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Effect of Sc on Al_(3)Fe phase and mechanical properties of as-cast AA5052 aluminum alloy

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China Foundry 2024年第3期21卷 257-264页

作者： Yang Li qing Yu feng-feng Chen Jia-wen He Hong-mei Yang meng-nie Li Faculty of Materials Science and Engineering Kunming University of Science and TechnologyKunming 650093China

The AA5052 aluminum alloy is widely used in automobile and aerospace manufacturing,and with the development of light-weight alloys,it is required that these materials exhibit better mechanical *** studies have demonstrated that the addition of Sc to aluminum alloys can improve both the microstructure and properties of the *** this study,the effect of Sc on the Fe-rich phase and properties of the AA5052 aluminum alloy was studied by adding 0%,0.05%,0.2%,and 0.3%*** results show that with the increase of Sc,the coarse needle-like Fe-rich phase gradually transforms into Chinese-script and then nearly spherical particles,reduce the size of Fe-rich phase,and refine the grain with increase of high angle grain boundaries(HAGBs).These microstructure changes enhance the strength of the AA5052 alloy through Sc *** ductility of the alloy is obviously improved because the addition of a lower amount of Sc changes the morphology of Fe-rich phase from needle-like into a Chinese-script,and it is subsequently reduced as a result of significant increase in HAGBs with increasing Sc content.

关键词： AA5052 aluminum alloy Al3Fe phase mechanical properties grain boundary

Corrugated Graphene Paper Reinforced Silicone Resin Composite for Efficient Interface Thermal Management

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Chinese Journal of Polymer Science 2024年第7期42卷 1002-1014,I0010页

作者： Bo-Wen Wang Heng Zhang qing-Xia He Hui-Tao Yu meng-meng Qin Wei feng Tianjin Key Laboratory of Composite and Functional Materials School of Materials Science and EngineeringTianjin UniversityTianjin300350China International Engineering Institute Tianjin UniversityTianjin300350China

With the rapid development of high-power-density electronic devices,interface thermal resistance has become a critical barrier for effective heat management in high-performance electronic ***,there is an urgent demand for advanced thermal interface materials(TIMs)with high cross-plane thermal conductivity and excellent compressibility to withstand increasingly complex operating *** achieve this aim,a promising strategy involves vertically arranging highly thermoconductive graphene on ***,with the currently available methods,achieving a balance between low interfacial thermal resistance,bidirectional high thermal conductivity,and large-scale production is ***,we prepared a graphene framework with continuous filler structures in in-plane and cross-plane directions by bonding corrugated graphene to planar graphene *** interface interaction between the graphene paper framework and polymer matrix was enhanced via surface functionalization to reduce the interface thermal *** resulting three-dimensional thermal framework endows the polymer composite material with a cross-plane thermal conductivity of 14.4 W·m^(-1)·K^(-1)and in-plane thermal conductivity of 130W·m^(-1)·K^(-1)when the thermal filler loading is 10.1 wt%,with a thermal conductivity enhancement per 1 wt%filler loading of 831%,outperforming various graphene structures as *** its high thermal conductivity,low contact thermal resistance,and low compressive modulus,the developed highly thermoconductive composite material demonstrates superior performance in TIM testing compared with TFLEX-700,an advanced commercial TIM,effectively solving the interfacial heat transfer issues in electronic *** novel filler structure framework also provides a solution for achieving a balance between efficient thermal management and ease of processing.

关键词： Graphene paper Vertically aligned structure Cross-plane thermal conductivity Low compressive modulus Thermal interface material

Irrigation mitigates the heat impacts on photosynthesis during grain filling in maize

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Journal of Integrative Agriculture 2023年第8期22卷 2370-2383页

作者： WANG Xing-long ZHU Yu-peng YAN Ye HOU Jia-min WANG Hai-jiang LUO Ning WEI Dan meng qing-feng WANG Pu College of Agronomy and Biotechnology China Agricultural UniversityBeijing 100093P.R.China

