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AH36钢焊接接头动态应力应变特性分析

焊接学报 2024年第7期45卷 50-58页

作者：刘伟朱永梅孙傲江苏科技大学机械工程学院镇江212008

基于热弹塑性法研究了160°对接AH36钢焊接接头动态应力应变过程,同时制作试样,利用三维全场应变测量分析系统记录焊接应变的动态变化,验证了焊接有限元结果的准确性.分析了预热温度和焊接速度对动态应力应变的影响.研究结果表明,随着... 详细信息

基于热弹塑性法研究了160°对接AH36钢焊接接头动态应力应变过程,同时制作试样,利用三维全场应变测量分析系统记录焊接应变的动态变化,验证了焊接有限元结果的准确性.分析了预热温度和焊接速度对动态应力应变的影响.研究结果表明,随着预热温度的增加,焊接变形逐渐减小.预热温度为200℃时的平均焊接变形量比未预热时的平均焊接变形量降低了34.6%,同时改善了焊接应力场的分布情况,增加焊缝及热影响区的压应力分布区域,但应力幅值对预热温度的改变不敏感.焊接变形随焊接速度增大而增大,当焊接速度大于5 mm/s时,增长趋势逐渐平缓,焊接变形场等势分布面积减小.随着焊接速度的增加,焊接压应力场分布区域减小,焊接拉应力场分布区域增大,焊接速度的改变还会造成平板厚度方向中间层厚度处的应力出现波动.

关键词：焊接接头动态应力应变数值模拟预热温度焊接速度

Effect of Eu3+,Bi3+,and Li+ doping on luminescent property of GdNbO4

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Journal of Rare Earths 2024年第1期42卷 66-75页

作者： s.W.Wi Y.s.Lee Department of Physics and Integrative Institute of Basic sciences Soongsil University

We investigated the emission properties of Eu3+-doped GdNbO4-based oxide phosphors,aiming at improving the Eu3+emission by codoping of Bi3+and Li+.Eu3+singly doped,Eu3+and Bi3+doubly doped,and Eu3+,Bi3+,and Li+triply doped GdNbO4were prepared using a high-temperature solid-state reaction *** red-orange emissions from Eu3+in the singly doped samples are significantly improved by the codoping of Bi3+,mainly due to the energy transfer from Bi3+to Eu3+.The additional codoping of Li+is found to increase the Eu3+emission *** improvement might be attributed to the increase in the photoluminescent quantum yield originating from larger grain sizes and better crystallinity.A detailed analysis of the X-ray diffraction pattern and the asymmetric ratio estimated from the photoluminescence spectra show that the local lattice environment around Eu3+in GdNbO4does not change significantly with the codoping of Bi3+and Li+.Our results indicate that Li+doping is a promising way to improve the emission properties of rare-earth ion-doped GdNbO4phosphors.

关键词： Eu 3+ GdNbO 4 Codoping of Li + Photoluminescence sensitizer Rare earths

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金融科技促进居民消费的作用机制与路径研究

西南金融 2024年第7期 15-25页

作者：敖华闫强贺州学院经济与管理学院广西贺州542899 西南财经大学北京研究院北京100032

本文基于金融科技的金融创新、科技创新和产业创新三大属性,从需求侧和供给侧两个角度出发,研究金融科技促进居民消费的作用机制与实现路径。金融科技作为连接金融、科技、产业的重要手段和关键环节,能够强化科技创新、产业发展和金融... 详细信息

本文基于金融科技的金融创新、科技创新和产业创新三大属性,从需求侧和供给侧两个角度出发,研究金融科技促进居民消费的作用机制与实现路径。金融科技作为连接金融、科技、产业的重要手段和关键环节,能够强化科技创新、产业发展和金融支持三者之间的紧密联系,推动“科技—产业—金融”良性循环。本文指出,除了金融创新属性之外,金融科技还具有科技创新属性和产业创新属性,这进一步拓展金融科技的内涵;金融科技促进居民消费可区分为直接和间接促进作用,直接促进作用由金融科技的金融创新属性决定,间接促进作用由金融科技的科技创新及产业创新属性决定。

