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Exploring the Effect of Plasticity on the Phase Imaging of TM-AFM Through Molecular Dynamics Simulations

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Acta Mechanica Solida Sinica 2024年第2期37卷 297-304页

作者： guolin Liu Yu Zeng Yaxin Chen Zheng Wei School of Mechanical and Electrical Engineering Beijing University of Chemical TechnologyBeijing100029China

In the tapping-mode atomic force microscope(TM-AFM),the probe tip continuously taps the sample surface,which may cause plastic deformation of the sample and result in energy dissipation.The energy dissipation of the probe is closely related to the scanned phase image.To quantify the energy dissipation due to plastic indentations of the sample,this study utilized a combination of molecular dynamics(MD)simulations and experiments on single-crystal copper samples,including multiple nano-indentation tests.The energy dissipation of the probe due to the plastic deformation of the sample was calculated by integrating the hysteresis curve of the indentation depth versus the force applied to the indenter.The simulation results are in good agreement with the experimental ones.Both sets of results have demonstrated that the plastic energy dissipation decreases as the number of indentations increases,and eventually the energy of the probe tends to stabilize.This equilibrium energy dissipation is associated with other dissipation mechanisms.Furthermore,it was observed that,after hundreds of taps,the dissipated energy of plastic deformation could be ignored,implying that the scanned image may not reflect the plasticity information of the sample after multiple taps of the probe on the sample surface for scanning.

关键词： Atomic force microscopy Force-distance curves Nano-indentations Plasticity Molecular dynamics

High‐altitude tunnel‐catenary gap impulse discharge characteristics and breakdown voltage correction

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High Voltage 2023年第6期8卷 1285-1295页

作者： Yi Liao Xingliang Jiang guolin yang Jianlin Hu Zhijin Zhang Qin Hu Chen Tan Haitao Wu Xuefeng Mountain Energy Equipment Safety National Observation and Research Station of Chongqing University ChongqingChina State Grid Chengdu Power Supply Company ChengduChina State Grid Chongqing Electric Power Research Institute ChongqingChina

Air gap impulse discharge characteristics of railway tunnel‐catenary at high‐altitude are of great significance to the electrical insulation design.The existing altitude correction methods for non‐uniform air gaps are not applicable to tunnel‐catenary.To investigate the impulse discharge characteristics of the tunnel‐catenary,a typical structural model was built in an artificial climate chamber.Different altitudes were simulated by adjusting the atmospheric pressure.The 50%breakdown voltages of the 300–700 mm tunnel‐catenary gap were tested at 243–4000 m.The test found that the altitude/atmospheric pressure and gap length have an evident effect on the 50%impulse breakdown voltage,and the influence of humidity is relatively small.The polarity effect was analysed by streamer theory.The{d,P,h}parameter method was employed to obtain the fitting formulas for the impulse breakdown voltage.A high‐altitude correction method for the tunnel‐catenary breakdown voltage based on 1 km altitude was proposed.Field natural tests were conducted to verify the accuracy of the proposed method.The results show that the breakdown voltage obtained by the correction method has an average error of 3.66%in the results of the field tests,indicating that the method has engineering application prospects.

关键词： breakdown altitude correction

Effect of solid particle type,concentration and size on DC breakdown voltage of short needle-plate air gap:An experiment and simulation study

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High Voltage 2023年第4期8卷 799-809页

作者： guolin yang Xingliang Jiang Jianlin Hu Xiaodong Ren Tao Li Jianguo Wu Zhijin Zhang Qin Hu Hualong Zheng Xuefeng Mountain Energy Equipment Safety National Observation and Research Station of Chongqing University ChongqingChina

