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Enhanced high-temperature mechanical properties of laser-arc hybrid additive manufacturing of Al-Zn-Mg-Cu alloy via microstructure control

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Journal of materials Science & Technology 2024年第2期169卷 220-234页

作者： dehua Liu Dongjiang Wu Yunsong Wang Zhuo Chen Changrong Ge Qingyu Zhao Fangyong Niu Guangyi ma State Key Laboratory of High-performance Precision manufacturing Dalian University of TechnologyDalian 116024China

Recently,rapid and cost-effective additive manufacturing solutions for lightweight aluminum alloys with excellent high-temperature mechanical properties have been increasingly in demand.In this study,we combined laser-arc hybrid additive manufacturing with solution and artificial aging treatments to achieve Al-Zn-Mg-Cu alloy with favorable high-temperature strength via microstructure control.Hydrogen pores became the major defect in the as-deposited and heat-treated specimens.The continuous distribution of eutectics with hard-brittle characteristics at the grain boundaries was destructed following heat treat-ment.High-densityηprecipitates were uniformly dispersed in the heat-treated Al-Zn-Mg-Cu alloy,whereas appeared coarsened and dissolved at 473 K,owing to the rapid diffusion of Zn and Mg.The average 0.2%yield strength(318±16 MPa)and ultimate tensile strength(362±20 MPa)at 473 K af-ter heat treatment were enhanced by approximately 58%and 51%,respectively,compared to those of the as-deposited specimen.In addition,theηprecipitates contributed to lattice distortions and strain fields,which prevented dislocation motion and increased slip deformation resistance at high temper-atures.The as-deposited specimen exhibited intergranular fracture at 473 K,with cracks preferring to propagate along the aggregated eutectics.However,crack propagation proceeded in the sections with more pores in the heat-treated specimen.Our approach may provide a valid option for achieving alu-minum alloys with excellent high-temperature mechanical properties.

关键词： Laser-arc hybrid additive manufacturing Al-Zn-Mg-Cu alloy High-temperature strength Heat treatment,Microstructure evolution

SGNR: A Social Graph Neural Network Based Interactive Recommendation Scheme for E-Commerce

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清华大学学报:自然科学版(英文版) 2023年第4期28卷 786-798页

作者： dehua ma Yufeng Wang Jianhua ma Qun Jin School of Communications and lnformation Engineering Nanjing University of Posts and TelecommunicationsNanjing 210003China Department the Faculty of Computer and Information SciencesHosei UniversityTokyo 194-0298Japan Networked Information Systems Laboratory Department of Human Informatics and Cognitive SciencesFaculty of Human SciencesWaseda UniversityTokyo 169-8050Japan

Interactive Recommendation(IR)formulates the recommendation as a multi-step decision-making process which can actively utilize the individuals’feedback in multiple steps and optimize the long-term user benefit of recommendation.Deep Reinforcement Learning(DRL)has witnessed great application in IR for ecommerce.However,user cold-start problem impairs the learning process of the DRL-based recommendation scheme.Moreover,most existing DRL-based recommendations ignore user relationships or only consider the single-hop social relationships,which cannot fully utilize the social network.The fact that those schemes can not capture the multiple-hop social relationships among users in IR will result in a sub-optimal recommendation.To address the above issues,this paper proposes a Social Graph Neural network-based interactive Recommendation scheme(SGNR),which is a multiple-hop social relationships enhanced DRL framework.Within this framework,the multiple-hop social relationships among users are extracted from the social network via the graph neural network which can sufficiently take advantage of the social network to provide more personalized recommendations and effectively alleviate the user cold-start problem.The experimental results on two real-world datasets demonstrate that the proposed SGNR outperforms other state-of-the-art DRL-based methods that fail to consider social relationships or only consider single-hop social relationships.

关键词： Interactive Recommendation(IR) Deep Reinforcement Learning(DRL) Graph Neural Network(GNN)

Development of lutetium oxide continuous fibers with excellent mechanical properties

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Journal of Advanced Ceramics 2023年第1期12卷 24-35页

作者： Yongshuai XIE Ying PENG Youmei WANG dehua ma Yuan CHENG Luyi ZHU Jiecai HAN Xinghong ZHANG National Key Laboratory of Science and Technology on Advanced Composites in Special Environments Harbin Institute of TechnologyHarbin 150001China State Key Laboratory of Crystal materials Institute of Crystal MaterialsShandong UniversityJinan 250100China