关键词：金融科技金融创新居民消费消费金融消费升级经济增长扩大内需产业转型升级

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地基森林点云单木检测的特征提取与组合方法

遥感信息 2024年第2期39卷 146-155页

作者：金泽会陈茂霖刘祥江重庆交通大学智慧城市学院重庆400074

针对基于点云特征进行单木检测的方法缺少对特征的重要性评估和选择等问题,提出一种体素特征参与单木检测的特征提取与组合的方法。首先,根据森林中不同类别的结构差异和空间分布特点提出一组体素特征,结合常用的三维、二维、格网以及... 详细信息

针对基于点云特征进行单木检测的方法缺少对特征的重要性评估和选择等问题,提出一种体素特征参与单木检测的特征提取与组合的方法。首先,根据森林中不同类别的结构差异和空间分布特点提出一组体素特征,结合常用的三维、二维、格网以及强度等基础特征实现树干点提取。然后,提出一种基于单木检测结果的特征选择方法用于确定适合相似林分结构的最佳特征组合。在3块不同森林样地上进行实验,结果表明:加入体素特征后,树干点提取精度分别提高7.3%、11.6%、9.5%,单木检测精度分别提高0.4%、2.6%、0.7%;与基于单点分类结果的特征选择方法以及其他研究中的特征组合相比,该方法能够通过更少的特征达到相似或更高的单木检测精度。

关键词：地面激光雷达点云体素特征树干提取单木检测

First evidence for chiral wobbling of triaxial nuclei

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Nuclear science and Techniques 2024年第7期35卷 4-7页

作者： s.Frauendorf Department of Physics and Astronomy University of Notre DameNotre DameIN 46556USA

Chirality(Greek“handiness”)is a property of many com-plex *** molecules exist in two forms,one being the mirror image of the *** for our hands,it is impossible to make the images identical by a suitable *** two forms are called left-handed and *** have the same binding energy,because the electro-magnetic interaction,which holds the molecule together,does not change under a *** properties that are insensitive to the geometry are also the *** different geometry is the reason why the left-handed form turns the polarization plane of transmitted light in one direction by some angle while the right-handed form turns it in the oppo-site direction by the same ***,the geometrical differences between the two species may have other *** two species of the carvon molecule shown in Fig.1 taste quite differently.

关键词： turns Chiral mirror

Tribological behavior of lubricant-impregnated porous polyimide

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Friction 2024年第4期12卷 711-725页

作者： Jinbang LI Ningning ZHOU Janet s.s.WONG school of Mechanical Engineering and Mechanics Ningbo UniversityNingbo 315211China Beijing Key Laboratory of Long-life Technology of Precise Rotation and Transmission Mechanisms Beijing Institute of Control EngineeringBeijing 100029China Department of Mechanical Engineering Imperial College LondonLondon SW72AZUK

Porous materials impregnated with lubricants can be used in conditions where limited lubricant is *** this work,three porous polyimides(PPI)with different densities were ***(Pao)impregnated PPI(iPPI)discs were rubbed against steel and sapphire *** operando observations of the iPPI-sapphire contacts show that oil is released under an applied load,forming a meniscus around *** at the outlet is created at high sliding *** amount of released oil increases with increasing PPI *** moduli,E*,estimated based on the actual contact size show that trapped oil in iPPIs contributes to load *** higher speeds,tribological rehydration of the contact occurs in low density iPPI,with that E*rises with *** high density PPIs,high speeds give a constantly high E*which is limited by the viscoelastic properties of the PPI network and possibly the rate of oil *** of iPPI-steel contacts is governed by the mechanical properties of the PPI,the flow of the lubricant,and the roughness of the PPI *** low-and medium-density(highly porous,high roughness)PPIs,large amount of oil is released,and lubrication is mainly via lubricant restricted in the contact in the pores and possibly tribological *** high density(low porosity)PPI,with lower roughness,hydrodynamic lubrication is achieved which gives the lowest *** results show that polymeric porous materials for effective lubrication require the optimization of its surface roughness,stiffness,oil flow,and oil retentions.