Unclean air discharge refers to the discharge phenomenon of a large number of polluting gases,droplets or solid particles floating in the air,which will cause insulation breakdown and safety accidents for the power transmission equipment that have been left outdoors for a long time.In order to investigate the effects of particle concentration,particle size and dielectric constant on DC breakdown characteristics of unclean air gap,a self-made discharge chamber was designed in this study.The air was filtered and passed into the discharge chamber to remove the influence of impurities contained in the air on the experimental results.Then,solid particles with different concentration,particle size and particle dielectric constant were added to the discharge chamber to carry out the DC positive polarity breakdown characteristic experiment.The experimental results show that compared with dry clean air,the presence of solid particle increases the breakdown voltage of the gap,and the increase proportion of breakdown voltage is related to the particle concentration,particle size and particle dielectric constant.With the same particle type and particle size,the increase proportion of breakdown voltage increases with the higher concentration,which up to 10.49%.For further investigating,the fluid mechanics model was selected to simulate the process of streamer discharge in unclean air.The results show that compared with dry clean air,the presence of particles enhances the gap discharge ionisation process,but also enhances the adsorption of particles,and the latter has stronger effect than the former,thus increases the gap breakdown voltage.At the same time,the enhancement of adsorption effect increases the electric field intensity of the gap and speeds up the development process of streamer discharge.

关键词： particle size solid

Tuning electronic structure of RuO_(2)by single atom Zn and oxygen vacancies to boost oxygen evolution reaction in acidic medium

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Journal of Energy Chemistry 2024年第1期88卷 94-102,I0003页

作者： Qing Qin Tiantian Wang Zijian Li guolin Zhang Haeseong Jang Liqiang Hou Yu Wang Min Gyu Kim Shangguo Liu Xien Liu College of Chemical Engineering Qingdao University of Science and TechnologyQingdao 266042ShandongChina Department of Chemistry City University of Hong KongHong Kong 999077China Department of Advanced Materials Engineering Chung-Ang UniversityAnseong-siGyeonggi-do 17546SeoulRepublic of Korea Beamline Research Division Pohang Accelerator Laboratory(PAL)Pohang 37673Gyeongsangbuk-doRepublic of Korea

The poor stability of RuO_(2)electrocatalysts has been the primary obstacles for their practical application in polymer electrolyte membrane electrolyzers.To dramatically enhance the durability of RuO_(2)to construct activity-stability trade-off model is full of significance but challenging.Herein,a single atom Zn stabilized RuO_(2)with enriched oxygen vacancies(SA Zn-RuO_(2))is developed as a promising alternative to iridium oxide for acidic oxygen evolution reaction(OER).Compared with commercial RuO_(2),the enhanced Ru–O bond strength of SA Zn-RuO_(2)by forming Zn-O-Ru local structure motif is favorable to stabilize surface Ru,while the electrons transferred from Zn single atoms to adjacent Ru atoms protects the Ru active sites from overoxidation.Simultaneously,the optimized surrounding electronic structure of Ru sites in SA ZnRuO_(2)decreases the adsorption energies of OER intermediates to reduce the reaction barrier.As a result,the representative SA Zn-RuO_(2)exhibits a low overpotential of 210 mV to achieve 10 mA cm^(-2)and a greatly enhanced durability than commercial RuO_(2).This work provides a promising dual-engineering strategy by coupling single atom doping and vacancy for the tradeoff of high activity and catalytic stability toward acidic OER.

关键词： Electrocatalyst Acidic oxygen evolution reaction Electronic structure engineering Durability Reaction barrier

典型建筑物群组模式的空间图卷积模型DGCNN识别方法

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武汉大学学报（信息科学版） 2024年第5期49卷 868-878页

作者：张自强刘涛杜萍杨国林兰州交通大学测绘与地理信息学院甘肃兰州730070 地理国情监测技术应用国家地方联合工程研究中心甘肃兰州730070 甘肃省地理国情监测工程实验室甘肃兰州730070

建筑物群组模式的识别是建筑物综合的重要步骤,高效的建筑物群组模式识别方法能有效提升地图自动综合的质量。建筑物群组模式的识别目前主要包括几何方法和传统的机器学习方法两种,存在规则定义复杂、特征工程庞大等缺点。图卷积神经网... 详细信息