The difficulty of reducing the diameter of lutetium oxide(Lu_(2)O_(3))continuous fibers below 50μm not only limits the flexibility of the sample but also seriously affects their application and development in high-energy lasers.In this work,a Lu-containing precursor with high ceramic yield was used as raw material,fiberized into precursor fibers by dry spinning.The pressure-assisted water vapor pretreatment(PAWVT)method was creatively proposed,and the effect of pretreatment temperature on the ceramization behavior of the precursor fibers was studied.By regulating the decomposition behavior of organic components in the precursor,the problem of fiber pulverization during heat treatment was effectively solved,and the Lu_(2)O_(3) continuous fibers with a diameter of 40μm were obtained.Compared with the current reported results,the diameter was reduced by about 50%,successfully breaking through the diameter limitation of Lu_(2)O_(3) continuous fibers.In addition,the tensile strength,elastic modulus,flexibility,and temperature resistance of Lu_(2)O_(3) continuous fibers were researched for the first time.The tensile strength and elastic modulus of Lu_(2)O_(3) continuous fibers were 373.23 MPa and 31.55 GPa,respectively.The as-obtained flexible Lu_(2)O_(3) continuous fibers with a limit radius of curvature of 3.5-4.5 mm had a temperature resistance of not lower than 1300℃,which established a solid foundation for the expansion of their application form in the field of high-energy lasers.

关键词： lutetium oxide(Lu_(2)O_(3)) continuous fibers tensile strength flexible temperature resistance

Modification of YSZ fiber composites by Al_(2)TiO_(5) fibers for high thermal shock resistance

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Journal of Advanced Ceramics 2022年第6期11卷 922-934页

作者： Wei LIU Yongshuai XIE Zhezhe DENG Ying PENG Jianhong DONG Ze ZHU dehua ma Luyi ZHU Guanghui ZHANG Xinqiang WANG State Key Laboratory of Crystal materials School of Crystal MaterialsShandong UniversityJinan 250100China

Yttria-stabilized zirconia(YSZ)fiber composites are highly efficient thermal insulating materials;however,the poor thermal shock resistance limits their versatile applications.In the present study,YSZ fiber was mixed directly with Al_(2)TiO_(5)fiber,which had an extremely low thermal expansion coefficient,to prepare YSZ–Al_(2)TiO_(5)(ZAT)fiber composites by compression molding and heat treatment.The minimum thermal expansion coefficient of the prepared ZAT fiber composites was measured to be 7.74×10^(−6)K^(−1),which was 26%lower than that of the YSZ fiber composites(10.42×10^(−6)K^(−1)).It was shown that the prepared ZAT fiber composites maintain the integrity after undergoing 51 thermal shock cycles between 1100℃and room temperature.Whereas,YSZ fiber composites burst immediately after only one thermal shock cycle under the same condition.In addition,the ZAT fiber composites also exhibit considerable mechanical and thermal insulating performance.

关键词： Al_(2)TiO_(5)fibers YSZ-Al_(2)TiO_(5)fiber composites thermal expansion thermal shock resistance thermal insulating

Biological removal of antiandrogenic activity in gray wastewater and coking wastewater by membrane reactor process

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Journal of Environmental Sciences 2015年第7期27卷 195-202页

作者： dehua ma Lujun Chen Cong Liu Chenjun Bao Rui Liu School of Environment Tsinghua University Zhejiang Provincial Key Laboratory of Water Science and Technology

A recombinant human androgen receptor yeast assay was applied to investigate the occurrence of antiandrogens as well as the mechanism for their removal during gray wastewater and coking wastewater treatment. The membrane reactor（MBR） system for gray wastewater treatment could remove 88.0% of antiandrogenic activity exerted by weakly polar extracts and 97.3% of that by moderately strong polar extracts, but only 32.5%of that contributed by strong polar extracts. Biodegradation by microorganisms in the MBR contributed to 95.9% of the total removal. After the treatment, the concentration of antiandrogenic activity in the effluent was still 1.05 μg flutamide equivalence（FEQ）/L, 36.2%of which was due to strong polar extracts. In the anaerobic reactor, anoxic reactor, and membrane reactor system for coking wastewater treatment, the antiandrogenic activity of raw coking wastewater was 78.6 mg FEQ/L, and the effluent of the treatment system had only 0.34 mg FEQ/L. The antiandrogenic activity mainly existed in the medium strong polar and strong polar extracts. Biodegradation by microorganisms contributed to at least 89.2%of the total antiandrogenic activity removal in the system. Biodegradation was the main removal mechanism of antiandrogenic activity in both the wastewater treatment systems.

