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高韧性PVA-SHCC多缝开裂后吸水特性研究 被引量:8
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作者 张鹏 F. H. WITTMANN +2 位作者 赵铁军 elehmann 田砾 《建筑材料学报》 EI CAS CSCD 北大核心 2011年第3期324-328,334,共6页
制备了高韧性PVA-SHCC(聚乙烯醇-应变硬化水泥基复合材料)试件,通过吸水试验和中子成像试验,研究了未开裂和直拉多缝开裂情况下SHCC的吸水特性.结果表明:中子成像能够对无裂缝和多缝开裂SHCC试件的吸水过程进行可视化追踪和定量分析计算... 制备了高韧性PVA-SHCC(聚乙烯醇-应变硬化水泥基复合材料)试件,通过吸水试验和中子成像试验,研究了未开裂和直拉多缝开裂情况下SHCC的吸水特性.结果表明:中子成像能够对无裂缝和多缝开裂SHCC试件的吸水过程进行可视化追踪和定量分析计算;SHCC在无裂缝时吸水很少,中子成像无肉眼可见的水分前锋;多缝开裂后,能够清晰探测到水分沿80~140μm的裂缝迅速侵入材料内部,并通过遭横向拉拔破坏的纤维与水泥基体界面而充满裂缝区;在这种情况下,应从耐久性角度限制SHCC多重裂缝宽度. 展开更多
关键词 应变硬化水泥基复合材料 聚乙烯醇纤维 多缝开裂 吸水 中子成像
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采用中子照相观测无裂缝和带裂缝混凝土的水分侵入(英文) 被引量:5
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作者 赵铁军 张鹏 +1 位作者 F.H.Wittmann e.lehmann 《青岛理工大学学报》 CAS 2008年第5期9-16,共8页
钢筋混凝土结构的使用寿命在很大程度上取决于混凝土材料本身的质量、保护层厚度、侵蚀环境等.水和溶解于水中的有害离子能够通过混凝土孔隙的毛细吸附、扩散或两者的复合作用侵入到混凝土内部.两者复合作用的机理非常复杂,无法通过简... 钢筋混凝土结构的使用寿命在很大程度上取决于混凝土材料本身的质量、保护层厚度、侵蚀环境等.水和溶解于水中的有害离子能够通过混凝土孔隙的毛细吸附、扩散或两者的复合作用侵入到混凝土内部.两者复合作用的机理非常复杂,无法通过简单的模型进行描述,因此,目前对侵蚀环境下钢筋混凝土结构的使用寿命预测方法还不完全成熟.成功采用了一种有力的检测方法———中子照相,来观测水分在多孔混凝土中的运动过程,试验结果为今后建立可靠的寿命预测模型提供了坚实的试验基础.在介绍中子照相基本原理的基础上,对无裂缝和带裂缝混凝土的毛细吸水过程进行了实时中子成像.水分在钢筋与混凝土的界面处以及在裂缝前方的断裂区内部的运动过程尤为特殊.首次就水分的侵入过程进行了详细的可视化研究,试验结果有助于进一步更好地理解钢筋混凝土的劣化机理,寻求提高混凝土耐久性的措施. 展开更多
关键词 中子照相 混凝土 毛细吸收 耐久性 使用寿命
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Does reconstruction affect outcomes following exclusively endoscopic endonasal resection of benign orbital tumors: A systematic review with meta-analysis 被引量:1
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作者 Ashton e.lehmann Manuela von Sneidern +3 位作者 Sarek A.Shen Ian M.Humphreys Waleed M.Abuzeid Aria Jafari 《World Journal of Otorhinolaryngology-Head and Neck Surgery》 2022年第1期25-35,共11页
Objective:As exclusively endoscopic endonasal resection of benign orbital tumors has become more widespread,high-quality outcomes data are lacking regarding the decision of when and how to reconstruct the medial orbit... Objective:As exclusively endoscopic endonasal resection of benign orbital tumors has become more widespread,high-quality outcomes data are lacking regarding the decision of when and how to reconstruct the medial orbital wall following resection.The goal of this study was to systematically review pertinent literature to assess clinical outcomes relative to orbital reconstruction practices.Methods:Data Sources:PubMed,EMBASE,Web of Science.A systematic review of studies reporting exclusively endoscopic endonasal resections of benign orbital tumors was conducted.Articles not reporting orbital reconstruction details were excluded.Patient and tumor characteristics,operative details,and outcomes were recorded.Variables were compared usingχ^(2),Fisher’s exact,and independentt tests.Results:Of 60 patients included from 24 studies,34(56.7%)underwent orbital reconstruction following resection.The most common types of reconstruction were pedicled flaps(n=15,44.1%)and free mucosal grafts(n=11,32.4%).Rigid reconstruction was uncommon(n=3,8.8%).Performance of orbital reconstruction was associated with preoperative vision compromise(P<0.01).The tendency to forego orbital reconstruction was associated with preoperative proptosis(P<0.001),larger tumor size(P=0.001),and operative exposure of orbital fat(P<0.001)and extraocular muscle(P=0.035).There were no statistically significant differences between the reconstruction and nonreconstruction groups in terms of short-or long-term outcomes when considering all patients.In patients with intraconal tumors,however,there was a higher rate of short-term postoperative diplopia when reconstruction was foregone(P=0.041).This potential benefit of reconstruction did not persist:At an average of two years postoperatively,all patients for whom reconstruction was foregone either had improved or unchanged diplopia.Conclusion:Most outcomes assessed did not appear affected by orbital reconstruction status.This general equivalence may suggest that orbital reconstruction is not a necessity in these 展开更多
关键词 cavernous hemangioma DIPLOPIA endoscopic endonasal surgery ENOPHTHALMOS MENINGIOMA orbital reconstruction orbital tumor OUTCOMES SCHWANNOMA
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