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Effect of heat treatment on microstructural evolution,mechanical properties and tribological properties of H13 steel prepared using selective laser melting

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Journal of Iron and Steel Research International 2024年第5期31卷 1246-1259页

作者： Li-xiong Han yan Wang Shi-feng Liu zhao-hui Zhang wei Liu Xin yang Dang-shen Ma Jian Zhou Ying-kang wei college of Metallurgical engineering Xi’an University of Architecture and TechnologyXi’an710055ShaanxiChina zhejiang university City college Hangzhou310015ZhejiangChina china Iron and Steel Research Institute Group Co. Ltd.Beijing100081China

H13 tool steel was successfully prepared by selective laser melting(SLM)*** effects of heat treatment on the microstructure,mechanical properties,and tribological properties of SLMed H13 steel were *** heat treatment process involved a solution treatment and a double aging treatment of the deposited H13 tool steel prepared by *** aim is to optimize the microstructure and mechanical properties of SLMed H13 *** to the rapid heating and cooling effects of SLM,carbide precipitation in the deposited H13 steel was not uniform and residual stresses were *** purpose of the solution treatment is to dissolve the solution at a high temperature to eliminate the residual stresses and defects introduced by the SLM-forming *** solution treatment and first aging treatment produced the precipitation of small carbides at the grain boundaries and inside the crystals,which increased the hardness of SLMed H13 *** hardness increased from 538±4.0 HV of the as-deposited sample to 548±5.8 HV of samples after the first aging ***,the ultimate tensile strength and the elongation at break decreased from 1882 MPa and 11.5%in the as-deposited sample to 1697 MPa and 7.9%in those after the first aging treatment,***,the friction coefficient and wear rate in the as-deposited sample decreased from 0.5160 and 2.36×10^(–6)mm^(−3)N^(−1)m^(−1)to 0.4244 and 1.04×10^(–6)mm^(−3)N^(−1)m^(−1),***,the distribution of carbides inside the crystals was not *** second aging treatment adjusted the morphology of carbide precipitation and made it more uniform,but the precipitation of carbides grew and settled at the bottom of the grain *** hardness decreased to 533±6.7 HV compared with that with the first aging treatment,but the ultimate tensile strength and plasticity reached a balance(1807 MPa,14.05%).Accordingly,the friction coefficient and wear rate also showed a stable and decreasin

关键词： Selective laser melting H13 steel Solution aging Double aging Friction and wear Retained austenite

Effect of coral sand on the mechanical properties and hydration mechanism of magnesium potassium phosphate cement mortar

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Journal of zhejiang university-Science A(Applied Physics & engineering) 2024年第2期25卷 116-129页

作者： Hao LIU Huamei yanG Houzhen wei Jining YU Qingshan MENG Rongtao yan college of civil engineering and architecture Guilin University of TechnologyGuilin541004China Guangxi Key Laboratory of geomechanics and geotechnical engineering Guilin University of TechnologyGuilin541004China State Key Laboratory of geomechanics and geotechnical engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan430071China School of Intelligent Construction Wuchang University of TechnologyWuhan430002China Hydraulic Concrete Institute China Three Gorges CorporationBeijing100038China The First Railway Survey and Design Institute Group Corporation Xi’an710043China

Damaged structures on coral islands have been spalling and cracking due to the dual corrosion of tides and *** ensure easy access to aggregate materials,magnesium potassium phosphate cement(MKPC)and coral sand(CS)are mixed to repair damaged structures on coral ***,CS is significantly different from land-sourced sand in mineral composition,particle morphology,and *** has a substantial impact on the hydration characteristics and macroscopic properties of MKPC ***,in this study we investigated the compressive strength,interfacial mechanical properties,and corrosion resistance of MKPC CS *** in the morphology,microstructure,and relative contents of hydration products were revealed by scanning electron microscope-energy dispersive spectrometer(SEM-EDS)and X-ray diffraction(XRD).The results indicated that the compressive strength increased linearly with the interfacial micro-hardness,and then stabilized after long-term immersion in pure water and Na2SO4 solution,showing excellent corrosion *** with MKPC river sand(RS)mortar,the hydration products of CS mortar were an intermediate product 6KPO2·8H2O with a relative content of 3.9%at 1 h and 4.1%at 12 *** hydration product MgKPO_(4)·6H_(2)O increased rapidly after 7-d curing,with an increased growth rate of 1100%.Our results showed that CS promoted the nucleation and formation of hydration products of MKPC,resulting in better crystallinity,tighter overlapping,and a denser interfacial transition *** results of this study provide technical support for applying MKPC mortar as a rapid repair material for damaged structures on coral islands.

