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Hysteresis in the ultrasonic parameters of saturated sandstone during freezing and thawing and correlations with unfrozen water content

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Journal of Rock Mechanics and Geotechnical Engineering 2021年第5期13卷 1078-1092页

作者： Liu Yang Hailiang Jia Li Han huimei zhang Liyun Tang College of Architecture and Civil Engineering Xi’an University of Science and TechnologyXi’an710054China

Determining the mechanical properties of frozen rock is highly important in cold-area *** properties are essentially correlated with the content of liquid water remaining in frozen ***,accurate determination of unfrozen water content could allow rapid evaluation of mechanical properties of frozen *** paper investigates the hysteresis characteristics of ultrasonic waves applied to sandstone(in terms of the parameters of P-wave velocity,amplitude,dominant frequency and quality factor Q)and their relationships with unfrozen water content during the freeze-thaw *** correlations are analysed in terms of their potential for use as indicators of freezing state and unfrozen water *** results show that:(1)During a freeze-thaw cycle,the ultrasonic parameters and unfrozen water content of sandstone have significant hysteresis with changes in temperature.(2)There are three clear stages of change during freezing:supercooled stage(0℃to-2℃),rapid freezing stage(-2℃to-3℃),and stable freezing stage(-3℃to-20℃).The changes in unfrozen water content and ultrasonic parameters with freezing temperature are inverse.(3)During a single freeze-thaw cycle,the ultrasonic parameters of sandstone are significantly correlated with its unfrozen water content,and this correlation is affected by the pore *** sandstones with mesopores greater than 50%,there are inflection points in the curves of ultrasonic parameters *** water content at-3℃during freezing and at-1℃during *** was found that thermal deformation of the mineral-grain skeleton and variations in the phase composition of pore water change the propagation path of ultrasonic *** inflection point in the curve of dominant frequency *** clearly marks the end of the rapid freezing stage of pore water,in which more than 70%of the pore water ***,the dominant frequency can be used as an index to conveniently estimate the unfrozen water conten

关键词： Frozen porous rocks Ultrasonic parameters Hysteresis Freeze-thaw Nuclear magnetic resonance(NMR) Unfrozen water content

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Namib desert beetle inspired special patterned fabric with programmable and gradient wettability for efficient fog harvesting

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Journal of Materials Science & Technology 2021年第2期61卷 85-92页

作者： Zhihua Yu huimei zhang Jianying Huang Shuhui Li Songnan zhang Yan Cheng Jiajun Mao Xiuli Dong Shouwei Gao Shanchi Wang Zhong Chen Yaoxing Jiang Yuekun Lai College of Chemical Engineering Fuzhou UniversityFuzhou 350116China National Engineering Laboratory for Modem Silk College of Textile and Clothing EngineeringSoochow UniversitySuzhou 215123China School of Materials Science and Engineering Nanyang Technological University50 Nanyang AvenueSingapore

Efficient collection of water from fog provides a potential solution to solve the global freshwater shortage problem, particularly in the desert or arid regions. In this work, a flexible and highly efficient fog collector was prepared by mimicking the back exoskeleton structure of the Namib desert beetle. The improved fog collector was constructed by a superhydrophobic-superhydrophilic patterned fabric via a simple weaving method, followed by in-situ deposition of copper particles. Compared with the conventional fog collector with a plane structure, the fabric has shown a higher water-harvesting rate at 1432.7 mg/h/cm2,owing to the biomimetic three-dimensional structure, its enhanced condensation performance enabled by the copper coating and the rational distribution of wetting units. The device construction makes use of the widely available textile materials through mature manufacturing technology, which makes it highly suitable for large-scale industrial production.

关键词： Superwettability Fabric Copper Namib desert beetle Fog harvesting

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Iron accumulation and its impact on osteoporotic fractures in postmenopausal women

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Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2023年第4期24卷 301-311页

作者： Hui CAI huimei zhang Weiting HE Heng zhang Department of Pharmacy the First Affiliated Hospital of Bengbu Medical CollegeBengbu Medical CollegeBengbu 233004China School of Pharmacy Bengbu Medical CollegeBengbu 233030China School of Clinical Medicine Bengbu Medical CollegeBengbu 233030China Department of Orthopedics the First Affiliated Hospital of Bengbu Medical CollegeLaboratory of Tissue and Transplant in Anhui ProvinceBengbu Medical CollegeBengbu 233004China Department of Orthopedics Jinling HospitalSchool of MedicineNanjing UniversityNanjing 210002China

