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砂土含水率对DAS振幅响应影响的试验研究

防灾减灾工程学报 2024年第2期44卷 434-441,458页

作者：李俊鹏张诚成施斌陈卓谢涛郭君仪南京大学地球科学与工程学院江苏南京210023

利用分布式声波传感(DAS)技术和地下通讯光纤网进行周界安防(入侵)监控、管道泄漏监测、交通状况评估等是城市安全动态监测的新方向。为探究DAS监测过程中暗光纤周围岩土介质含水率变化对DAS振幅响应特性的影响,设计了小球撞击圆盘与小... 详细信息

利用分布式声波传感(DAS)技术和地下通讯光纤网进行周界安防(入侵)监控、管道泄漏监测、交通状况评估等是城市安全动态监测的新方向。为探究DAS监测过程中暗光纤周围岩土介质含水率变化对DAS振幅响应特性的影响,设计了小球撞击圆盘与小球直接撞击砂土面二种激振方式下五种质量含水率0%、5%、10%、15%和20%砂土的DAS振幅响应试验。试验结果表明:(1)小球自由下落撞击砂土面激发的振动信号和传感光纤圆环布设可提高DAS信噪比,试验装置可靠性高、试验结果重复性好;(2)受砂土似黏聚力和声波传播衰减两个因素共同影响,DAS信号振幅随砂土含水率变化存在一个临界含水率。当砂土含水率小于临界含水率时,DAS信号振幅随含水率增大而减小,而当砂土含水率大于临界含水率时,DAS信号振幅随含水率增大而增大;(3)因砂土似黏聚力作用和小球撞击时能量转化的差异,小球与砂土的接触形式对DAS振幅响应有显著影响。研究结果为城市地下工程安全动态DAS精细监测提供理论依据。

关键词： DAS 砂土含水率振幅响应特性似黏聚力声波衰减

Characteristics of inclusions in high-Al steel during electroslag remelting process

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International Journal of Minerals,Metallurgy and Materials 2012年第4期19卷 295-302页

作者： Cheng-bin shi Xi-chun Chen Han-jie Guo State Key Laboratory of Advanced Metallurgy University of Science and Technology Beijing Beijing 100083 China School of Metallurgical and Ecological Engineering University of Science and Technology Beijing Beijing 100083 China Research Institute of High Temperature Materials Central Iron and Steel Research Institute Beijing 100081 China

The characteristics of inclusions in high-A1 steel refmed by electroslag remelting （ESR） were investigated by image analysis, scanning electron microscopy （SEM）, and energy-dispersive spectrometry （EDS）. The results show that the size of almost all the inclusions observed in ESR ingots is less than 5 μm. Inclusions smaller than 3 μm take nearly 75% of the total inclusions observed in each ingot. Inclu- sions observed in ESR ingots are pure AIN as dominating precipitates and some fine spherical Al2O3 inclusions with a size of 1 μm or less. It is also found that protective gas operation and slag deoxidation treatment during ESR process have significant effects on the number of inclusions smaller than 2μm but little effects on that of inclusions larger than 2 μm. Thermodynamic calculations show that AIN inclusions are unable to precipitate in the liquid metal pool under the present experimental conditions, while the precipitation of AlN inclusions could take place at the solidifying front due to the microsegregation orAl and N in liquid steel during solidification.

关键词： electroslag remelting aluminum nitride inclusions thermodynamics

Micro mechanical properties of n-Al2O3/Ni composite coating by nanoindentation

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中国有色金属学会会刊：英文版 2004年第z1期14卷 115-119页

作者： WANG Hong-mei XU bin-shi MA shi-ning DONG shi-yun LI Xiao-ying National Key Laboratory for Remanufacturing Academy of Armored Force Engineering Beijing 100072 China National Key Laboratory for RemanufacturingAcademy of Armored Force Engineering Beijing 100072 China National Key Laboratory for RemanufacturingAcademy of Armored Force Engineering Beijing 100072 China National Key Laboratory for RemanufacturingAcademy of Armored Force Engineering Beijing 100072 China School of Metallurgy and Materials The University of Birmingham Birmingham B152TT UK

