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Influence of cerium treatment on inclusion modification and as-cast microstructure of high-strength low-alloy steel

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Journal of Iron and Steel Research International 2022年第10期29卷 1659-1668页

作者： Ru-ming geng Jing Li Cheng-bin Shi State Key Laboratory of Advanced Metallurgy University of Science and Technology BeijingBeijing100083China

The influence of cerium treatment on the inclusion evolution and as-cast microstructure of high-strength low-alloy steel was *** including the inclusions characteristics,element distribution,and the in situ solidification were analyzed by scanning electron microscopy,energy-dispersive spectroscopy,and high-temperature confocal laser scanning microscopy,*** results indicated that,after the addition of Ce,the Al_(2)O_(3) inclusions evolved to form Ce_(2)O_(2)S and CeAlO_(3) inclusions,which exhibited a decrease in size alongside corresponding increase in their number *** equiaxed grain ratio exhibited by the as-cast microstructure increased significantly upon the addition of Ce,while a reduction in the segregation and a corresponding increase in the homogeneity of the carbon distribution within the as-cast microstructure were also *** results of the in situ observation of the solidification suggested that the addition of Ce significantly reduced the solidification temperature range,thus reducing the carbon *** nucleation effect imparted by Al_(2)O_(3),Ce_(2)O_(2)S,and CeAlO_(3) on theδ-Fe formation was discussed in the context of the disregistry theory,which revealed that the formation of a large number of fine Ce_(2)O_(2)S inclusions promotedδ-Fe formation via heterogeneous nucleation.

关键词： Ce treatment Non-metallic inclusion As-cast microstructure In situ observation Disregistry theory

CR400BF动车组车体端墙焊接模拟仿真与变形控制研究

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电焊机 2024年第3期54卷 99-104页

作者：耿明王亚男肖宇耿非张力中车长春轨道客车股份有限公司工程技术中心工程技术部吉林长春130062

CR400BF动车组车体端墙为封闭腔体铝合金型材拼焊结构,焊接量大,焊接变形大,尺寸不易控制,影响车辆装配精度和外观质量。针对CR400BF动车组车体端墙焊接变形的控制方法进行研究,通过焊接模拟仿真和实际生产相结合的方式,从结构优化、焊... 详细信息

CR400BF动车组车体端墙为封闭腔体铝合金型材拼焊结构,焊接量大,焊接变形大,尺寸不易控制,影响车辆装配精度和外观质量。针对CR400BF动车组车体端墙焊接变形的控制方法进行研究,通过焊接模拟仿真和实际生产相结合的方式,从结构优化、焊前预制反变形和焊接工艺优化三个方面提出了一套较为优化的端墙焊接变形控制方法。在结构优化方面,采用带立柱的封闭式型材结构代替传统开式型材结构,增加了端墙的刚度。焊前反变形方面,通过调整侧弯梁单件的外形弧度和外部弯梁的组对宽度,实现了对焊接变形的有效控制。焊接工艺优化方面,采用“先长后短、先大后小”正反面交替焊接顺序,并调整段焊间距和数量,进一步减小了焊接变形,保证了端墙各项关键尺寸,进而提高了产品质量和生产效率。

关键词： CR400BF 车体端墙焊接变形模拟仿真结构优化焊前反变形焊接工艺优化

Facile preparation of methylcellulose/poly(vinyl alcohol)physical complex hydrogels with tunable thermosensitivity

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Chinese Chemical Letters 2009年第1期20卷 111-114页

作者： Nan Nan geng Cong ming Xiao College of Material Science and Engineering Huaqiao University Quanzhou 362021 China

Novel complex hydrogels of methylcellulose （MC） and poly（vinyl alcohol）（PVA） with wide-spectrum thermoresponsivity were prepared via physical and mild process. Thermal phase transition of MC/PVA hydrogels exhibited two forms including sol/sol to gel/sol and sol/gel to gel/gel. The phase transition temperature of MC/PVA solution ranged from 38,7 to 60.6 ℃ and was able to be adjusted by simply changing the feeding ratios of two components. The interior morphology of MC/PVA gels was examined with fluorescence analysis and scanning electron microscopy analysis, which showed that MC was well dispersed in matrix before and after thermally gelling.