Postmenopausal osteoporosis is a kind of degenerative disease,also described as“invisible killer.”Estrogen is generally considered as the key hormone for women to maintain bone mineral content during their *** accumulation refers to a state of human serum ferritin that is higher than the normal value but less than 1000μg/*** has been found that iron accumulation and osteoporosis could occur simultaneously with the decrease in estrogen level after *** recent years,many studies indicated that iron accumulation plays a vital role in postmenopausal osteoporosis,and a significant correlation has been found between iron accumulation and fragility *** this review,we summarize and analyze the relevant literature including randomized controlled trials,systematic reviews,and meta-analyses between January 1996 and July *** investigate the mechanism of the effect of iron accumulation on bone metabolism and discuss the relationship of iron accumulation,osteoporosis,and postmenopausal fragility fractures,as well as the main clinical treatment *** conclude that it is necessary to pay attention to the phenomenon of iron accumulation in postmenopausal women with osteoporosis and explore the in-depth mechanism of abnormal bone metabolism caused by iron accumulation,in order to facilitate the discovery of effective therapeutic targets for postmenopausal osteoporosis.

关键词： Iron accumulation Postmenopausal osteoporosis Bone metabolism Osteoporotic fracture

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Studies on the egg, larval and juvenile development of Bostrichthys sinensis (Lacepede)

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Acta Oceanologica Sinica 1988年第2期7卷 290-303页

作者： Li huimei, zhang Dan and Shi Pinhua South China Sea Fisheries Research Institute, Chinese Academy of Fisheries Science, China China

Artificial hatching and fry culture of Bostrichthys sinensis (Lacepede) has been successful under conditions of enclosed seawater circulation system in the Aquarium Lab, South China Sea Fish. Res. Inst, on the 13th of April, 1984. The development of each stage of the eggs, larvae and juveniles are described, and colour photographs of every development stage were taken. According to their physiological characteristics in each stage, necessary ecological conditions for the developments are preliminarily discussed.

关键词： larval and juvenile development of Bostrichthys sinensis Lacepede Studies on the egg

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冻融与荷载耦合作用下岩石损伤模型的研究

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岩石力学与工程学报 2010年第3期29卷 471-476页

作者：张慧梅杨更社西安科技大学力学系陕西西安710054 西安科技大学建筑与土木工程学院陕西西安710054

针对寒区工程结构的冻融受荷岩石,提出冻融损伤、受荷损伤与总损伤的概念,拓展损伤变量的内涵;以岩石的初始损伤状态为基准状态,充分考虑岩石细观结构的非均匀性,运用损伤力学理论及推广后的应变等价原理,建立冻融受荷岩石损伤模型;通... 详细信息

针对寒区工程结构的冻融受荷岩石,提出冻融损伤、受荷损伤与总损伤的概念,拓展损伤变量的内涵;以岩石的初始损伤状态为基准状态,充分考虑岩石细观结构的非均匀性,运用损伤力学理论及推广后的应变等价原理,建立冻融受荷岩石损伤模型;通过损伤变量及本构方程来描述岩石材料细观结构的损伤演化及其宏观损伤行为,与岩石实际冻融破坏情况符合较好。研究结果表明:寒区工程结构的受荷岩石,其力学性能由冻融因子、荷载因子及其耦合效应所决定;冻融与荷载的共同作用使岩石总损伤加剧,并表现出明显的非线性特征,而其耦合效应使总损伤有所弱化;岩石的岩性和初始损伤状态确定各影响因素的权重,表现出不同的损伤扩展特性;相比而言,砂岩对冻融循环更敏感,而受荷损伤最终导致页岩破坏。

关键词：岩石力学冻融受荷岩石耦合作用非均匀性损伤演化本构方程

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公众参与公共图书馆文化治理的逻辑阐释与佛山实践

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图书馆论坛 2023年第4期43卷 50-56页

作者：张惠梅佛山市图书馆

公共图书馆是国家实施文化治理功能的重要载体,公众参与是公共图书馆文化治理的基础。文章阐释公众参与公共图书馆文化治理的内在逻辑;分析公众参与文化治理的现实困境和法治保障;通过邻里图书馆、“易本书”项目、市民馆长等实践案例,... 详细信息

公共图书馆是国家实施文化治理功能的重要载体,公众参与是公共图书馆文化治理的基础。文章阐释公众参与公共图书馆文化治理的内在逻辑;分析公众参与文化治理的现实困境和法治保障;通过邻里图书馆、“易本书”项目、市民馆长等实践案例,探究公众参与公共图书馆建设与服务过程中的需求表达、有序参与、服务供给、用户体验、考核激励和信任构建等创新机制;提出公共图书馆推动和培育公众参与文化治理的实施路径。