关键词： Magnesium potassium phosphate cement(MKPC) Coral sand(CS) Mechanical properties Corrosion resistance Hydration mechanism

Automatic detection and assessment of crack development in ultra-high performance concrete in the spatial and Fourier domains

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Frontiers of Structural and civil engineering 2024年第3期18卷 350-364页

作者： Jixing CAO Yao ZHANG Haijie HE weibing PENG weigang zhao Zhiguo yan Hehua ZHU School of Safety engineering and Emergency Management Shijiazhuang Tiedao UniversityShijiazhuang 050043China college of civil engineering and architecture Zhejiang UniversityHangzhou 310058China college of civil and Architectural engineering Taizhou UniversityTaizhou 318000China college of civil engineering and architecture Zhejiang University of TechnologyHangzhou 310014China Department of geotechnical engineering Tongji UniversityShanghai 200092China

Automatic detection and assessment of surface cracks are beneficial for understanding the mechanical performance of ultra-high performance concrete(UHPC).This study detects crack evolution using a novel dynamic mode decomposition(DMD)*** this method,the sparse matrix‘determined’from images is used to reconstruct the foreground that contains cracks,and the global threshold method is adopted to extract the crack *** application of the DMD method to the three-point bending test demonstrates the efficiency in inspecting cracks with high ***,the geometric features,including the area and its projection in two major directions,are evaluated over *** relationship between the geometric properties of cracks and load-displacement curves of UHPC is *** to the irregular shape of cracks in the spatial domain,the cracks are then transformed into the Fourier domain to assess their *** indicate that crack patterns in the Fourier domain exhibit a distinct concentration around a central ***,the power spectral density of cracks exhibits an increasing trend over *** investigation into crack evolution in both the spatial and Fourier domains contributes significantly to elucidating the mechanical behavior of UHPC.

关键词： dynamic mode decomposition ultra-high performance concrete crack detection geometric features Fourier domain

Semitransparent organic photovoltaics enabled by transparent p-type inorganic semiconductor and near-infrared acceptor

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Journal of Energy Chemistry 2024年第9期96卷 351-358页

作者： Xue yan Jiayu Wang wei He Top Archie Dela Peña Can Zhu Hailin Yu Yingyue Hu Cenqi yan Shengqiang Ren Xingyu Chen Zhe Wang Jiaying Wu Mingjie Li Jianlong Xia Lei Meng Shirong Lu Dewei zhao Mikhail Artemyev Yongfang Li Pei Cheng college of Polymer Science and engineering State Key Laboratory of Polymer Materials EngineeringSichuan UniversityChengdu 610065SichuanChina Department of Applied Physics The Hong Kong Polytechnic UniversityKowloonHong Kong 999077China Beijing National Laboratory for Molecular Sciences CAS Key Laboratory of Organic SolidsInstitute of ChemistryChinese Academy of SciencesBeijing 100190China college of Materials Science and engineering&engineering Research Center of Alternative Energy Materials&Devices Ministry of EducationSichuan UniversityChengdu 610065SichuanChina Department of Material Science and Technology Taizhou UniversityTaizhou 318000ZhejiangChina Advanced Materials Thrust Function HubThe Hong Kong University of Science and Technology(Guangzhou)Guangzhou 511400GuangdongChina State Key Laboratory of Advanced Technology for Materials Science and Processing Center of Smart Materials and DevicesWuhan University of TechnologyWuhan 430070HubeiChina Department of civil1nd Environmental engineering The Hong Kong University of Science and TechnologyHong Kong 999077China Research Institute for Physical Chemical Problems Belarusian State UniversityMinsk 220006Belarus