关键词： Methylcellulose Poly(vinyl alcohol) Hydrogel Thermosensitive Controllable

干旱胁迫下油菜素内酯对植物-土壤化学计量特征及内稳性的影响

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草地学报 2024年第4期32卷 1068-1077页

作者：李铭怡王冉贾濠基耿启明郭士维王福豪刘黎明董文豪许文年三峡库区地质灾害教育部重点实验室(三峡大学) 湖北宜昌443002 三峡大学土木与建筑学院湖北宜昌443002 水泥基生态修复技术湖北省工程研究中心(三峡大学) 湖北宜昌443002 湖北润智生态科技有限公司湖北宜昌443002

为探究施用油菜素内酯(Brassinosteroid,BR)对不同干旱条件下植物与土壤的生态化学计量特征及其相互关系,本研究以黄花决明(Cassia glauca Lam.)为研究对象,采用盆栽控水法,设置正常水分、中度胁迫、重度胁迫处理(田间持水量的75%±5%,... 详细信息

为探究施用油菜素内酯(Brassinosteroid,BR)对不同干旱条件下植物与土壤的生态化学计量特征及其相互关系,本研究以黄花决明(Cassia glauca Lam.)为研究对象,采用盆栽控水法,设置正常水分、中度胁迫、重度胁迫处理(田间持水量的75%±5%,55%±5%,35%±5%)及4种BR浓度处理(0,0.05,0.2和0.5 mg·L^(-1)),在干旱90天后测定株高、生物量和植物、土壤的养分含量及化学计量特征。研究发现:干旱胁迫导致株高、地上和地下生物量降低;随着施用BR浓度的增加,株高、生物量表现为先上升后下降;0.2 mg·L^(-1)BR有利于植物养分含量提升,地上部提升效果更好;干旱区生态修复中黄花决明的生长对N元素的供应需求较大;施用BR有助于提高黄花决明株高和生物量,调节养分分配策略,缓解干旱对植物的不利影响。本研究可为干旱地区的生态修复和植被重建提供新思路与新方法。

关键词：生态修复干旱胁迫油菜素内酯化学计量养分特征内稳性

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一种含中心驱动五自由度并联机构运动学分析

机械设计与制造 2024年第8期402卷 178-181页

作者：张灿果宋占锋倪笑宇耿明超河北建筑工程学院机械工程学院河北张家口075024

设计了一种含中心驱动五自由度并联机构,分析了该机构的自由度和结构特点。利用矢量法建立了含中心驱动五自由度并联机构中各驱动分支和动平台运动之间的映射关系,利用中心驱动分支中的约束力/约束矩,推导了该并联机构的Jacobean矩阵和H... 详细信息

设计了一种含中心驱动五自由度并联机构,分析了该机构的自由度和结构特点。利用矢量法建立了含中心驱动五自由度并联机构中各驱动分支和动平台运动之间的映射关系,利用中心驱动分支中的约束力/约束矩,推导了该并联机构的Jacobean矩阵和Hessian矩阵。建立了含中心驱动五自由度并联机构的运动学模型。利用先进CAD软件验证了并联机构运动学模型的正确性。分析了含中心驱动五自由度并联机构定姿态工作空间,为该类并联机构的应用奠定了理论基础。

关键词：并联机构运动学中心驱动工作空间

NaOH/PMS对MBR中空平板陶瓷膜的化学清洗特性

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中国给水排水 2024年第15期40卷 16-22页

作者：田家宇司文艳耿明月刘禧文高珊珊河北工业大学土木与交通学院天津300401

膜生物反应器(MBR)的不可逆膜污染是限制其长效稳定运行的关键因素,而传统次氯酸钠(NaClO)清洗可能加剧MBR系统后续膜污染。为此,针对中空平板陶瓷膜MBR提出了一种碱活化过一硫酸盐(PMS)的免氯化学清洗方法。在PMS浓度为1.0 mmol/L和NaO... 详细信息

膜生物反应器(MBR)的不可逆膜污染是限制其长效稳定运行的关键因素,而传统次氯酸钠(NaClO)清洗可能加剧MBR系统后续膜污染。为此,针对中空平板陶瓷膜MBR提出了一种碱活化过一硫酸盐(PMS)的免氯化学清洗方法。在PMS浓度为1.0 mmol/L和NaOH浓度为0.03 mol/L时,化学清洗效率达到70.9%,优于相同条件下NaClO的清洗效果(60.6%)。NaOH/PMS体系可优先去除膜表面多糖、蛋白质等大分子物质,并有效剥离滤饼层,从而恢复膜通量。机理分析显示,NaOH/PMS体系中起主要清洗作用的活性物种为单线态氧(1O2)。NaOH/PMS体系的清洗液药剂成本约为1.11元/m3,是一种高效、清洁的陶瓷膜化学清洗方法。

关键词：膜生物反应器平板陶瓷膜化学清洗过一硫酸盐碱活化

东洞庭湖洪水前后典型湿地植物化学计量特征动态变化

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环境生态学 2024年第2期6卷 65-70页

作者：曾静侯志勇李旭耿明明谢永宏中国科学院亚热带农业生态研究所、中国科学院亚热带农业生态过程重点实验室、洞庭湖湿地生态系统观测研究站湖南长沙410125

洪水对湿地土壤-植被系统养分循环有重要影响。本研究以东洞庭湖湿地典型植物短尖苔草(Carex brevicuspis)和南荻(Triarrhena lutarioriparia)为研究对象,于2018年洪水期前后(5月、10月)测定短尖苔草和南荻生长特征、生态化学计量特征... 详细信息