Elevating soil water content(SWC)through irrigation was one of the simple mitigation measures to improve crop resilience to heat *** response of leaf function,such as photosynthetic capacity based on chlorophyll fluorescence during the mitigation,has received limited attention,especially in field conditions.A two-year field experiment with three treatments(control treatment(CK),high-temperature treatment(H),and high-temperature together with elevating SWC treatment(HW))was carried out during grain filling with two maize hybrids at a typical station in North China ***,the net photosynthetic rate(Pn)was improved by 20%,and the canopy temperature decreased by 1–3℃ in HW compared with in H in both ***,the higher SWC in HW significantly improved the actual photosynthetic rate(Phi2),linear electron flow(LEF),variable fluorescence(F_(v)),and the maximal potential quantum efficiency(F_(v)/F_(m))for both ***,different responses in chlorophyll fluorescence between hybrids were also *** higher SWC in HW significantly improved thylakoid proton conductivity(g H^(+))and the maximal fluorescence(F_(m))for the hybrid *** the hybrid XY335,the proton conductivity of chloroplast ATP synthase(v H^(+))and the minimal fluorescence(Fo)was increased by the *** structural equation model(SEM)further showed that SWC had significantly positive relationships with Pn,LEF,and F_(v)/F_(m).The elevating SWC alleviated heat stress with the delayed leaf senescence to prolong the effective period of photosynthesis and enhanced leaf photosynthetic capacity by improving Phi2,LEF,Fv,and F_(v)/F_(m).This research demonstrates that elevating SWC through enhancing leaf photosynthesis during grain filling would be an important mitigation strategy for adapting to the warming climate in maize production.

关键词： high temperature soil water content photosynthesis chlorophyll fluorescence maize

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大磅山隧道施工与溶洞处治关键技术研究

建筑机械 2024年第7期 193-197,203页

作者：王战胜孟庆锋赵永发郑志伟刘延钊中交三公局第一工程有限公司北京100012

为解决岩溶发育区隧道施工难题,文章以大磅山隧道为工程背景,研究了复杂地质岩溶发育地区隧道施工及溶洞处治的关键技术。首先结合地勘报告与现场情况分析了隧址区地质及岩溶发育情况等,并根据溶洞大小及位置的不同制定了不同处治方法,... 详细信息

为解决岩溶发育区隧道施工难题,文章以大磅山隧道为工程背景,研究了复杂地质岩溶发育地区隧道施工及溶洞处治的关键技术。首先结合地勘报告与现场情况分析了隧址区地质及岩溶发育情况等,并根据溶洞大小及位置的不同制定了不同处治方法,主要包括换填、跨越、打钢管桩、超前支护等。对隧道施工及溶洞处治的关键施工技术进行了研究,主要包括超前支护、洞身开挖、超欠挖处理及超前地质预报等。本项目于2022年9月通车,运营检验隧道和施工及溶洞处治技术合理,保证了隧道施工运营的安全性与经济效益。

关键词：隧道工程岩溶发育溶洞地质预报施工技术

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Nanoscopic tribological characteristics of a cryogenically cycled Zr-based metallic glass

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Science China(Physics,Mechanics & Astronomy) 2024年第6期67卷 113-126页

作者： Qian Jia Qiaosheng Xia qing Zhou Yucheng Wang Yue Ren Yu meng Haifeng Wang feng Zhou State Key Laboratory of Solidification Processing Center of Advanced Lubrication and Seal MaterialsNorthwestern Polytechnical UniversityXi’an 710072China Shaanxi Key Laboratory of Surface Engineering and Remanufacturing Xi’an UniversityXi’an 710065China State Key Laboratory of Solid Lubrication Lanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhou 730000China

Optimized macroscopic tribological behavior can be anticipated in metallic glasses(MGs)by cryogenic cycling treatment(CCT),which is attributed to enhanced ***,the intrinsic friction mechanisms of MGs induced by cryogenic rejuvenation are still poorly *** the present study,nanoscopic wear tests were conducted on the Zr-based MGs surface with different CCT cycles using atomic force microscopy(AFM).After CCT treatment with 100 cycles,the MG displays the highest adhesion and ploughing frictions,but significantly improved anti-wear *** tests and molecular dynamics simulations disclose that the increased adhesion is attributed to the dominance of liquid-like regions in the CCT-treated MGs,and the impact of reduced hardness and weak elastic recovery results in the deteriorated ploughing *** enhanced plasticity effectively dissipates the strain from the AFM tip through multiple shear bands and weakens the adhesion during deformation,giving rise to excellent wear *** study elucidates the promoting effect of CCT on the outstanding antiwear performance of MGs,and is helpful for the development of novel alloys.

