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交联型淀粉/云母基高吸水性聚合物的制备及吸附性能研究

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化工新型材料 2021年第5期49卷 270-275页

作者：韦爱芬朱鸿雁韦莉敏广西民族大学化学化工学院南宁530008 广西林产化学与工程重点实验室广西林产化学与工程协同创新中心南宁530008

以N,N-亚甲基双丙烯酰胺(MBA)为交联剂,玉米淀粉和云母粉为复配基体,丙烯酸(AA)和丙烯酰胺(AM)为单体,通过超声波辅助合成了交联型淀粉/云母基高吸水性聚合物。采用傅里叶变换红外光谱仪和扫描电子显微镜对聚合物进行表征,考察了交联改... 详细信息

以N,N-亚甲基双丙烯酰胺(MBA)为交联剂,玉米淀粉和云母粉为复配基体,丙烯酸(AA)和丙烯酰胺(AM)为单体,通过超声波辅助合成了交联型淀粉/云母基高吸水性聚合物。采用傅里叶变换红外光谱仪和扫描电子显微镜对聚合物进行表征,考察了交联改性对聚合物吸液性能的影响,采用准一级动力学模型、准二级动力学模型和颗粒内扩散模型研究了聚合物对生理盐水、模拟尿液及模拟经血液的吸附行为。结果表明:当交联剂用量为淀粉/云母和单体总质量的0.25%时,聚合物对生理盐水、模拟尿液及模拟经血液的平衡吸附量分别为44.5g/g、36.6g/g和30.2g/g,对模拟经血液的吸收速度为49s,吸经血液凝胶保水率为90.2%;准二级动力学模型能更好地描述聚合物对生理盐水、模拟尿液及模拟经血液的吸附行为,吸附速率常数大小依次为生理盐水>模拟尿液>模拟经血液。

关键词：交联型淀粉/云母基高吸水性聚合物生理盐水模拟尿液模拟经血液吸附

Humic acid-mediated transport of a typical soil passivation remediation product(chloropyromorphite)in saturated porous media

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Journal of Environmental Sciences 2024年第7期141卷 51-62页

作者： Xinying Li Mengjia Zhang Siyuan Li wei wei School of Environment Jiangsu Engineering Lab of Water and Soil Eco-remediationJiangsu Province Engineering Research Center of Environmental Risk Prevention and Emergency Response TechnologyNanjing Normal UniversityNanjing 210023China Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application Nanjing 210023China

Conversion of labile Pb species into chloropyromorphite(CPY)using phosphorus-bearing amendments was considered to be an ideal strategy in soil passivation ***,the fate and transport of CPY in the soil are poorly *** study aims to fill the knowledge gap by evaluating the fate and transport of CPY under environmentally relevant conditions of humic acid(HA),pH,electrolyte concentration,and species through the saturated sandy *** showed that bare CPY colloids are basically immobile in sandy porous media while the co-existence of HA made the transport of CPY improved by30%-93.5%.Facilitated transport of CPY was attributed to the increased stability of CPY and the repulsive interaction between CPY particles and sands due to HA *** mobility of CPY was also increased with increasing pH from 5.0 to *** the pH was 9 with a10 mmol/L NaCl background solution,the stronger energy barrier between CPY and sand led to enhanced transport *** divalent Ca^(2+)had a more dramatic effect than monovalent Na^(+)on the aggregation and sedimentation of CPY colloids due to its effectivescreening of the surface charge of CPY and bridging interaction with CPY ***-LandauVerwey-Overbeek theory and attachment efficiency calculation indicated that high energy barriers were responsible for the high mobility of CPY colloids,while the retention of CPY in sands was mainly caused by secondary energy minimum and physically *** findings of this work can help to evaluate the fate of soil passivation remediation products in natural water and soil.

关键词： Chloropyromorphite DLVO theory Stability Saturated porous medium Transport

压路机激励下重载铁路路桥过渡段动力特性研究

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振动与冲击 2021年第4期40卷 120-129页

作者：李双龙魏丽敏徐长红何群周宏中南大学土木工程学院长沙410075 中南大学高速铁路建造技术国家工程实验室长沙410075

以蒙华重载铁路某路桥过渡区为试验对象,开展压路机激励下过渡区的动力特性试验,研究过渡区动力响应的分布规律;建立考虑振动轮-路基耦合的动力分析数值模型,研究过渡区等效刚度分布及振动轮-路基面接触力变化特性。结果表明:随着路基... 详细信息