A new type of nano test system was introduced, the test principle and the indentation data analysis method were described. It was used to test the micro mechanical properties, such as hardness, elastic modulus and indentation creep property of n-Al2O3/Ni composite coating on steel prepared by brush plating, and the variety of mechanical properties with coating thickness was researched. The results show that the mechanical properties are basically identical within the whole coating, the hardness and modulus decrease in the defect fields, especially within the dendritic crystals, whereas the mechanical properties are not influenced greatly at the interspaces among dendritic crystals. The average hardness and elastic modulus of n-Al2O3/Ni coating are 6.34 GPa and 154 GPa respectively, and the hardness is 2.4 times higher than that of steel and the indentation creep curve of n-Al2O3/Ni coating is similar to that of the uniaxial compression creep, and the creep rate of steady-state is about 0. 104 nm/s. These results will supply useful data for process improvement, new type material development and application expansion.

关键词： nanoindentation hardness elastic modulus creep property nano composite coating

Dielectric loss enhancement induced by the microstructure of CoFe_(2)O_(4) foam to realize broadband electromagnetic wave absorption

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International Journal of Minerals,Metallurgy and Materials 2023年第7期30卷 1388-1397页

作者： bin shi Hongsheng Liang Zijun Xie Qing Chang Hongjing Wu College of Chemistry and Chemical Engineering Shaanxi Key Laboratory of Chemical Reaction EngineeringYan’an UniversityYan’an 716000China MOE Key Laboratory of Material Physics and Chemistry Under Extraordinary School of Physical Science and TechnologyNorthwestern Polytechnical UniversityXi’an 710072China

CoFe_(2)O_(4)has been widely used for electromagnetic wave absorption owing to its high Snoek limit,high anisotropy,and suitable saturation magnetization;however,its inherent shortcomings,including low dielectric loss,high density,and magnetic agglomeration,limit its application as an ideal *** study investigated a microstructure regulation strategy to mitigate the inherent disadvantages of pristine CoFe_(2)O_(4)synthesized via a sol–gel auto-combustion method.A series of CoFe_(2)O_(4)foams(S0.5,S1.0,and S1.5,corresponding to foams with citric acid(CA)-to-Fe(NO_(3))_(3)·9H_(2)O molar ratios of 0.5,1.0,and 1.5,respectively)with two-dimensional(2D)curved surfaces were obtained through the adjustment of CA-to-Fe^(3+)ratio,and the electromagnetic parameters were adjusted through morphology *** to the appropriate impedance matching and conductance loss provided by moderate complex permittivity,the effective absorption bandwidth(EAB)of S0.5 was as high as 7.3 GHz,exceeding those of most CoFe_(2)O_(4)-based ***,the EAB of S1.5 reached 5.0 GHz(8.9–13.9 GHz),covering most of the X band,owing to the intense polarization provided by lattice defects and the heterogeneous *** three-dimensional(3D)foam structure circumvented the high density and magnetic agglomeration issues of CoFe_(2)O_(4)nanoparticles,and the good conductivity of 2D curved surfaces could effectively elevate the complex permittivity to ameliorate the dielectric loss of pure CoFe_(2)O_(4).This study provides a novel idea for the theoretical design and practical production of lightweight and broadband pure ferrites.

关键词： CoFe_(2)O_(4)foam lightweight broadband absorption microstructure regulation dielectric loss

Effect of nitrogen on microstructure and microsegregation of martensitic stainless steel 4Cr13 produced by electroslag remelting

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Journal of Iron and Steel Research International 2023年第9期30卷 1854-1861页

作者： Shou-hui Li Jing Li Jie Zhang Cheng-bin shi State Key Laboratory of Advanced Metallurgy University of Science and Technology BeijingBeijing 100083China