Semitransparent organic photovoltaics(STOPVs)have gained wide attention owing to their promising applications in building-integrated photovoltaics,agrivoltaics,and floating *** semiconductors with high charge carrier mobility usually have planar and conjugated structures,thereby showing strong absorption in visible *** this work,a new concept of incorporating transparent inorganic semiconductors is proposed for high-performance ***(I)thiocyanate(CuSCN)is a visible-transparent inorganic semiconductor with an ionization potential of 5.45 eV and high hole *** transparency of CuSCN benefits high average visible transmittance(AVT)of *** energy levels of CuSCN as donor match those of near-infrared small molecule acceptor BTP-eC9,and the formed heterojunction exhibits an ability of exciton *** mobility of CuSCN contributes to a more favorable charge transport channel and suppresses charge *** control STOPVs based on PM6/BTP-eC9 exhibit an AVT of 19.0%with a power conversion efficiency(PCE)of 12.7%.Partial replacement of PM6 with CuSCN leads to a 63%increase in transmittance,resulting in a higher AVT of 30.9%and a comparable PCE of 10.8%.

关键词： Copper(I)thiocyanate Inorganic semiconductor Semitransparent Organic photovoltaics Charge dissociation

Advancing Normative Urban Planning Education in china:A Study of Educational Institutions and Urban Planning Curricula

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china City Planning Review 2009年第3期18卷 42-49页

作者： wei Yaping,PhD,Lecturer,college of civil engineering and architecture,zhejiang university,hangzhou,P.R.china.zhao Min,Professor,college of architecture and Urban Planning,Tongji university,Shanghai,P.R.china. QIAN Fang

1. Introduction As a result of the social and economic reforms in china and the changing dynam-ics of the administrative, financial and social spheres, it is more and more diffi cult to tackle problems of space and

关键词： administrative professional spheres disciplines ed

The States-of-arts and Key Scientific Issues on Durability Research of Concrete Structures

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Journal of Wuhan university of Technology(Materials Science) 2006年第Z1期21卷 1-8页

作者：金伟良赵羽习 college of civil engineering and architecture zhejiang university Hangzhou 310027 China

Concrete has traditionally been regarded as a durable material requiring little or no maintenance. However, over the past several decades, a number of durability related problems have emerged and stimulated research into the factors relating to concrete durability globally. The challenge now facing practicing engineers is how to design and build structures that not only satisfy the specified structural requirements, but also achieve the performance levels required from a durability standpoint. Research works on concrete structural durability have been widely reported in the literature over the last several decades. In this paper, reviews of four stages of research work on durability, i e, environments, materials, components, and structures, were presented. Afterwards, the key scientific issues in this field were also pointed out.

关键词： concrete structures durability state of the art key scientific issues

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“阶跃型”滑坡位移监测动态预警系统

长江科学院院报 2024年第7期41卷 148-157页

作者：贲琰棋易武魏兆亨周迎刘伟邓欣雨三峡大学湖北长江三峡滑坡国家野外科学观测研究站湖北宜昌443002 三峡大学土木与建筑学院湖北宜昌443002 湖北省地质局第五地质大队湖北鄂州436000 十堰市自然资源和规划局湖北十堰442000 三峡大学科技学院湖北宜昌442002

“阶跃型”演化规律是滑坡在等速变形阶段受外界因素影响表现出的一种波动特性,具有变形周期长、机制复杂、临灾预警难度大的特点。基于“阶跃型”滑坡变形-时间曲线的特征和规律,通过引入“一个降雨过程”定义滑坡监测序列的多期降雨区... 详细信息

“阶跃型”演化规律是滑坡在等速变形阶段受外界因素影响表现出的一种波动特性,具有变形周期长、机制复杂、临灾预警难度大的特点。基于“阶跃型”滑坡变形-时间曲线的特征和规律,通过引入“一个降雨过程”定义滑坡监测序列的多期降雨区间,将预警过程划分为前期+当期降雨和当期降雨两种模式,以诱因-时间-空间作为滑坡预警的重要指标,建立了滑坡综合预警判据模型,据此提出设计麻池村1号滑坡综合动态分级预警系统的方法。并结合麻池村1号滑坡的地质条件、监测数据等信息,深入分析了滑坡的变形演化规律及预警阈值。结果表明:①滑坡变形破坏模式为牵引式,属于典型的降雨诱发的“阶跃型”堆积层滑坡;②前期降雨有效持时为10 d,前期+当期降雨模式下的降雨阈值分别为24、32 mm,当期降雨模式下滑坡的的降雨阈值为37 mm,滑坡的位移速率阈值为12 mm;③以降雨量、位移速率到达阈值时为Ⅲ级黄色预警中心面(线),构建滑坡的综合动态分级预警系统,将滑坡预警从传统的“阈值预警”升级为“过程预警”,使得预警更具针对性。