以蒙华重载铁路某路桥过渡区为试验对象,开展压路机激励下过渡区的动力特性试验,研究过渡区动力响应的分布规律;建立考虑振动轮-路基耦合的动力分析数值模型,研究过渡区等效刚度分布及振动轮-路基面接触力变化特性。结果表明:随着路基深度增大,动应力扩散角逐渐减小,埋深0.2~3.0 m处扩散角在78.2°~55.0°,倒梯形过渡段动应力扩散角要大于一般路基扩散角;相比列车荷载,压路机激励引起的竖向动应力在路基中衰减更快,并且在基床表层中衰减最大;压路机驶离桥台方向的基床表层动侧压力系数为0.35~0.53,驶向桥台方向为0.24~0.36,倒梯形过渡段的动侧压力系数要小于一般路基段;过渡段路基等效刚度在74.8~87.2 kN/mm,随离桥台距离增大而呈线性减小趋势;振动轮激励过程中,过渡段内的振动轮-路基面最大接触力峰值比一般路基段大,且随着过渡区刚度差的增大而增大。

关键词：路桥过渡段重载铁路压路机动力特性等效刚度

基于高精度全自动监测系统的静压群桩现场试验

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岩石力学与工程学报 2020年第S02期39卷 3627-3635页

作者：魏丽敏杜猛何群廖鹏庆李双龙中南大学土木工程学院湖南长沙410075

预应力高强度混凝土管桩挤土效应是岩土工程界关注的热点问题之一。依托鲁南高铁曲阜东站并轨段路基工程,在曲阜东站新建鲁南场东侧进行静压群桩试验,采用高精度全自动监测系统,对试桩IV区(引孔15 m)、试桩VI区(引孔20m及无引孔)静压预... 详细信息

预应力高强度混凝土管桩挤土效应是岩土工程界关注的热点问题之一。依托鲁南高铁曲阜东站并轨段路基工程,在曲阜东站新建鲁南场东侧进行静压群桩试验,采用高精度全自动监测系统,对试桩IV区(引孔15 m)、试桩VI区(引孔20m及无引孔)静压预应力管桩群桩挤土效应引起的地表水平及竖向位移、深层水平位移、超孔隙水压力及地下水位变化进行全天候、高频率监测,获得其分布与发展规律,并分析引孔效果及前排桩的隔离效应。结果表明:(1)以1.5mm为界限值,试桩IV区、VI区静压群桩地表水平位移影响范围分别为边界以外50.0和37.0 m;(2)先成桩的5~8排管桩能有效隔离后排成桩的挤土效应;(3)引孔对减小挤土效应效果良好,以相同加固宽度下距试验区边界5 m测点为例,引孔长度20 m对应的最大深层水平位移为引孔15 m的74%,引孔15 m时其最大值是无引孔条件下的25.8%。

关键词：桩基础静压群桩挤土效应全自动监测系统地表位移深层水平位移

桩筏复合结构加固高速铁路深厚软基长期性状的现场试验研究

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中南大学学报（自然科学版） 2017年第8期48卷 2195-2202页

作者：付贵海魏丽敏邓宗伟蒋建清中南大学土木工程学院湖南长沙410075 湖南城市学院土木工程学院湖南益阳413000

结合杭甬高速铁路上虞北站深厚软土地基处理加固工程,开展典型路基断面桩筏复合结构长期工作特性的现场试验研究,测试获得筏板变形、地基沉降、桩顶反力、筏板钢筋应力及筏板下土压力随时间的变化规律。研究结果表明:桩筏复合结构可以... 详细信息

结合杭甬高速铁路上虞北站深厚软土地基处理加固工程,开展典型路基断面桩筏复合结构长期工作特性的现场试验研究,测试获得筏板变形、地基沉降、桩顶反力、筏板钢筋应力及筏板下土压力随时间的变化规律。研究结果表明:桩筏复合结构可以满足深厚软基高铁无砟轨道工后沉降控制要求;筏板沉降沿路基横向呈现中心大、边缘小的分布形式,桩顶反力则沿筏板横向呈边缘大、中间小的马鞍形分布;铺轨6月后,筏板的累计工后沉降仅为0.48 mm,边缘处桩顶反力约为平均桩顶荷载的1.41倍、中心处桩顶反力约为平均桩顶荷载的0.75倍;筏板与其下的地基之间存在接触压力,且沿筏板横向呈抛物线型分布,大约承担30%上部荷载。

关键词：高速铁路路基桩筏复合结构软土地基现场试验

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螺纹桩竖向承载特性及承载机理研究

铁道工程学报 2020年第5期37卷 1-6,35页

作者：冷伍明魏广帅聂如松魏丽敏董俊利中南大学长沙410075

研究目的:螺纹桩是一种新型异型桩,具有高效、环保、经济的优点。但目前对螺纹桩承载机理尚无准确的认识,因此本文通过模型试验和数值模拟,对比分析螺纹桩和直桩竖向承载性状的不同,研究螺纹桩桩身轴力及桩侧摩阻力分布规律,分析桩顶荷... 详细信息