Two ingots of 4Cr13 martensitic stainless steel with different nitrogen contents,0.023 and 0.121 mass%,were produced by vacuum induction furnace and electroslag *** microstructure and the microsegregation of the electroslag remelting ingot were analyzed by optical microscopy,scanning electron microscopy and electron microprobe ***-Calc software was used to calculate the nitrogen solubility changes during solidification of high nitrogen martensitic stainless steel and the equilibrium and non-equilibrium phase diagrams of 4Cr13 steel with different nitrogen *** solubility of nitrogen in 4Cr13 steel reached the lowest value of 0.118%before the start of the peritectic *** microstructure of 4Cr13 steel was martensite,retained austenite and primary carbide M_(7)C_(3).Higher nitrogen content increased the content of retained austenite in martensitic stainless steel,inhibited the precipitation of primary carbides and refined the *** nitrogen content could effectively inhibit the microsegregation of C element in martensitic stainless steel;however,it had little effect on Cr,V,Nb and *** peritectic reaction was first carried out in high nitrogen steel during solidification,which advanced the transformation of austenite and inhibited the microsegregation of C element.

关键词： Nitrogen Martensitic stainless steel Electroslag remelting Microsegregation Microstructure

平台对接式种植体生物学并发症:一项回顾性病例分析

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中国口腔种植学杂志 2024年第4期29卷 352-357页

作者：陈真琪晏奇陈艳施斌武汉大学口腔医院种植科 430079

目的回顾性分析使用平台对接式种植系统最终修复后发生生物学并发症的病例,并探讨相关危险因素。方法对2012至2022年在武汉大学口腔医院种植科采用平台对接式种植体(Zimmer,美国)进行修复的共739例患者,1624颗种植体发生种植生物学并发... 详细信息

目的回顾性分析使用平台对接式种植系统最终修复后发生生物学并发症的病例,并探讨相关危险因素。方法对2012至2022年在武汉大学口腔医院种植科采用平台对接式种植体(Zimmer,美国)进行修复的共739例患者,1624颗种植体发生种植生物学并发症的病例进行分析。结果采用平台对接式的种植体完成正式修复后在随访期内发生生物学并发症的种植体65颗,其发生率为4%,其中59颗种植体发生种植体周黏膜炎,6颗种植体发生种植体周炎。患者平均年龄为(56.20±11.46)岁,修复体平均负荷时间为(4.06±2.36)年。结论上颌及磨牙区是该平台对接式种植体生物学并发症的好发部位,尤其注意远中游离端种植修复体的咬合设计,避免咬合过载带来的不利影响。尽管“冷焊”效应有利于减少界面微渗漏的影响,但增加了机械并发症的风险。

关键词：种植体周围疾病种植体周黏膜炎种植体周炎平台对接

过去40年兰州市榆中县土地利用景观格局变化及驱动力分析

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国土与自然资源研究 2024年第2期 20-26页

作者：郭思岩侯艳丽石斌甘肃省自然资源规划研究院甘肃兰州730000

兰州市榆中县作为兰州市城市副中心,过去近40年土地利用景观格局发生了显著变化。本研究基于榆中县5期土地利用/覆盖数据,采用状态转移矩阵和景观生态学方法分析了1980-2018年榆中县土地利用景观格局变化。结果表明,(1)土地利用景观格... 详细信息

兰州市榆中县作为兰州市城市副中心,过去近40年土地利用景观格局发生了显著变化。本研究基于榆中县5期土地利用/覆盖数据,采用状态转移矩阵和景观生态学方法分析了1980-2018年榆中县土地利用景观格局变化。结果表明,(1)土地利用景观格局发生显著变化的地区主要集中在中部川塬河谷区,且主要集中在2010-2018年。(2)大面积耕地、草地、未利用地被建设用地置换,耕地、草地、未利用地和建设用地的面积分别从1980年的988.99 km^(2)、1971.94 km^(2)、40.05 km^(2)和62.27km^(2)变更为2018年的962.11 km^(2)、1963.29 km^(2)、36.58 km^(2)和102.18 km^(2)。(3)景观多样性和优势度未发生显著变化,草地和耕地始终是优势景观类型且两者面积占比接近景观总面积的90%,但是景观破碎性增加、斑块形状趋于复杂。(4)工业园建设、科教城建设、优势/特色农业基地建设和县域人口增加是榆中县区域近40年土地利用格局变化的主要驱动力,促使过去的耕地、草地、未利用地被建设用地类型所取代。