关键词： metallic glasses cryogenic cycling treatment nanoscope wear friction mechanism

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沥青路面刚度对路面层温度的依赖性研究

建筑机械 2024年第3期 104-107页

作者：刘俊乐郭云杰王战胜孟庆锋柏兴雄中交三公局第一工程有限公司北京100012

下落重量偏转仪(FWD)是测量路面结构强度最常用的装置,利用该装置模拟重型车辆车轮对路面的冲击来评估路面强度。而沥青路面层的刚度以及FWD测量的E0模量值,在很大程度上和路面温度有很大的关系。当使用偏转仪测量不同环境条件和不同季... 详细信息

下落重量偏转仪(FWD)是测量路面结构强度最常用的装置,利用该装置模拟重型车辆车轮对路面的冲击来评估路面强度。而沥青路面层的刚度以及FWD测量的E0模量值,在很大程度上和路面温度有很大的关系。当使用偏转仪测量不同环境条件和不同季节的沥青路面强度时,E0模量的值应降低到假定的标准温度。文章修正了实验沥青路面结构的温度修正系数,使用该系数可以将下落重量偏角计测量的沥青路面层的刚度值降低到20℃的标准温度,能够很好的评价沥青路面层温度对沥青刚度和E0模量的影响。

关键词：道路路面路面强度路面刚度温度系数 E0模量下降重量偏转计(FWD)

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Dielectric and energy storage properties of PbO–SrO–Nb_(2)O_(5)–Na_(2)O–Si thin films by annealing

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Rare Metals 2024年第1期43卷 351-355页

作者： Fei-Hu Tan qing-meng Zhang feng Wei Hong-Bin Zhao Xiao Zhang Jun Du State Key Laboratory of Advanced Materials for Smart Sensing General Research Institute for Nonferrous MetalsBeijing 100088China Advanced Electronic Materials Institute General Research Institute for Nonferrous MetalsBeijing 100088China

Dielectric and energy storage properties of PbOSrO-Na_(2)O-Nb_(2)O_(5)-SiO_(2)(PSNNS) thin films with annealing temperature from 700 to 850 ℃ were investigated by measuring their capacitance-electric filed curve and hysteresis *** results show that the highest dielectric constant and energy density are 81.2 and 17.0 J·cm^(-3),respectively,which is obtained in the sample with annealing temperature of 800 ℃.Annealed from 700 to800 ℃,the dielectric constant and energy storage performance of PSNNS films are continuously ***,with annealing temperature up to 850 ℃,their dielectric constant decreases,which might be related with the removal of interfacial defects as a function of annealing *** is one of the causes of space charge phenomenon,resulting in the increase in dielectric ***,the micro structure analysis by X-ray diffraction(XRD) and transmission electron microscope(TEM) indicates that the change of crystallization phase and interfacial polarization takes responsibility to the results.

关键词： Thin film Pulse laser deposition Annealing temperature Energy storage density

Attractor for the Extensible Beam Equation with Nonlocal Weak Damping on Time–Dependent Space

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Acta Mathematica Sinica,English Series 2024年第4期40卷 1115-1126页

作者： Chun Xiang ZHAO feng Juan meng Institute of Applied System Analysis Jiangsu UniversityZhenjiang 212013P.R.China School of Mathematics and Physics Jiangsu University of TechnologyChangzhou 213001P.R.China

In this article,we consider the long-time behavior of extensible beams with nonlocal weak damping:ε(t)u_(tt)+Δ^(2)u-m(‖▽u‖^(2))Δu+‖u_(t)‖^(p_(u_(t)))+f(u)=h,whereε(t)is a decreasing function vanishing at *** the theory of process on time-dependent spaces,we investigate the existence of the time-dependent attractor by using the Condition(C_(t))method and more detailed *** results obtained essentially improve and complete some previous works.

关键词： Time-dependent attractor extensible beams equation nonlocal weak damping

Covariate-Assisted Matrix Completion with Multiple Structural Breaks

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Journal of Systems Science & Complexity 2024年第2期37卷 692-728页

作者： meng Jing feng Long ZOU Changliang WANG Zhaojun School of Statistics and Data Science KLMDASRLEBPSand LPMCNankai UniversityTianjin 300071China

In matrix completion,additional covariates often provide valuable information for completing the unobserved entries of a high-dimensional low-rank matrix *** this paper,the authors consider the matrix recovery problem when there are multiple structural breaks in the coefficient matrix β under the column-space-decomposition model A=Xβ+B.A cumulative sum(CUSUM)statistic is constructed based on the penalized estimation of β.Then the CUSUM is incorporated into the Wild Binary Segmentation(WBS)algorithm to consistently estimate the location of ***,a nearly-optimal recovery of A is *** findings are further corroborated via numerical experiments and a real-data application.

关键词： Additional covariates matrix completion multiple structural breaks wild Binary Segmentation

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