关键词： Biological removal Antiandrogenic activity Gray wastewater Coking wastewater Membrane reactor

主动健康视角下上海市55岁以上人群轻度认知障碍疾病认知及就诊意愿研究

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中国全科医学 2024年第10期27卷 1208-1214页

作者：张敏陆媛高松马佳刘亚林翟佳燚于德华同济大学附属杨浦医院全科医学科上海市200090 同济大学医学院全科医学系上海市200090 上海市全科医学与社区卫生发展研究中心 200090 上海市杨浦区定海社区卫生服务中心 200090 上海市嘉定区嘉定镇街道社区卫生服务中心 201899

背景主动健康是实施健康中国战略的重要措施。轻度认知障碍(MCI)是认知障碍疾病早期发现和干预的重要切入点,是实现脑健康的关键环节。目的了解上海市55岁以上社区人群对MCI的认知情况、就诊意愿及影响因素,调动人群对MCI的主动健康干预... 详细信息

背景主动健康是实施健康中国战略的重要措施。轻度认知障碍(MCI)是认知障碍疾病早期发现和干预的重要切入点,是实现脑健康的关键环节。目的了解上海市55岁以上社区人群对MCI的认知情况、就诊意愿及影响因素,调动人群对MCI的主动健康干预,全面实现健康中国建设。方法2021年10—12月,随机抽取上海市城区、郊区各一区(城区为杨浦区、郊区为嘉定区),每区随机抽取1~2家社区卫生服务中心(杨浦区为大桥社区卫生服务中心、定海社区卫生服务中心,嘉定区为嘉定镇街道社区卫生服务中心),按纳入标准对社区卫生服务中心门诊候诊居民进行现场面对面问卷调查。MCI疾病认知度调查问卷内容包括:(1)一般人口学特征;(2)社区人群MCI疾病认知水平;(3)社区人群疾病就诊意愿。采用Logistic回归分析探讨社区人群MCI就诊意愿的影响因素。结果本调查共发放问卷970份,回收有效问卷951份,有效回收率98.04%。(1)55岁以上社区人群对MCI的认知问卷得分为(14.55±5.24)分。51.3%(488/951)的社区人群知晓“轻度认知障碍”的概念,获知途径以媒体途径为主[61.7%,301/488];59.9%(570/951)的人群认为“年纪大了都会出现轻度认知障碍”;14.1%(134/951)的人群参加过相关筛查活动;6.2%(59/951)的人群曾因记忆障碍或怀疑有认知障碍而就诊。(2)对社区人群的MCI就诊意愿进行单因素及多因素分析发现,认知障碍家族史、对MCI的认识与理解及个人相关经历是社区人群MCI就诊意愿的影响因素(P<0.05)。结论55岁以上社区人群MCI疾病认知水平较差,疾病就诊意愿不强烈。MCI相关知识知晓不佳、对MCI的理解存在偏差及相关实践经历缺乏的人群就诊意愿差。建议多角度宣传,提高社区人群MCI疾病认知度;提供全方位支持,提高主动健康可及性,探索促进主动健康的有效途径。

关键词：认知障碍主动健康健康中国轻度认知障碍疾病认知就诊意愿影响因素分析

上海市社区卫生服务机构幽门螺杆菌感染诊疗质量分析

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中国全科医学 2024年第19期27卷 2401-2408页

作者：马乐金花史玲易春涛侯进陈晨宦红梅倪衡如于德华同济大学附属杨浦医院全科医学科上海市200090 上海市全科医学与社区卫生发展研究中心 200090 同济大学医学院全科医学研究中心上海市200090 上海市全科医学临床质量控制中心 200090 上海市普陀区卫生健康事务管理中心 200062 上海市徐汇区卫生健康委员会监督所 200031 上海市浦东新区社区卫生指导中心 201300 上海市静安区江宁路街道社区卫生服务中心 200040 上海市闵行区古美社区卫生服务中心 201102 上海市宝山区顾村镇社区卫生服务中心 201906

背景上海市社区卫生服务机构对于幽门螺杆菌(Hp)感染的诊疗水平和质量尚不明确,缺乏系统的评价和监测。目的了解上海市社区卫生服务机构对于Hp感染的诊疗及管理现状,评价其诊疗质量,并探讨其存在的问题和改进措施。方法于2022年5—6月... 详细信息