关键词： polyimide porous material friction mechanism polymer limited lubrication

Enhancing fatigue performance of AZ31 magnesium alloy components fabricated by cold metal transfer-based wire arc directed energy deposition through LPB

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Journal of Magnesium and Alloys 2024年第4期12卷 1638-1662页

作者： shambhu Kumar Manjhi srikanth Bontha A.s.s.Balan Department of Mechanical Engineering National Institute of Technology KarnatakaSurathkalSrinivasanagarMangaloreKarnataka 575025India

Cold Metal Transfer-Based Wire Arc Directed Energy Deposition(CMT-WA-DED)presents a promising avenue for the rapid fabrication of components crucial to automotive,shipbuilding,and aerospace ***,the susceptibility to fatigue of CMT-WA-DED-produced AZ31 Mg alloy components has impeded their widespread adoption for critical load-bearing *** this study,a comprehensive investigation into the fatigue behaviour of WA-DED-fabricated AZ31 Mg alloy has been carried out and compared to commercially available wrought AZ31 *** findings indicate that the as-deposited parts exhibit a lower fatigue life than wrought Mg alloy,primarily due to poor surface finish,tensile residual stress,porosity,and coarse grain microstructure inherent in the WA-DED *** Plasticity Burnishing(LPB)treatment is applied to mitigate these issues,which induce significant plastic deformation on the *** treatment resulted in a remarkable improvement of fatigue life by 42%,accompanied by a reduction in surface roughness,grain refinement and enhancement of compressive residual stress ***,during cyclic deformation,WA-DED specimens exhibited higher plasticity and dislocation density compared to both wrought and WA-DED+LPB specimens.A higher fraction of Low Angle Grain Boundaries(LAGBs)in WA-DED specimens contributed to multiple crack initiation sites and convoluted crack paths,ultimately leading to premature *** contrast,wrought and WA-DED+LPB specimens displayed a higher percentage of High Angle Grain Boundaries(HAGBs),which hindered dislocation movement and resulted in fewer crack initiation sites and less complex crack paths,thereby extending fatigue *** findings underscore the effectiveness of LPB as a post-processing technique to enhance the fatigue performance of WA-DED-fabricated AZ31 Mg alloy *** study highlights the importance of LPB surface treatment on AZ31 Mg components produced by CMT-WA-DED to remove surface d

关键词： Wire arc additive manufacturing AZ31 Mg alloy Low plasticity burnishing Low cycle fatigue test strain amplitude

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陈塘探秘

China's Tibet 2024年第1期35卷 56-63页

作者： ao Chao Li Nan 不详

In the vast Xizang Autonomous Region,numerous small villages and towns are scattered at the foot of snow-capped mountains and deep in the grasslands,drawing people from afar with their unique social and cultural tapes... 详细信息

关键词： mountains scattered drawing

共同体的多重想象--民族地区的社会治理共同体及其建设路径

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西北民族研究 2024年第4期 129-141页

作者：文军敖淑凤华东师范大学中国现代城市研究中心暨社会发展学院上海市“中国特色的转型社会学研究”社会科学创新研究基地华东师范大学铸牢中华民族共同体意识研究基地上海200241 西北农林科技大学人文社会发展学院咸阳712000

共同体的形式及其内涵在社会实践中经历了多维的拓展和深化,并出现多重理论想象及其现实转向。如果将“治理共同体”的概念从西方学者的共同体研究脉络中抽离出来,并置于中国民族地区的社会治理实践中进行剖析,那么共同体的要义在于使... 详细信息

共同体的形式及其内涵在社会实践中经历了多维的拓展和深化,并出现多重理论想象及其现实转向。如果将“治理共同体”的概念从西方学者的共同体研究脉络中抽离出来,并置于中国民族地区的社会治理实践中进行剖析,那么共同体的要义在于使社会治理的功能、价值和意义最终回归人们的日常生活之中,是人本理念的价值回归。做好民族地区治理共同体的构建,一是需要完善地域性的多民族生活共同体,夯实民族交往交流交融的客观环境基础;二是创建参与性的多民族组织共同体,推动形成功能耦合的互补式协同治理;三是建立情感性的中华文化共同体,铸牢中华民族共同体意识。此外,要在行动层面引导和推动不同民族融入中华民族伟大复兴的实践之中。

关键词：共同体多重想象治理共同体民族地区