研究目的:螺纹桩是一种新型异型桩,具有高效、环保、经济的优点。但目前对螺纹桩承载机理尚无准确的认识,因此本文通过模型试验和数值模拟,对比分析螺纹桩和直桩竖向承载性状的不同,研究螺纹桩桩身轴力及桩侧摩阻力分布规律,分析桩顶荷载作用下桩身与桩周土体的变形规律,揭示螺纹桩竖向承载机理,并讨论螺纹结构参数对螺纹桩承载力的影响。研究结论:(1)竖向荷载作用下长径比为12的直桩和螺纹桩分别表现为摩擦端承桩和端承摩擦桩的承载特性;(2)螺纹桩极限承载力和桩身材料利用率都明显优于直桩;(3)螺纹结构参数中,螺距和螺纹宽度是影响螺纹桩承载力的主要因素,螺纹厚度对承载力影响很小;(4)螺纹桩桩侧承载力主要由桩周土体的剪切力提供,存在最优螺距使螺纹桩桩周土体抗剪强度发挥程度最大,极限承载力最大;(5)实际工程中,过大的螺纹宽度或过小的螺纹厚度会引起螺纹强度不足,并加大施工难度,因此,设计时要兼顾承载力、螺纹强度、施工难度及工程成本;(6)本研究成果可为螺纹桩地基或路基处理工程提供有用参考。

关键词：螺纹桩模型试验数值模拟极限承载力螺纹结构参数

The Existence of a Meridional Curve in Closed Incompressible Surfaces in Fully Alternating Link Complements

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Chinese Annals of Mathematics,Series B 2024年第1期45卷 73-80页

作者： wei LIN School of Mathematical Sciences Dalian University of TechnologyDalian 116024LiaoningChina

Menasco showed that a closed incompressible surface in the complement of a non-split prime alternating link in S^(3) contains a circle isotopic in the link complement to a meridian of the *** on this result,he was able to argue the hyperbolicity of non-split prime alternating links in *** et *** that if F■S×I\L is an essential torus,then F contains a circle which is isotopic in S×I\L to a meridian of *** author generalizes his result as follows:Let S be a closed orientable surface,L be a fully alternating link in S×I\If F ■ S×I\L is a closed essential surface,then F contains a circle which is isotopic in S×I\L to a meridian of L.

关键词： Fully alternating Incompressible surfaces Meridionally incompressible

Zeros of Complete Symmetric Polynomials over Finite Fields

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Journal of Systems Science & Complexity 2024年第4期37卷 1772-1788页

作者： CAO wei School of Mathematics and Statistics Minnan Normal UniversityZhangzhou 363000China

Wan and Zhang(2021) obtained a nontrivial lower bound for the number of zeros of complete symmetric polynomials over finite fields,and proposed a problem whether their bound can be *** this paper,the author improves Wan-Zhang's bound from three *** proposed results are based on the estimates related to the number of certain permutations and the value sets of non-permutation polynomials associated to the complete symmetric *** the author believes that there are still possibilities to improve the bounds and hence Wan-Zhang's bound.

关键词： Complete symmetric polynomial finite field permutation polynomial value set

High Speed Sintering:Assessing the Influence of Energy Input on Microstructure and Mechanical Properties of Polyether Block Amide(PEBA)Parts

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Chinese Journal of Polymer Science 2024年第5期42卷 675-682,I0004,I0010页

作者： Jiang-Tao Sun Zhi-Yong Fan Yi-wei Mao wei Li wei Zhu Dao-Sheng Cai Qing-Song wei State Key Laboratory of Materials Processing and Die&Mould Technology Huazhong University of Science and TechnologyWuhan430074China State Key Laboratory of Refractories and Metallurgy Wuhan University of Science and TechnologyWuhan430074China National Engineering Research Centre for High Efficiency Grinding Hunan UniversityChangsha410082China Wuhan EasyMFG Technology CO. LTDWuhan430074China

High speed sintering,a new powder-bed fusion additive manufacturing technology,utilizes infrared lights(IR)to intensely heat and melt polymer *** presence of defects such as porosity,which is associated with particle coalescence,is highly dependdent on the level of energy *** study investigate the influcence of energy input on porosity and its subsequent effects on the mechanical properties and microstructures of PEBA *** parts were manufactured with a variety of lamp powers,resulting in a range of energy input levels spanning from low to ***,they underwent testing using Archimedes’method,followed by tensile *** porosity,mechanical characteristics,and energy input exhibit a strong correlation;inadequate energy input was the primary cause of pore *** the reduced IR light power resulted in the following outcomes:porosity,ultimate tensile strength,and elongation of 1.37%,7.6 MPa,and 194.2%,*** the energy input was further increased,the porosity was reduced to as low as 0.05%and the ultimate tensile strength and elongation were increased to their peak values of 233.8%and 9.1 MPa,respectively.

关键词： High speed sintering Additive manufacturing Energy input Powder bed fusion PEBA