关键词： “阶跃型”滑坡滑坡监测降雨过程阈值预警预警系统

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融合碳激励潜变量的低碳出行方式选择模型

浙江大学学报（工学版） 2024年第8期58卷 1628-1635,1658页

作者：何艳孙轶琳赵志健疏阳浙江大学建筑工程学院浙江杭州310058 浙江大学平衡建筑研究中心浙江杭州310000 浙江大学建筑设计研究院有限公司浙江杭州310013 浙江大学工程师学院浙江杭州310058

以计划行为理论与价值-信念-规范理论为理论基础,综合考虑影响出行者低碳出行意愿的潜变量,以分析出行者低碳出行行为及内在机理.基于杭州市实证数据,建立多原因多指标模型,标定潜变量适配值.构建混合选择模型与无潜变量的Logit模型,对... 详细信息

以计划行为理论与价值-信念-规范理论为理论基础,综合考虑影响出行者低碳出行意愿的潜变量,以分析出行者低碳出行行为及内在机理.基于杭州市实证数据,建立多原因多指标模型,标定潜变量适配值.构建混合选择模型与无潜变量的Logit模型,对比分析出行者工作日方式的选择行为.建立二元混合选择模型,分析碳激励下高碳人群的出行行为转变.结果表明,态度、知觉感知控制、激励态度等潜变量显著影响出行者的低碳出行意愿与出行方式选择,混合选择模型比无潜变量的Logit模型具有更好的拟合优度,预测精度提升了4.6%,碳激励下64.4%的高碳人群倾向于选择低碳出行,碳激励可以有效促进公众的出行方式转变,变量态度、出行时间在公众出行方式转变上存在一定的异质性.

关键词：交通工程低碳出行方式选择碳激励混合选择模型

基于改进Mask R-CNN与双目视觉的智能配筋检测

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浙江大学学报（工学版） 2024年第5期58卷 1009-1019页

作者：魏翠婷赵唯坚孙博超刘芸怡浙江大学建筑工程学院浙江杭州310058 浙江大学平衡建筑研究中心浙江杭州310028

为了提高配筋检测的智能化水平,提出基于改进掩膜区域卷积神经网络(Mask R-CNN)模型与双目视觉技术的配筋检测方法.通过在Mask R-CNN中加入自下而上的注意力机制路径,形成了带通道注意力和空间注意力的掩膜区域卷积神经网络(Mask R-CNN+... 详细信息

为了提高配筋检测的智能化水平,提出基于改进掩膜区域卷积神经网络(Mask R-CNN)模型与双目视觉技术的配筋检测方法.通过在Mask R-CNN中加入自下而上的注意力机制路径,形成了带通道注意力和空间注意力的掩膜区域卷积神经网络(Mask R-CNN+CA-SA)改进模型.结合双目视觉技术进行坐标转换,获取钢筋直径与间距,实现智能配筋检测.在自建的包含3 450张钢筋图片的数据集上进行训练,结果表明,改进模型的F1分数和全类平均精确率(mAP)相较于Mask R-CNN基础网络分别提高了2.54%和2.47%.通过钢筋网验证试验和复杂背景测试,钢筋直径的绝对误差和相对误差基本小于1.7 mm和10%,钢筋间距的绝对误差和相对误差分别小于4mm和3.2%,所提方法在实际应用中具有较强的可操作性.智能配筋检测技术在保证足够的检测精度的同时,能够大大提升工效,降低人工成本.

关键词：配筋质量检测 Mask R-CNN 注意力机制深度学习双目视觉技术