a higher response compared to Fe-Pc at the same concentration of C_(4)F_(7)***,the theoretical and experimental insights offer valuable guidance for C_(4)F_(7)N detection and provide a systematic approach to screen and explore organometallic polymer-based gas sensors applicable in various fields.

关键词： adsorption phthalocyanine Adsorption

Microscopic defects formation and dynamic mechanical response analysis of Q345 steel plate subjected to explosive load

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Defence Technology（防务技术） 2024年第2期32卷 430-442页

作者： Zhengqing Zhou Zechen Du Yulong zhang Guili Yang Ruixiang Wang Yuzhe Liu Peize zhang Yaxin zhang xiao Wang Research Institute of Macro-Safety Science University of Science and TechnologyBeijing100083China School of Civil and Resource Engineering University of Science and TechnologyBeijing100083China China North Industry Advanced Technology Generalization Institute Beijing100089China College of Field Engineering PLA Army Engineering UniversityNanjing210007China School of Mechanical Engineering Nantong UniversityNantong226019China

As the basic protective element, steel plate had attracted world-wide attention because of frequent threats of explosive loads. This paper reports the relationships between microscopic defects of Q345 steel plate under the explosive load and its macroscopic dynamics simulation. Firstly, the defect characteristics of the steel plate were investigated by stereoscopic microscope(SM) and scanning electron microscope(SEM). At the macroscopic level, the defect was the formation of cave which was concentrated in the range of 0-3.0 cm from the explosion center, while at the microscopic level, the cavity and void formation were the typical damage characteristics. It also explains that the difference in defect morphology at different positions was the combining results of high temperature and high pressure. Secondly, the variation rules of mechanical properties of steel plate under explosive load were studied. The Arbitrary Lagrange-Euler(ALE) algorithm and multi-material fluid-structure coupling method were used to simulate the explosion process of steel plate. The accuracy of the method was verified by comparing the deformation of the simulation results with the experimental results, the pressure and stress at different positions on the surface of the steel plate were obtained. The simulation results indicated that the critical pressure causing the plate defects may be approximately 2.01 GPa. On this basis, it was found that the variation rules of surface pressure and microscopic defect area of the Q345 steel plate were strikingly similar, and the corresponding mathematical relationship between them was established. Compared with Monomolecular growth fitting models(MGFM) and Logistic fitting models(LFM), the relationship can be better expressed by cubic polynomial fitting model(CPFM). This paper illustrated that the explosive defect characteristics of metal plate at the microscopic level can be explored by analyzing its macroscopic dynamic mechanical response.

关键词： Explosive load Q345 steel Micro defect Finite element simulation Dynamic response Data fitting

Crystalline-amorphous M@MN_x(M=Co,Fe,Ni)encapsulated in nitrogen-doped carbon for enhanced efficient and durable hydrogen evolution reaction

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Rare Metals 2024年第4期43卷 1547-1556页

作者： Yang Yang xiao-Chuan Duan Shao-Hui Guo Xian-Ming zhang College of Materials Science and Engineering College of ChemistryKey Laboratory of Interface Science and Engineering in Advanced MaterialsTaiyuan University of TechnologyYuci030600China

Developing earth-abundant electrocatalysts for hydrogen evolution reaction(HER)is important for the sustainable energy ***,efficient and stable heterocatalysts consisting of crystalline-amorphous M@MN_(x)(M=Co,Fe,Ni)encapsulated in N-doped carbon layers supported with N-doped graphene sheets(denoted as M@MN_(x)@NC-NG)are synthesized by facile hydrothermal reaction and nitridation *** the nitriding process,metal ions in M(tzbc)_2(H_(2)O)_4(tzbc=4-(1H-1,2,4-triazol-1-yl)benzoic acid)complexes are reduced to crystalline M cores,accompanied by the formation of amorphous MN_(x)shells;the tzbc ligands are insitu carbonized to form outermost N-doped carbon(NC)layers that connect with inner MN_(x)via M-N-C motifs inherited from the complex precursors and inhibit the transition of MN_(x)from amorphous to crystalline *** Co@CoN_(x)@NC-NG catalyst exhibits excellent HER activity with small overpotentials of 45 and 64 mV at a cathode current density of 10 mA·cm^(-2)and low Tafel slopes of 40 and 85 mV·dec^(-1)in 0.5 mol·L^(-1)H_(2)SO_4 and1.0 mol·L^(-1)KOH electrolytes,*** Co@CoN_(x)@NC-NG retains 97%of the initial overpotential after 100,000 s in both acidic and alkaline *** outstanding HER performance originates from the crystalline-amorphous Co@CoN_(x)that redistributes electrons around the heterointerfaces,facilitating the conversion process of H^(+)/H_(2)O to hydrogen and thereby promoting HER *** outermost NC layers serve as the armor of Co@CoN_(x),and graphene nanosheets act as carriers of egg-like Co@CoN_(x)@NC and conduction paths for electron shuttles,ensuring stable and continuous electrocatalytic hydrogen production.