关键词：土地利用/土地覆被变化驱动力景观生态榆中县

Interfacial engineering of holey platinum nanotubes for formic acid electrooxidation boosted water splitting

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Journal of Energy Chemistry 2023年第2期77卷 209-216,I0006页

作者： Zi-Xin Ge Yu Ding Tian-Jiao Wang Feng shi Pu-Jun Jin Pei Chen bin He shi-bin Yin Yu Chen Key Laboratory of Macromolecular Science of Shaanxi Province Key Laboratory of Applied Surface and Colloid Chemistry(Ministry of Education)Shaanxi Key Laboratory for Advanced Energy DevicesShaanxi Engineering Lab for Advanced Energy TechnologySchool of Materials Science and EngineeringShaanxi Normal UniversityXi’an 710062ShaanxiChina College of New Materials and New Energies Shenzhen Technology UniversityShenzhen 518118GuangdongChina MOE Key Laboratory of New Processing Technology for Non-ferrous Metals and Materials Guangxi Key Laboratory of Processing for Non-ferrous Metals and Featured MaterialsGuangxi UniversityNanning 530004GuangxiChina

Both structure and interface engineering are highly effective strategies for enhancing the catalytic activity and selectivity of precious metal *** this work,we develop a facile pyrolysis strategy to synthesize the high-quality holey platinum nanotubes(Pt-H-NTs)using nanorods-like Pt^(Ⅱ)-phenanthroline(PT)coordination compound as self-template and self-reduction ***,an up-bottom strategy is used to further synthesize polyallylamine(PA)modified Pt-H-NTs(Pt-HNTs@PA).PA modification sharply promotes the catalytic activity of Pt-H-NTs for the formic acid electrooxidation reaction(FAEOR)by the direct reaction ***,PA modification also elevates the catalytic activity of Pt-H-NTs for the hydrogen evolution reaction(HER)by the proton enrichment at electrolyte/electrode *** from the high catalytic activity of Pt-H-NTs@PA for both FAEOR and HER,a two-electrode FAEOR boosted water electrolysis system is fabricated by using Pt-H-NTs@PA as bifunctio nal *** FAEOR boosted water electrolysis system only requires the operational voltage of 0.47 V to achieve the high-purity hydrogen production,showing an energy-saving hydrogen production strategy compared to traditional water electrolysis system.

关键词： Holey platinum nanotubes Chemical functionalization Formic acid oxidation reaction Hydrogen evolution reaction Water splitting

基于ANSYS的粉末精整压机主机结构设计与分析

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兰州文理学院学报（自然科学版） 2024年第1期38卷 66-71页

作者：方传宝吴士宾安徽职业技术学院智能制造学院安徽合肥230011 中国三峡新能源股份有限公司河北保定073100

粉末精整液压机的机架刚度和强度直接影响到设备的性能以及制件的精度,本文首先通过理论经验计算对5000 kN粉末精整液压机机架的各组成部分设计结果进行了初步定量分析,其次利用有限元分析软件ANSYS Workbench在施加工况载荷条件下对主... 详细信息

粉末精整液压机的机架刚度和强度直接影响到设备的性能以及制件的精度,本文首先通过理论经验计算对5000 kN粉末精整液压机机架的各组成部分设计结果进行了初步定量分析,其次利用有限元分析软件ANSYS Workbench在施加工况载荷条件下对主机进行仿真,得到主机机身详细的应力、应变分布云图和最大变形情况.实验结果表明液压机主机在承受工况载荷的情况下,刚度和强度能够满足设计要求,仿真结果对粉末精整液压机机架的结构优化设计有一定的指导作用,同时也为工程实践提供定量的分析参考依据.

关键词：粉末精整液压机 Workbench 刚度强度有限元分析工况载荷