洪水对湿地土壤-植被系统养分循环有重要影响。本研究以东洞庭湖湿地典型植物短尖苔草(Carex brevicuspis)和南荻(Triarrhena lutarioriparia)为研究对象,于2018年洪水期前后(5月、10月)测定短尖苔草和南荻生长特征、生态化学计量特征及土壤理化性质,并对化学计量学特征与环境特征的相关性进行了分析。结果表明:南荻植株的生物量和密度洪水前显著高于洪水后,短尖苔草生物量和密度洪水前后都没有显著差异;短尖苔草、南荻叶片有机碳(SOC)洪水后显著高于洪水前;短尖苔草叶片全氮(TN)洪水前显著低于洪水后;南荻叶片TN、全磷(TP)洪水前显著高于洪水后;短尖苔草叶片TP洪水前后没有显著差异。短尖苔草叶片C∶N、C∶P、N∶P洪水前后均无显著差异,南荻叶片C∶N、C∶P洪水前显著低于洪水后,但N∶P洪水前后无显著差异。东洞庭湖短尖苔草、南荻叶片N∶P<14,东洞庭湖短尖苔草、南荻生长更多的受N限制,洪水前后都与土壤N、P含量无显著相关性。本研究结果对阐明洪水对湿地植物化学计量特征的影响有重要意义。

关键词：东洞庭湖湿地化学计量学营养元素限制

Numerical study of the splashing wave induced by a seaplane using mesh-based and particle-based methods

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Theoretical & Applied Mechanics Letters 2023年第5期13卷 375-381页

作者： Yang Xu Peng-Nan Sun Xiao-Ting Huang Salvatore Marrone Lei-ming geng School of Ocean Engineering and Technology Sun Yat-sen UniversityZhuhai 519082China CNR-INM.Institute of Marine Engineering Rome 00128Italy AVIC General Huanan Aircraft Industry Co. LtdZhuhai 519080China

In recent years,forest fires and maritime accidents have occurred frequently,which have had a bad impact on human production and ***,the development of seaplanes is an increasingly urgent *** is important to study the taxiing process of seaplanes for the development of seaplanes,which is a strong nonlinear fluid-structure interaction *** this paper,the smoothed particle hydrodynamics(SPH)method based on the Lagrangian framework is utilized to simulate the taxiing process of seaplanes,and the SPH results are compared with those of the finite volume method(FVM)based on the Eulerian *** results show that the SPH method can not only give the same accuracy as the FVM but also have a strong ability to capture the splashing waves in the taxiing process,which is quite meaningful for the subsequent study of the effect of a splash on other parts of the seaplane.

关键词： Seaplane Splashing Fluid-structure interactions SPH Method

Experimental Study of Local Scour Around Four Piles Under Different Attack Angles and Gap Ratios

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China Ocean Engineering 2024年第4期38卷 612-624页

作者： LIU ming-ming TANG Guo-qiang JIN Xin geng Shao-yang School of Architecture and Engineering Liaocheng UniversityLiaocheng 252000China Water-Sediment Regulation and Sand Effective Utilization Special Laboratory of Shandong Provincial Education Department Liaocheng UniversityLiaocheng 252000China State Key Laboratory of Coastal and Offshore Engineering Dalian University of TechnologyDalian 116024China College of Electronic Engineering Chengdu University of Information TechnologyChengdu 610225China College of Energy Chengdu University of TechnologyChengdu 610059China

In an effort to investigate and quantify the patterns of local scour,researchers embarked on an in-depth study using a systematic experimental *** research focused on the effects of local scour around a set of four piles,each subjected to different hydromechanical *** particular,this study aimed to determine how different attack angles—the angles at which the water flow impinges on the piles,and gap ratios—the ratios of the spacing between the piles to their diameters,influence the extent and nature of scour.A comprehensive series of 35 carefully designed experiments were orchestrated,each designed to dissect the nuances in how the gap ratio and attack angle might contribute to changes in the local scour observed at the base of pile *** these experimental trials,a wealth of local scour data were collected to support the *** data included precise topographic profiles of the sediment bed around the pile groups,as well as detailed scour time histories showing the evolution of scour at strategic feature points throughout the test *** analysis of the experimental data provided interesting *** study revealed that the interplay between the gap ratio and the attack angle had a pronounced influence on the scouring dynamics of the pile *** of the key observations was that the initial phases of scour,particularly within the first hour of water flow exposure,were characterized by a sharp increase in the scour depth occurring immediately in front of the *** this initial rapid development,the scour depth transitioned to a more gradual change *** contrast,the scour topography around the piles continuously *** suggests that sediment displacement and the associated sculpting of the seabed around pile foundations are sustained and progressive processes,altering the underwater landscape over *** results of this empirical investigation have significant implications for the design and constructio

关键词： local scour piles gap ratio attack angle