建筑物群组模式的识别是建筑物综合的重要步骤,高效的建筑物群组模式识别方法能有效提升地图自动综合的质量。建筑物群组模式的识别目前主要包括几何方法和传统的机器学习方法两种,存在规则定义复杂、特征工程庞大等缺点。图卷积神经网络方法克服了传统方法的局限性,已成功地应用于建筑物的模式分析。然而,目前使用图卷积进行建筑物群组多模式识别的相关研究较少,且已有的图卷积大多基于谱域图卷积,对空间局部信息考虑不足。引入空间图卷积模型DGCNN(deep graph convolutional neural network)进行建筑物群组的多模式识别,首先聚类建筑物数据形成群组,并构建建筑物群组的几何模型;然后定义建筑物的特征向量,建立建筑物群组的图结构;最后将图结构输入DGCNN模型训练,得到建筑物群组模式。结果发现,该模型在训练集的精度达到97.60%,测试集的精度达到95%,优于谱域图卷积方法,能有效用于建筑物群组模式分类。

关键词：建筑物群组模式识别空间图卷积模型深度学习

基于多种动力-统计方法的中国夏季降水集成预测研究

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地球物理学报 2024年第3期67卷 982-996页

作者：杨子寒托雅杨杰吴银忠龚志强封国林苏州科技大学物理科学与技术学院苏州215009 复旦大学大气与海洋科学系/大气科学研究院上海200438 江苏省气象局江苏省气候中心南京210009 国家气候中心气候研究开放实验室北京100081

中国夏季降水预报对中国社会和经济发展具有重要意义,但由于气候系统的不确定性,中国夏季降水预报在当前气象研究中仍然是一个具有挑战性的问题.本文在分析7种动力-统计预报方法对我国夏季降水预报效果的基础上,提出了动态加权集成预报... 详细信息

中国夏季降水预报对中国社会和经济发展具有重要意义,但由于气候系统的不确定性,中国夏季降水预报在当前气象研究中仍然是一个具有挑战性的问题.本文在分析7种动力-统计预报方法对我国夏季降水预报效果的基础上,提出了动态加权集成预报方法.通过比较动态加权集成预报方法与模式系统误差订正、单个动力-统计方法和等权重集成预报的空间距平相关系数(ACC)和预报评分(PS)值,发现动态加权集成预报较系统误差订正、单个动力-统计方法和等权重集成均有更好的预报效果.主要表现为:(1)动态加权集成预报方法2011—2020年夏季降水预报的ACC均值为0.05~0.10,较系统误差订正(-0.08)提高了0.13~0.18,较等权重集成提高了0.02~0.04,且优于绝大多数单个动力-统计预报方法的结果.(2)动态加权集成预报PS均值达到69.3~70.7,明显优于等权重集成预报的67.8~68.5和多数单方案动力-统计预报结果.(3)2021年独立样本检验中,动态加权集成预报中国夏季降水ACC值最高为0.21,明显优于等权重集成预报的最高值0.14,且PS评分值均高于70分.因此,动态加权集成预报可以在单个动力-统计方案预报的基础上,进一步提高中国夏季降水预报的准确率,改进预报技巧稳定性,具有较好的潜在应用价值.

关键词：降水误差订正动力-统计预测集成预测

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沉头孔螺旋铣削加工有限元仿真分析

航空学报 2024年第1期45卷 275-286页

作者：盛方怡杨国林孟凡通董志刚康仁科高性能精密制造全国重点实验室大连116024

航空航天构件装配过程中需要加工大量沉头孔,难加工材料的大量使用给装配制孔技术带来了新挑战。螺旋铣孔是一种装配制孔新方法,配合特殊刀具可实现沉头孔加工,并且能够利用螺旋铣孔切削原理上的特点来提高沉头孔加工质量。首先,进行了... 详细信息