关键词： Hydrogen evolution reaction Electrocatalysts Iron group metals Heterojunction Crystalline-amorphous structure

Feature Matching via Topology-Aware Graph Interaction Model

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IEEE/CAA Journal of Automatica Sinica 2024年第1期11卷 113-130页

作者： Yifan Lu Jiayi Ma xiaoguang Mei Jun Huang xiao-Ping zhang the Electronic Information School Wuhan UniversityWuhan 430072China IEEE Tsinghua Berkeley Shenzhen Institute Shenzhen 518071China the Department of Electrical Computer and Biomedical EngineeringToronto Metropolitan UniversityToronto ON M5B 2K3Canada

Feature matching plays a key role in computer vision. However, due to the limitations of the descriptors, the putative matches are inevitably contaminated by massive *** paper attempts to tackle the outlier filtering problem from two aspects. First, a robust and efficient graph interaction model,is proposed, with the assumption that matches are correlated with each other rather than independently distributed. To this end, we construct a graph based on the local relationships of matches and formulate the outlier filtering task as a binary labeling energy minimization problem, where the pairwise term encodes the interaction between matches. We further show that this formulation can be solved globally by graph cut algorithm. Our new formulation always improves the performance of previous localitybased method without noticeable deterioration in processing time,adding a few milliseconds. Second, to construct a better graph structure, a robust and geometrically meaningful topology-aware relationship is developed to capture the topology relationship between matches. The two components in sum lead to topology interaction matching(TIM), an effective and efficient method for outlier filtering. Extensive experiments on several large and diverse datasets for multiple vision tasks including general feature matching, as well as relative pose estimation, homography and fundamental matrix estimation, loop-closure detection, and multi-modal image matching, demonstrate that our TIM is more competitive than current state-of-the-art methods, in terms of generality, efficiency, and effectiveness. The source code is publicly available at http://***/YifanLu2000/TIM.

关键词： Feature matching graph cut outlier filtering topology preserving

The Q-index and Connectivity of Graphs

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Journal of the Operations Research Society of China 2024年第2期12卷 505-519页

作者： Peng-Li zhang Li-Hua Feng Wei-Jun Liu xiao-Dong zhang School of Mathematical Sciences MOE-LSCSHL-MACShanghai Jiao Tong UniversityShanghai 200240China School of Mathematics and Statistics Central South UniversityChangsha 410083HunanChina

A connected graph G is said to be k-connected if it has more than k vertices and remains connected whenever fewer than k vertices are *** this paper,for a connected graph G with sufficiently large order,we present a tight sufficient condition for G with fixed minimum degree to be k-connected based on the *** result can be viewed as a spectral counterpart of the corresponding Dirac-type condition.

关键词： Q-index Minimum degree k-connected

Impact wear properties of dissimilar joints between bainitic frogs and pearlite rails

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Journal of Iron and Steel Research International 2024年第1期31卷 275-287页

作者： Pin-yong Zeng Chun-guang Zuo xiao-yu zhang Wei Li Tribology Research Institute Southwest Jiaotong UniversityChengdu610031SichuanChina

The impact wear behavior and damage mechanism of dissimilar welded joints between U26Mn frog and U75 V rail before and after normalizing treatment were studied by cyclic impact *** experiment indicated that the impact wear volume of the joints increased with the increasing number of impact *** main wear mechanisms include pitting wear,mild fatigue wear,delamination wear,and fatigue wear,and plastic deformation was the primary impact wear *** them,fatigue wear had the greatest influence on wear volume,while other wear mechanisms had limited *** impact wear resistance of the base material was better than that of the heat-affected *** treatment was beneficial to improving the impact wear resistance of welded joints owing to its effect to promote pearlite recovery,grain refinement,and uniform distribution of *** martensite generated in the rail welded joints aggravated the impact wear damage to the materials,which should be avoided.

关键词： Dissimilar welded joint Impact wear Bainitic steel Damage mechanism Wear rate