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激光熔覆涂层材料的研究现状

热加工工艺 2024年第6期53卷 1-5,9页

作者：田宪华杨晓东刘亚王磊中国矿业大学机电工程学院江苏徐州221116 浪潮电子信息产业股份有限公司山东济南250000

金属陶瓷和高熵合金具有良好热稳定性、耐高温性和抗腐蚀等优点成为涂层领域新的研究点。激光熔覆技术是获得其高超性能的涂层制备方法之一。阐述了激光熔覆涂层材料最新研究进展,重点讨论了利用激光熔覆技术在基体表面制备金属陶瓷和... 详细信息

金属陶瓷和高熵合金具有良好热稳定性、耐高温性和抗腐蚀等优点成为涂层领域新的研究点。激光熔覆技术是获得其高超性能的涂层制备方法之一。阐述了激光熔覆涂层材料最新研究进展,重点讨论了利用激光熔覆技术在基体表面制备金属陶瓷和高熵合金涂层的研究现状,介绍了熔覆金属陶瓷和高熵合金涂层的相关技术问题及它们的性能特点,并分析了其未来的发展趋势。

关键词：激光熔覆涂层金属陶瓷高熵合金

Relationship between surface pollen assemblages and vegetation in Luonan Basin, Eastern Qinling Mountains, Central China

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Journal of Geographical Sciences 2014年第3期24卷 427-445页

作者： ZHANG Wenchao LI Chunhai LU Huayu tian xianhua ZHANG Hongyan LEI Fang TANG Lingyu School of Geographic and Oceanographic Sciences Nanjing University Jiangsu Collaborative Innovation Center for Climate Change Nanjing 210093 China State Key Laboratory of Lake Science and Environment Nanjing institute of Geography and Limnology CAS Nanjing 210008 China College of Life Sciences Shaanxi Normal University Xi'an 710062 China Nanjing Institute of Geology and Paleontology CAS Nanjing 210008 China

The catchment of South Luohe River in Central China is an important region for investigating modern pollen-environment relationship, because it is located in the transitional zone between south and north China, an environment which is sensitive to climate changes. In this study, 40 surface samples under ten vegetation types were collected to reveal the relationship between pollen assemblages and vegetation. The results show that the surface pollen assemblages reflect the vegetation quite well. In forest topsoils, the average of arbo- real pollen content is greater than 40%, and the Selaginella sinensis spore is high. As to sparse forest grassland and shrub community, the average arboreal pollen is 13.2% and 16.6% respectively, and the shrub pollen is relatively higher than that of grassland samples. The grassland and farmland are characterized by low percentage of tree and shrub pollen （〈10% and 〈1%）, and high percentage of herbs （〉80%）. Pinus, Quercus and some other arboreal pollen can indicate the regional vegetation because of their dispersal ability. Quercus pollen is under-representative and so is Pinus. Artemisia pollen is significantly over-represented, has poor correlation with the plant coverage, and may reflect human dis- turbance. Gramineae can indicate plant quite well, but with low representation. High content of Chenopodiaceae probably suggests human impact. Predominant Selaginella sinensis can be used as an indicator of forest environment. Cluster analysis and principal components analysis of pollen assemblages can distinguish forest and non-forest vegetation well. The former method is better at separating pine and mixed forests, while the latter is more stable and could better differentiate farmland and other non-forest area. The first axis of PCA mainly reflects the humidity.

关键词： surface pollen vegetation type cluster analysis PCA Luonan Basin

Multi-Branch High-Dimensional Guided Transformer-Based 3D Human Posture Estimation

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Computers, Materials & Continua 2024年第3期78卷 3551-3564页

作者： xianhua Li Haohao Yu Shuoyu tian Fengtao Lin Usama Masood School of Mechanical Engineering Anhui University of TechnologyHuainan232001China School of Artificial Intelligence Anhui University of TechnologyHuainan232001China Key Laboratory of Conveyance Equipment(East China Jiaotong University) Ministry of EducationNanchang330013China

The human pose paradigm is estimated using a transformer-based multi-branch multidimensional directed the three-dimensional(3D)method that takes into account self-occlusion,badly posedness,and a lack of depth data in the per-frame 3D posture estimation from two-dimensional(2D)mapping to 3D ***,by examining the relationship between the movements of different bones in the human body,four virtual skeletons are proposed to enhance the cyclic constraints of limb ***,multiple parameters describing the skeleton are fused and projected into a high-dimensional *** a multi-branch network,motion features between bones and overall motion features are extracted to mitigate the drift error in the estimation ***,the estimated relative depth is projected into 3D space,and the error is calculated against real 3D data,forming a loss function along with the relative depth *** article adopts the average joint pixel error as the primary performance *** to the benchmark approach,the estimation findings indicate an increase in average precision of 1.8 mm within the Human3.6M sample.