背景上海市社区卫生服务机构对于幽门螺杆菌(Hp)感染的诊疗水平和质量尚不明确,缺乏系统的评价和监测。目的了解上海市社区卫生服务机构对于Hp感染的诊疗及管理现状,评价其诊疗质量,并探讨其存在的问题和改进措施。方法于2022年5—6月向上海市16个行政区共计249家社区卫生服务中心及3875名在社区卫生服务中心工作的全科医生发放调查问卷,调查社区卫生服务中心Hp感染根治处方规范化情况、Hp感染检测情况、Hp感染根治药物配备情况、Hp感染诊疗管理情况、Hp感染诊疗中困难问题,以及社区全科医生对Hp感染诊疗认知情况等。结果上海社区卫生服务机构Hp感染处方根治方案正确率仅为32.0%。上海社区卫生服务机构中有能力开展Hp感染检测的卫生服务中心比例较高,近80.0%。大部分社区卫生服务中心能配备基本的根治Hp所需的药物,但铋剂配备率低,为54.6%。Hp诊疗规范督查率80.0%。Hp感染规范化诊疗培训需求较高,占66.7%。在Hp感染诊疗中,存在主要困难为药物配备不齐全、医生诊疗能力不足和设备不足。社区全科医生对Hp感染诊治相关基础知识掌握不足。结论上海市各社区卫生服务机构需进一步加强开展Hp检测的能力,特别是远郊社区卫生服务中心,包括增加购入Hp相关检测设备、试剂,完备Hp根治所需相关药物等。此外,需进一步加强对社区卫生服务中心Hp感染规范化诊疗培训,提高全科医师对Hp感染的诊疗能力,同时加强Hp诊疗规范督查,进一步提高社区全科医生Hp感染诊疗能力。

关键词：幽门螺杆菌社区卫生服务中心诊疗规范诊疗质量系统管理上海市

Environmentally regulated intrinsic oxygen-ion transport for oxideion conductors

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Journal of materiomics 2023年第5期9卷 867-873页

作者： Yu Huan Mengyue ma Yuanhui Su dehua Dong Xun Hu Tao Wei School of material Science and Engineering University of Jinan336 Nanxinzhuang West RoadJinanShandong250022China Spintronics Institute University of Jinan336 Nanxinzhuang West RoadJinanShandong250022China

Oxide-ion conductors have been widely used as catalytic,conductive,detecting and other materials under oxidizing,reducing,inert,mixed environments and the like.However,so far the evaluation of their oxygen-ion transport(such as oxide-ion conductivity and oxygen permeability)either is extrinsic or is limited only in oxidizing or inert environment.Herein,the evaluation of intrinsic oxygen-ion transport for oxide-ion conductors in all environments seems especially important.In this work,a new test system was designed to enable the oxide-ion conductors placing in single oxidizing,reducing,inert or mixed environment separately,which also realized all the oxygen-vacancy concentrations of oxide-ion conductors are in equilibrium in all environments.The intrinsic oxide-ion conductivity and oxygen permeability were evaluated in all environments,and the influencing factors regulated by environments also were analyzed to correlate the variation of oxygen-ion transport.

关键词： Oxide-ion conductivity Oxygen-ion transport Oxygen-vacancy Oxygen permeability

激光-电弧复合增材制造Al-Cu合金T型结构微观组织演变与熔池流动行为分析

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航空制造技术 2024年第9期67卷 62-69,77页

作者：王儒政马广义吴胜男刘德华牛方勇吴东江中国航发控制系统研究所无锡214063 大连理工大学高性能精密制造全国重点实验室大连116024

在T型结构增材制造过程中,交叉节点处易出现冶金结合不良及重熔缺陷等问题,制约该结构性能的提升。采用激光-电弧复合增材制造技术制备了Al-Cu合金T型结构,对交叉节点处的组织形貌进行了表征,并通过数值模拟分析了节点处熔池内的温度分... 详细信息

在T型结构增材制造过程中,交叉节点处易出现冶金结合不良及重熔缺陷等问题,制约该结构性能的提升。采用激光-电弧复合增材制造技术制备了Al-Cu合金T型结构,对交叉节点处的组织形貌进行了表征,并通过数值模拟分析了节点处熔池内的温度分布以及流动特征。结果表明,在T型结构节点处能够观察到重熔作用所导致的弧形条纹特征,该区域的模拟形貌与实际结果具有良好的一致性;熔池边界处等温线分布较为密集,内部marangoni对流导致逆时针涡流的形成,最高流速可达0.16 m/s。依据顶层晶粒形态差异,分为顶层节点重熔区(RZI)和顶层热影响区(HAZ)。其中RZI内主要为细小的树枝晶,平均晶粒尺寸相比于HAZ降低了20.8%,内部析出相主要为与α-Al基体呈非共格界面的大尺寸θ(Al_(2)Cu)相;平均显微硬度可达(98.4±6.4)HV_(0.1),相比于未重熔区最高提升约14.0%。

关键词：激光-电弧复合增材制造 Al-Cu合金 T型结构组织形貌熔池流动