关键词：公众参与公共图书馆文化治理易本书邻里图书馆市民馆长佛山市图书馆

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考虑局部损伤区变化的能量平衡尺寸效应模型

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力学学报 2024年第1期56卷 157-172页

作者：刘小宇张慧梅杨政西安科技大学理学院西安710600 西安交通大学人居环境与建筑工程学院西安710049

尽管研究者已经提出各种各样的尺寸效应模型,但是建立能描述不同类型尺寸效应规律的模型依旧是力学和材料学中最具挑战性的问题之一.首先通过系统深入分析局部损伤区(localized damage zone,LDZ)随试件尺寸的变化规律,提出能够准确地描... 详细信息

尽管研究者已经提出各种各样的尺寸效应模型,但是建立能描述不同类型尺寸效应规律的模型依旧是力学和材料学中最具挑战性的问题之一.首先通过系统深入分析局部损伤区(localized damage zone,LDZ)随试件尺寸的变化规律,提出能够准确地描述LDZ非线性尺寸效应的理论模型并验证.在此基础上,建立考虑LDZ随尺寸变化的能量平衡尺寸效应模型.考虑LDZ变化的能量平衡尺寸效应模型能体现5种不同类型的尺寸效应规律.随着尺寸增大,类型1:名义抗压强度逐渐减小,最终趋于单轴压缩弹性极限;类型2:名义抗压强度先在一定尺寸范围内为真实抗压强度,然后逐渐减小,最终趋于单轴压缩弹性极限;类型3:名义抗压强度先增加,然后逐渐减小,最终趋于单轴压缩弹性极限;类型4:名义抗压强度先逐渐增加到真实抗压强度,然后在一定尺寸范围恒为真实抗压强度,再逐渐减小,最终趋于单轴压缩弹性极限;类型5:名义抗压强度不随尺寸变化.文章模型首次理论预测类型4尺寸效应存在,并证实微纳尺度钛合金尺寸效应试验中存在这一规律.对考虑LDZ变化的能量平衡尺寸效应模型分析表明:LDZ尺寸与试件尺寸相对变化率之间的竞争是本文尺寸效应模型能体现5种类型的尺寸效应的原因.由于笔者先前已经证明能量平衡尺寸效应模型能很好预测类型1,2和5尺寸效应,但其不能体现类型3和4尺寸效应.因此,文章应用考虑LDZ变化的能量平衡尺寸效应模型和IUSEL(improved unified size-effect law)预测类型3和4尺寸效应试验数据,结果表明:考虑LDZ变化的能量平衡尺寸效应模型能很好预测各种材料类型3和4尺寸效应试验数据变化规律,而IUSEL不能描述类型4尺寸效应数据变化规律.考虑LDZ变化的能量平衡尺寸效应模型和IUSEL预测所有尺寸效应数据的总平均确定系数接近.

关键词：局部损伤区抗压强度能量平衡不同类型尺寸效应

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准脆性材料抗压强度能量平衡尺寸效应模型

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力学学报 2022年第6期54卷 1613-1629,I0003页

作者：刘小宇杨政张慧梅西安科技大学理学院西安710600 西安交通大学人居环境与建筑工程学院西安710049

针对现有尺寸效应模型难以体现准脆性材料完整的抗压强度尺寸效应变化规律及其内在机理,本文通过分析准脆性材料单轴压缩破坏过程中能量输入、储存、整体和局部能量耗散,建立体现整体和局部损伤的力学模型及描述上述能量演化过程的双线... 详细信息

针对现有尺寸效应模型难以体现准脆性材料完整的抗压强度尺寸效应变化规律及其内在机理,本文通过分析准脆性材料单轴压缩破坏过程中能量输入、储存、整体和局部能量耗散,建立体现整体和局部损伤的力学模型及描述上述能量演化过程的双线性名义和真实应力应变曲线,在此基础上确定了名义应力最大时输入能量、储存弹性能、整体和局部能量耗散的表达式,最后基于能量平衡原理建立抗压强度尺寸效应模型.抗压强度能量平衡尺寸效应模型能完整体现名义抗压强度尺寸效应,即随试样尺寸增大,名义抗压强度在试样尺寸小于等于局部损伤区尺寸时为真实强度,然后逐渐减小,最终当试样尺寸趋于无穷大时趋于弹性极限强度;抗压强度能量平衡尺寸效应模型也能同时体现高径比和试样直径对名义强度的影响,其包含的参数具有明确的物理意义,可以反映真实强度、弹性极限强度、名义损伤模量非线性、局部损伤区大小和方向对准脆性材料名义抗压强度尺寸效应的影响;通过把抗压强度能量平衡尺寸效应模型和现有尺寸效应模型应用于预测各种材料尺寸效应试验和数值模拟数据,结果表明:抗压强度能量平衡尺寸效应模型能很好描述试验和数值模拟尺寸效应的非线性变化规律及内在机理,和现有尺寸效应模型相比,其总体平均误差最小,且小于5%.

关键词：准脆性材料抗压强度能量平衡尺寸效应

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