关键词： Key point detection 3D human posture estimation computer vision deep learning

A Review of Intelligent Configuration and Its Security for Complex Networks

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Chinese Journal of Electronics 2024年第04期33卷 920-947页

作者： Yue ZHAO Bin YANG Fei TENG xianhua NIU Ning HU Bo tian Science and Technology on Communication Security Laboratory School of Computer and Information Engineering Chuzhou University School of Computing and Artificial Intelligence Southwest Jiaotong University School of Computer and Software Engineering Xihua University Cyberspace Institute of Advanced Technology Guangzhou University

Complex networks are becoming more complex because of the use of many components with diverse technologies. In fact, manual configuration that makes each component interoperable has breed latent danger to system security. There is still no comprehensive review of these studies and prospects for further research. According to the complexity of component configuration and difficulty of security assurance in typical complex networks, this paper systematically reviews the abstract models and formal analysis methods required for intelligent configuration of complex networks, specifically analyzes, and compares the current key technologies such as configuration semantic awareness, automatic generation of security configuration, dynamic deployment, and verification evaluation. These technologies can effectively improve the security of complex networks intelligent configuration and reduce the complexity of operation and maintenance. This paper also summarizes the mainstream construction methods of complex networks configuration and its security test environment and detection index system, which lays a theoretical foundation for the formation of the comprehensive effectiveness verification capability of configuration security. The whole lifecycle management system of configuration security process proposed in this paper provides an important technical reference for reducing the complexity of network operation and maintenance and improving network security.

关键词： Complex networks Intelligent configuration Configuration security Software defined network Lifecycle management SOFTWARE ALGORITHM AGENT

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A First-principles Study on the Adhesion Strength,Interfacial Stability,and Electronic Properties of Mg/Mg_(2)Y Interface

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Acta Metallurgica Sinica(English Letters) 2024年第3期37卷 537-550页

作者： Yunxuan Zhou Wenjun tian Quan Dong Hailian Wang Jun Tan xianhua Chen Kaihong Zheng Fusheng Pan College of Materials Science and Engineering National Engineering Research Center for Magnesium AlloysChongqing UniversityChongqing 400044China State Key Laboratory of Mechanical Transmission Chongqing UniversityChongqing 400044China Institute of New Materials Guangdong Academy of SciencesGuangzhou 510650China

The interfacial microstructures and configurations directly affect the comprehensive properties of the composites,but their interfacial adhesion mechanism is complicated to expound by experimental *** this work,based on the stacking sequence of the Mg/Mg_(2)Y interface models,nine different Mg/Mg_(2)Y interface configurations with top site,bridge site,and hollow site(HCP)under Mg1,Mg_(2),and Y terminations were successfully constructed and systematically explored by first-principles *** results showed that the Mg_(2)Y(0001)surface with Y termination is the most stable when the yttrium chemical potential()is less than-1.09 eV;otherwise,Mg_(2)Y(0001)surface with Mg1 termination is the most *** seven-layer Mg(0001)and eleven-layer Mg_(2)Y(0001)slabs are employed to reflect the bulk-like interior ***,the Mg(0001)/Mg_(2)Y(0001)with the Y-HCP stacking has the largest interface thermodynamic stability with the value of 2.383 J/m^(2) in all interface configurations owing to its largest work of *** addition,the interfacial energy of Y-HCP stacking is significantly smaller than those of Mg1-HCP when is approximately less than-0.55 eV,showing that it is more *** thermodynamic stability of Mg/Mg_(2)Y with Y-HCP is due to Mg-Y chemical bonds formed between Mg and Y ***,the Mg/Mg_(2)Y interfaces are strong interfaces based on the Griffith fracture theory.

关键词： Mg/Mg_(2)Y interface Interface stability Work of adhesion Electronic structure First-principles calculations

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对民航非法干扰行为精准防控模式的探索

民航学报 2023年第5期7卷 127-131页

作者：田先华南昌理工学院

民航非法干扰行为是危及民航安全、破坏航空秩序、损害航空器及其所载人员人身安全及财产安全的一类非法行为,是犯罪学中的犯罪行为在民航领域的特殊表现形式,两者之间是一般与特殊的关系。借鉴犯罪防控理论,本文从民航非法干扰行为现... 详细信息

民航非法干扰行为是危及民航安全、破坏航空秩序、损害航空器及其所载人员人身安全及财产安全的一类非法行为,是犯罪学中的犯罪行为在民航领域的特殊表现形式,两者之间是一般与特殊的关系。借鉴犯罪防控理论,本文从民航非法干扰行为现状、典型案例着手分析这一社会病态行为在民航运输中的形成机理,针对非法干扰行为形成因素、发生发展的时间顺序来构建精准防控模式,将有助于提高民航非法干扰行为防控的效率,有利于保障我国民航运输事业持续、健康发展。

关键词：民航安全非法干扰行为精准防控防控模式

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受威胁植物濒危等级和标准

陕西师范大学继续教育学报 2003年第2期20卷 117-119页

作者：田先华陕西师范大学生命科学学院副教授，西安710062

国际自然保护联盟(IUCN)自1984年以来,多次制定和修订有关受威胁物种的类型和分类标准.1984年,国际自然保护联盟将受威胁物种分为5个主要类别,即绝灭类、濒危类、渐危类、稀有类和知之甚少类;1991年,Mace和Lande又提出了一个以灭绝概率... 详细信息