航空航天构件装配过程中需要加工大量沉头孔,难加工材料的大量使用给装配制孔技术带来了新挑战。螺旋铣孔是一种装配制孔新方法,配合特殊刀具可实现沉头孔加工,并且能够利用螺旋铣孔切削原理上的特点来提高沉头孔加工质量。首先,进行了沉头孔螺旋铣削加工的运动学分析,然后利用有限元仿真了钛合金材料沉头孔螺旋铣削过程。接下来,通过沉头孔螺旋铣削试验中的切削力和切屑形态对有限元仿真的准确性进行了验证。最后,使用建立的仿真模型分析了锪窝深度和工艺参数对钛合金沉头孔螺旋铣削过程中刀具所受切削力的影响规律。

关键词：螺旋铣孔锪窝沉头孔切削力有限元仿真

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侵彻爆炸作用下钢纤维混凝土结构的破坏模式

爆炸与冲击 2024年第1期44卷 149-161页

作者：杨石刚罗泽许继恒方秦杨亚徐国琳汤俊杰陆军工程大学国防工程学院江苏南京210094

基于大口径发射平台进行了155 mm杀伤爆破榴弹毁伤钢纤维混凝土结构的试验,得到了打击不同位置时结构的破坏情况;结合LS-DYNA数值模拟,分析了不同打击位置和不同命中速度下钢纤维混凝土结构的毁伤效应,讨论了侵彻与爆炸联合作用下钢纤... 详细信息

基于大口径发射平台进行了155 mm杀伤爆破榴弹毁伤钢纤维混凝土结构的试验,得到了打击不同位置时结构的破坏情况;结合LS-DYNA数值模拟,分析了不同打击位置和不同命中速度下钢纤维混凝土结构的毁伤效应,讨论了侵彻与爆炸联合作用下钢纤维混凝土结构的损伤过程和破坏模式。结果表明:钢纤维混凝土结构在155 mm榴弹作用下,配置钢筋的顶板和侧墙发生较轻的爆炸成坑破坏,无配筋的前墙发生严重的爆炸震塌破坏。SPG(smooth particle Galerkin method)-结构化ALE(arbitrary Lagrange-Euler)(S-ALE)流固耦合算法能够有效预测钢筋混凝土结构在侵彻和爆炸共同作用下的损伤发展过程和破坏模式。大口径弹体侵彻有限边界靶的加速度时程曲线特征为突增骤减单峰值形式,弹体速度呈现先快速降低后缓慢减小的特征;靶标在基于侵彻损伤的爆炸作用下,主要破坏模式为混凝土块大量崩塌和裂缝的生长,且随着侵彻速度的增加,爆炸造成的毁伤由局部破坏向结构整体破坏发展;混凝土破碎区内,垂直于弹体的钢筋在侵彻作用下达到屈服,板顶和板底的钢筋在爆炸后达到屈服。

关键词：钢纤维混凝土结构侵彻爆炸破坏模式

Effects of vacancy and external electric field on the electronic properties of the MoSi_(2)N_(4)/graphene heterostructure

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Chinese Physics B 2024年第3期33卷 542-550页

作者：梁前罗祥燕钱国林王远帆梁永超谢泉 College of Big Data and Information Engineering Institute of New Optoelectronic Materials and TechnologyGuizhou UniversityGuiyang 550025China

Recently,the newly synthesized septuple-atomic layer two-dimensional(2D)material MoSi_(2)N_(4)(MSN)has attracted attention worldwide.Our work delves into the effect of vacancies and external electric fields on the electronic properties of the MSN/graphene(Gr)heterostructure using first-principles calculation.We find that four types of defective structures,N-in,N-out,Si and Mo vacancy defects of monolayer MSN and MSN/Gr heterostructure are stable in air.Moreover,vacancy defects can effectively modulate the charge transfer at the interface of the MSN/Gr heterostructure as well as the work function of the pristine monolayer MSN and MSN/Gr heterostructure.Finally,the application of an external electric field enables the dynamic switching between n-type and p-type Schottky contacts.Our work may offer the possibility of exceeding the capabilities of conventional Schottky diodes based on MSN/Gr heterostructures.

关键词： MoSi_(2)N_(4) vacancy defects external electric field Schottky contacts