国际自然保护联盟(IUCN)自1984年以来,多次制定和修订有关受威胁物种的类型和分类标准.1984年,国际自然保护联盟将受威胁物种分为5个主要类别,即绝灭类、濒危类、渐危类、稀有类和知之甚少类;1991年,Mace和Lande又提出了一个以灭绝概率为根据、含有三个水平的分类系统,将受威胁物种分为三个类别,即临危类、濒危类和渐危类;至1994年经过多年的研究和酝酿,国际自然保护联盟颁布了一个更有说服力的新的受威胁物种类型划分和标准.在经过几年的使用之后,由世界自然保护联盟物种生存委员会再次修订,经世界自然保护联盟理事会第51次会议(2000年2月9日)通过,于2001年再次颁布使用,这就是--.在这个文件中,共列出9个不同类别和等级,这些等级和标准的提出,为受威胁物种的评估和保护措施的制定提供了科学依据.我国于1984年公布的中,根据国际上通用的标准,结合我国的具体情况,将我国珍稀濒危植物分为濒危类、稀有类和渐危类三类.本文以我国植物现状为例,详细介绍了上述有关等级和标准.

关键词：生物多样性保护胁植物濒濒危等级标准

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中国裸子植物的物种多样性

陕西师范大学继续教育学报 2002年第1期19卷 113-115页

作者：田先华陕西师范大学生命科学学院，西安710062

中国是世界上裸子植物最多的国家,共有250余种,隶属于34个属、10个科.中国裸子植物物种多样性具有种类丰富、起源古老、多古残遗和孑遗成分、特有成分繁多和针叶林类型多样等特点;中国也是裸子植物受威胁最严重的国家,有63种裸子植物受... 详细信息

中国是世界上裸子植物最多的国家,共有250余种,隶属于34个属、10个科.中国裸子植物物种多样性具有种类丰富、起源古老、多古残遗和孑遗成分、特有成分繁多和针叶林类型多样等特点;中国也是裸子植物受威胁最严重的国家,有63种裸子植物受到不同程度的威胁,裸子植物所组成的针叶林面积日益缩减,资源遭到严重破坏.我国的裸子植物保护受到有关部门的高度重视,先后有40种和4类裸子植物被列为国家重点保护野生植物;通过建立自然保护区和一系列的科学研究,使一大批珍稀濒危的裸子植物得到相应的保护.

关键词：中国裸子植物物种多样性珍稀濒危植物

基于多尺度晶粒细化演变的TC4加工表层硬度预测

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华南理工大学学报（自然科学版） 2023年第2期51卷 35-46页

作者：王情情刘战强程延海田宪华中国矿业大学机电工程学院江苏徐州221116 江苏矿山智能采掘装备协同创新中心江苏徐州221116 山东大学机电工程学院山东济南250061

表面层微观组织结构变化决定了零件的宏观性能,准确实现零件加工表层微观组织演变预测,进而提高零件加工表层力学性能(如硬度),是改善零件服役效能以及实现零件长服役寿命可控加工的一种有效方法。切削加工是钛合金TC4零件制造工艺中最... 详细信息

表面层微观组织结构变化决定了零件的宏观性能,准确实现零件加工表层微观组织演变预测,进而提高零件加工表层力学性能(如硬度),是改善零件服役效能以及实现零件长服役寿命可控加工的一种有效方法。切削加工是钛合金TC4零件制造工艺中最基本的加工方法之一,切削过程中材料的剧烈塑性变形导致TC4加工表层微观组织变化复杂,本文针对TC4切削过程中的晶粒细化现象,对不同切削速度(100~500 m/min)下TC4组织结构多尺度分布特征、晶粒细化演变规律及其对表面材料硬度影响进行了研究。结果表明:TC4加工表层介观尺度(10^(-6)~10^(-5)m)晶粒细化程度随切削速度提高呈现先增大后减小趋势,切削速度为300 m/min时,加工表面晶粒细化程度达69.7%,切屑剪切带晶粒尺寸细化至2~6μm;微观尺度(10^(-8)~10^(-7)m)上表现为复杂位错组态和纳米孪晶,纳米孪晶类型主要为■压缩孪晶,且纳米孪晶在较高切削速度(>200 m/min)下产生;基于修正的Z-H晶粒细化模型和纳米孪晶体积分数预测模型,并考虑切削过程中晶粒细化引起的硬化作用,实现了TC4切削过程中晶粒尺寸以及硬化规律预测;构建了切削过程中晶粒细化引起的硬化规律与材料显微硬度的关系,通过模拟钛合金切削过程中晶粒细化程度和纳米孪晶形成,实现了TC4加工表层硬度预测,揭示了TC4加工表层微观尺度硬化机理。

关键词：切削加工晶粒细化演变预测表面硬度钛合金